Merge tag 'powerpc-6.6-6' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc...

[platform/kernel/linux-starfive.git] / net / core / dev.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      NET3    Protocol independent device support routines.
 *
 *      Derived from the non IP parts of dev.c 1.0.19
 *              Authors:        Ross Biro
 *                              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *                              Mark Evans, <evansmp@uhura.aston.ac.uk>
 *
 *      Additional Authors:
 *              Florian la Roche <rzsfl@rz.uni-sb.de>
 *              Alan Cox <gw4pts@gw4pts.ampr.org>
 *              David Hinds <dahinds@users.sourceforge.net>
 *              Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
 *              Adam Sulmicki <adam@cfar.umd.edu>
 *              Pekka Riikonen <priikone@poesidon.pspt.fi>
 *
 *      Changes:
 *              D.J. Barrow     :       Fixed bug where dev->refcnt gets set
 *                                      to 2 if register_netdev gets called
 *                                      before net_dev_init & also removed a
 *                                      few lines of code in the process.
 *              Alan Cox        :       device private ioctl copies fields back.
 *              Alan Cox        :       Transmit queue code does relevant
 *                                      stunts to keep the queue safe.
 *              Alan Cox        :       Fixed double lock.
 *              Alan Cox        :       Fixed promisc NULL pointer trap
 *              ????????        :       Support the full private ioctl range
 *              Alan Cox        :       Moved ioctl permission check into
 *                                      drivers
 *              Tim Kordas      :       SIOCADDMULTI/SIOCDELMULTI
 *              Alan Cox        :       100 backlog just doesn't cut it when
 *                                      you start doing multicast video 8)
 *              Alan Cox        :       Rewrote net_bh and list manager.
 *              Alan Cox        :       Fix ETH_P_ALL echoback lengths.
 *              Alan Cox        :       Took out transmit every packet pass
 *                                      Saved a few bytes in the ioctl handler
 *              Alan Cox        :       Network driver sets packet type before
 *                                      calling netif_rx. Saves a function
 *                                      call a packet.
 *              Alan Cox        :       Hashed net_bh()
 *              Richard Kooijman:       Timestamp fixes.
 *              Alan Cox        :       Wrong field in SIOCGIFDSTADDR
 *              Alan Cox        :       Device lock protection.
 *              Alan Cox        :       Fixed nasty side effect of device close
 *                                      changes.
 *              Rudi Cilibrasi  :       Pass the right thing to
 *                                      set_mac_address()
 *              Dave Miller     :       32bit quantity for the device lock to
 *                                      make it work out on a Sparc.
 *              Bjorn Ekwall    :       Added KERNELD hack.
 *              Alan Cox        :       Cleaned up the backlog initialise.
 *              Craig Metz      :       SIOCGIFCONF fix if space for under
 *                                      1 device.
 *          Thomas Bogendoerfer :       Return ENODEV for dev_open, if there
 *                                      is no device open function.
 *              Andi Kleen      :       Fix error reporting for SIOCGIFCONF
 *          Michael Chastain    :       Fix signed/unsigned for SIOCGIFCONF
 *              Cyrus Durgin    :       Cleaned for KMOD
 *              Adam Sulmicki   :       Bug Fix : Network Device Unload
 *                                      A network device unload needs to purge
 *                                      the backlog queue.
 *      Paul Rusty Russell      :       SIOCSIFNAME
 *              Pekka Riikonen  :       Netdev boot-time settings code
 *              Andrew Morton   :       Make unregister_netdevice wait
 *                                      indefinitely on dev->refcnt
 *              J Hadi Salim    :       - Backlog queue sampling
 *                                      - netif_rx() feedback
 */

#include <linux/uaccess.h>
#include <linux/bitmap.h>
#include <linux/capability.h>
#include <linux/cpu.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/hash.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/sched/mm.h>
#include <linux/mutex.h>
#include <linux/rwsem.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/if_ether.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/skbuff.h>
#include <linux/kthread.h>
#include <linux/bpf.h>
#include <linux/bpf_trace.h>
#include <net/net_namespace.h>
#include <net/sock.h>
#include <net/busy_poll.h>
#include <linux/rtnetlink.h>
#include <linux/stat.h>
#include <net/dsa.h>
#include <net/dst.h>
#include <net/dst_metadata.h>
#include <net/gro.h>
#include <net/pkt_sched.h>
#include <net/pkt_cls.h>
#include <net/checksum.h>
#include <net/xfrm.h>
#include <net/tcx.h>
#include <linux/highmem.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/netpoll.h>
#include <linux/rcupdate.h>
#include <linux/delay.h>
#include <net/iw_handler.h>
#include <asm/current.h>
#include <linux/audit.h>
#include <linux/dmaengine.h>
#include <linux/err.h>
#include <linux/ctype.h>
#include <linux/if_arp.h>
#include <linux/if_vlan.h>
#include <linux/ip.h>
#include <net/ip.h>
#include <net/mpls.h>
#include <linux/ipv6.h>
#include <linux/in.h>
#include <linux/jhash.h>
#include <linux/random.h>
#include <trace/events/napi.h>
#include <trace/events/net.h>
#include <trace/events/skb.h>
#include <trace/events/qdisc.h>
#include <trace/events/xdp.h>
#include <linux/inetdevice.h>
#include <linux/cpu_rmap.h>
#include <linux/static_key.h>
#include <linux/hashtable.h>
#include <linux/vmalloc.h>
#include <linux/if_macvlan.h>
#include <linux/errqueue.h>
#include <linux/hrtimer.h>
#include <linux/netfilter_netdev.h>
#include <linux/crash_dump.h>
#include <linux/sctp.h>
#include <net/udp_tunnel.h>
#include <linux/net_namespace.h>
#include <linux/indirect_call_wrapper.h>
#include <net/devlink.h>
#include <linux/pm_runtime.h>
#include <linux/prandom.h>
#include <linux/once_lite.h>
#include <net/netdev_rx_queue.h>

#include "dev.h"
#include "net-sysfs.h"

static DEFINE_SPINLOCK(ptype_lock);
struct list_head ptype_base[PTYPE_HASH_SIZE] __read_mostly;
struct list_head ptype_all __read_mostly;       /* Taps */

static int netif_rx_internal(struct sk_buff *skb);
static int call_netdevice_notifiers_extack(unsigned long val,
                                           struct net_device *dev,
                                           struct netlink_ext_ack *extack);
static struct napi_struct *napi_by_id(unsigned int napi_id);

/*
 * The @dev_base_head list is protected by @dev_base_lock and the rtnl
 * semaphore.
 *
 * Pure readers hold dev_base_lock for reading, or rcu_read_lock()
 *
 * Writers must hold the rtnl semaphore while they loop through the
 * dev_base_head list, and hold dev_base_lock for writing when they do the
 * actual updates.  This allows pure readers to access the list even
 * while a writer is preparing to update it.
 *
 * To put it another way, dev_base_lock is held for writing only to
 * protect against pure readers; the rtnl semaphore provides the
 * protection against other writers.
 *
 * See, for example usages, register_netdevice() and
 * unregister_netdevice(), which must be called with the rtnl
 * semaphore held.
 */
DEFINE_RWLOCK(dev_base_lock);
EXPORT_SYMBOL(dev_base_lock);

static DEFINE_MUTEX(ifalias_mutex);

/* protects napi_hash addition/deletion and napi_gen_id */
static DEFINE_SPINLOCK(napi_hash_lock);

static unsigned int napi_gen_id = NR_CPUS;
static DEFINE_READ_MOSTLY_HASHTABLE(napi_hash, 8);

static DECLARE_RWSEM(devnet_rename_sem);

static inline void dev_base_seq_inc(struct net *net)
{
        while (++net->dev_base_seq == 0)
                ;
}

static inline struct hlist_head *dev_name_hash(struct net *net, const char *name)
{
        unsigned int hash = full_name_hash(net, name, strnlen(name, IFNAMSIZ));

        return &net->dev_name_head[hash_32(hash, NETDEV_HASHBITS)];
}

static inline struct hlist_head *dev_index_hash(struct net *net, int ifindex)
{
        return &net->dev_index_head[ifindex & (NETDEV_HASHENTRIES - 1)];
}

static inline void rps_lock_irqsave(struct softnet_data *sd,
                                    unsigned long *flags)
{
        if (IS_ENABLED(CONFIG_RPS))
                spin_lock_irqsave(&sd->input_pkt_queue.lock, *flags);
        else if (!IS_ENABLED(CONFIG_PREEMPT_RT))
                local_irq_save(*flags);
}

static inline void rps_lock_irq_disable(struct softnet_data *sd)
{
        if (IS_ENABLED(CONFIG_RPS))
                spin_lock_irq(&sd->input_pkt_queue.lock);
        else if (!IS_ENABLED(CONFIG_PREEMPT_RT))
                local_irq_disable();
}

static inline void rps_unlock_irq_restore(struct softnet_data *sd,
                                          unsigned long *flags)
{
        if (IS_ENABLED(CONFIG_RPS))
                spin_unlock_irqrestore(&sd->input_pkt_queue.lock, *flags);
        else if (!IS_ENABLED(CONFIG_PREEMPT_RT))
                local_irq_restore(*flags);
}

static inline void rps_unlock_irq_enable(struct softnet_data *sd)
{
        if (IS_ENABLED(CONFIG_RPS))
                spin_unlock_irq(&sd->input_pkt_queue.lock);
        else if (!IS_ENABLED(CONFIG_PREEMPT_RT))
                local_irq_enable();
}

static struct netdev_name_node *netdev_name_node_alloc(struct net_device *dev,
                                                       const char *name)
{
        struct netdev_name_node *name_node;

        name_node = kmalloc(sizeof(*name_node), GFP_KERNEL);
        if (!name_node)
                return NULL;
        INIT_HLIST_NODE(&name_node->hlist);
        name_node->dev = dev;
        name_node->name = name;
        return name_node;
}

static struct netdev_name_node *
netdev_name_node_head_alloc(struct net_device *dev)
{
        struct netdev_name_node *name_node;

        name_node = netdev_name_node_alloc(dev, dev->name);
        if (!name_node)
                return NULL;
        INIT_LIST_HEAD(&name_node->list);
        return name_node;
}

static void netdev_name_node_free(struct netdev_name_node *name_node)
{
        kfree(name_node);
}

static void netdev_name_node_add(struct net *net,
                                 struct netdev_name_node *name_node)
{
        hlist_add_head_rcu(&name_node->hlist,
                           dev_name_hash(net, name_node->name));
}

static void netdev_name_node_del(struct netdev_name_node *name_node)
{
        hlist_del_rcu(&name_node->hlist);
}

static struct netdev_name_node *netdev_name_node_lookup(struct net *net,
                                                        const char *name)
{
        struct hlist_head *head = dev_name_hash(net, name);
        struct netdev_name_node *name_node;

        hlist_for_each_entry(name_node, head, hlist)
                if (!strcmp(name_node->name, name))
                        return name_node;
        return NULL;
}

static struct netdev_name_node *netdev_name_node_lookup_rcu(struct net *net,
                                                            const char *name)
{
        struct hlist_head *head = dev_name_hash(net, name);
        struct netdev_name_node *name_node;

        hlist_for_each_entry_rcu(name_node, head, hlist)
                if (!strcmp(name_node->name, name))
                        return name_node;
        return NULL;
}

bool netdev_name_in_use(struct net *net, const char *name)
{
        return netdev_name_node_lookup(net, name);
}
EXPORT_SYMBOL(netdev_name_in_use);

int netdev_name_node_alt_create(struct net_device *dev, const char *name)
{
        struct netdev_name_node *name_node;
        struct net *net = dev_net(dev);

        name_node = netdev_name_node_lookup(net, name);
        if (name_node)
                return -EEXIST;
        name_node = netdev_name_node_alloc(dev, name);
        if (!name_node)
                return -ENOMEM;
        netdev_name_node_add(net, name_node);
        /* The node that holds dev->name acts as a head of per-device list. */
        list_add_tail(&name_node->list, &dev->name_node->list);

        return 0;
}

static void __netdev_name_node_alt_destroy(struct netdev_name_node *name_node)
{
        list_del(&name_node->list);
        kfree(name_node->name);
        netdev_name_node_free(name_node);
}

int netdev_name_node_alt_destroy(struct net_device *dev, const char *name)
{
        struct netdev_name_node *name_node;
        struct net *net = dev_net(dev);

        name_node = netdev_name_node_lookup(net, name);
        if (!name_node)
                return -ENOENT;
        /* lookup might have found our primary name or a name belonging
         * to another device.
         */
        if (name_node == dev->name_node || name_node->dev != dev)
                return -EINVAL;

        netdev_name_node_del(name_node);
        synchronize_rcu();
        __netdev_name_node_alt_destroy(name_node);

        return 0;
}

static void netdev_name_node_alt_flush(struct net_device *dev)
{
        struct netdev_name_node *name_node, *tmp;

        list_for_each_entry_safe(name_node, tmp, &dev->name_node->list, list)
                __netdev_name_node_alt_destroy(name_node);
}

/* Device list insertion */
static void list_netdevice(struct net_device *dev)
{
        struct netdev_name_node *name_node;
        struct net *net = dev_net(dev);

        ASSERT_RTNL();

        write_lock(&dev_base_lock);
        list_add_tail_rcu(&dev->dev_list, &net->dev_base_head);
        netdev_name_node_add(net, dev->name_node);
        hlist_add_head_rcu(&dev->index_hlist,
                           dev_index_hash(net, dev->ifindex));
        write_unlock(&dev_base_lock);

        netdev_for_each_altname(dev, name_node)
                netdev_name_node_add(net, name_node);

        /* We reserved the ifindex, this can't fail */
        WARN_ON(xa_store(&net->dev_by_index, dev->ifindex, dev, GFP_KERNEL));

        dev_base_seq_inc(net);
}

/* Device list removal
 * caller must respect a RCU grace period before freeing/reusing dev
 */
static void unlist_netdevice(struct net_device *dev, bool lock)
{
        struct netdev_name_node *name_node;
        struct net *net = dev_net(dev);

        ASSERT_RTNL();

        xa_erase(&net->dev_by_index, dev->ifindex);

        netdev_for_each_altname(dev, name_node)
                netdev_name_node_del(name_node);

        /* Unlink dev from the device chain */
        if (lock)
                write_lock(&dev_base_lock);
        list_del_rcu(&dev->dev_list);
        netdev_name_node_del(dev->name_node);
        hlist_del_rcu(&dev->index_hlist);
        if (lock)
                write_unlock(&dev_base_lock);

        dev_base_seq_inc(dev_net(dev));
}

/*
 *      Our notifier list
 */

static RAW_NOTIFIER_HEAD(netdev_chain);

/*
 *      Device drivers call our routines to queue packets here. We empty the
 *      queue in the local softnet handler.
 */

DEFINE_PER_CPU_ALIGNED(struct softnet_data, softnet_data);
EXPORT_PER_CPU_SYMBOL(softnet_data);

#ifdef CONFIG_LOCKDEP
/*
 * register_netdevice() inits txq->_xmit_lock and sets lockdep class
 * according to dev->type
 */
static const unsigned short netdev_lock_type[] = {
         ARPHRD_NETROM, ARPHRD_ETHER, ARPHRD_EETHER, ARPHRD_AX25,
         ARPHRD_PRONET, ARPHRD_CHAOS, ARPHRD_IEEE802, ARPHRD_ARCNET,
         ARPHRD_APPLETLK, ARPHRD_DLCI, ARPHRD_ATM, ARPHRD_METRICOM,
         ARPHRD_IEEE1394, ARPHRD_EUI64, ARPHRD_INFINIBAND, ARPHRD_SLIP,
         ARPHRD_CSLIP, ARPHRD_SLIP6, ARPHRD_CSLIP6, ARPHRD_RSRVD,
         ARPHRD_ADAPT, ARPHRD_ROSE, ARPHRD_X25, ARPHRD_HWX25,
         ARPHRD_PPP, ARPHRD_CISCO, ARPHRD_LAPB, ARPHRD_DDCMP,
         ARPHRD_RAWHDLC, ARPHRD_TUNNEL, ARPHRD_TUNNEL6, ARPHRD_FRAD,
         ARPHRD_SKIP, ARPHRD_LOOPBACK, ARPHRD_LOCALTLK, ARPHRD_FDDI,
         ARPHRD_BIF, ARPHRD_SIT, ARPHRD_IPDDP, ARPHRD_IPGRE,
         ARPHRD_PIMREG, ARPHRD_HIPPI, ARPHRD_ASH, ARPHRD_ECONET,
         ARPHRD_IRDA, ARPHRD_FCPP, ARPHRD_FCAL, ARPHRD_FCPL,
         ARPHRD_FCFABRIC, ARPHRD_IEEE80211, ARPHRD_IEEE80211_PRISM,
         ARPHRD_IEEE80211_RADIOTAP, ARPHRD_PHONET, ARPHRD_PHONET_PIPE,
         ARPHRD_IEEE802154, ARPHRD_VOID, ARPHRD_NONE};

static const char *const netdev_lock_name[] = {
        "_xmit_NETROM", "_xmit_ETHER", "_xmit_EETHER", "_xmit_AX25",
        "_xmit_PRONET", "_xmit_CHAOS", "_xmit_IEEE802", "_xmit_ARCNET",
        "_xmit_APPLETLK", "_xmit_DLCI", "_xmit_ATM", "_xmit_METRICOM",
        "_xmit_IEEE1394", "_xmit_EUI64", "_xmit_INFINIBAND", "_xmit_SLIP",
        "_xmit_CSLIP", "_xmit_SLIP6", "_xmit_CSLIP6", "_xmit_RSRVD",
        "_xmit_ADAPT", "_xmit_ROSE", "_xmit_X25", "_xmit_HWX25",
        "_xmit_PPP", "_xmit_CISCO", "_xmit_LAPB", "_xmit_DDCMP",
        "_xmit_RAWHDLC", "_xmit_TUNNEL", "_xmit_TUNNEL6", "_xmit_FRAD",
        "_xmit_SKIP", "_xmit_LOOPBACK", "_xmit_LOCALTLK", "_xmit_FDDI",
        "_xmit_BIF", "_xmit_SIT", "_xmit_IPDDP", "_xmit_IPGRE",
        "_xmit_PIMREG", "_xmit_HIPPI", "_xmit_ASH", "_xmit_ECONET",
        "_xmit_IRDA", "_xmit_FCPP", "_xmit_FCAL", "_xmit_FCPL",
        "_xmit_FCFABRIC", "_xmit_IEEE80211", "_xmit_IEEE80211_PRISM",
        "_xmit_IEEE80211_RADIOTAP", "_xmit_PHONET", "_xmit_PHONET_PIPE",
        "_xmit_IEEE802154", "_xmit_VOID", "_xmit_NONE"};

static struct lock_class_key netdev_xmit_lock_key[ARRAY_SIZE(netdev_lock_type)];
static struct lock_class_key netdev_addr_lock_key[ARRAY_SIZE(netdev_lock_type)];

static inline unsigned short netdev_lock_pos(unsigned short dev_type)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(netdev_lock_type); i++)
                if (netdev_lock_type[i] == dev_type)
                        return i;
        /* the last key is used by default */
        return ARRAY_SIZE(netdev_lock_type) - 1;
}

static inline void netdev_set_xmit_lockdep_class(spinlock_t *lock,
                                                 unsigned short dev_type)
{
        int i;

        i = netdev_lock_pos(dev_type);
        lockdep_set_class_and_name(lock, &netdev_xmit_lock_key[i],
                                   netdev_lock_name[i]);
}

static inline void netdev_set_addr_lockdep_class(struct net_device *dev)
{
        int i;

        i = netdev_lock_pos(dev->type);
        lockdep_set_class_and_name(&dev->addr_list_lock,
                                   &netdev_addr_lock_key[i],
                                   netdev_lock_name[i]);
}
#else
static inline void netdev_set_xmit_lockdep_class(spinlock_t *lock,
                                                 unsigned short dev_type)
{
}

static inline void netdev_set_addr_lockdep_class(struct net_device *dev)
{
}
#endif

/*******************************************************************************
 *
 *              Protocol management and registration routines
 *
 *******************************************************************************/


/*
 *      Add a protocol ID to the list. Now that the input handler is
 *      smarter we can dispense with all the messy stuff that used to be
 *      here.
 *
 *      BEWARE!!! Protocol handlers, mangling input packets,
 *      MUST BE last in hash buckets and checking protocol handlers
 *      MUST start from promiscuous ptype_all chain in net_bh.
 *      It is true now, do not change it.
 *      Explanation follows: if protocol handler, mangling packet, will
 *      be the first on list, it is not able to sense, that packet
 *      is cloned and should be copied-on-write, so that it will
 *      change it and subsequent readers will get broken packet.
 *                                                      --ANK (980803)
 */

static inline struct list_head *ptype_head(const struct packet_type *pt)
{
        if (pt->type == htons(ETH_P_ALL))
                return pt->dev ? &pt->dev->ptype_all : &ptype_all;
        else
                return pt->dev ? &pt->dev->ptype_specific :
                                 &ptype_base[ntohs(pt->type) & PTYPE_HASH_MASK];
}

/**
 *      dev_add_pack - add packet handler
 *      @pt: packet type declaration
 *
 *      Add a protocol handler to the networking stack. The passed &packet_type
 *      is linked into kernel lists and may not be freed until it has been
 *      removed from the kernel lists.
 *
 *      This call does not sleep therefore it can not
 *      guarantee all CPU's that are in middle of receiving packets
 *      will see the new packet type (until the next received packet).
 */

void dev_add_pack(struct packet_type *pt)
{
        struct list_head *head = ptype_head(pt);

        spin_lock(&ptype_lock);
        list_add_rcu(&pt->list, head);
        spin_unlock(&ptype_lock);
}
EXPORT_SYMBOL(dev_add_pack);

/**
 *      __dev_remove_pack        - remove packet handler
 *      @pt: packet type declaration
 *
 *      Remove a protocol handler that was previously added to the kernel
 *      protocol handlers by dev_add_pack(). The passed &packet_type is removed
 *      from the kernel lists and can be freed or reused once this function
 *      returns.
 *
 *      The packet type might still be in use by receivers
 *      and must not be freed until after all the CPU's have gone
 *      through a quiescent state.
 */
void __dev_remove_pack(struct packet_type *pt)
{
        struct list_head *head = ptype_head(pt);
        struct packet_type *pt1;

        spin_lock(&ptype_lock);

        list_for_each_entry(pt1, head, list) {
                if (pt == pt1) {
                        list_del_rcu(&pt->list);
                        goto out;
                }
        }

        pr_warn("dev_remove_pack: %p not found\n", pt);
out:
        spin_unlock(&ptype_lock);
}
EXPORT_SYMBOL(__dev_remove_pack);

/**
 *      dev_remove_pack  - remove packet handler
 *      @pt: packet type declaration
 *
 *      Remove a protocol handler that was previously added to the kernel
 *      protocol handlers by dev_add_pack(). The passed &packet_type is removed
 *      from the kernel lists and can be freed or reused once this function
 *      returns.
 *
 *      This call sleeps to guarantee that no CPU is looking at the packet
 *      type after return.
 */
void dev_remove_pack(struct packet_type *pt)
{
        __dev_remove_pack(pt);

        synchronize_net();
}
EXPORT_SYMBOL(dev_remove_pack);


/*******************************************************************************
 *
 *                          Device Interface Subroutines
 *
 *******************************************************************************/

/**
 *      dev_get_iflink  - get 'iflink' value of a interface
 *      @dev: targeted interface
 *
 *      Indicates the ifindex the interface is linked to.
 *      Physical interfaces have the same 'ifindex' and 'iflink' values.
 */

int dev_get_iflink(const struct net_device *dev)
{
        if (dev->netdev_ops && dev->netdev_ops->ndo_get_iflink)
                return dev->netdev_ops->ndo_get_iflink(dev);

        return dev->ifindex;
}
EXPORT_SYMBOL(dev_get_iflink);

/**
 *      dev_fill_metadata_dst - Retrieve tunnel egress information.
 *      @dev: targeted interface
 *      @skb: The packet.
 *
 *      For better visibility of tunnel traffic OVS needs to retrieve
 *      egress tunnel information for a packet. Following API allows
 *      user to get this info.
 */
int dev_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb)
{
        struct ip_tunnel_info *info;

        if (!dev->netdev_ops  || !dev->netdev_ops->ndo_fill_metadata_dst)
                return -EINVAL;

        info = skb_tunnel_info_unclone(skb);
        if (!info)
                return -ENOMEM;
        if (unlikely(!(info->mode & IP_TUNNEL_INFO_TX)))
                return -EINVAL;

        return dev->netdev_ops->ndo_fill_metadata_dst(dev, skb);
}
EXPORT_SYMBOL_GPL(dev_fill_metadata_dst);

static struct net_device_path *dev_fwd_path(struct net_device_path_stack *stack)
{
        int k = stack->num_paths++;

        if (WARN_ON_ONCE(k >= NET_DEVICE_PATH_STACK_MAX))
                return NULL;

        return &stack->path[k];
}

int dev_fill_forward_path(const struct net_device *dev, const u8 *daddr,
                          struct net_device_path_stack *stack)
{
        const struct net_device *last_dev;
        struct net_device_path_ctx ctx = {
                .dev    = dev,
        };
        struct net_device_path *path;
        int ret = 0;

        memcpy(ctx.daddr, daddr, sizeof(ctx.daddr));
        stack->num_paths = 0;
        while (ctx.dev && ctx.dev->netdev_ops->ndo_fill_forward_path) {
                last_dev = ctx.dev;
                path = dev_fwd_path(stack);
                if (!path)
                        return -1;

                memset(path, 0, sizeof(struct net_device_path));
                ret = ctx.dev->netdev_ops->ndo_fill_forward_path(&ctx, path);
                if (ret < 0)
                        return -1;

                if (WARN_ON_ONCE(last_dev == ctx.dev))
                        return -1;
        }

        if (!ctx.dev)
                return ret;

        path = dev_fwd_path(stack);
        if (!path)
                return -1;
        path->type = DEV_PATH_ETHERNET;
        path->dev = ctx.dev;

        return ret;
}
EXPORT_SYMBOL_GPL(dev_fill_forward_path);

/**
 *      __dev_get_by_name       - find a device by its name
 *      @net: the applicable net namespace
 *      @name: name to find
 *
 *      Find an interface by name. Must be called under RTNL semaphore
 *      or @dev_base_lock. If the name is found a pointer to the device
 *      is returned. If the name is not found then %NULL is returned. The
 *      reference counters are not incremented so the caller must be
 *      careful with locks.
 */

struct net_device *__dev_get_by_name(struct net *net, const char *name)
{
        struct netdev_name_node *node_name;

        node_name = netdev_name_node_lookup(net, name);
        return node_name ? node_name->dev : NULL;
}
EXPORT_SYMBOL(__dev_get_by_name);

/**
 * dev_get_by_name_rcu  - find a device by its name
 * @net: the applicable net namespace
 * @name: name to find
 *
 * Find an interface by name.
 * If the name is found a pointer to the device is returned.
 * If the name is not found then %NULL is returned.
 * The reference counters are not incremented so the caller must be
 * careful with locks. The caller must hold RCU lock.
 */

struct net_device *dev_get_by_name_rcu(struct net *net, const char *name)
{
        struct netdev_name_node *node_name;

        node_name = netdev_name_node_lookup_rcu(net, name);
        return node_name ? node_name->dev : NULL;
}
EXPORT_SYMBOL(dev_get_by_name_rcu);

/* Deprecated for new users, call netdev_get_by_name() instead */
struct net_device *dev_get_by_name(struct net *net, const char *name)
{
        struct net_device *dev;

        rcu_read_lock();
        dev = dev_get_by_name_rcu(net, name);
        dev_hold(dev);
        rcu_read_unlock();
        return dev;
}
EXPORT_SYMBOL(dev_get_by_name);

/**
 *      netdev_get_by_name() - find a device by its name
 *      @net: the applicable net namespace
 *      @name: name to find
 *      @tracker: tracking object for the acquired reference
 *      @gfp: allocation flags for the tracker
 *
 *      Find an interface by name. This can be called from any
 *      context and does its own locking. The returned handle has
 *      the usage count incremented and the caller must use netdev_put() to
 *      release it when it is no longer needed. %NULL is returned if no
 *      matching device is found.
 */
struct net_device *netdev_get_by_name(struct net *net, const char *name,
                                      netdevice_tracker *tracker, gfp_t gfp)
{
        struct net_device *dev;

        dev = dev_get_by_name(net, name);
        if (dev)
                netdev_tracker_alloc(dev, tracker, gfp);
        return dev;
}
EXPORT_SYMBOL(netdev_get_by_name);

/**
 *      __dev_get_by_index - find a device by its ifindex
 *      @net: the applicable net namespace
 *      @ifindex: index of device
 *
 *      Search for an interface by index. Returns %NULL if the device
 *      is not found or a pointer to the device. The device has not
 *      had its reference counter increased so the caller must be careful
 *      about locking. The caller must hold either the RTNL semaphore
 *      or @dev_base_lock.
 */

struct net_device *__dev_get_by_index(struct net *net, int ifindex)
{
        struct net_device *dev;
        struct hlist_head *head = dev_index_hash(net, ifindex);

        hlist_for_each_entry(dev, head, index_hlist)
                if (dev->ifindex == ifindex)
                        return dev;

        return NULL;
}
EXPORT_SYMBOL(__dev_get_by_index);

/**
 *      dev_get_by_index_rcu - find a device by its ifindex
 *      @net: the applicable net namespace
 *      @ifindex: index of device
 *
 *      Search for an interface by index. Returns %NULL if the device
 *      is not found or a pointer to the device. The device has not
 *      had its reference counter increased so the caller must be careful
 *      about locking. The caller must hold RCU lock.
 */

struct net_device *dev_get_by_index_rcu(struct net *net, int ifindex)
{
        struct net_device *dev;
        struct hlist_head *head = dev_index_hash(net, ifindex);

        hlist_for_each_entry_rcu(dev, head, index_hlist)
                if (dev->ifindex == ifindex)
                        return dev;

        return NULL;
}
EXPORT_SYMBOL(dev_get_by_index_rcu);

/* Deprecated for new users, call netdev_get_by_index() instead */
struct net_device *dev_get_by_index(struct net *net, int ifindex)
{
        struct net_device *dev;

        rcu_read_lock();
        dev = dev_get_by_index_rcu(net, ifindex);
        dev_hold(dev);
        rcu_read_unlock();
        return dev;
}
EXPORT_SYMBOL(dev_get_by_index);

/**
 *      netdev_get_by_index() - find a device by its ifindex
 *      @net: the applicable net namespace
 *      @ifindex: index of device
 *      @tracker: tracking object for the acquired reference
 *      @gfp: allocation flags for the tracker
 *
 *      Search for an interface by index. Returns NULL if the device
 *      is not found or a pointer to the device. The device returned has
 *      had a reference added and the pointer is safe until the user calls
 *      netdev_put() to indicate they have finished with it.
 */
struct net_device *netdev_get_by_index(struct net *net, int ifindex,
                                       netdevice_tracker *tracker, gfp_t gfp)
{
        struct net_device *dev;

        dev = dev_get_by_index(net, ifindex);
        if (dev)
                netdev_tracker_alloc(dev, tracker, gfp);
        return dev;
}
EXPORT_SYMBOL(netdev_get_by_index);

/**
 *      dev_get_by_napi_id - find a device by napi_id
 *      @napi_id: ID of the NAPI struct
 *
 *      Search for an interface by NAPI ID. Returns %NULL if the device
 *      is not found or a pointer to the device. The device has not had
 *      its reference counter increased so the caller must be careful
 *      about locking. The caller must hold RCU lock.
 */

struct net_device *dev_get_by_napi_id(unsigned int napi_id)
{
        struct napi_struct *napi;

        WARN_ON_ONCE(!rcu_read_lock_held());

        if (napi_id < MIN_NAPI_ID)
                return NULL;

        napi = napi_by_id(napi_id);

        return napi ? napi->dev : NULL;
}
EXPORT_SYMBOL(dev_get_by_napi_id);

/**
 *      netdev_get_name - get a netdevice name, knowing its ifindex.
 *      @net: network namespace
 *      @name: a pointer to the buffer where the name will be stored.
 *      @ifindex: the ifindex of the interface to get the name from.
 */
int netdev_get_name(struct net *net, char *name, int ifindex)
{
        struct net_device *dev;
        int ret;

        down_read(&devnet_rename_sem);
        rcu_read_lock();

        dev = dev_get_by_index_rcu(net, ifindex);
        if (!dev) {
                ret = -ENODEV;
                goto out;
        }

        strcpy(name, dev->name);

        ret = 0;
out:
        rcu_read_unlock();
        up_read(&devnet_rename_sem);
        return ret;
}

/**
 *      dev_getbyhwaddr_rcu - find a device by its hardware address
 *      @net: the applicable net namespace
 *      @type: media type of device
 *      @ha: hardware address
 *
 *      Search for an interface by MAC address. Returns NULL if the device
 *      is not found or a pointer to the device.
 *      The caller must hold RCU or RTNL.
 *      The returned device has not had its ref count increased
 *      and the caller must therefore be careful about locking
 *
 */

struct net_device *dev_getbyhwaddr_rcu(struct net *net, unsigned short type,
                                       const char *ha)
{
        struct net_device *dev;

        for_each_netdev_rcu(net, dev)
                if (dev->type == type &&
                    !memcmp(dev->dev_addr, ha, dev->addr_len))
                        return dev;

        return NULL;
}
EXPORT_SYMBOL(dev_getbyhwaddr_rcu);

struct net_device *dev_getfirstbyhwtype(struct net *net, unsigned short type)
{
        struct net_device *dev, *ret = NULL;

        rcu_read_lock();
        for_each_netdev_rcu(net, dev)
                if (dev->type == type) {
                        dev_hold(dev);
                        ret = dev;
                        break;
                }
        rcu_read_unlock();
        return ret;
}
EXPORT_SYMBOL(dev_getfirstbyhwtype);

/**
 *      __dev_get_by_flags - find any device with given flags
 *      @net: the applicable net namespace
 *      @if_flags: IFF_* values
 *      @mask: bitmask of bits in if_flags to check
 *
 *      Search for any interface with the given flags. Returns NULL if a device
 *      is not found or a pointer to the device. Must be called inside
 *      rtnl_lock(), and result refcount is unchanged.
 */

struct net_device *__dev_get_by_flags(struct net *net, unsigned short if_flags,
                                      unsigned short mask)
{
        struct net_device *dev, *ret;

        ASSERT_RTNL();

        ret = NULL;
        for_each_netdev(net, dev) {
                if (((dev->flags ^ if_flags) & mask) == 0) {
                        ret = dev;
                        break;
                }
        }
        return ret;
}
EXPORT_SYMBOL(__dev_get_by_flags);

/**
 *      dev_valid_name - check if name is okay for network device
 *      @name: name string
 *
 *      Network device names need to be valid file names to
 *      allow sysfs to work.  We also disallow any kind of
 *      whitespace.
 */
bool dev_valid_name(const char *name)
{
        if (*name == '\0')
                return false;
        if (strnlen(name, IFNAMSIZ) == IFNAMSIZ)
                return false;
        if (!strcmp(name, ".") || !strcmp(name, ".."))
                return false;

        while (*name) {
                if (*name == '/' || *name == ':' || isspace(*name))
                        return false;
                name++;
        }
        return true;
}
EXPORT_SYMBOL(dev_valid_name);

/**
 *      __dev_alloc_name - allocate a name for a device
 *      @net: network namespace to allocate the device name in
 *      @name: name format string
 *      @buf:  scratch buffer and result name string
 *
 *      Passed a format string - eg "lt%d" it will try and find a suitable
 *      id. It scans list of devices to build up a free map, then chooses
 *      the first empty slot. The caller must hold the dev_base or rtnl lock
 *      while allocating the name and adding the device in order to avoid
 *      duplicates.
 *      Limited to bits_per_byte * page size devices (ie 32K on most platforms).
 *      Returns the number of the unit assigned or a negative errno code.
 */

static int __dev_alloc_name(struct net *net, const char *name, char *buf)
{
        int i = 0;
        const char *p;
        const int max_netdevices = 8*PAGE_SIZE;
        unsigned long *inuse;
        struct net_device *d;

        if (!dev_valid_name(name))
                return -EINVAL;

        p = strchr(name, '%');
        if (p) {
                /*
                 * Verify the string as this thing may have come from
                 * the user.  There must be either one "%d" and no other "%"
                 * characters.
                 */
                if (p[1] != 'd' || strchr(p + 2, '%'))
                        return -EINVAL;

                /* Use one page as a bit array of possible slots */
                inuse = bitmap_zalloc(max_netdevices, GFP_ATOMIC);
                if (!inuse)
                        return -ENOMEM;

                for_each_netdev(net, d) {
                        struct netdev_name_node *name_node;

                        netdev_for_each_altname(d, name_node) {
                                if (!sscanf(name_node->name, name, &i))
                                        continue;
                                if (i < 0 || i >= max_netdevices)
                                        continue;

                                /*  avoid cases where sscanf is not exact inverse of printf */
                                snprintf(buf, IFNAMSIZ, name, i);
                                if (!strncmp(buf, name_node->name, IFNAMSIZ))
                                        __set_bit(i, inuse);
                        }
                        if (!sscanf(d->name, name, &i))
                                continue;
                        if (i < 0 || i >= max_netdevices)
                                continue;

                        /*  avoid cases where sscanf is not exact inverse of printf */
                        snprintf(buf, IFNAMSIZ, name, i);
                        if (!strncmp(buf, d->name, IFNAMSIZ))
                                __set_bit(i, inuse);
                }

                i = find_first_zero_bit(inuse, max_netdevices);
                bitmap_free(inuse);
        }

        snprintf(buf, IFNAMSIZ, name, i);
        if (!netdev_name_in_use(net, buf))
                return i;

        /* It is possible to run out of possible slots
         * when the name is long and there isn't enough space left
         * for the digits, or if all bits are used.
         */
        return -ENFILE;
}

static int dev_prep_valid_name(struct net *net, struct net_device *dev,
                               const char *want_name, char *out_name)
{
        int ret;

        if (!dev_valid_name(want_name))
                return -EINVAL;

        if (strchr(want_name, '%')) {
                ret = __dev_alloc_name(net, want_name, out_name);
                return ret < 0 ? ret : 0;
        } else if (netdev_name_in_use(net, want_name)) {
                return -EEXIST;
        } else if (out_name != want_name) {
                strscpy(out_name, want_name, IFNAMSIZ);
        }

        return 0;
}

static int dev_alloc_name_ns(struct net *net,
                             struct net_device *dev,
                             const char *name)
{
        char buf[IFNAMSIZ];
        int ret;

        BUG_ON(!net);
        ret = __dev_alloc_name(net, name, buf);
        if (ret >= 0)
                strscpy(dev->name, buf, IFNAMSIZ);
        return ret;
}

/**
 *      dev_alloc_name - allocate a name for a device
 *      @dev: device
 *      @name: name format string
 *
 *      Passed a format string - eg "lt%d" it will try and find a suitable
 *      id. It scans list of devices to build up a free map, then chooses
 *      the first empty slot. The caller must hold the dev_base or rtnl lock
 *      while allocating the name and adding the device in order to avoid
 *      duplicates.
 *      Limited to bits_per_byte * page size devices (ie 32K on most platforms).
 *      Returns the number of the unit assigned or a negative errno code.
 */

int dev_alloc_name(struct net_device *dev, const char *name)
{
        return dev_alloc_name_ns(dev_net(dev), dev, name);
}
EXPORT_SYMBOL(dev_alloc_name);

static int dev_get_valid_name(struct net *net, struct net_device *dev,
                              const char *name)
{
        char buf[IFNAMSIZ];
        int ret;

        ret = dev_prep_valid_name(net, dev, name, buf);
        if (ret >= 0)
                strscpy(dev->name, buf, IFNAMSIZ);
        return ret;
}

/**
 *      dev_change_name - change name of a device
 *      @dev: device
 *      @newname: name (or format string) must be at least IFNAMSIZ
 *
 *      Change name of a device, can pass format strings "eth%d".
 *      for wildcarding.
 */
int dev_change_name(struct net_device *dev, const char *newname)
{
        unsigned char old_assign_type;
        char oldname[IFNAMSIZ];
        int err = 0;
        int ret;
        struct net *net;

        ASSERT_RTNL();
        BUG_ON(!dev_net(dev));

        net = dev_net(dev);

        down_write(&devnet_rename_sem);

        if (strncmp(newname, dev->name, IFNAMSIZ) == 0) {
                up_write(&devnet_rename_sem);
                return 0;
        }

        memcpy(oldname, dev->name, IFNAMSIZ);

        err = dev_get_valid_name(net, dev, newname);
        if (err < 0) {
                up_write(&devnet_rename_sem);
                return err;
        }

        if (oldname[0] && !strchr(oldname, '%'))
                netdev_info(dev, "renamed from %s%s\n", oldname,
                            dev->flags & IFF_UP ? " (while UP)" : "");

        old_assign_type = dev->name_assign_type;
        dev->name_assign_type = NET_NAME_RENAMED;

rollback:
        ret = device_rename(&dev->dev, dev->name);
        if (ret) {
                memcpy(dev->name, oldname, IFNAMSIZ);
                dev->name_assign_type = old_assign_type;
                up_write(&devnet_rename_sem);
                return ret;
        }

        up_write(&devnet_rename_sem);

        netdev_adjacent_rename_links(dev, oldname);

        write_lock(&dev_base_lock);
        netdev_name_node_del(dev->name_node);
        write_unlock(&dev_base_lock);

        synchronize_rcu();

        write_lock(&dev_base_lock);
        netdev_name_node_add(net, dev->name_node);
        write_unlock(&dev_base_lock);

        ret = call_netdevice_notifiers(NETDEV_CHANGENAME, dev);
        ret = notifier_to_errno(ret);

        if (ret) {
                /* err >= 0 after dev_alloc_name() or stores the first errno */
                if (err >= 0) {
                        err = ret;
                        down_write(&devnet_rename_sem);
                        memcpy(dev->name, oldname, IFNAMSIZ);
                        memcpy(oldname, newname, IFNAMSIZ);
                        dev->name_assign_type = old_assign_type;
                        old_assign_type = NET_NAME_RENAMED;
                        goto rollback;
                } else {
                        netdev_err(dev, "name change rollback failed: %d\n",
                                   ret);
                }
        }

        return err;
}

/**
 *      dev_set_alias - change ifalias of a device
 *      @dev: device
 *      @alias: name up to IFALIASZ
 *      @len: limit of bytes to copy from info
 *
 *      Set ifalias for a device,
 */
int dev_set_alias(struct net_device *dev, const char *alias, size_t len)
{
        struct dev_ifalias *new_alias = NULL;

        if (len >= IFALIASZ)
                return -EINVAL;

        if (len) {
                new_alias = kmalloc(sizeof(*new_alias) + len + 1, GFP_KERNEL);
                if (!new_alias)
                        return -ENOMEM;

                memcpy(new_alias->ifalias, alias, len);
                new_alias->ifalias[len] = 0;
        }

        mutex_lock(&ifalias_mutex);
        new_alias = rcu_replace_pointer(dev->ifalias, new_alias,
                                        mutex_is_locked(&ifalias_mutex));
        mutex_unlock(&ifalias_mutex);

        if (new_alias)
                kfree_rcu(new_alias, rcuhead);

        return len;
}
EXPORT_SYMBOL(dev_set_alias);

/**
 *      dev_get_alias - get ifalias of a device
 *      @dev: device
 *      @name: buffer to store name of ifalias
 *      @len: size of buffer
 *
 *      get ifalias for a device.  Caller must make sure dev cannot go
 *      away,  e.g. rcu read lock or own a reference count to device.
 */
int dev_get_alias(const struct net_device *dev, char *name, size_t len)
{
        const struct dev_ifalias *alias;
        int ret = 0;

        rcu_read_lock();
        alias = rcu_dereference(dev->ifalias);
        if (alias)
                ret = snprintf(name, len, "%s", alias->ifalias);
        rcu_read_unlock();

        return ret;
}

/**
 *      netdev_features_change - device changes features
 *      @dev: device to cause notification
 *
 *      Called to indicate a device has changed features.
 */
void netdev_features_change(struct net_device *dev)
{
        call_netdevice_notifiers(NETDEV_FEAT_CHANGE, dev);
}
EXPORT_SYMBOL(netdev_features_change);

/**
 *      netdev_state_change - device changes state
 *      @dev: device to cause notification
 *
 *      Called to indicate a device has changed state. This function calls
 *      the notifier chains for netdev_chain and sends a NEWLINK message
 *      to the routing socket.
 */
void netdev_state_change(struct net_device *dev)
{
        if (dev->flags & IFF_UP) {
                struct netdev_notifier_change_info change_info = {
                        .info.dev = dev,
                };

                call_netdevice_notifiers_info(NETDEV_CHANGE,
                                              &change_info.info);
                rtmsg_ifinfo(RTM_NEWLINK, dev, 0, GFP_KERNEL, 0, NULL);
        }
}
EXPORT_SYMBOL(netdev_state_change);

/**
 * __netdev_notify_peers - notify network peers about existence of @dev,
 * to be called when rtnl lock is already held.
 * @dev: network device
 *
 * Generate traffic such that interested network peers are aware of
 * @dev, such as by generating a gratuitous ARP. This may be used when
 * a device wants to inform the rest of the network about some sort of
 * reconfiguration such as a failover event or virtual machine
 * migration.
 */
void __netdev_notify_peers(struct net_device *dev)
{
        ASSERT_RTNL();
        call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, dev);
        call_netdevice_notifiers(NETDEV_RESEND_IGMP, dev);
}
EXPORT_SYMBOL(__netdev_notify_peers);

/**
 * netdev_notify_peers - notify network peers about existence of @dev
 * @dev: network device
 *
 * Generate traffic such that interested network peers are aware of
 * @dev, such as by generating a gratuitous ARP. This may be used when
 * a device wants to inform the rest of the network about some sort of
 * reconfiguration such as a failover event or virtual machine
 * migration.
 */
void netdev_notify_peers(struct net_device *dev)
{
        rtnl_lock();
        __netdev_notify_peers(dev);
        rtnl_unlock();
}
EXPORT_SYMBOL(netdev_notify_peers);

static int napi_threaded_poll(void *data);

static int napi_kthread_create(struct napi_struct *n)
{
        int err = 0;

        /* Create and wake up the kthread once to put it in
         * TASK_INTERRUPTIBLE mode to avoid the blocked task
         * warning and work with loadavg.
         */
        n->thread = kthread_run(napi_threaded_poll, n, "napi/%s-%d",
                                n->dev->name, n->napi_id);
        if (IS_ERR(n->thread)) {
                err = PTR_ERR(n->thread);
                pr_err("kthread_run failed with err %d\n", err);
                n->thread = NULL;
        }

        return err;
}

static int __dev_open(struct net_device *dev, struct netlink_ext_ack *extack)
{
        const struct net_device_ops *ops = dev->netdev_ops;
        int ret;

        ASSERT_RTNL();
        dev_addr_check(dev);

        if (!netif_device_present(dev)) {
                /* may be detached because parent is runtime-suspended */
                if (dev->dev.parent)
                        pm_runtime_resume(dev->dev.parent);
                if (!netif_device_present(dev))
                        return -ENODEV;
        }

        /* Block netpoll from trying to do any rx path servicing.
         * If we don't do this there is a chance ndo_poll_controller
         * or ndo_poll may be running while we open the device
         */
        netpoll_poll_disable(dev);

        ret = call_netdevice_notifiers_extack(NETDEV_PRE_UP, dev, extack);
        ret = notifier_to_errno(ret);
        if (ret)
                return ret;

        set_bit(__LINK_STATE_START, &dev->state);

        if (ops->ndo_validate_addr)
                ret = ops->ndo_validate_addr(dev);

        if (!ret && ops->ndo_open)
                ret = ops->ndo_open(dev);

        netpoll_poll_enable(dev);

        if (ret)
                clear_bit(__LINK_STATE_START, &dev->state);
        else {
                dev->flags |= IFF_UP;
                dev_set_rx_mode(dev);
                dev_activate(dev);
                add_device_randomness(dev->dev_addr, dev->addr_len);
        }

        return ret;
}

/**
 *      dev_open        - prepare an interface for use.
 *      @dev: device to open
 *      @extack: netlink extended ack
 *
 *      Takes a device from down to up state. The device's private open
 *      function is invoked and then the multicast lists are loaded. Finally
 *      the device is moved into the up state and a %NETDEV_UP message is
 *      sent to the netdev notifier chain.
 *
 *      Calling this function on an active interface is a nop. On a failure
 *      a negative errno code is returned.
 */
int dev_open(struct net_device *dev, struct netlink_ext_ack *extack)
{
        int ret;

        if (dev->flags & IFF_UP)
                return 0;

        ret = __dev_open(dev, extack);
        if (ret < 0)
                return ret;

        rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP | IFF_RUNNING, GFP_KERNEL, 0, NULL);
        call_netdevice_notifiers(NETDEV_UP, dev);

        return ret;
}
EXPORT_SYMBOL(dev_open);

static void __dev_close_many(struct list_head *head)
{
        struct net_device *dev;

        ASSERT_RTNL();
        might_sleep();

        list_for_each_entry(dev, head, close_list) {
                /* Temporarily disable netpoll until the interface is down */
                netpoll_poll_disable(dev);

                call_netdevice_notifiers(NETDEV_GOING_DOWN, dev);

                clear_bit(__LINK_STATE_START, &dev->state);

                /* Synchronize to scheduled poll. We cannot touch poll list, it
                 * can be even on different cpu. So just clear netif_running().
                 *
                 * dev->stop() will invoke napi_disable() on all of it's
                 * napi_struct instances on this device.
                 */
                smp_mb__after_atomic(); /* Commit netif_running(). */
        }

        dev_deactivate_many(head);

        list_for_each_entry(dev, head, close_list) {
                const struct net_device_ops *ops = dev->netdev_ops;

                /*
                 *      Call the device specific close. This cannot fail.
                 *      Only if device is UP
                 *
                 *      We allow it to be called even after a DETACH hot-plug
                 *      event.
                 */
                if (ops->ndo_stop)
                        ops->ndo_stop(dev);

                dev->flags &= ~IFF_UP;
                netpoll_poll_enable(dev);
        }
}

static void __dev_close(struct net_device *dev)
{
        LIST_HEAD(single);

        list_add(&dev->close_list, &single);
        __dev_close_many(&single);
        list_del(&single);
}

void dev_close_many(struct list_head *head, bool unlink)
{
        struct net_device *dev, *tmp;

        /* Remove the devices that don't need to be closed */
        list_for_each_entry_safe(dev, tmp, head, close_list)
                if (!(dev->flags & IFF_UP))
                        list_del_init(&dev->close_list);

        __dev_close_many(head);

        list_for_each_entry_safe(dev, tmp, head, close_list) {
                rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP | IFF_RUNNING, GFP_KERNEL, 0, NULL);
                call_netdevice_notifiers(NETDEV_DOWN, dev);
                if (unlink)
                        list_del_init(&dev->close_list);
        }
}
EXPORT_SYMBOL(dev_close_many);

/**
 *      dev_close - shutdown an interface.
 *      @dev: device to shutdown
 *
 *      This function moves an active device into down state. A
 *      %NETDEV_GOING_DOWN is sent to the netdev notifier chain. The device
 *      is then deactivated and finally a %NETDEV_DOWN is sent to the notifier
 *      chain.
 */
void dev_close(struct net_device *dev)
{
        if (dev->flags & IFF_UP) {
                LIST_HEAD(single);

                list_add(&dev->close_list, &single);
                dev_close_many(&single, true);
                list_del(&single);
        }
}
EXPORT_SYMBOL(dev_close);


/**
 *      dev_disable_lro - disable Large Receive Offload on a device
 *      @dev: device
 *
 *      Disable Large Receive Offload (LRO) on a net device.  Must be
 *      called under RTNL.  This is needed if received packets may be
 *      forwarded to another interface.
 */
void dev_disable_lro(struct net_device *dev)
{
        struct net_device *lower_dev;
        struct list_head *iter;

        dev->wanted_features &= ~NETIF_F_LRO;
        netdev_update_features(dev);

        if (unlikely(dev->features & NETIF_F_LRO))
                netdev_WARN(dev, "failed to disable LRO!\n");

        netdev_for_each_lower_dev(dev, lower_dev, iter)
                dev_disable_lro(lower_dev);
}
EXPORT_SYMBOL(dev_disable_lro);

/**
 *      dev_disable_gro_hw - disable HW Generic Receive Offload on a device
 *      @dev: device
 *
 *      Disable HW Generic Receive Offload (GRO_HW) on a net device.  Must be
 *      called under RTNL.  This is needed if Generic XDP is installed on
 *      the device.
 */
static void dev_disable_gro_hw(struct net_device *dev)
{
        dev->wanted_features &= ~NETIF_F_GRO_HW;
        netdev_update_features(dev);

        if (unlikely(dev->features & NETIF_F_GRO_HW))
                netdev_WARN(dev, "failed to disable GRO_HW!\n");
}

const char *netdev_cmd_to_name(enum netdev_cmd cmd)
{
#define N(val)                                          \
        case NETDEV_##val:                              \
                return "NETDEV_" __stringify(val);
        switch (cmd) {
        N(UP) N(DOWN) N(REBOOT) N(CHANGE) N(REGISTER) N(UNREGISTER)
        N(CHANGEMTU) N(CHANGEADDR) N(GOING_DOWN) N(CHANGENAME) N(FEAT_CHANGE)
        N(BONDING_FAILOVER) N(PRE_UP) N(PRE_TYPE_CHANGE) N(POST_TYPE_CHANGE)
        N(POST_INIT) N(PRE_UNINIT) N(RELEASE) N(NOTIFY_PEERS) N(JOIN)
        N(CHANGEUPPER) N(RESEND_IGMP) N(PRECHANGEMTU) N(CHANGEINFODATA)
        N(BONDING_INFO) N(PRECHANGEUPPER) N(CHANGELOWERSTATE)
        N(UDP_TUNNEL_PUSH_INFO) N(UDP_TUNNEL_DROP_INFO) N(CHANGE_TX_QUEUE_LEN)
        N(CVLAN_FILTER_PUSH_INFO) N(CVLAN_FILTER_DROP_INFO)
        N(SVLAN_FILTER_PUSH_INFO) N(SVLAN_FILTER_DROP_INFO)
        N(PRE_CHANGEADDR) N(OFFLOAD_XSTATS_ENABLE) N(OFFLOAD_XSTATS_DISABLE)
        N(OFFLOAD_XSTATS_REPORT_USED) N(OFFLOAD_XSTATS_REPORT_DELTA)
        N(XDP_FEAT_CHANGE)
        }
#undef N
        return "UNKNOWN_NETDEV_EVENT";
}
EXPORT_SYMBOL_GPL(netdev_cmd_to_name);

static int call_netdevice_notifier(struct notifier_block *nb, unsigned long val,
                                   struct net_device *dev)
{
        struct netdev_notifier_info info = {
                .dev = dev,
        };

        return nb->notifier_call(nb, val, &info);
}

static int call_netdevice_register_notifiers(struct notifier_block *nb,
                                             struct net_device *dev)
{
        int err;

        err = call_netdevice_notifier(nb, NETDEV_REGISTER, dev);
        err = notifier_to_errno(err);
        if (err)
                return err;

        if (!(dev->flags & IFF_UP))
                return 0;

        call_netdevice_notifier(nb, NETDEV_UP, dev);
        return 0;
}

static void call_netdevice_unregister_notifiers(struct notifier_block *nb,
                                                struct net_device *dev)
{
        if (dev->flags & IFF_UP) {
                call_netdevice_notifier(nb, NETDEV_GOING_DOWN,
                                        dev);
                call_netdevice_notifier(nb, NETDEV_DOWN, dev);
        }
        call_netdevice_notifier(nb, NETDEV_UNREGISTER, dev);
}

static int call_netdevice_register_net_notifiers(struct notifier_block *nb,
                                                 struct net *net)
{
        struct net_device *dev;
        int err;

        for_each_netdev(net, dev) {
                err = call_netdevice_register_notifiers(nb, dev);
                if (err)
                        goto rollback;
        }
        return 0;

rollback:
        for_each_netdev_continue_reverse(net, dev)
                call_netdevice_unregister_notifiers(nb, dev);
        return err;
}

static void call_netdevice_unregister_net_notifiers(struct notifier_block *nb,
                                                    struct net *net)
{
        struct net_device *dev;

        for_each_netdev(net, dev)
                call_netdevice_unregister_notifiers(nb, dev);
}

static int dev_boot_phase = 1;

/**
 * register_netdevice_notifier - register a network notifier block
 * @nb: notifier
 *
 * Register a notifier to be called when network device events occur.
 * The notifier passed is linked into the kernel structures and must
 * not be reused until it has been unregistered. A negative errno code
 * is returned on a failure.
 *
 * When registered all registration and up events are replayed
 * to the new notifier to allow device to have a race free
 * view of the network device list.
 */

int register_netdevice_notifier(struct notifier_block *nb)
{
        struct net *net;
        int err;

        /* Close race with setup_net() and cleanup_net() */
        down_write(&pernet_ops_rwsem);
        rtnl_lock();
        err = raw_notifier_chain_register(&netdev_chain, nb);
        if (err)
                goto unlock;
        if (dev_boot_phase)
                goto unlock;
        for_each_net(net) {
                err = call_netdevice_register_net_notifiers(nb, net);
                if (err)
                        goto rollback;
        }

unlock:
        rtnl_unlock();
        up_write(&pernet_ops_rwsem);
        return err;

rollback:
        for_each_net_continue_reverse(net)
                call_netdevice_unregister_net_notifiers(nb, net);

        raw_notifier_chain_unregister(&netdev_chain, nb);
        goto unlock;
}
EXPORT_SYMBOL(register_netdevice_notifier);

/**
 * unregister_netdevice_notifier - unregister a network notifier block
 * @nb: notifier
 *
 * Unregister a notifier previously registered by
 * register_netdevice_notifier(). The notifier is unlinked into the
 * kernel structures and may then be reused. A negative errno code
 * is returned on a failure.
 *
 * After unregistering unregister and down device events are synthesized
 * for all devices on the device list to the removed notifier to remove
 * the need for special case cleanup code.
 */

int unregister_netdevice_notifier(struct notifier_block *nb)
{
        struct net *net;
        int err;

        /* Close race with setup_net() and cleanup_net() */
        down_write(&pernet_ops_rwsem);
        rtnl_lock();
        err = raw_notifier_chain_unregister(&netdev_chain, nb);
        if (err)
                goto unlock;

        for_each_net(net)
                call_netdevice_unregister_net_notifiers(nb, net);

unlock:
        rtnl_unlock();
        up_write(&pernet_ops_rwsem);
        return err;
}
EXPORT_SYMBOL(unregister_netdevice_notifier);

static int __register_netdevice_notifier_net(struct net *net,
                                             struct notifier_block *nb,
                                             bool ignore_call_fail)
{
        int err;

        err = raw_notifier_chain_register(&net->netdev_chain, nb);
        if (err)
                return err;
        if (dev_boot_phase)
                return 0;

        err = call_netdevice_register_net_notifiers(nb, net);
        if (err && !ignore_call_fail)
                goto chain_unregister;

        return 0;

chain_unregister:
        raw_notifier_chain_unregister(&net->netdev_chain, nb);
        return err;
}

static int __unregister_netdevice_notifier_net(struct net *net,
                                               struct notifier_block *nb)
{
        int err;

        err = raw_notifier_chain_unregister(&net->netdev_chain, nb);
        if (err)
                return err;

        call_netdevice_unregister_net_notifiers(nb, net);
        return 0;
}

/**
 * register_netdevice_notifier_net - register a per-netns network notifier block
 * @net: network namespace
 * @nb: notifier
 *
 * Register a notifier to be called when network device events occur.
 * The notifier passed is linked into the kernel structures and must
 * not be reused until it has been unregistered. A negative errno code
 * is returned on a failure.
 *
 * When registered all registration and up events are replayed
 * to the new notifier to allow device to have a race free
 * view of the network device list.
 */

int register_netdevice_notifier_net(struct net *net, struct notifier_block *nb)
{
        int err;

        rtnl_lock();
        err = __register_netdevice_notifier_net(net, nb, false);
        rtnl_unlock();
        return err;
}
EXPORT_SYMBOL(register_netdevice_notifier_net);

/**
 * unregister_netdevice_notifier_net - unregister a per-netns
 *                                     network notifier block
 * @net: network namespace
 * @nb: notifier
 *
 * Unregister a notifier previously registered by
 * register_netdevice_notifier_net(). The notifier is unlinked from the
 * kernel structures and may then be reused. A negative errno code
 * is returned on a failure.
 *
 * After unregistering unregister and down device events are synthesized
 * for all devices on the device list to the removed notifier to remove
 * the need for special case cleanup code.
 */

int unregister_netdevice_notifier_net(struct net *net,
                                      struct notifier_block *nb)
{
        int err;

        rtnl_lock();
        err = __unregister_netdevice_notifier_net(net, nb);
        rtnl_unlock();
        return err;
}
EXPORT_SYMBOL(unregister_netdevice_notifier_net);

static void __move_netdevice_notifier_net(struct net *src_net,
                                          struct net *dst_net,
                                          struct notifier_block *nb)
{
        __unregister_netdevice_notifier_net(src_net, nb);
        __register_netdevice_notifier_net(dst_net, nb, true);
}

int register_netdevice_notifier_dev_net(struct net_device *dev,
                                        struct notifier_block *nb,
                                        struct netdev_net_notifier *nn)
{
        int err;

        rtnl_lock();
        err = __register_netdevice_notifier_net(dev_net(dev), nb, false);
        if (!err) {
                nn->nb = nb;
                list_add(&nn->list, &dev->net_notifier_list);
        }
        rtnl_unlock();
        return err;
}
EXPORT_SYMBOL(register_netdevice_notifier_dev_net);

int unregister_netdevice_notifier_dev_net(struct net_device *dev,
                                          struct notifier_block *nb,
                                          struct netdev_net_notifier *nn)
{
        int err;

        rtnl_lock();
        list_del(&nn->list);
        err = __unregister_netdevice_notifier_net(dev_net(dev), nb);
        rtnl_unlock();
        return err;
}
EXPORT_SYMBOL(unregister_netdevice_notifier_dev_net);

static void move_netdevice_notifiers_dev_net(struct net_device *dev,
                                             struct net *net)
{
        struct netdev_net_notifier *nn;

        list_for_each_entry(nn, &dev->net_notifier_list, list)
                __move_netdevice_notifier_net(dev_net(dev), net, nn->nb);
}

/**
 *      call_netdevice_notifiers_info - call all network notifier blocks
 *      @val: value passed unmodified to notifier function
 *      @info: notifier information data
 *
 *      Call all network notifier blocks.  Parameters and return value
 *      are as for raw_notifier_call_chain().
 */

int call_netdevice_notifiers_info(unsigned long val,
                                  struct netdev_notifier_info *info)
{
        struct net *net = dev_net(info->dev);
        int ret;

        ASSERT_RTNL();

        /* Run per-netns notifier block chain first, then run the global one.
         * Hopefully, one day, the global one is going to be removed after
         * all notifier block registrators get converted to be per-netns.
         */
        ret = raw_notifier_call_chain(&net->netdev_chain, val, info);
        if (ret & NOTIFY_STOP_MASK)
                return ret;
        return raw_notifier_call_chain(&netdev_chain, val, info);
}

/**
 *      call_netdevice_notifiers_info_robust - call per-netns notifier blocks
 *                                             for and rollback on error
 *      @val_up: value passed unmodified to notifier function
 *      @val_down: value passed unmodified to the notifier function when
 *                 recovering from an error on @val_up
 *      @info: notifier information data
 *
 *      Call all per-netns network notifier blocks, but not notifier blocks on
 *      the global notifier chain. Parameters and return value are as for
 *      raw_notifier_call_chain_robust().
 */

static int
call_netdevice_notifiers_info_robust(unsigned long val_up,
                                     unsigned long val_down,
                                     struct netdev_notifier_info *info)
{
        struct net *net = dev_net(info->dev);

        ASSERT_RTNL();

        return raw_notifier_call_chain_robust(&net->netdev_chain,
                                              val_up, val_down, info);
}

static int call_netdevice_notifiers_extack(unsigned long val,
                                           struct net_device *dev,
                                           struct netlink_ext_ack *extack)
{
        struct netdev_notifier_info info = {
                .dev = dev,
                .extack = extack,
        };

        return call_netdevice_notifiers_info(val, &info);
}

/**
 *      call_netdevice_notifiers - call all network notifier blocks
 *      @val: value passed unmodified to notifier function
 *      @dev: net_device pointer passed unmodified to notifier function
 *
 *      Call all network notifier blocks.  Parameters and return value
 *      are as for raw_notifier_call_chain().
 */

int call_netdevice_notifiers(unsigned long val, struct net_device *dev)
{
        return call_netdevice_notifiers_extack(val, dev, NULL);
}
EXPORT_SYMBOL(call_netdevice_notifiers);

/**
 *      call_netdevice_notifiers_mtu - call all network notifier blocks
 *      @val: value passed unmodified to notifier function
 *      @dev: net_device pointer passed unmodified to notifier function
 *      @arg: additional u32 argument passed to the notifier function
 *
 *      Call all network notifier blocks.  Parameters and return value
 *      are as for raw_notifier_call_chain().
 */
static int call_netdevice_notifiers_mtu(unsigned long val,
                                        struct net_device *dev, u32 arg)
{
        struct netdev_notifier_info_ext info = {
                .info.dev = dev,
                .ext.mtu = arg,
        };

        BUILD_BUG_ON(offsetof(struct netdev_notifier_info_ext, info) != 0);

        return call_netdevice_notifiers_info(val, &info.info);
}

#ifdef CONFIG_NET_INGRESS
static DEFINE_STATIC_KEY_FALSE(ingress_needed_key);

void net_inc_ingress_queue(void)
{
        static_branch_inc(&ingress_needed_key);
}
EXPORT_SYMBOL_GPL(net_inc_ingress_queue);

void net_dec_ingress_queue(void)
{
        static_branch_dec(&ingress_needed_key);
}
EXPORT_SYMBOL_GPL(net_dec_ingress_queue);
#endif

#ifdef CONFIG_NET_EGRESS
static DEFINE_STATIC_KEY_FALSE(egress_needed_key);

void net_inc_egress_queue(void)
{
        static_branch_inc(&egress_needed_key);
}
EXPORT_SYMBOL_GPL(net_inc_egress_queue);

void net_dec_egress_queue(void)
{
        static_branch_dec(&egress_needed_key);
}
EXPORT_SYMBOL_GPL(net_dec_egress_queue);
#endif

DEFINE_STATIC_KEY_FALSE(netstamp_needed_key);
EXPORT_SYMBOL(netstamp_needed_key);
#ifdef CONFIG_JUMP_LABEL
static atomic_t netstamp_needed_deferred;
static atomic_t netstamp_wanted;
static void netstamp_clear(struct work_struct *work)
{
        int deferred = atomic_xchg(&netstamp_needed_deferred, 0);
        int wanted;

        wanted = atomic_add_return(deferred, &netstamp_wanted);
        if (wanted > 0)
                static_branch_enable(&netstamp_needed_key);
        else
                static_branch_disable(&netstamp_needed_key);
}
static DECLARE_WORK(netstamp_work, netstamp_clear);
#endif

void net_enable_timestamp(void)
{
#ifdef CONFIG_JUMP_LABEL
        int wanted = atomic_read(&netstamp_wanted);

        while (wanted > 0) {
                if (atomic_try_cmpxchg(&netstamp_wanted, &wanted, wanted + 1))
                        return;
        }
        atomic_inc(&netstamp_needed_deferred);
        schedule_work(&netstamp_work);
#else
        static_branch_inc(&netstamp_needed_key);
#endif
}
EXPORT_SYMBOL(net_enable_timestamp);

void net_disable_timestamp(void)
{
#ifdef CONFIG_JUMP_LABEL
        int wanted = atomic_read(&netstamp_wanted);

        while (wanted > 1) {
                if (atomic_try_cmpxchg(&netstamp_wanted, &wanted, wanted - 1))
                        return;
        }
        atomic_dec(&netstamp_needed_deferred);
        schedule_work(&netstamp_work);
#else
        static_branch_dec(&netstamp_needed_key);
#endif
}
EXPORT_SYMBOL(net_disable_timestamp);

static inline void net_timestamp_set(struct sk_buff *skb)
{
        skb->tstamp = 0;
        skb->mono_delivery_time = 0;
        if (static_branch_unlikely(&netstamp_needed_key))
                skb->tstamp = ktime_get_real();
}

#define net_timestamp_check(COND, SKB)                          \
        if (static_branch_unlikely(&netstamp_needed_key)) {     \
                if ((COND) && !(SKB)->tstamp)                   \
                        (SKB)->tstamp = ktime_get_real();       \
        }                                                       \

bool is_skb_forwardable(const struct net_device *dev, const struct sk_buff *skb)
{
        return __is_skb_forwardable(dev, skb, true);
}
EXPORT_SYMBOL_GPL(is_skb_forwardable);

static int __dev_forward_skb2(struct net_device *dev, struct sk_buff *skb,
                              bool check_mtu)
{
        int ret = ____dev_forward_skb(dev, skb, check_mtu);

        if (likely(!ret)) {
                skb->protocol = eth_type_trans(skb, dev);
                skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);
        }

        return ret;
}

int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb)
{
        return __dev_forward_skb2(dev, skb, true);
}
EXPORT_SYMBOL_GPL(__dev_forward_skb);

/**
 * dev_forward_skb - loopback an skb to another netif
 *
 * @dev: destination network device
 * @skb: buffer to forward
 *
 * return values:
 *      NET_RX_SUCCESS  (no congestion)
 *      NET_RX_DROP     (packet was dropped, but freed)
 *
 * dev_forward_skb can be used for injecting an skb from the
 * start_xmit function of one device into the receive queue
 * of another device.
 *
 * The receiving device may be in another namespace, so
 * we have to clear all information in the skb that could
 * impact namespace isolation.
 */
int dev_forward_skb(struct net_device *dev, struct sk_buff *skb)
{
        return __dev_forward_skb(dev, skb) ?: netif_rx_internal(skb);
}
EXPORT_SYMBOL_GPL(dev_forward_skb);

int dev_forward_skb_nomtu(struct net_device *dev, struct sk_buff *skb)
{
        return __dev_forward_skb2(dev, skb, false) ?: netif_rx_internal(skb);
}

static inline int deliver_skb(struct sk_buff *skb,
                              struct packet_type *pt_prev,
                              struct net_device *orig_dev)
{
        if (unlikely(skb_orphan_frags_rx(skb, GFP_ATOMIC)))
                return -ENOMEM;
        refcount_inc(&skb->users);
        return pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
}

static inline void deliver_ptype_list_skb(struct sk_buff *skb,
                                          struct packet_type **pt,
                                          struct net_device *orig_dev,
                                          __be16 type,
                                          struct list_head *ptype_list)
{
        struct packet_type *ptype, *pt_prev = *pt;

        list_for_each_entry_rcu(ptype, ptype_list, list) {
                if (ptype->type != type)
                        continue;
                if (pt_prev)
                        deliver_skb(skb, pt_prev, orig_dev);
                pt_prev = ptype;
        }
        *pt = pt_prev;
}

static inline bool skb_loop_sk(struct packet_type *ptype, struct sk_buff *skb)
{
        if (!ptype->af_packet_priv || !skb->sk)
                return false;

        if (ptype->id_match)
                return ptype->id_match(ptype, skb->sk);
        else if ((struct sock *)ptype->af_packet_priv == skb->sk)
                return true;

        return false;
}

/**
 * dev_nit_active - return true if any network interface taps are in use
 *
 * @dev: network device to check for the presence of taps
 */
bool dev_nit_active(struct net_device *dev)
{
        return !list_empty(&ptype_all) || !list_empty(&dev->ptype_all);
}
EXPORT_SYMBOL_GPL(dev_nit_active);

/*
 *      Support routine. Sends outgoing frames to any network
 *      taps currently in use.
 */

void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)
{
        struct packet_type *ptype;
        struct sk_buff *skb2 = NULL;
        struct packet_type *pt_prev = NULL;
        struct list_head *ptype_list = &ptype_all;

        rcu_read_lock();
again:
        list_for_each_entry_rcu(ptype, ptype_list, list) {
                if (ptype->ignore_outgoing)
                        continue;

                /* Never send packets back to the socket
                 * they originated from - MvS (miquels@drinkel.ow.org)
                 */
                if (skb_loop_sk(ptype, skb))
                        continue;

                if (pt_prev) {
                        deliver_skb(skb2, pt_prev, skb->dev);
                        pt_prev = ptype;
                        continue;
                }

                /* need to clone skb, done only once */
                skb2 = skb_clone(skb, GFP_ATOMIC);
                if (!skb2)
                        goto out_unlock;

                net_timestamp_set(skb2);

                /* skb->nh should be correctly
                 * set by sender, so that the second statement is
                 * just protection against buggy protocols.
                 */
                skb_reset_mac_header(skb2);

                if (skb_network_header(skb2) < skb2->data ||
                    skb_network_header(skb2) > skb_tail_pointer(skb2)) {
                        net_crit_ratelimited("protocol %04x is buggy, dev %s\n",
                                             ntohs(skb2->protocol),
                                             dev->name);
                        skb_reset_network_header(skb2);
                }

                skb2->transport_header = skb2->network_header;
                skb2->pkt_type = PACKET_OUTGOING;
                pt_prev = ptype;
        }

        if (ptype_list == &ptype_all) {
                ptype_list = &dev->ptype_all;
                goto again;
        }
out_unlock:
        if (pt_prev) {
                if (!skb_orphan_frags_rx(skb2, GFP_ATOMIC))
                        pt_prev->func(skb2, skb->dev, pt_prev, skb->dev);
                else
                        kfree_skb(skb2);
        }
        rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(dev_queue_xmit_nit);

/**
 * netif_setup_tc - Handle tc mappings on real_num_tx_queues change
 * @dev: Network device
 * @txq: number of queues available
 *
 * If real_num_tx_queues is changed the tc mappings may no longer be
 * valid. To resolve this verify the tc mapping remains valid and if
 * not NULL the mapping. With no priorities mapping to this
 * offset/count pair it will no longer be used. In the worst case TC0
 * is invalid nothing can be done so disable priority mappings. If is
 * expected that drivers will fix this mapping if they can before
 * calling netif_set_real_num_tx_queues.
 */
static void netif_setup_tc(struct net_device *dev, unsigned int txq)
{
        int i;
        struct netdev_tc_txq *tc = &dev->tc_to_txq[0];

        /* If TC0 is invalidated disable TC mapping */
        if (tc->offset + tc->count > txq) {
                netdev_warn(dev, "Number of in use tx queues changed invalidating tc mappings. Priority traffic classification disabled!\n");
                dev->num_tc = 0;
                return;
        }

        /* Invalidated prio to tc mappings set to TC0 */
        for (i = 1; i < TC_BITMASK + 1; i++) {
                int q = netdev_get_prio_tc_map(dev, i);

                tc = &dev->tc_to_txq[q];
                if (tc->offset + tc->count > txq) {
                        netdev_warn(dev, "Number of in use tx queues changed. Priority %i to tc mapping %i is no longer valid. Setting map to 0\n",
                                    i, q);
                        netdev_set_prio_tc_map(dev, i, 0);
                }
        }
}

int netdev_txq_to_tc(struct net_device *dev, unsigned int txq)
{
        if (dev->num_tc) {
                struct netdev_tc_txq *tc = &dev->tc_to_txq[0];
                int i;

                /* walk through the TCs and see if it falls into any of them */
                for (i = 0; i < TC_MAX_QUEUE; i++, tc++) {
                        if ((txq - tc->offset) < tc->count)
                                return i;
                }

                /* didn't find it, just return -1 to indicate no match */
                return -1;
        }

        return 0;
}
EXPORT_SYMBOL(netdev_txq_to_tc);

#ifdef CONFIG_XPS
static struct static_key xps_needed __read_mostly;
static struct static_key xps_rxqs_needed __read_mostly;
static DEFINE_MUTEX(xps_map_mutex);
#define xmap_dereference(P)             \
        rcu_dereference_protected((P), lockdep_is_held(&xps_map_mutex))

static bool remove_xps_queue(struct xps_dev_maps *dev_maps,
                             struct xps_dev_maps *old_maps, int tci, u16 index)
{
        struct xps_map *map = NULL;
        int pos;

        map = xmap_dereference(dev_maps->attr_map[tci]);
        if (!map)
                return false;

        for (pos = map->len; pos--;) {
                if (map->queues[pos] != index)
                        continue;

                if (map->len > 1) {
                        map->queues[pos] = map->queues[--map->len];
                        break;
                }

                if (old_maps)
                        RCU_INIT_POINTER(old_maps->attr_map[tci], NULL);
                RCU_INIT_POINTER(dev_maps->attr_map[tci], NULL);
                kfree_rcu(map, rcu);
                return false;
        }

        return true;
}

static bool remove_xps_queue_cpu(struct net_device *dev,
                                 struct xps_dev_maps *dev_maps,
                                 int cpu, u16 offset, u16 count)
{
        int num_tc = dev_maps->num_tc;
        bool active = false;
        int tci;

        for (tci = cpu * num_tc; num_tc--; tci++) {
                int i, j;

                for (i = count, j = offset; i--; j++) {
                        if (!remove_xps_queue(dev_maps, NULL, tci, j))
                                break;
                }

                active |= i < 0;
        }

        return active;
}

static void reset_xps_maps(struct net_device *dev,
                           struct xps_dev_maps *dev_maps,
                           enum xps_map_type type)
{
        static_key_slow_dec_cpuslocked(&xps_needed);
        if (type == XPS_RXQS)
                static_key_slow_dec_cpuslocked(&xps_rxqs_needed);

        RCU_INIT_POINTER(dev->xps_maps[type], NULL);

        kfree_rcu(dev_maps, rcu);
}

static void clean_xps_maps(struct net_device *dev, enum xps_map_type type,
                           u16 offset, u16 count)
{
        struct xps_dev_maps *dev_maps;
        bool active = false;
        int i, j;

        dev_maps = xmap_dereference(dev->xps_maps[type]);
        if (!dev_maps)
                return;

        for (j = 0; j < dev_maps->nr_ids; j++)
                active |= remove_xps_queue_cpu(dev, dev_maps, j, offset, count);
        if (!active)
                reset_xps_maps(dev, dev_maps, type);

        if (type == XPS_CPUS) {
                for (i = offset + (count - 1); count--; i--)
                        netdev_queue_numa_node_write(
                                netdev_get_tx_queue(dev, i), NUMA_NO_NODE);
        }
}

static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
                                   u16 count)
{
        if (!static_key_false(&xps_needed))
                return;

        cpus_read_lock();
        mutex_lock(&xps_map_mutex);

        if (static_key_false(&xps_rxqs_needed))
                clean_xps_maps(dev, XPS_RXQS, offset, count);

        clean_xps_maps(dev, XPS_CPUS, offset, count);

        mutex_unlock(&xps_map_mutex);
        cpus_read_unlock();
}

static void netif_reset_xps_queues_gt(struct net_device *dev, u16 index)
{
        netif_reset_xps_queues(dev, index, dev->num_tx_queues - index);
}

static struct xps_map *expand_xps_map(struct xps_map *map, int attr_index,
                                      u16 index, bool is_rxqs_map)
{
        struct xps_map *new_map;
        int alloc_len = XPS_MIN_MAP_ALLOC;
        int i, pos;

        for (pos = 0; map && pos < map->len; pos++) {
                if (map->queues[pos] != index)
                        continue;
                return map;
        }

        /* Need to add tx-queue to this CPU's/rx-queue's existing map */
        if (map) {
                if (pos < map->alloc_len)
                        return map;

                alloc_len = map->alloc_len * 2;
        }

        /* Need to allocate new map to store tx-queue on this CPU's/rx-queue's
         *  map
         */
        if (is_rxqs_map)
                new_map = kzalloc(XPS_MAP_SIZE(alloc_len), GFP_KERNEL);
        else
                new_map = kzalloc_node(XPS_MAP_SIZE(alloc_len), GFP_KERNEL,
                                       cpu_to_node(attr_index));
        if (!new_map)
                return NULL;

        for (i = 0; i < pos; i++)
                new_map->queues[i] = map->queues[i];
        new_map->alloc_len = alloc_len;
        new_map->len = pos;

        return new_map;
}

/* Copy xps maps at a given index */
static void xps_copy_dev_maps(struct xps_dev_maps *dev_maps,
                              struct xps_dev_maps *new_dev_maps, int index,
                              int tc, bool skip_tc)
{
        int i, tci = index * dev_maps->num_tc;
        struct xps_map *map;

        /* copy maps belonging to foreign traffic classes */
        for (i = 0; i < dev_maps->num_tc; i++, tci++) {
                if (i == tc && skip_tc)
                        continue;

                /* fill in the new device map from the old device map */
                map = xmap_dereference(dev_maps->attr_map[tci]);
                RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
        }
}

/* Must be called under cpus_read_lock */
int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
                          u16 index, enum xps_map_type type)
{
        struct xps_dev_maps *dev_maps, *new_dev_maps = NULL, *old_dev_maps = NULL;
        const unsigned long *online_mask = NULL;
        bool active = false, copy = false;
        int i, j, tci, numa_node_id = -2;
        int maps_sz, num_tc = 1, tc = 0;
        struct xps_map *map, *new_map;
        unsigned int nr_ids;

        WARN_ON_ONCE(index >= dev->num_tx_queues);

        if (dev->num_tc) {
                /* Do not allow XPS on subordinate device directly */
                num_tc = dev->num_tc;
                if (num_tc < 0)
                        return -EINVAL;

                /* If queue belongs to subordinate dev use its map */
                dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;

                tc = netdev_txq_to_tc(dev, index);
                if (tc < 0)
                        return -EINVAL;
        }

        mutex_lock(&xps_map_mutex);

        dev_maps = xmap_dereference(dev->xps_maps[type]);
        if (type == XPS_RXQS) {
                maps_sz = XPS_RXQ_DEV_MAPS_SIZE(num_tc, dev->num_rx_queues);
                nr_ids = dev->num_rx_queues;
        } else {
                maps_sz = XPS_CPU_DEV_MAPS_SIZE(num_tc);
                if (num_possible_cpus() > 1)
                        online_mask = cpumask_bits(cpu_online_mask);
                nr_ids = nr_cpu_ids;
        }

        if (maps_sz < L1_CACHE_BYTES)
                maps_sz = L1_CACHE_BYTES;

        /* The old dev_maps could be larger or smaller than the one we're
         * setting up now, as dev->num_tc or nr_ids could have been updated in
         * between. We could try to be smart, but let's be safe instead and only
         * copy foreign traffic classes if the two map sizes match.
         */
        if (dev_maps &&
            dev_maps->num_tc == num_tc && dev_maps->nr_ids == nr_ids)
                copy = true;

        /* allocate memory for queue storage */
        for (j = -1; j = netif_attrmask_next_and(j, online_mask, mask, nr_ids),
             j < nr_ids;) {
                if (!new_dev_maps) {
                        new_dev_maps = kzalloc(maps_sz, GFP_KERNEL);
                        if (!new_dev_maps) {
                                mutex_unlock(&xps_map_mutex);
                                return -ENOMEM;
                        }

                        new_dev_maps->nr_ids = nr_ids;
                        new_dev_maps->num_tc = num_tc;
                }

                tci = j * num_tc + tc;
                map = copy ? xmap_dereference(dev_maps->attr_map[tci]) : NULL;

                map = expand_xps_map(map, j, index, type == XPS_RXQS);
                if (!map)
                        goto error;

                RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map);
        }

        if (!new_dev_maps)
                goto out_no_new_maps;

        if (!dev_maps) {
                /* Increment static keys at most once per type */
                static_key_slow_inc_cpuslocked(&xps_needed);
                if (type == XPS_RXQS)
                        static_key_slow_inc_cpuslocked(&xps_rxqs_needed);
        }

        for (j = 0; j < nr_ids; j++) {
                bool skip_tc = false;

                tci = j * num_tc + tc;
                if (netif_attr_test_mask(j, mask, nr_ids) &&
                    netif_attr_test_online(j, online_mask, nr_ids)) {
                        /* add tx-queue to CPU/rx-queue maps */
                        int pos = 0;

                        skip_tc = true;

                        map = xmap_dereference(new_dev_maps->attr_map[tci]);
                        while ((pos < map->len) && (map->queues[pos] != index))
                                pos++;

                        if (pos == map->len)
                                map->queues[map->len++] = index;
#ifdef CONFIG_NUMA
                        if (type == XPS_CPUS) {
                                if (numa_node_id == -2)
                                        numa_node_id = cpu_to_node(j);
                                else if (numa_node_id != cpu_to_node(j))
                                        numa_node_id = -1;
                        }
#endif
                }

                if (copy)
                        xps_copy_dev_maps(dev_maps, new_dev_maps, j, tc,
                                          skip_tc);
        }

        rcu_assign_pointer(dev->xps_maps[type], new_dev_maps);

        /* Cleanup old maps */
        if (!dev_maps)
                goto out_no_old_maps;

        for (j = 0; j < dev_maps->nr_ids; j++) {
                for (i = num_tc, tci = j * dev_maps->num_tc; i--; tci++) {
                        map = xmap_dereference(dev_maps->attr_map[tci]);
                        if (!map)
                                continue;

                        if (copy) {
                                new_map = xmap_dereference(new_dev_maps->attr_map[tci]);
                                if (map == new_map)
                                        continue;
                        }

                        RCU_INIT_POINTER(dev_maps->attr_map[tci], NULL);
                        kfree_rcu(map, rcu);
                }
        }

        old_dev_maps = dev_maps;

out_no_old_maps:
        dev_maps = new_dev_maps;
        active = true;

out_no_new_maps:
        if (type == XPS_CPUS)
                /* update Tx queue numa node */
                netdev_queue_numa_node_write(netdev_get_tx_queue(dev, index),
                                             (numa_node_id >= 0) ?
                                             numa_node_id : NUMA_NO_NODE);

        if (!dev_maps)
                goto out_no_maps;

        /* removes tx-queue from unused CPUs/rx-queues */
        for (j = 0; j < dev_maps->nr_ids; j++) {
                tci = j * dev_maps->num_tc;

                for (i = 0; i < dev_maps->num_tc; i++, tci++) {
                        if (i == tc &&
                            netif_attr_test_mask(j, mask, dev_maps->nr_ids) &&
                            netif_attr_test_online(j, online_mask, dev_maps->nr_ids))
                                continue;

                        active |= remove_xps_queue(dev_maps,
                                                   copy ? old_dev_maps : NULL,
                                                   tci, index);
                }
        }

        if (old_dev_maps)
                kfree_rcu(old_dev_maps, rcu);

        /* free map if not active */
        if (!active)
                reset_xps_maps(dev, dev_maps, type);

out_no_maps:
        mutex_unlock(&xps_map_mutex);

        return 0;
error:
        /* remove any maps that we added */
        for (j = 0; j < nr_ids; j++) {
                for (i = num_tc, tci = j * num_tc; i--; tci++) {
                        new_map = xmap_dereference(new_dev_maps->attr_map[tci]);
                        map = copy ?
                              xmap_dereference(dev_maps->attr_map[tci]) :
                              NULL;
                        if (new_map && new_map != map)
                                kfree(new_map);
                }
        }

        mutex_unlock(&xps_map_mutex);

        kfree(new_dev_maps);
        return -ENOMEM;
}
EXPORT_SYMBOL_GPL(__netif_set_xps_queue);

int netif_set_xps_queue(struct net_device *dev, const struct cpumask *mask,
                        u16 index)
{
        int ret;

        cpus_read_lock();
        ret =  __netif_set_xps_queue(dev, cpumask_bits(mask), index, XPS_CPUS);
        cpus_read_unlock();

        return ret;
}
EXPORT_SYMBOL(netif_set_xps_queue);

#endif
static void netdev_unbind_all_sb_channels(struct net_device *dev)
{
        struct netdev_queue *txq = &dev->_tx[dev->num_tx_queues];

        /* Unbind any subordinate channels */
        while (txq-- != &dev->_tx[0]) {
                if (txq->sb_dev)
                        netdev_unbind_sb_channel(dev, txq->sb_dev);
        }
}

void netdev_reset_tc(struct net_device *dev)
{
#ifdef CONFIG_XPS
        netif_reset_xps_queues_gt(dev, 0);
#endif
        netdev_unbind_all_sb_channels(dev);

        /* Reset TC configuration of device */
        dev->num_tc = 0;
        memset(dev->tc_to_txq, 0, sizeof(dev->tc_to_txq));
        memset(dev->prio_tc_map, 0, sizeof(dev->prio_tc_map));
}
EXPORT_SYMBOL(netdev_reset_tc);

int netdev_set_tc_queue(struct net_device *dev, u8 tc, u16 count, u16 offset)
{
        if (tc >= dev->num_tc)
                return -EINVAL;

#ifdef CONFIG_XPS
        netif_reset_xps_queues(dev, offset, count);
#endif
        dev->tc_to_txq[tc].count = count;
        dev->tc_to_txq[tc].offset = offset;
        return 0;
}
EXPORT_SYMBOL(netdev_set_tc_queue);

int netdev_set_num_tc(struct net_device *dev, u8 num_tc)
{
        if (num_tc > TC_MAX_QUEUE)
                return -EINVAL;

#ifdef CONFIG_XPS
        netif_reset_xps_queues_gt(dev, 0);
#endif
        netdev_unbind_all_sb_channels(dev);

        dev->num_tc = num_tc;
        return 0;
}
EXPORT_SYMBOL(netdev_set_num_tc);

void netdev_unbind_sb_channel(struct net_device *dev,
                              struct net_device *sb_dev)
{
        struct netdev_queue *txq = &dev->_tx[dev->num_tx_queues];

#ifdef CONFIG_XPS
        netif_reset_xps_queues_gt(sb_dev, 0);
#endif
        memset(sb_dev->tc_to_txq, 0, sizeof(sb_dev->tc_to_txq));
        memset(sb_dev->prio_tc_map, 0, sizeof(sb_dev->prio_tc_map));

        while (txq-- != &dev->_tx[0]) {
                if (txq->sb_dev == sb_dev)
                        txq->sb_dev = NULL;
        }
}
EXPORT_SYMBOL(netdev_unbind_sb_channel);

int netdev_bind_sb_channel_queue(struct net_device *dev,
                                 struct net_device *sb_dev,
                                 u8 tc, u16 count, u16 offset)
{
        /* Make certain the sb_dev and dev are already configured */
        if (sb_dev->num_tc >= 0 || tc >= dev->num_tc)
                return -EINVAL;

        /* We cannot hand out queues we don't have */
        if ((offset + count) > dev->real_num_tx_queues)
                return -EINVAL;

        /* Record the mapping */
        sb_dev->tc_to_txq[tc].count = count;
        sb_dev->tc_to_txq[tc].offset = offset;

        /* Provide a way for Tx queue to find the tc_to_txq map or
         * XPS map for itself.
         */
        while (count--)
                netdev_get_tx_queue(dev, count + offset)->sb_dev = sb_dev;

        return 0;
}
EXPORT_SYMBOL(netdev_bind_sb_channel_queue);

int netdev_set_sb_channel(struct net_device *dev, u16 channel)
{
        /* Do not use a multiqueue device to represent a subordinate channel */
        if (netif_is_multiqueue(dev))
                return -ENODEV;

        /* We allow channels 1 - 32767 to be used for subordinate channels.
         * Channel 0 is meant to be "native" mode and used only to represent
         * the main root device. We allow writing 0 to reset the device back
         * to normal mode after being used as a subordinate channel.
         */
        if (channel > S16_MAX)
                return -EINVAL;

        dev->num_tc = -channel;

        return 0;
}
EXPORT_SYMBOL(netdev_set_sb_channel);

/*
 * Routine to help set real_num_tx_queues. To avoid skbs mapped to queues
 * greater than real_num_tx_queues stale skbs on the qdisc must be flushed.
 */
int netif_set_real_num_tx_queues(struct net_device *dev, unsigned int txq)
{
        bool disabling;
        int rc;

        disabling = txq < dev->real_num_tx_queues;

        if (txq < 1 || txq > dev->num_tx_queues)
                return -EINVAL;

        if (dev->reg_state == NETREG_REGISTERED ||
            dev->reg_state == NETREG_UNREGISTERING) {
                ASSERT_RTNL();

                rc = netdev_queue_update_kobjects(dev, dev->real_num_tx_queues,
                                                  txq);
                if (rc)
                        return rc;

                if (dev->num_tc)
                        netif_setup_tc(dev, txq);

                dev_qdisc_change_real_num_tx(dev, txq);

                dev->real_num_tx_queues = txq;

                if (disabling) {
                        synchronize_net();
                        qdisc_reset_all_tx_gt(dev, txq);
#ifdef CONFIG_XPS
                        netif_reset_xps_queues_gt(dev, txq);
#endif
                }
        } else {
                dev->real_num_tx_queues = txq;
        }

        return 0;
}
EXPORT_SYMBOL(netif_set_real_num_tx_queues);

#ifdef CONFIG_SYSFS
/**
 *      netif_set_real_num_rx_queues - set actual number of RX queues used
 *      @dev: Network device
 *      @rxq: Actual number of RX queues
 *
 *      This must be called either with the rtnl_lock held or before
 *      registration of the net device.  Returns 0 on success, or a
 *      negative error code.  If called before registration, it always
 *      succeeds.
 */
int netif_set_real_num_rx_queues(struct net_device *dev, unsigned int rxq)
{
        int rc;

        if (rxq < 1 || rxq > dev->num_rx_queues)
                return -EINVAL;

        if (dev->reg_state == NETREG_REGISTERED) {
                ASSERT_RTNL();

                rc = net_rx_queue_update_kobjects(dev, dev->real_num_rx_queues,
                                                  rxq);
                if (rc)
                        return rc;
        }

        dev->real_num_rx_queues = rxq;
        return 0;
}
EXPORT_SYMBOL(netif_set_real_num_rx_queues);
#endif

/**
 *      netif_set_real_num_queues - set actual number of RX and TX queues used
 *      @dev: Network device
 *      @txq: Actual number of TX queues
 *      @rxq: Actual number of RX queues
 *
 *      Set the real number of both TX and RX queues.
 *      Does nothing if the number of queues is already correct.
 */
int netif_set_real_num_queues(struct net_device *dev,
                              unsigned int txq, unsigned int rxq)
{
        unsigned int old_rxq = dev->real_num_rx_queues;
        int err;

        if (txq < 1 || txq > dev->num_tx_queues ||
            rxq < 1 || rxq > dev->num_rx_queues)
                return -EINVAL;

        /* Start from increases, so the error path only does decreases -
         * decreases can't fail.
         */
        if (rxq > dev->real_num_rx_queues) {
                err = netif_set_real_num_rx_queues(dev, rxq);
                if (err)
                        return err;
        }
        if (txq > dev->real_num_tx_queues) {
                err = netif_set_real_num_tx_queues(dev, txq);
                if (err)
                        goto undo_rx;
        }
        if (rxq < dev->real_num_rx_queues)
                WARN_ON(netif_set_real_num_rx_queues(dev, rxq));
        if (txq < dev->real_num_tx_queues)
                WARN_ON(netif_set_real_num_tx_queues(dev, txq));

        return 0;
undo_rx:
        WARN_ON(netif_set_real_num_rx_queues(dev, old_rxq));
        return err;
}
EXPORT_SYMBOL(netif_set_real_num_queues);

/**
 * netif_set_tso_max_size() - set the max size of TSO frames supported
 * @dev:        netdev to update
 * @size:       max skb->len of a TSO frame
 *
 * Set the limit on the size of TSO super-frames the device can handle.
 * Unless explicitly set the stack will assume the value of
 * %GSO_LEGACY_MAX_SIZE.
 */
void netif_set_tso_max_size(struct net_device *dev, unsigned int size)
{
        dev->tso_max_size = min(GSO_MAX_SIZE, size);
        if (size < READ_ONCE(dev->gso_max_size))
                netif_set_gso_max_size(dev, size);
        if (size < READ_ONCE(dev->gso_ipv4_max_size))
                netif_set_gso_ipv4_max_size(dev, size);
}
EXPORT_SYMBOL(netif_set_tso_max_size);

/**
 * netif_set_tso_max_segs() - set the max number of segs supported for TSO
 * @dev:        netdev to update
 * @segs:       max number of TCP segments
 *
 * Set the limit on the number of TCP segments the device can generate from
 * a single TSO super-frame.
 * Unless explicitly set the stack will assume the value of %GSO_MAX_SEGS.
 */
void netif_set_tso_max_segs(struct net_device *dev, unsigned int segs)
{
        dev->tso_max_segs = segs;
        if (segs < READ_ONCE(dev->gso_max_segs))
                netif_set_gso_max_segs(dev, segs);
}
EXPORT_SYMBOL(netif_set_tso_max_segs);

/**
 * netif_inherit_tso_max() - copy all TSO limits from a lower device to an upper
 * @to:         netdev to update
 * @from:       netdev from which to copy the limits
 */
void netif_inherit_tso_max(struct net_device *to, const struct net_device *from)
{
        netif_set_tso_max_size(to, from->tso_max_size);
        netif_set_tso_max_segs(to, from->tso_max_segs);
}
EXPORT_SYMBOL(netif_inherit_tso_max);

/**
 * netif_get_num_default_rss_queues - default number of RSS queues
 *
 * Default value is the number of physical cores if there are only 1 or 2, or
 * divided by 2 if there are more.
 */
int netif_get_num_default_rss_queues(void)
{
        cpumask_var_t cpus;
        int cpu, count = 0;

        if (unlikely(is_kdump_kernel() || !zalloc_cpumask_var(&cpus, GFP_KERNEL)))
                return 1;

        cpumask_copy(cpus, cpu_online_mask);
        for_each_cpu(cpu, cpus) {
                ++count;
                cpumask_andnot(cpus, cpus, topology_sibling_cpumask(cpu));
        }
        free_cpumask_var(cpus);

        return count > 2 ? DIV_ROUND_UP(count, 2) : count;
}
EXPORT_SYMBOL(netif_get_num_default_rss_queues);

static void __netif_reschedule(struct Qdisc *q)
{
        struct softnet_data *sd;
        unsigned long flags;

        local_irq_save(flags);
        sd = this_cpu_ptr(&softnet_data);
        q->next_sched = NULL;
        *sd->output_queue_tailp = q;
        sd->output_queue_tailp = &q->next_sched;
        raise_softirq_irqoff(NET_TX_SOFTIRQ);
        local_irq_restore(flags);
}

void __netif_schedule(struct Qdisc *q)
{
        if (!test_and_set_bit(__QDISC_STATE_SCHED, &q->state))
                __netif_reschedule(q);
}
EXPORT_SYMBOL(__netif_schedule);

struct dev_kfree_skb_cb {
        enum skb_drop_reason reason;
};

static struct dev_kfree_skb_cb *get_kfree_skb_cb(const struct sk_buff *skb)
{
        return (struct dev_kfree_skb_cb *)skb->cb;
}

void netif_schedule_queue(struct netdev_queue *txq)
{
        rcu_read_lock();
        if (!netif_xmit_stopped(txq)) {
                struct Qdisc *q = rcu_dereference(txq->qdisc);

                __netif_schedule(q);
        }
        rcu_read_unlock();
}
EXPORT_SYMBOL(netif_schedule_queue);

void netif_tx_wake_queue(struct netdev_queue *dev_queue)
{
        if (test_and_clear_bit(__QUEUE_STATE_DRV_XOFF, &dev_queue->state)) {
                struct Qdisc *q;

                rcu_read_lock();
                q = rcu_dereference(dev_queue->qdisc);
                __netif_schedule(q);
                rcu_read_unlock();
        }
}
EXPORT_SYMBOL(netif_tx_wake_queue);

void dev_kfree_skb_irq_reason(struct sk_buff *skb, enum skb_drop_reason reason)
{
        unsigned long flags;

        if (unlikely(!skb))
                return;

        if (likely(refcount_read(&skb->users) == 1)) {
                smp_rmb();
                refcount_set(&skb->users, 0);
        } else if (likely(!refcount_dec_and_test(&skb->users))) {
                return;
        }
        get_kfree_skb_cb(skb)->reason = reason;
        local_irq_save(flags);
        skb->next = __this_cpu_read(softnet_data.completion_queue);
        __this_cpu_write(softnet_data.completion_queue, skb);
        raise_softirq_irqoff(NET_TX_SOFTIRQ);
        local_irq_restore(flags);
}
EXPORT_SYMBOL(dev_kfree_skb_irq_reason);

void dev_kfree_skb_any_reason(struct sk_buff *skb, enum skb_drop_reason reason)
{
        if (in_hardirq() || irqs_disabled())
                dev_kfree_skb_irq_reason(skb, reason);
        else
                kfree_skb_reason(skb, reason);
}
EXPORT_SYMBOL(dev_kfree_skb_any_reason);


/**
 * netif_device_detach - mark device as removed
 * @dev: network device
 *
 * Mark device as removed from system and therefore no longer available.
 */
void netif_device_detach(struct net_device *dev)
{
        if (test_and_clear_bit(__LINK_STATE_PRESENT, &dev->state) &&
            netif_running(dev)) {
                netif_tx_stop_all_queues(dev);
        }
}
EXPORT_SYMBOL(netif_device_detach);

/**
 * netif_device_attach - mark device as attached
 * @dev: network device
 *
 * Mark device as attached from system and restart if needed.
 */
void netif_device_attach(struct net_device *dev)
{
        if (!test_and_set_bit(__LINK_STATE_PRESENT, &dev->state) &&
            netif_running(dev)) {
                netif_tx_wake_all_queues(dev);
                __netdev_watchdog_up(dev);
        }
}
EXPORT_SYMBOL(netif_device_attach);

/*
 * Returns a Tx hash based on the given packet descriptor a Tx queues' number
 * to be used as a distribution range.
 */
static u16 skb_tx_hash(const struct net_device *dev,
                       const struct net_device *sb_dev,
                       struct sk_buff *skb)
{
        u32 hash;
        u16 qoffset = 0;
        u16 qcount = dev->real_num_tx_queues;

        if (dev->num_tc) {
                u8 tc = netdev_get_prio_tc_map(dev, skb->priority);

                qoffset = sb_dev->tc_to_txq[tc].offset;
                qcount = sb_dev->tc_to_txq[tc].count;
                if (unlikely(!qcount)) {
                        net_warn_ratelimited("%s: invalid qcount, qoffset %u for tc %u\n",
                                             sb_dev->name, qoffset, tc);
                        qoffset = 0;
                        qcount = dev->real_num_tx_queues;
                }
        }

        if (skb_rx_queue_recorded(skb)) {
                DEBUG_NET_WARN_ON_ONCE(qcount == 0);
                hash = skb_get_rx_queue(skb);
                if (hash >= qoffset)
                        hash -= qoffset;
                while (unlikely(hash >= qcount))
                        hash -= qcount;
                return hash + qoffset;
        }

        return (u16) reciprocal_scale(skb_get_hash(skb), qcount) + qoffset;
}

void skb_warn_bad_offload(const struct sk_buff *skb)
{
        static const netdev_features_t null_features;
        struct net_device *dev = skb->dev;
        const char *name = "";

        if (!net_ratelimit())
                return;

        if (dev) {
                if (dev->dev.parent)
                        name = dev_driver_string(dev->dev.parent);
                else
                        name = netdev_name(dev);
        }
        skb_dump(KERN_WARNING, skb, false);
        WARN(1, "%s: caps=(%pNF, %pNF)\n",
             name, dev ? &dev->features : &null_features,
             skb->sk ? &skb->sk->sk_route_caps : &null_features);
}

/*
 * Invalidate hardware checksum when packet is to be mangled, and
 * complete checksum manually on outgoing path.
 */
int skb_checksum_help(struct sk_buff *skb)
{
        __wsum csum;
        int ret = 0, offset;

        if (skb->ip_summed == CHECKSUM_COMPLETE)
                goto out_set_summed;

        if (unlikely(skb_is_gso(skb))) {
                skb_warn_bad_offload(skb);
                return -EINVAL;
        }

        /* Before computing a checksum, we should make sure no frag could
         * be modified by an external entity : checksum could be wrong.
         */
        if (skb_has_shared_frag(skb)) {
                ret = __skb_linearize(skb);
                if (ret)
                        goto out;
        }

        offset = skb_checksum_start_offset(skb);
        ret = -EINVAL;
        if (unlikely(offset >= skb_headlen(skb))) {
                DO_ONCE_LITE(skb_dump, KERN_ERR, skb, false);
                WARN_ONCE(true, "offset (%d) >= skb_headlen() (%u)\n",
                          offset, skb_headlen(skb));
                goto out;
        }
        csum = skb_checksum(skb, offset, skb->len - offset, 0);

        offset += skb->csum_offset;
        if (unlikely(offset + sizeof(__sum16) > skb_headlen(skb))) {
                DO_ONCE_LITE(skb_dump, KERN_ERR, skb, false);
                WARN_ONCE(true, "offset+2 (%zu) > skb_headlen() (%u)\n",
                          offset + sizeof(__sum16), skb_headlen(skb));
                goto out;
        }
        ret = skb_ensure_writable(skb, offset + sizeof(__sum16));
        if (ret)
                goto out;

        *(__sum16 *)(skb->data + offset) = csum_fold(csum) ?: CSUM_MANGLED_0;
out_set_summed:
        skb->ip_summed = CHECKSUM_NONE;
out:
        return ret;
}
EXPORT_SYMBOL(skb_checksum_help);

int skb_crc32c_csum_help(struct sk_buff *skb)
{
        __le32 crc32c_csum;
        int ret = 0, offset, start;

        if (skb->ip_summed != CHECKSUM_PARTIAL)
                goto out;

        if (unlikely(skb_is_gso(skb)))
                goto out;

        /* Before computing a checksum, we should make sure no frag could
         * be modified by an external entity : checksum could be wrong.
         */
        if (unlikely(skb_has_shared_frag(skb))) {
                ret = __skb_linearize(skb);
                if (ret)
                        goto out;
        }
        start = skb_checksum_start_offset(skb);
        offset = start + offsetof(struct sctphdr, checksum);
        if (WARN_ON_ONCE(offset >= skb_headlen(skb))) {
                ret = -EINVAL;
                goto out;
        }

        ret = skb_ensure_writable(skb, offset + sizeof(__le32));
        if (ret)
                goto out;

        crc32c_csum = cpu_to_le32(~__skb_checksum(skb, start,
                                                  skb->len - start, ~(__u32)0,
                                                  crc32c_csum_stub));
        *(__le32 *)(skb->data + offset) = crc32c_csum;
        skb_reset_csum_not_inet(skb);
out:
        return ret;
}

__be16 skb_network_protocol(struct sk_buff *skb, int *depth)
{
        __be16 type = skb->protocol;

        /* Tunnel gso handlers can set protocol to ethernet. */
        if (type == htons(ETH_P_TEB)) {
                struct ethhdr *eth;

                if (unlikely(!pskb_may_pull(skb, sizeof(struct ethhdr))))
                        return 0;

                eth = (struct ethhdr *)skb->data;
                type = eth->h_proto;
        }

        return vlan_get_protocol_and_depth(skb, type, depth);
}


/* Take action when hardware reception checksum errors are detected. */
#ifdef CONFIG_BUG
static void do_netdev_rx_csum_fault(struct net_device *dev, struct sk_buff *skb)
{
        netdev_err(dev, "hw csum failure\n");
        skb_dump(KERN_ERR, skb, true);
        dump_stack();
}

void netdev_rx_csum_fault(struct net_device *dev, struct sk_buff *skb)
{
        DO_ONCE_LITE(do_netdev_rx_csum_fault, dev, skb);
}
EXPORT_SYMBOL(netdev_rx_csum_fault);
#endif

/* XXX: check that highmem exists at all on the given machine. */
static int illegal_highdma(struct net_device *dev, struct sk_buff *skb)
{
#ifdef CONFIG_HIGHMEM
        int i;

        if (!(dev->features & NETIF_F_HIGHDMA)) {
                for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
                        skb_frag_t *frag = &skb_shinfo(skb)->frags[i];

                        if (PageHighMem(skb_frag_page(frag)))
                                return 1;
                }
        }
#endif
        return 0;
}

/* If MPLS offload request, verify we are testing hardware MPLS features
 * instead of standard features for the netdev.
 */
#if IS_ENABLED(CONFIG_NET_MPLS_GSO)
static netdev_features_t net_mpls_features(struct sk_buff *skb,
                                           netdev_features_t features,
                                           __be16 type)
{
        if (eth_p_mpls(type))
                features &= skb->dev->mpls_features;

        return features;
}
#else
static netdev_features_t net_mpls_features(struct sk_buff *skb,
                                           netdev_features_t features,
                                           __be16 type)
{
        return features;
}
#endif

static netdev_features_t harmonize_features(struct sk_buff *skb,
        netdev_features_t features)
{
        __be16 type;

        type = skb_network_protocol(skb, NULL);
        features = net_mpls_features(skb, features, type);

        if (skb->ip_summed != CHECKSUM_NONE &&
            !can_checksum_protocol(features, type)) {
                features &= ~(NETIF_F_CSUM_MASK | NETIF_F_GSO_MASK);
        }
        if (illegal_highdma(skb->dev, skb))
                features &= ~NETIF_F_SG;

        return features;
}

netdev_features_t passthru_features_check(struct sk_buff *skb,
                                          struct net_device *dev,
                                          netdev_features_t features)
{
        return features;
}
EXPORT_SYMBOL(passthru_features_check);

static netdev_features_t dflt_features_check(struct sk_buff *skb,
                                             struct net_device *dev,
                                             netdev_features_t features)
{
        return vlan_features_check(skb, features);
}

static netdev_features_t gso_features_check(const struct sk_buff *skb,
                                            struct net_device *dev,
                                            netdev_features_t features)
{
        u16 gso_segs = skb_shinfo(skb)->gso_segs;

        if (gso_segs > READ_ONCE(dev->gso_max_segs))
                return features & ~NETIF_F_GSO_MASK;

        if (!skb_shinfo(skb)->gso_type) {
                skb_warn_bad_offload(skb);
                return features & ~NETIF_F_GSO_MASK;
        }

        /* Support for GSO partial features requires software
         * intervention before we can actually process the packets
         * so we need to strip support for any partial features now
         * and we can pull them back in after we have partially
         * segmented the frame.
         */
        if (!(skb_shinfo(skb)->gso_type & SKB_GSO_PARTIAL))
                features &= ~dev->gso_partial_features;

        /* Make sure to clear the IPv4 ID mangling feature if the
         * IPv4 header has the potential to be fragmented.
         */
        if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4) {
                struct iphdr *iph = skb->encapsulation ?
                                    inner_ip_hdr(skb) : ip_hdr(skb);

                if (!(iph->frag_off & htons(IP_DF)))
                        features &= ~NETIF_F_TSO_MANGLEID;
        }

        return features;
}

netdev_features_t netif_skb_features(struct sk_buff *skb)
{
        struct net_device *dev = skb->dev;
        netdev_features_t features = dev->features;

        if (skb_is_gso(skb))
                features = gso_features_check(skb, dev, features);

        /* If encapsulation offload request, verify we are testing
         * hardware encapsulation features instead of standard
         * features for the netdev
         */
        if (skb->encapsulation)
                features &= dev->hw_enc_features;

        if (skb_vlan_tagged(skb))
                features = netdev_intersect_features(features,
                                                     dev->vlan_features |
                                                     NETIF_F_HW_VLAN_CTAG_TX |
                                                     NETIF_F_HW_VLAN_STAG_TX);

        if (dev->netdev_ops->ndo_features_check)
                features &= dev->netdev_ops->ndo_features_check(skb, dev,
                                                                features);
        else
                features &= dflt_features_check(skb, dev, features);

        return harmonize_features(skb, features);
}
EXPORT_SYMBOL(netif_skb_features);

static int xmit_one(struct sk_buff *skb, struct net_device *dev,
                    struct netdev_queue *txq, bool more)
{
        unsigned int len;
        int rc;

        if (dev_nit_active(dev))
                dev_queue_xmit_nit(skb, dev);

        len = skb->len;
        trace_net_dev_start_xmit(skb, dev);
        rc = netdev_start_xmit(skb, dev, txq, more);
        trace_net_dev_xmit(skb, rc, dev, len);

        return rc;
}

struct sk_buff *dev_hard_start_xmit(struct sk_buff *first, struct net_device *dev,
                                    struct netdev_queue *txq, int *ret)
{
        struct sk_buff *skb = first;
        int rc = NETDEV_TX_OK;

        while (skb) {
                struct sk_buff *next = skb->next;

                skb_mark_not_on_list(skb);
                rc = xmit_one(skb, dev, txq, next != NULL);
                if (unlikely(!dev_xmit_complete(rc))) {
                        skb->next = next;
                        goto out;
                }

                skb = next;
                if (netif_tx_queue_stopped(txq) && skb) {
                        rc = NETDEV_TX_BUSY;
                        break;
                }
        }

out:
        *ret = rc;
        return skb;
}

static struct sk_buff *validate_xmit_vlan(struct sk_buff *skb,
                                          netdev_features_t features)
{
        if (skb_vlan_tag_present(skb) &&
            !vlan_hw_offload_capable(features, skb->vlan_proto))
                skb = __vlan_hwaccel_push_inside(skb);
        return skb;
}

int skb_csum_hwoffload_help(struct sk_buff *skb,
                            const netdev_features_t features)
{
        if (unlikely(skb_csum_is_sctp(skb)))
                return !!(features & NETIF_F_SCTP_CRC) ? 0 :
                        skb_crc32c_csum_help(skb);

        if (features & NETIF_F_HW_CSUM)
                return 0;

        if (features & (NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM)) {
                switch (skb->csum_offset) {
                case offsetof(struct tcphdr, check):
                case offsetof(struct udphdr, check):
                        return 0;
                }
        }

        return skb_checksum_help(skb);
}
EXPORT_SYMBOL(skb_csum_hwoffload_help);

static struct sk_buff *validate_xmit_skb(struct sk_buff *skb, struct net_device *dev, bool *again)
{
        netdev_features_t features;

        features = netif_skb_features(skb);
        skb = validate_xmit_vlan(skb, features);
        if (unlikely(!skb))
                goto out_null;

        skb = sk_validate_xmit_skb(skb, dev);
        if (unlikely(!skb))
                goto out_null;

        if (netif_needs_gso(skb, features)) {
                struct sk_buff *segs;

                segs = skb_gso_segment(skb, features);
                if (IS_ERR(segs)) {
                        goto out_kfree_skb;
                } else if (segs) {
                        consume_skb(skb);
                        skb = segs;
                }
        } else {
                if (skb_needs_linearize(skb, features) &&
                    __skb_linearize(skb))
                        goto out_kfree_skb;

                /* If packet is not checksummed and device does not
                 * support checksumming for this protocol, complete
                 * checksumming here.
                 */
                if (skb->ip_summed == CHECKSUM_PARTIAL) {
                        if (skb->encapsulation)
                                skb_set_inner_transport_header(skb,
                                                               skb_checksum_start_offset(skb));
                        else
                                skb_set_transport_header(skb,
                                                         skb_checksum_start_offset(skb));
                        if (skb_csum_hwoffload_help(skb, features))
                                goto out_kfree_skb;
                }
        }

        skb = validate_xmit_xfrm(skb, features, again);

        return skb;

out_kfree_skb:
        kfree_skb(skb);
out_null:
        dev_core_stats_tx_dropped_inc(dev);
        return NULL;
}

struct sk_buff *validate_xmit_skb_list(struct sk_buff *skb, struct net_device *dev, bool *again)
{
        struct sk_buff *next, *head = NULL, *tail;

        for (; skb != NULL; skb = next) {
                next = skb->next;
                skb_mark_not_on_list(skb);

                /* in case skb wont be segmented, point to itself */
                skb->prev = skb;

                skb = validate_xmit_skb(skb, dev, again);
                if (!skb)
                        continue;

                if (!head)
                        head = skb;
                else
                        tail->next = skb;
                /* If skb was segmented, skb->prev points to
                 * the last segment. If not, it still contains skb.
                 */
                tail = skb->prev;
        }
        return head;
}
EXPORT_SYMBOL_GPL(validate_xmit_skb_list);

static void qdisc_pkt_len_init(struct sk_buff *skb)
{
        const struct skb_shared_info *shinfo = skb_shinfo(skb);

        qdisc_skb_cb(skb)->pkt_len = skb->len;

        /* To get more precise estimation of bytes sent on wire,
         * we add to pkt_len the headers size of all segments
         */
        if (shinfo->gso_size && skb_transport_header_was_set(skb)) {
                u16 gso_segs = shinfo->gso_segs;
                unsigned int hdr_len;

                /* mac layer + network layer */
                hdr_len = skb_transport_offset(skb);

                /* + transport layer */
                if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) {
                        const struct tcphdr *th;
                        struct tcphdr _tcphdr;

                        th = skb_header_pointer(skb, hdr_len,
                                                sizeof(_tcphdr), &_tcphdr);
                        if (likely(th))
                                hdr_len += __tcp_hdrlen(th);
                } else {
                        struct udphdr _udphdr;

                        if (skb_header_pointer(skb, hdr_len,
                                               sizeof(_udphdr), &_udphdr))
                                hdr_len += sizeof(struct udphdr);
                }

                if (shinfo->gso_type & SKB_GSO_DODGY)
                        gso_segs = DIV_ROUND_UP(skb->len - hdr_len,
                                                shinfo->gso_size);

                qdisc_skb_cb(skb)->pkt_len += (gso_segs - 1) * hdr_len;
        }
}

static int dev_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *q,
                             struct sk_buff **to_free,
                             struct netdev_queue *txq)
{
        int rc;

        rc = q->enqueue(skb, q, to_free) & NET_XMIT_MASK;
        if (rc == NET_XMIT_SUCCESS)
                trace_qdisc_enqueue(q, txq, skb);
        return rc;
}

static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q,
                                 struct net_device *dev,
                                 struct netdev_queue *txq)
{
        spinlock_t *root_lock = qdisc_lock(q);
        struct sk_buff *to_free = NULL;
        bool contended;
        int rc;

        qdisc_calculate_pkt_len(skb, q);

        if (q->flags & TCQ_F_NOLOCK) {
                if (q->flags & TCQ_F_CAN_BYPASS && nolock_qdisc_is_empty(q) &&
                    qdisc_run_begin(q)) {
                        /* Retest nolock_qdisc_is_empty() within the protection
                         * of q->seqlock to protect from racing with requeuing.
                         */
                        if (unlikely(!nolock_qdisc_is_empty(q))) {
                                rc = dev_qdisc_enqueue(skb, q, &to_free, txq);
                                __qdisc_run(q);
                                qdisc_run_end(q);

                                goto no_lock_out;
                        }

                        qdisc_bstats_cpu_update(q, skb);
                        if (sch_direct_xmit(skb, q, dev, txq, NULL, true) &&
                            !nolock_qdisc_is_empty(q))
                                __qdisc_run(q);

                        qdisc_run_end(q);
                        return NET_XMIT_SUCCESS;
                }

                rc = dev_qdisc_enqueue(skb, q, &to_free, txq);
                qdisc_run(q);

no_lock_out:
                if (unlikely(to_free))
                        kfree_skb_list_reason(to_free,
                                              SKB_DROP_REASON_QDISC_DROP);
                return rc;
        }

        /*
         * Heuristic to force contended enqueues to serialize on a
         * separate lock before trying to get qdisc main lock.
         * This permits qdisc->running owner to get the lock more
         * often and dequeue packets faster.
         * On PREEMPT_RT it is possible to preempt the qdisc owner during xmit
         * and then other tasks will only enqueue packets. The packets will be
         * sent after the qdisc owner is scheduled again. To prevent this
         * scenario the task always serialize on the lock.
         */
        contended = qdisc_is_running(q) || IS_ENABLED(CONFIG_PREEMPT_RT);
        if (unlikely(contended))
                spin_lock(&q->busylock);

        spin_lock(root_lock);
        if (unlikely(test_bit(__QDISC_STATE_DEACTIVATED, &q->state))) {
                __qdisc_drop(skb, &to_free);
                rc = NET_XMIT_DROP;
        } else if ((q->flags & TCQ_F_CAN_BYPASS) && !qdisc_qlen(q) &&
                   qdisc_run_begin(q)) {
                /*
                 * This is a work-conserving queue; there are no old skbs
                 * waiting to be sent out; and the qdisc is not running -
                 * xmit the skb directly.
                 */

                qdisc_bstats_update(q, skb);

                if (sch_direct_xmit(skb, q, dev, txq, root_lock, true)) {
                        if (unlikely(contended)) {
                                spin_unlock(&q->busylock);
                                contended = false;
                        }
                        __qdisc_run(q);
                }

                qdisc_run_end(q);
                rc = NET_XMIT_SUCCESS;
        } else {
                rc = dev_qdisc_enqueue(skb, q, &to_free, txq);
                if (qdisc_run_begin(q)) {
                        if (unlikely(contended)) {
                                spin_unlock(&q->busylock);
                                contended = false;
                        }
                        __qdisc_run(q);
                        qdisc_run_end(q);
                }
        }
        spin_unlock(root_lock);
        if (unlikely(to_free))
                kfree_skb_list_reason(to_free, SKB_DROP_REASON_QDISC_DROP);
        if (unlikely(contended))
                spin_unlock(&q->busylock);
        return rc;
}

#if IS_ENABLED(CONFIG_CGROUP_NET_PRIO)
static void skb_update_prio(struct sk_buff *skb)
{
        const struct netprio_map *map;
        const struct sock *sk;
        unsigned int prioidx;

        if (skb->priority)
                return;
        map = rcu_dereference_bh(skb->dev->priomap);
        if (!map)
                return;
        sk = skb_to_full_sk(skb);
        if (!sk)
                return;

        prioidx = sock_cgroup_prioidx(&sk->sk_cgrp_data);

        if (prioidx < map->priomap_len)
                skb->priority = map->priomap[prioidx];
}
#else
#define skb_update_prio(skb)
#endif

/**
 *      dev_loopback_xmit - loop back @skb
 *      @net: network namespace this loopback is happening in
 *      @sk:  sk needed to be a netfilter okfn
 *      @skb: buffer to transmit
 */
int dev_loopback_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
{
        skb_reset_mac_header(skb);
        __skb_pull(skb, skb_network_offset(skb));
        skb->pkt_type = PACKET_LOOPBACK;
        if (skb->ip_summed == CHECKSUM_NONE)
                skb->ip_summed = CHECKSUM_UNNECESSARY;
        DEBUG_NET_WARN_ON_ONCE(!skb_dst(skb));
        skb_dst_force(skb);
        netif_rx(skb);
        return 0;
}
EXPORT_SYMBOL(dev_loopback_xmit);

#ifdef CONFIG_NET_EGRESS
static struct netdev_queue *
netdev_tx_queue_mapping(struct net_device *dev, struct sk_buff *skb)
{
        int qm = skb_get_queue_mapping(skb);

        return netdev_get_tx_queue(dev, netdev_cap_txqueue(dev, qm));
}

static bool netdev_xmit_txqueue_skipped(void)
{
        return __this_cpu_read(softnet_data.xmit.skip_txqueue);
}

void netdev_xmit_skip_txqueue(bool skip)
{
        __this_cpu_write(softnet_data.xmit.skip_txqueue, skip);
}
EXPORT_SYMBOL_GPL(netdev_xmit_skip_txqueue);
#endif /* CONFIG_NET_EGRESS */

#ifdef CONFIG_NET_XGRESS
static int tc_run(struct tcx_entry *entry, struct sk_buff *skb)
{
        int ret = TC_ACT_UNSPEC;
#ifdef CONFIG_NET_CLS_ACT
        struct mini_Qdisc *miniq = rcu_dereference_bh(entry->miniq);
        struct tcf_result res;

        if (!miniq)
                return ret;

        tc_skb_cb(skb)->mru = 0;
        tc_skb_cb(skb)->post_ct = false;

        mini_qdisc_bstats_cpu_update(miniq, skb);
        ret = tcf_classify(skb, miniq->block, miniq->filter_list, &res, false);
        /* Only tcf related quirks below. */
        switch (ret) {
        case TC_ACT_SHOT:
                mini_qdisc_qstats_cpu_drop(miniq);
                break;
        case TC_ACT_OK:
        case TC_ACT_RECLASSIFY:
                skb->tc_index = TC_H_MIN(res.classid);
                break;
        }
#endif /* CONFIG_NET_CLS_ACT */
        return ret;
}

static DEFINE_STATIC_KEY_FALSE(tcx_needed_key);

void tcx_inc(void)
{
        static_branch_inc(&tcx_needed_key);
}

void tcx_dec(void)
{
        static_branch_dec(&tcx_needed_key);
}

static __always_inline enum tcx_action_base
tcx_run(const struct bpf_mprog_entry *entry, struct sk_buff *skb,
        const bool needs_mac)
{
        const struct bpf_mprog_fp *fp;
        const struct bpf_prog *prog;
        int ret = TCX_NEXT;

        if (needs_mac)
                __skb_push(skb, skb->mac_len);
        bpf_mprog_foreach_prog(entry, fp, prog) {
                bpf_compute_data_pointers(skb);
                ret = bpf_prog_run(prog, skb);
                if (ret != TCX_NEXT)
                        break;
        }
        if (needs_mac)
                __skb_pull(skb, skb->mac_len);
        return tcx_action_code(skb, ret);
}

static __always_inline struct sk_buff *
sch_handle_ingress(struct sk_buff *skb, struct packet_type **pt_prev, int *ret,
                   struct net_device *orig_dev, bool *another)
{
        struct bpf_mprog_entry *entry = rcu_dereference_bh(skb->dev->tcx_ingress);
        int sch_ret;

        if (!entry)
                return skb;
        if (*pt_prev) {
                *ret = deliver_skb(skb, *pt_prev, orig_dev);
                *pt_prev = NULL;
        }

        qdisc_skb_cb(skb)->pkt_len = skb->len;
        tcx_set_ingress(skb, true);

        if (static_branch_unlikely(&tcx_needed_key)) {
                sch_ret = tcx_run(entry, skb, true);
                if (sch_ret != TC_ACT_UNSPEC)
                        goto ingress_verdict;
        }
        sch_ret = tc_run(tcx_entry(entry), skb);
ingress_verdict:
        switch (sch_ret) {
        case TC_ACT_REDIRECT:
                /* skb_mac_header check was done by BPF, so we can safely
                 * push the L2 header back before redirecting to another
                 * netdev.
                 */
                __skb_push(skb, skb->mac_len);
                if (skb_do_redirect(skb) == -EAGAIN) {
                        __skb_pull(skb, skb->mac_len);
                        *another = true;
                        break;
                }
                *ret = NET_RX_SUCCESS;
                return NULL;
        case TC_ACT_SHOT:
                kfree_skb_reason(skb, SKB_DROP_REASON_TC_INGRESS);
                *ret = NET_RX_DROP;
                return NULL;
        /* used by tc_run */
        case TC_ACT_STOLEN:
        case TC_ACT_QUEUED:
        case TC_ACT_TRAP:
                consume_skb(skb);
                fallthrough;
        case TC_ACT_CONSUMED:
                *ret = NET_RX_SUCCESS;
                return NULL;
        }

        return skb;
}

static __always_inline struct sk_buff *
sch_handle_egress(struct sk_buff *skb, int *ret, struct net_device *dev)
{
        struct bpf_mprog_entry *entry = rcu_dereference_bh(dev->tcx_egress);
        int sch_ret;

        if (!entry)
                return skb;

        /* qdisc_skb_cb(skb)->pkt_len & tcx_set_ingress() was
         * already set by the caller.
         */
        if (static_branch_unlikely(&tcx_needed_key)) {
                sch_ret = tcx_run(entry, skb, false);
                if (sch_ret != TC_ACT_UNSPEC)
                        goto egress_verdict;
        }
        sch_ret = tc_run(tcx_entry(entry), skb);
egress_verdict:
        switch (sch_ret) {
        case TC_ACT_REDIRECT:
                /* No need to push/pop skb's mac_header here on egress! */
                skb_do_redirect(skb);
                *ret = NET_XMIT_SUCCESS;
                return NULL;
        case TC_ACT_SHOT:
                kfree_skb_reason(skb, SKB_DROP_REASON_TC_EGRESS);
                *ret = NET_XMIT_DROP;
                return NULL;
        /* used by tc_run */
        case TC_ACT_STOLEN:
        case TC_ACT_QUEUED:
        case TC_ACT_TRAP:
                consume_skb(skb);
                fallthrough;
        case TC_ACT_CONSUMED:
                *ret = NET_XMIT_SUCCESS;
                return NULL;
        }

        return skb;
}
#else
static __always_inline struct sk_buff *
sch_handle_ingress(struct sk_buff *skb, struct packet_type **pt_prev, int *ret,
                   struct net_device *orig_dev, bool *another)
{
        return skb;
}

static __always_inline struct sk_buff *
sch_handle_egress(struct sk_buff *skb, int *ret, struct net_device *dev)
{
        return skb;
}
#endif /* CONFIG_NET_XGRESS */

#ifdef CONFIG_XPS
static int __get_xps_queue_idx(struct net_device *dev, struct sk_buff *skb,
                               struct xps_dev_maps *dev_maps, unsigned int tci)
{
        int tc = netdev_get_prio_tc_map(dev, skb->priority);
        struct xps_map *map;
        int queue_index = -1;

        if (tc >= dev_maps->num_tc || tci >= dev_maps->nr_ids)
                return queue_index;

        tci *= dev_maps->num_tc;
        tci += tc;

        map = rcu_dereference(dev_maps->attr_map[tci]);
        if (map) {
                if (map->len == 1)
                        queue_index = map->queues[0];
                else
                        queue_index = map->queues[reciprocal_scale(
                                                skb_get_hash(skb), map->len)];
                if (unlikely(queue_index >= dev->real_num_tx_queues))
                        queue_index = -1;
        }
        return queue_index;
}
#endif

static int get_xps_queue(struct net_device *dev, struct net_device *sb_dev,
                         struct sk_buff *skb)
{
#ifdef CONFIG_XPS
        struct xps_dev_maps *dev_maps;
        struct sock *sk = skb->sk;
        int queue_index = -1;

        if (!static_key_false(&xps_needed))
                return -1;

        rcu_read_lock();
        if (!static_key_false(&xps_rxqs_needed))
                goto get_cpus_map;

        dev_maps = rcu_dereference(sb_dev->xps_maps[XPS_RXQS]);
        if (dev_maps) {
                int tci = sk_rx_queue_get(sk);

                if (tci >= 0)
                        queue_index = __get_xps_queue_idx(dev, skb, dev_maps,
                                                          tci);
        }

get_cpus_map:
        if (queue_index < 0) {
                dev_maps = rcu_dereference(sb_dev->xps_maps[XPS_CPUS]);
                if (dev_maps) {
                        unsigned int tci = skb->sender_cpu - 1;

                        queue_index = __get_xps_queue_idx(dev, skb, dev_maps,
                                                          tci);
                }
        }
        rcu_read_unlock();

        return queue_index;
#else
        return -1;
#endif
}

u16 dev_pick_tx_zero(struct net_device *dev, struct sk_buff *skb,
                     struct net_device *sb_dev)
{
        return 0;
}
EXPORT_SYMBOL(dev_pick_tx_zero);

u16 dev_pick_tx_cpu_id(struct net_device *dev, struct sk_buff *skb,
                       struct net_device *sb_dev)
{
        return (u16)raw_smp_processor_id() % dev->real_num_tx_queues;
}
EXPORT_SYMBOL(dev_pick_tx_cpu_id);

u16 netdev_pick_tx(struct net_device *dev, struct sk_buff *skb,
                     struct net_device *sb_dev)
{
        struct sock *sk = skb->sk;
        int queue_index = sk_tx_queue_get(sk);

        sb_dev = sb_dev ? : dev;

        if (queue_index < 0 || skb->ooo_okay ||
            queue_index >= dev->real_num_tx_queues) {
                int new_index = get_xps_queue(dev, sb_dev, skb);

                if (new_index < 0)
                        new_index = skb_tx_hash(dev, sb_dev, skb);

                if (queue_index != new_index && sk &&
                    sk_fullsock(sk) &&
                    rcu_access_pointer(sk->sk_dst_cache))
                        sk_tx_queue_set(sk, new_index);

                queue_index = new_index;
        }

        return queue_index;
}
EXPORT_SYMBOL(netdev_pick_tx);

struct netdev_queue *netdev_core_pick_tx(struct net_device *dev,
                                         struct sk_buff *skb,
                                         struct net_device *sb_dev)
{
        int queue_index = 0;

#ifdef CONFIG_XPS
        u32 sender_cpu = skb->sender_cpu - 1;

        if (sender_cpu >= (u32)NR_CPUS)
                skb->sender_cpu = raw_smp_processor_id() + 1;
#endif

        if (dev->real_num_tx_queues != 1) {
                const struct net_device_ops *ops = dev->netdev_ops;

                if (ops->ndo_select_queue)
                        queue_index = ops->ndo_select_queue(dev, skb, sb_dev);
                else
                        queue_index = netdev_pick_tx(dev, skb, sb_dev);

                queue_index = netdev_cap_txqueue(dev, queue_index);
        }

        skb_set_queue_mapping(skb, queue_index);
        return netdev_get_tx_queue(dev, queue_index);
}

/**
 * __dev_queue_xmit() - transmit a buffer
 * @skb:        buffer to transmit
 * @sb_dev:     suboordinate device used for L2 forwarding offload
 *
 * Queue a buffer for transmission to a network device. The caller must
 * have set the device and priority and built the buffer before calling
 * this function. The function can be called from an interrupt.
 *
 * When calling this method, interrupts MUST be enabled. This is because
 * the BH enable code must have IRQs enabled so that it will not deadlock.
 *
 * Regardless of the return value, the skb is consumed, so it is currently
 * difficult to retry a send to this method. (You can bump the ref count
 * before sending to hold a reference for retry if you are careful.)
 *
 * Return:
 * * 0                          - buffer successfully transmitted
 * * positive qdisc return code - NET_XMIT_DROP etc.
 * * negative errno             - other errors
 */
int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev)
{
        struct net_device *dev = skb->dev;
        struct netdev_queue *txq = NULL;
        struct Qdisc *q;
        int rc = -ENOMEM;
        bool again = false;

        skb_reset_mac_header(skb);
        skb_assert_len(skb);

        if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_SCHED_TSTAMP))
                __skb_tstamp_tx(skb, NULL, NULL, skb->sk, SCM_TSTAMP_SCHED);

        /* Disable soft irqs for various locks below. Also
         * stops preemption for RCU.
         */
        rcu_read_lock_bh();

        skb_update_prio(skb);

        qdisc_pkt_len_init(skb);
        tcx_set_ingress(skb, false);
#ifdef CONFIG_NET_EGRESS
        if (static_branch_unlikely(&egress_needed_key)) {
                if (nf_hook_egress_active()) {
                        skb = nf_hook_egress(skb, &rc, dev);
                        if (!skb)
                                goto out;
                }

                netdev_xmit_skip_txqueue(false);

                nf_skip_egress(skb, true);
                skb = sch_handle_egress(skb, &rc, dev);
                if (!skb)
                        goto out;
                nf_skip_egress(skb, false);

                if (netdev_xmit_txqueue_skipped())
                        txq = netdev_tx_queue_mapping(dev, skb);
        }
#endif
        /* If device/qdisc don't need skb->dst, release it right now while
         * its hot in this cpu cache.
         */
        if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
                skb_dst_drop(skb);
        else
                skb_dst_force(skb);

        if (!txq)
                txq = netdev_core_pick_tx(dev, skb, sb_dev);

        q = rcu_dereference_bh(txq->qdisc);

        trace_net_dev_queue(skb);
        if (q->enqueue) {
                rc = __dev_xmit_skb(skb, q, dev, txq);
                goto out;
        }

        /* The device has no queue. Common case for software devices:
         * loopback, all the sorts of tunnels...

         * Really, it is unlikely that netif_tx_lock protection is necessary
         * here.  (f.e. loopback and IP tunnels are clean ignoring statistics
         * counters.)
         * However, it is possible, that they rely on protection
         * made by us here.

         * Check this and shot the lock. It is not prone from deadlocks.
         *Either shot noqueue qdisc, it is even simpler 8)
         */
        if (dev->flags & IFF_UP) {
                int cpu = smp_processor_id(); /* ok because BHs are off */

                /* Other cpus might concurrently change txq->xmit_lock_owner
                 * to -1 or to their cpu id, but not to our id.
                 */
                if (READ_ONCE(txq->xmit_lock_owner) != cpu) {
                        if (dev_xmit_recursion())
                                goto recursion_alert;

                        skb = validate_xmit_skb(skb, dev, &again);
                        if (!skb)
                                goto out;

                        HARD_TX_LOCK(dev, txq, cpu);

                        if (!netif_xmit_stopped(txq)) {
                                dev_xmit_recursion_inc();
                                skb = dev_hard_start_xmit(skb, dev, txq, &rc);
                                dev_xmit_recursion_dec();
                                if (dev_xmit_complete(rc)) {
                                        HARD_TX_UNLOCK(dev, txq);
                                        goto out;
                                }
                        }
                        HARD_TX_UNLOCK(dev, txq);
                        net_crit_ratelimited("Virtual device %s asks to queue packet!\n",
                                             dev->name);
                } else {
                        /* Recursion is detected! It is possible,
                         * unfortunately
                         */
recursion_alert:
                        net_crit_ratelimited("Dead loop on virtual device %s, fix it urgently!\n",
                                             dev->name);
                }
        }

        rc = -ENETDOWN;
        rcu_read_unlock_bh();

        dev_core_stats_tx_dropped_inc(dev);
        kfree_skb_list(skb);
        return rc;
out:
        rcu_read_unlock_bh();
        return rc;
}
EXPORT_SYMBOL(__dev_queue_xmit);

int __dev_direct_xmit(struct sk_buff *skb, u16 queue_id)
{
        struct net_device *dev = skb->dev;
        struct sk_buff *orig_skb = skb;
        struct netdev_queue *txq;
        int ret = NETDEV_TX_BUSY;
        bool again = false;

        if (unlikely(!netif_running(dev) ||
                     !netif_carrier_ok(dev)))
                goto drop;

        skb = validate_xmit_skb_list(skb, dev, &again);
        if (skb != orig_skb)
                goto drop;

        skb_set_queue_mapping(skb, queue_id);
        txq = skb_get_tx_queue(dev, skb);

        local_bh_disable();

        dev_xmit_recursion_inc();
        HARD_TX_LOCK(dev, txq, smp_processor_id());
        if (!netif_xmit_frozen_or_drv_stopped(txq))
                ret = netdev_start_xmit(skb, dev, txq, false);
        HARD_TX_UNLOCK(dev, txq);
        dev_xmit_recursion_dec();

        local_bh_enable();
        return ret;
drop:
        dev_core_stats_tx_dropped_inc(dev);
        kfree_skb_list(skb);
        return NET_XMIT_DROP;
}
EXPORT_SYMBOL(__dev_direct_xmit);

/*************************************************************************
 *                      Receiver routines
 *************************************************************************/

int netdev_max_backlog __read_mostly = 1000;
EXPORT_SYMBOL(netdev_max_backlog);

int netdev_tstamp_prequeue __read_mostly = 1;
unsigned int sysctl_skb_defer_max __read_mostly = 64;
int netdev_budget __read_mostly = 300;
/* Must be at least 2 jiffes to guarantee 1 jiffy timeout */
unsigned int __read_mostly netdev_budget_usecs = 2 * USEC_PER_SEC / HZ;
int weight_p __read_mostly = 64;           /* old backlog weight */
int dev_weight_rx_bias __read_mostly = 1;  /* bias for backlog weight */
int dev_weight_tx_bias __read_mostly = 1;  /* bias for output_queue quota */
int dev_rx_weight __read_mostly = 64;
int dev_tx_weight __read_mostly = 64;

/* Called with irq disabled */
static inline void ____napi_schedule(struct softnet_data *sd,
                                     struct napi_struct *napi)
{
        struct task_struct *thread;

        lockdep_assert_irqs_disabled();

        if (test_bit(NAPI_STATE_THREADED, &napi->state)) {
                /* Paired with smp_mb__before_atomic() in
                 * napi_enable()/dev_set_threaded().
                 * Use READ_ONCE() to guarantee a complete
                 * read on napi->thread. Only call
                 * wake_up_process() when it's not NULL.
                 */
                thread = READ_ONCE(napi->thread);
                if (thread) {
                        /* Avoid doing set_bit() if the thread is in
                         * INTERRUPTIBLE state, cause napi_thread_wait()
                         * makes sure to proceed with napi polling
                         * if the thread is explicitly woken from here.
                         */
                        if (READ_ONCE(thread->__state) != TASK_INTERRUPTIBLE)
                                set_bit(NAPI_STATE_SCHED_THREADED, &napi->state);
                        wake_up_process(thread);
                        return;
                }
        }

        list_add_tail(&napi->poll_list, &sd->poll_list);
        WRITE_ONCE(napi->list_owner, smp_processor_id());
        /* If not called from net_rx_action()
         * we have to raise NET_RX_SOFTIRQ.
         */
        if (!sd->in_net_rx_action)
                __raise_softirq_irqoff(NET_RX_SOFTIRQ);
}

#ifdef CONFIG_RPS

/* One global table that all flow-based protocols share. */
struct rps_sock_flow_table __rcu *rps_sock_flow_table __read_mostly;
EXPORT_SYMBOL(rps_sock_flow_table);
u32 rps_cpu_mask __read_mostly;
EXPORT_SYMBOL(rps_cpu_mask);

struct static_key_false rps_needed __read_mostly;
EXPORT_SYMBOL(rps_needed);
struct static_key_false rfs_needed __read_mostly;
EXPORT_SYMBOL(rfs_needed);

static struct rps_dev_flow *
set_rps_cpu(struct net_device *dev, struct sk_buff *skb,
            struct rps_dev_flow *rflow, u16 next_cpu)
{
        if (next_cpu < nr_cpu_ids) {
#ifdef CONFIG_RFS_ACCEL
                struct netdev_rx_queue *rxqueue;
                struct rps_dev_flow_table *flow_table;
                struct rps_dev_flow *old_rflow;
                u32 flow_id;
                u16 rxq_index;
                int rc;

                /* Should we steer this flow to a different hardware queue? */
                if (!skb_rx_queue_recorded(skb) || !dev->rx_cpu_rmap ||
                    !(dev->features & NETIF_F_NTUPLE))
                        goto out;
                rxq_index = cpu_rmap_lookup_index(dev->rx_cpu_rmap, next_cpu);
                if (rxq_index == skb_get_rx_queue(skb))
                        goto out;

                rxqueue = dev->_rx + rxq_index;
                flow_table = rcu_dereference(rxqueue->rps_flow_table);
                if (!flow_table)
                        goto out;
                flow_id = skb_get_hash(skb) & flow_table->mask;
                rc = dev->netdev_ops->ndo_rx_flow_steer(dev, skb,
                                                        rxq_index, flow_id);
                if (rc < 0)
                        goto out;
                old_rflow = rflow;
                rflow = &flow_table->flows[flow_id];
                rflow->filter = rc;
                if (old_rflow->filter == rflow->filter)
                        old_rflow->filter = RPS_NO_FILTER;
        out:
#endif
                rflow->last_qtail =
                        per_cpu(softnet_data, next_cpu).input_queue_head;
        }

        rflow->cpu = next_cpu;
        return rflow;
}

/*
 * get_rps_cpu is called from netif_receive_skb and returns the target
 * CPU from the RPS map of the receiving queue for a given skb.
 * rcu_read_lock must be held on entry.
 */
static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
                       struct rps_dev_flow **rflowp)
{
        const struct rps_sock_flow_table *sock_flow_table;
        struct netdev_rx_queue *rxqueue = dev->_rx;
        struct rps_dev_flow_table *flow_table;
        struct rps_map *map;
        int cpu = -1;
        u32 tcpu;
        u32 hash;

        if (skb_rx_queue_recorded(skb)) {
                u16 index = skb_get_rx_queue(skb);

                if (unlikely(index >= dev->real_num_rx_queues)) {
                        WARN_ONCE(dev->real_num_rx_queues > 1,
                                  "%s received packet on queue %u, but number "
                                  "of RX queues is %u\n",
                                  dev->name, index, dev->real_num_rx_queues);
                        goto done;
                }
                rxqueue += index;
        }

        /* Avoid computing hash if RFS/RPS is not active for this rxqueue */

        flow_table = rcu_dereference(rxqueue->rps_flow_table);
        map = rcu_dereference(rxqueue->rps_map);
        if (!flow_table && !map)
                goto done;

        skb_reset_network_header(skb);
        hash = skb_get_hash(skb);
        if (!hash)
                goto done;

        sock_flow_table = rcu_dereference(rps_sock_flow_table);
        if (flow_table && sock_flow_table) {
                struct rps_dev_flow *rflow;
                u32 next_cpu;
                u32 ident;

                /* First check into global flow table if there is a match.
                 * This READ_ONCE() pairs with WRITE_ONCE() from rps_record_sock_flow().
                 */
                ident = READ_ONCE(sock_flow_table->ents[hash & sock_flow_table->mask]);
                if ((ident ^ hash) & ~rps_cpu_mask)
                        goto try_rps;

                next_cpu = ident & rps_cpu_mask;

                /* OK, now we know there is a match,
                 * we can look at the local (per receive queue) flow table
                 */
                rflow = &flow_table->flows[hash & flow_table->mask];
                tcpu = rflow->cpu;

                /*
                 * If the desired CPU (where last recvmsg was done) is
                 * different from current CPU (one in the rx-queue flow
                 * table entry), switch if one of the following holds:
                 *   - Current CPU is unset (>= nr_cpu_ids).
                 *   - Current CPU is offline.
                 *   - The current CPU's queue tail has advanced beyond the
                 *     last packet that was enqueued using this table entry.
                 *     This guarantees that all previous packets for the flow
                 *     have been dequeued, thus preserving in order delivery.
                 */
                if (unlikely(tcpu != next_cpu) &&
                    (tcpu >= nr_cpu_ids || !cpu_online(tcpu) ||
                     ((int)(per_cpu(softnet_data, tcpu).input_queue_head -
                      rflow->last_qtail)) >= 0)) {
                        tcpu = next_cpu;
                        rflow = set_rps_cpu(dev, skb, rflow, next_cpu);
                }

                if (tcpu < nr_cpu_ids && cpu_online(tcpu)) {
                        *rflowp = rflow;
                        cpu = tcpu;
                        goto done;
                }
        }

try_rps:

        if (map) {
                tcpu = map->cpus[reciprocal_scale(hash, map->len)];
                if (cpu_online(tcpu)) {
                        cpu = tcpu;
                        goto done;
                }
        }

done:
        return cpu;
}

#ifdef CONFIG_RFS_ACCEL

/**
 * rps_may_expire_flow - check whether an RFS hardware filter may be removed
 * @dev: Device on which the filter was set
 * @rxq_index: RX queue index
 * @flow_id: Flow ID passed to ndo_rx_flow_steer()
 * @filter_id: Filter ID returned by ndo_rx_flow_steer()
 *
 * Drivers that implement ndo_rx_flow_steer() should periodically call
 * this function for each installed filter and remove the filters for
 * which it returns %true.
 */
bool rps_may_expire_flow(struct net_device *dev, u16 rxq_index,
                         u32 flow_id, u16 filter_id)
{
        struct netdev_rx_queue *rxqueue = dev->_rx + rxq_index;
        struct rps_dev_flow_table *flow_table;
        struct rps_dev_flow *rflow;
        bool expire = true;
        unsigned int cpu;

        rcu_read_lock();
        flow_table = rcu_dereference(rxqueue->rps_flow_table);
        if (flow_table && flow_id <= flow_table->mask) {
                rflow = &flow_table->flows[flow_id];
                cpu = READ_ONCE(rflow->cpu);
                if (rflow->filter == filter_id && cpu < nr_cpu_ids &&
                    ((int)(per_cpu(softnet_data, cpu).input_queue_head -
                           rflow->last_qtail) <
                     (int)(10 * flow_table->mask)))
                        expire = false;
        }
        rcu_read_unlock();
        return expire;
}
EXPORT_SYMBOL(rps_may_expire_flow);

#endif /* CONFIG_RFS_ACCEL */

/* Called from hardirq (IPI) context */
static void rps_trigger_softirq(void *data)
{
        struct softnet_data *sd = data;

        ____napi_schedule(sd, &sd->backlog);
        sd->received_rps++;
}

#endif /* CONFIG_RPS */

/* Called from hardirq (IPI) context */
static void trigger_rx_softirq(void *data)
{
        struct softnet_data *sd = data;

        __raise_softirq_irqoff(NET_RX_SOFTIRQ);
        smp_store_release(&sd->defer_ipi_scheduled, 0);
}

/*
 * After we queued a packet into sd->input_pkt_queue,
 * we need to make sure this queue is serviced soon.
 *
 * - If this is another cpu queue, link it to our rps_ipi_list,
 *   and make sure we will process rps_ipi_list from net_rx_action().
 *
 * - If this is our own queue, NAPI schedule our backlog.
 *   Note that this also raises NET_RX_SOFTIRQ.
 */
static void napi_schedule_rps(struct softnet_data *sd)
{
        struct softnet_data *mysd = this_cpu_ptr(&softnet_data);

#ifdef CONFIG_RPS
        if (sd != mysd) {
                sd->rps_ipi_next = mysd->rps_ipi_list;
                mysd->rps_ipi_list = sd;

                /* If not called from net_rx_action() or napi_threaded_poll()
                 * we have to raise NET_RX_SOFTIRQ.
                 */
                if (!mysd->in_net_rx_action && !mysd->in_napi_threaded_poll)
                        __raise_softirq_irqoff(NET_RX_SOFTIRQ);
                return;
        }
#endif /* CONFIG_RPS */
        __napi_schedule_irqoff(&mysd->backlog);
}

#ifdef CONFIG_NET_FLOW_LIMIT
int netdev_flow_limit_table_len __read_mostly = (1 << 12);
#endif

static bool skb_flow_limit(struct sk_buff *skb, unsigned int qlen)
{
#ifdef CONFIG_NET_FLOW_LIMIT
        struct sd_flow_limit *fl;
        struct softnet_data *sd;
        unsigned int old_flow, new_flow;

        if (qlen < (READ_ONCE(netdev_max_backlog) >> 1))
                return false;

        sd = this_cpu_ptr(&softnet_data);

        rcu_read_lock();
        fl = rcu_dereference(sd->flow_limit);
        if (fl) {
                new_flow = skb_get_hash(skb) & (fl->num_buckets - 1);
                old_flow = fl->history[fl->history_head];
                fl->history[fl->history_head] = new_flow;

                fl->history_head++;
                fl->history_head &= FLOW_LIMIT_HISTORY - 1;

                if (likely(fl->buckets[old_flow]))
                        fl->buckets[old_flow]--;

                if (++fl->buckets[new_flow] > (FLOW_LIMIT_HISTORY >> 1)) {
                        fl->count++;
                        rcu_read_unlock();
                        return true;
                }
        }
        rcu_read_unlock();
#endif
        return false;
}

/*
 * enqueue_to_backlog is called to queue an skb to a per CPU backlog
 * queue (may be a remote CPU queue).
 */
static int enqueue_to_backlog(struct sk_buff *skb, int cpu,
                              unsigned int *qtail)
{
        enum skb_drop_reason reason;
        struct softnet_data *sd;
        unsigned long flags;
        unsigned int qlen;

        reason = SKB_DROP_REASON_NOT_SPECIFIED;
        sd = &per_cpu(softnet_data, cpu);

        rps_lock_irqsave(sd, &flags);
        if (!netif_running(skb->dev))
                goto drop;
        qlen = skb_queue_len(&sd->input_pkt_queue);
        if (qlen <= READ_ONCE(netdev_max_backlog) && !skb_flow_limit(skb, qlen)) {
                if (qlen) {
enqueue:
                        __skb_queue_tail(&sd->input_pkt_queue, skb);
                        input_queue_tail_incr_save(sd, qtail);
                        rps_unlock_irq_restore(sd, &flags);
                        return NET_RX_SUCCESS;
                }

                /* Schedule NAPI for backlog device
                 * We can use non atomic operation since we own the queue lock
                 */
                if (!__test_and_set_bit(NAPI_STATE_SCHED, &sd->backlog.state))
                        napi_schedule_rps(sd);
                goto enqueue;
        }
        reason = SKB_DROP_REASON_CPU_BACKLOG;

drop:
        sd->dropped++;
        rps_unlock_irq_restore(sd, &flags);

        dev_core_stats_rx_dropped_inc(skb->dev);
        kfree_skb_reason(skb, reason);
        return NET_RX_DROP;
}

static struct netdev_rx_queue *netif_get_rxqueue(struct sk_buff *skb)
{
        struct net_device *dev = skb->dev;
        struct netdev_rx_queue *rxqueue;

        rxqueue = dev->_rx;

        if (skb_rx_queue_recorded(skb)) {
                u16 index = skb_get_rx_queue(skb);

                if (unlikely(index >= dev->real_num_rx_queues)) {
                        WARN_ONCE(dev->real_num_rx_queues > 1,
                                  "%s received packet on queue %u, but number "
                                  "of RX queues is %u\n",
                                  dev->name, index, dev->real_num_rx_queues);

                        return rxqueue; /* Return first rxqueue */
                }
                rxqueue += index;
        }
        return rxqueue;
}

u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
                             struct bpf_prog *xdp_prog)
{
        void *orig_data, *orig_data_end, *hard_start;
        struct netdev_rx_queue *rxqueue;
        bool orig_bcast, orig_host;
        u32 mac_len, frame_sz;
        __be16 orig_eth_type;
        struct ethhdr *eth;
        u32 metalen, act;
        int off;

        /* The XDP program wants to see the packet starting at the MAC
         * header.
         */
        mac_len = skb->data - skb_mac_header(skb);
        hard_start = skb->data - skb_headroom(skb);

        /* SKB "head" area always have tailroom for skb_shared_info */
        frame_sz = (void *)skb_end_pointer(skb) - hard_start;
        frame_sz += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));

        rxqueue = netif_get_rxqueue(skb);
        xdp_init_buff(xdp, frame_sz, &rxqueue->xdp_rxq);
        xdp_prepare_buff(xdp, hard_start, skb_headroom(skb) - mac_len,
                         skb_headlen(skb) + mac_len, true);

        orig_data_end = xdp->data_end;
        orig_data = xdp->data;
        eth = (struct ethhdr *)xdp->data;
        orig_host = ether_addr_equal_64bits(eth->h_dest, skb->dev->dev_addr);
        orig_bcast = is_multicast_ether_addr_64bits(eth->h_dest);
        orig_eth_type = eth->h_proto;

        act = bpf_prog_run_xdp(xdp_prog, xdp);

        /* check if bpf_xdp_adjust_head was used */
        off = xdp->data - orig_data;
        if (off) {
                if (off > 0)
                        __skb_pull(skb, off);
                else if (off < 0)
                        __skb_push(skb, -off);

                skb->mac_header += off;
                skb_reset_network_header(skb);
        }

        /* check if bpf_xdp_adjust_tail was used */
        off = xdp->data_end - orig_data_end;
        if (off != 0) {
                skb_set_tail_pointer(skb, xdp->data_end - xdp->data);
                skb->len += off; /* positive on grow, negative on shrink */
        }

        /* check if XDP changed eth hdr such SKB needs update */
        eth = (struct ethhdr *)xdp->data;
        if ((orig_eth_type != eth->h_proto) ||
            (orig_host != ether_addr_equal_64bits(eth->h_dest,
                                                  skb->dev->dev_addr)) ||
            (orig_bcast != is_multicast_ether_addr_64bits(eth->h_dest))) {
                __skb_push(skb, ETH_HLEN);
                skb->pkt_type = PACKET_HOST;
                skb->protocol = eth_type_trans(skb, skb->dev);
        }

        /* Redirect/Tx gives L2 packet, code that will reuse skb must __skb_pull
         * before calling us again on redirect path. We do not call do_redirect
         * as we leave that up to the caller.
         *
         * Caller is responsible for managing lifetime of skb (i.e. calling
         * kfree_skb in response to actions it cannot handle/XDP_DROP).
         */
        switch (act) {
        case XDP_REDIRECT:
        case XDP_TX:
                __skb_push(skb, mac_len);
                break;
        case XDP_PASS:
                metalen = xdp->data - xdp->data_meta;
                if (metalen)
                        skb_metadata_set(skb, metalen);
                break;
        }

        return act;
}

static u32 netif_receive_generic_xdp(struct sk_buff *skb,
                                     struct xdp_buff *xdp,
                                     struct bpf_prog *xdp_prog)
{
        u32 act = XDP_DROP;

        /* Reinjected packets coming from act_mirred or similar should
         * not get XDP generic processing.
         */
        if (skb_is_redirected(skb))
                return XDP_PASS;

        /* XDP packets must be linear and must have sufficient headroom
         * of XDP_PACKET_HEADROOM bytes. This is the guarantee that also
         * native XDP provides, thus we need to do it here as well.
         */
        if (skb_cloned(skb) || skb_is_nonlinear(skb) ||
            skb_headroom(skb) < XDP_PACKET_HEADROOM) {
                int hroom = XDP_PACKET_HEADROOM - skb_headroom(skb);
                int troom = skb->tail + skb->data_len - skb->end;

                /* In case we have to go down the path and also linearize,
                 * then lets do the pskb_expand_head() work just once here.
                 */
                if (pskb_expand_head(skb,
                                     hroom > 0 ? ALIGN(hroom, NET_SKB_PAD) : 0,
                                     troom > 0 ? troom + 128 : 0, GFP_ATOMIC))
                        goto do_drop;
                if (skb_linearize(skb))
                        goto do_drop;
        }

        act = bpf_prog_run_generic_xdp(skb, xdp, xdp_prog);
        switch (act) {
        case XDP_REDIRECT:
        case XDP_TX:
        case XDP_PASS:
                break;
        default:
                bpf_warn_invalid_xdp_action(skb->dev, xdp_prog, act);
                fallthrough;
        case XDP_ABORTED:
                trace_xdp_exception(skb->dev, xdp_prog, act);
                fallthrough;
        case XDP_DROP:
        do_drop:
                kfree_skb(skb);
                break;
        }

        return act;
}

/* When doing generic XDP we have to bypass the qdisc layer and the
 * network taps in order to match in-driver-XDP behavior. This also means
 * that XDP packets are able to starve other packets going through a qdisc,
 * and DDOS attacks will be more effective. In-driver-XDP use dedicated TX
 * queues, so they do not have this starvation issue.
 */
void generic_xdp_tx(struct sk_buff *skb, struct bpf_prog *xdp_prog)
{
        struct net_device *dev = skb->dev;
        struct netdev_queue *txq;
        bool free_skb = true;
        int cpu, rc;

        txq = netdev_core_pick_tx(dev, skb, NULL);
        cpu = smp_processor_id();
        HARD_TX_LOCK(dev, txq, cpu);
        if (!netif_xmit_frozen_or_drv_stopped(txq)) {
                rc = netdev_start_xmit(skb, dev, txq, 0);
                if (dev_xmit_complete(rc))
                        free_skb = false;
        }
        HARD_TX_UNLOCK(dev, txq);
        if (free_skb) {
                trace_xdp_exception(dev, xdp_prog, XDP_TX);
                dev_core_stats_tx_dropped_inc(dev);
                kfree_skb(skb);
        }
}

static DEFINE_STATIC_KEY_FALSE(generic_xdp_needed_key);

int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb)
{
        if (xdp_prog) {
                struct xdp_buff xdp;
                u32 act;
                int err;

                act = netif_receive_generic_xdp(skb, &xdp, xdp_prog);
                if (act != XDP_PASS) {
                        switch (act) {
                        case XDP_REDIRECT:
                                err = xdp_do_generic_redirect(skb->dev, skb,
                                                              &xdp, xdp_prog);
                                if (err)
                                        goto out_redir;
                                break;
                        case XDP_TX:
                                generic_xdp_tx(skb, xdp_prog);
                                break;
                        }
                        return XDP_DROP;
                }
        }
        return XDP_PASS;
out_redir:
        kfree_skb_reason(skb, SKB_DROP_REASON_XDP);
        return XDP_DROP;
}
EXPORT_SYMBOL_GPL(do_xdp_generic);

static int netif_rx_internal(struct sk_buff *skb)
{
        int ret;

        net_timestamp_check(READ_ONCE(netdev_tstamp_prequeue), skb);

        trace_netif_rx(skb);

#ifdef CONFIG_RPS
        if (static_branch_unlikely(&rps_needed)) {
                struct rps_dev_flow voidflow, *rflow = &voidflow;
                int cpu;

                rcu_read_lock();

                cpu = get_rps_cpu(skb->dev, skb, &rflow);
                if (cpu < 0)
                        cpu = smp_processor_id();

                ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);

                rcu_read_unlock();
        } else
#endif
        {
                unsigned int qtail;

                ret = enqueue_to_backlog(skb, smp_processor_id(), &qtail);
        }
        return ret;
}

/**
 *      __netif_rx      -       Slightly optimized version of netif_rx
 *      @skb: buffer to post
 *
 *      This behaves as netif_rx except that it does not disable bottom halves.
 *      As a result this function may only be invoked from the interrupt context
 *      (either hard or soft interrupt).
 */
int __netif_rx(struct sk_buff *skb)
{
        int ret;

        lockdep_assert_once(hardirq_count() | softirq_count());

        trace_netif_rx_entry(skb);
        ret = netif_rx_internal(skb);
        trace_netif_rx_exit(ret);
        return ret;
}
EXPORT_SYMBOL(__netif_rx);

/**
 *      netif_rx        -       post buffer to the network code
 *      @skb: buffer to post
 *
 *      This function receives a packet from a device driver and queues it for
 *      the upper (protocol) levels to process via the backlog NAPI device. It
 *      always succeeds. The buffer may be dropped during processing for
 *      congestion control or by the protocol layers.
 *      The network buffer is passed via the backlog NAPI device. Modern NIC
 *      driver should use NAPI and GRO.
 *      This function can used from interrupt and from process context. The
 *      caller from process context must not disable interrupts before invoking
 *      this function.
 *
 *      return values:
 *      NET_RX_SUCCESS  (no congestion)
 *      NET_RX_DROP     (packet was dropped)
 *
 */
int netif_rx(struct sk_buff *skb)
{
        bool need_bh_off = !(hardirq_count() | softirq_count());
        int ret;

        if (need_bh_off)
                local_bh_disable();
        trace_netif_rx_entry(skb);
        ret = netif_rx_internal(skb);
        trace_netif_rx_exit(ret);
        if (need_bh_off)
                local_bh_enable();
        return ret;
}
EXPORT_SYMBOL(netif_rx);

static __latent_entropy void net_tx_action(struct softirq_action *h)
{
        struct softnet_data *sd = this_cpu_ptr(&softnet_data);

        if (sd->completion_queue) {
                struct sk_buff *clist;

                local_irq_disable();
                clist = sd->completion_queue;
                sd->completion_queue = NULL;
                local_irq_enable();

                while (clist) {
                        struct sk_buff *skb = clist;

                        clist = clist->next;

                        WARN_ON(refcount_read(&skb->users));
                        if (likely(get_kfree_skb_cb(skb)->reason == SKB_CONSUMED))
                                trace_consume_skb(skb, net_tx_action);
                        else
                                trace_kfree_skb(skb, net_tx_action,
                                                get_kfree_skb_cb(skb)->reason);

                        if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
                                __kfree_skb(skb);
                        else
                                __napi_kfree_skb(skb,
                                                 get_kfree_skb_cb(skb)->reason);
                }
        }

        if (sd->output_queue) {
                struct Qdisc *head;

                local_irq_disable();
                head = sd->output_queue;
                sd->output_queue = NULL;
                sd->output_queue_tailp = &sd->output_queue;
                local_irq_enable();

                rcu_read_lock();

                while (head) {
                        struct Qdisc *q = head;
                        spinlock_t *root_lock = NULL;

                        head = head->next_sched;

                        /* We need to make sure head->next_sched is read
                         * before clearing __QDISC_STATE_SCHED
                         */
                        smp_mb__before_atomic();

                        if (!(q->flags & TCQ_F_NOLOCK)) {
                                root_lock = qdisc_lock(q);
                                spin_lock(root_lock);
                        } else if (unlikely(test_bit(__QDISC_STATE_DEACTIVATED,
                                                     &q->state))) {
                                /* There is a synchronize_net() between
                                 * STATE_DEACTIVATED flag being set and
                                 * qdisc_reset()/some_qdisc_is_busy() in
                                 * dev_deactivate(), so we can safely bail out
                                 * early here to avoid data race between
                                 * qdisc_deactivate() and some_qdisc_is_busy()
                                 * for lockless qdisc.
                                 */
                                clear_bit(__QDISC_STATE_SCHED, &q->state);
                                continue;
                        }

                        clear_bit(__QDISC_STATE_SCHED, &q->state);
                        qdisc_run(q);
                        if (root_lock)
                                spin_unlock(root_lock);
                }

                rcu_read_unlock();
        }

        xfrm_dev_backlog(sd);
}

#if IS_ENABLED(CONFIG_BRIDGE) && IS_ENABLED(CONFIG_ATM_LANE)
/* This hook is defined here for ATM LANE */
int (*br_fdb_test_addr_hook)(struct net_device *dev,
                             unsigned char *addr) __read_mostly;
EXPORT_SYMBOL_GPL(br_fdb_test_addr_hook);
#endif

/**
 *      netdev_is_rx_handler_busy - check if receive handler is registered
 *      @dev: device to check
 *
 *      Check if a receive handler is already registered for a given device.
 *      Return true if there one.
 *
 *      The caller must hold the rtnl_mutex.
 */
bool netdev_is_rx_handler_busy(struct net_device *dev)
{
        ASSERT_RTNL();
        return dev && rtnl_dereference(dev->rx_handler);
}
EXPORT_SYMBOL_GPL(netdev_is_rx_handler_busy);

/**
 *      netdev_rx_handler_register - register receive handler
 *      @dev: device to register a handler for
 *      @rx_handler: receive handler to register
 *      @rx_handler_data: data pointer that is used by rx handler
 *
 *      Register a receive handler for a device. This handler will then be
 *      called from __netif_receive_skb. A negative errno code is returned
 *      on a failure.
 *
 *      The caller must hold the rtnl_mutex.
 *
 *      For a general description of rx_handler, see enum rx_handler_result.
 */
int netdev_rx_handler_register(struct net_device *dev,
                               rx_handler_func_t *rx_handler,
                               void *rx_handler_data)
{
        if (netdev_is_rx_handler_busy(dev))
                return -EBUSY;

        if (dev->priv_flags & IFF_NO_RX_HANDLER)
                return -EINVAL;

        /* Note: rx_handler_data must be set before rx_handler */
        rcu_assign_pointer(dev->rx_handler_data, rx_handler_data);
        rcu_assign_pointer(dev->rx_handler, rx_handler);

        return 0;
}
EXPORT_SYMBOL_GPL(netdev_rx_handler_register);

/**
 *      netdev_rx_handler_unregister - unregister receive handler
 *      @dev: device to unregister a handler from
 *
 *      Unregister a receive handler from a device.
 *
 *      The caller must hold the rtnl_mutex.
 */
void netdev_rx_handler_unregister(struct net_device *dev)
{

        ASSERT_RTNL();
        RCU_INIT_POINTER(dev->rx_handler, NULL);
        /* a reader seeing a non NULL rx_handler in a rcu_read_lock()
         * section has a guarantee to see a non NULL rx_handler_data
         * as well.
         */
        synchronize_net();
        RCU_INIT_POINTER(dev->rx_handler_data, NULL);
}
EXPORT_SYMBOL_GPL(netdev_rx_handler_unregister);

/*
 * Limit the use of PFMEMALLOC reserves to those protocols that implement
 * the special handling of PFMEMALLOC skbs.
 */
static bool skb_pfmemalloc_protocol(struct sk_buff *skb)
{
        switch (skb->protocol) {
        case htons(ETH_P_ARP):
        case htons(ETH_P_IP):
        case htons(ETH_P_IPV6):
        case htons(ETH_P_8021Q):
        case htons(ETH_P_8021AD):
                return true;
        default:
                return false;
        }
}

static inline int nf_ingress(struct sk_buff *skb, struct packet_type **pt_prev,
                             int *ret, struct net_device *orig_dev)
{
        if (nf_hook_ingress_active(skb)) {
                int ingress_retval;

                if (*pt_prev) {
                        *ret = deliver_skb(skb, *pt_prev, orig_dev);
                        *pt_prev = NULL;
                }

                rcu_read_lock();
                ingress_retval = nf_hook_ingress(skb);
                rcu_read_unlock();
                return ingress_retval;
        }
        return 0;
}

static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc,
                                    struct packet_type **ppt_prev)
{
        struct packet_type *ptype, *pt_prev;
        rx_handler_func_t *rx_handler;
        struct sk_buff *skb = *pskb;
        struct net_device *orig_dev;
        bool deliver_exact = false;
        int ret = NET_RX_DROP;
        __be16 type;

        net_timestamp_check(!READ_ONCE(netdev_tstamp_prequeue), skb);

        trace_netif_receive_skb(skb);

        orig_dev = skb->dev;

        skb_reset_network_header(skb);
        if (!skb_transport_header_was_set(skb))
                skb_reset_transport_header(skb);
        skb_reset_mac_len(skb);

        pt_prev = NULL;

another_round:
        skb->skb_iif = skb->dev->ifindex;

        __this_cpu_inc(softnet_data.processed);

        if (static_branch_unlikely(&generic_xdp_needed_key)) {
                int ret2;

                migrate_disable();
                ret2 = do_xdp_generic(rcu_dereference(skb->dev->xdp_prog), skb);
                migrate_enable();

                if (ret2 != XDP_PASS) {
                        ret = NET_RX_DROP;
                        goto out;
                }
        }

        if (eth_type_vlan(skb->protocol)) {
                skb = skb_vlan_untag(skb);
                if (unlikely(!skb))
                        goto out;
        }

        if (skb_skip_tc_classify(skb))
                goto skip_classify;

        if (pfmemalloc)
                goto skip_taps;

        list_for_each_entry_rcu(ptype, &ptype_all, list) {
                if (pt_prev)
                        ret = deliver_skb(skb, pt_prev, orig_dev);
                pt_prev = ptype;
        }

        list_for_each_entry_rcu(ptype, &skb->dev->ptype_all, list) {
                if (pt_prev)
                        ret = deliver_skb(skb, pt_prev, orig_dev);
                pt_prev = ptype;
        }

skip_taps:
#ifdef CONFIG_NET_INGRESS
        if (static_branch_unlikely(&ingress_needed_key)) {
                bool another = false;

                nf_skip_egress(skb, true);
                skb = sch_handle_ingress(skb, &pt_prev, &ret, orig_dev,
                                         &another);
                if (another)
                        goto another_round;
                if (!skb)
                        goto out;

                nf_skip_egress(skb, false);
                if (nf_ingress(skb, &pt_prev, &ret, orig_dev) < 0)
                        goto out;
        }
#endif
        skb_reset_redirect(skb);
skip_classify:
        if (pfmemalloc && !skb_pfmemalloc_protocol(skb))
                goto drop;

        if (skb_vlan_tag_present(skb)) {
                if (pt_prev) {
                        ret = deliver_skb(skb, pt_prev, orig_dev);
                        pt_prev = NULL;
                }
                if (vlan_do_receive(&skb))
                        goto another_round;
                else if (unlikely(!skb))
                        goto out;
        }

        rx_handler = rcu_dereference(skb->dev->rx_handler);
        if (rx_handler) {
                if (pt_prev) {
                        ret = deliver_skb(skb, pt_prev, orig_dev);
                        pt_prev = NULL;
                }
                switch (rx_handler(&skb)) {
                case RX_HANDLER_CONSUMED:
                        ret = NET_RX_SUCCESS;
                        goto out;
                case RX_HANDLER_ANOTHER:
                        goto another_round;
                case RX_HANDLER_EXACT:
                        deliver_exact = true;
                        break;
                case RX_HANDLER_PASS:
                        break;
                default:
                        BUG();
                }
        }

        if (unlikely(skb_vlan_tag_present(skb)) && !netdev_uses_dsa(skb->dev)) {
check_vlan_id:
                if (skb_vlan_tag_get_id(skb)) {
                        /* Vlan id is non 0 and vlan_do_receive() above couldn't
                         * find vlan device.
                         */
                        skb->pkt_type = PACKET_OTHERHOST;
                } else if (eth_type_vlan(skb->protocol)) {
                        /* Outer header is 802.1P with vlan 0, inner header is
                         * 802.1Q or 802.1AD and vlan_do_receive() above could
                         * not find vlan dev for vlan id 0.
                         */
                        __vlan_hwaccel_clear_tag(skb);
                        skb = skb_vlan_untag(skb);
                        if (unlikely(!skb))
                                goto out;
                        if (vlan_do_receive(&skb))
                                /* After stripping off 802.1P header with vlan 0
                                 * vlan dev is found for inner header.
                                 */
                                goto another_round;
                        else if (unlikely(!skb))
                                goto out;
                        else
                                /* We have stripped outer 802.1P vlan 0 header.
                                 * But could not find vlan dev.
                                 * check again for vlan id to set OTHERHOST.
                                 */
                                goto check_vlan_id;
                }
                /* Note: we might in the future use prio bits
                 * and set skb->priority like in vlan_do_receive()
                 * For the time being, just ignore Priority Code Point
                 */
                __vlan_hwaccel_clear_tag(skb);
        }

        type = skb->protocol;

        /* deliver only exact match when indicated */
        if (likely(!deliver_exact)) {
                deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type,
                                       &ptype_base[ntohs(type) &
                                                   PTYPE_HASH_MASK]);
        }

        deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type,
                               &orig_dev->ptype_specific);

        if (unlikely(skb->dev != orig_dev)) {
                deliver_ptype_list_skb(skb, &pt_prev, orig_dev, type,
                                       &skb->dev->ptype_specific);
        }

        if (pt_prev) {
                if (unlikely(skb_orphan_frags_rx(skb, GFP_ATOMIC)))
                        goto drop;
                *ppt_prev = pt_prev;
        } else {
drop:
                if (!deliver_exact)
                        dev_core_stats_rx_dropped_inc(skb->dev);
                else
                        dev_core_stats_rx_nohandler_inc(skb->dev);
                kfree_skb_reason(skb, SKB_DROP_REASON_UNHANDLED_PROTO);
                /* Jamal, now you will not able to escape explaining
                 * me how you were going to use this. :-)
                 */
                ret = NET_RX_DROP;
        }

out:
        /* The invariant here is that if *ppt_prev is not NULL
         * then skb should also be non-NULL.
         *
         * Apparently *ppt_prev assignment above holds this invariant due to
         * skb dereferencing near it.
         */
        *pskb = skb;
        return ret;
}

static int __netif_receive_skb_one_core(struct sk_buff *skb, bool pfmemalloc)
{
        struct net_device *orig_dev = skb->dev;
        struct packet_type *pt_prev = NULL;
        int ret;

        ret = __netif_receive_skb_core(&skb, pfmemalloc, &pt_prev);
        if (pt_prev)
                ret = INDIRECT_CALL_INET(pt_prev->func, ipv6_rcv, ip_rcv, skb,
                                         skb->dev, pt_prev, orig_dev);
        return ret;
}

/**
 *      netif_receive_skb_core - special purpose version of netif_receive_skb
 *      @skb: buffer to process
 *
 *      More direct receive version of netif_receive_skb().  It should
 *      only be used by callers that have a need to skip RPS and Generic XDP.
 *      Caller must also take care of handling if ``(page_is_)pfmemalloc``.
 *
 *      This function may only be called from softirq context and interrupts
 *      should be enabled.
 *
 *      Return values (usually ignored):
 *      NET_RX_SUCCESS: no congestion
 *      NET_RX_DROP: packet was dropped
 */
int netif_receive_skb_core(struct sk_buff *skb)
{
        int ret;

        rcu_read_lock();
        ret = __netif_receive_skb_one_core(skb, false);
        rcu_read_unlock();

        return ret;
}
EXPORT_SYMBOL(netif_receive_skb_core);

static inline void __netif_receive_skb_list_ptype(struct list_head *head,
                                                  struct packet_type *pt_prev,
                                                  struct net_device *orig_dev)
{
        struct sk_buff *skb, *next;

        if (!pt_prev)
                return;
        if (list_empty(head))
                return;
        if (pt_prev->list_func != NULL)
                INDIRECT_CALL_INET(pt_prev->list_func, ipv6_list_rcv,
                                   ip_list_rcv, head, pt_prev, orig_dev);
        else
                list_for_each_entry_safe(skb, next, head, list) {
                        skb_list_del_init(skb);
                        pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
                }
}

static void __netif_receive_skb_list_core(struct list_head *head, bool pfmemalloc)
{
        /* Fast-path assumptions:
         * - There is no RX handler.
         * - Only one packet_type matches.
         * If either of these fails, we will end up doing some per-packet
         * processing in-line, then handling the 'last ptype' for the whole
         * sublist.  This can't cause out-of-order delivery to any single ptype,
         * because the 'last ptype' must be constant across the sublist, and all
         * other ptypes are handled per-packet.
         */
        /* Current (common) ptype of sublist */
        struct packet_type *pt_curr = NULL;
        /* Current (common) orig_dev of sublist */
        struct net_device *od_curr = NULL;
        struct list_head sublist;
        struct sk_buff *skb, *next;

        INIT_LIST_HEAD(&sublist);
        list_for_each_entry_safe(skb, next, head, list) {
                struct net_device *orig_dev = skb->dev;
                struct packet_type *pt_prev = NULL;

                skb_list_del_init(skb);
                __netif_receive_skb_core(&skb, pfmemalloc, &pt_prev);
                if (!pt_prev)
                        continue;
                if (pt_curr != pt_prev || od_curr != orig_dev) {
                        /* dispatch old sublist */
                        __netif_receive_skb_list_ptype(&sublist, pt_curr, od_curr);
                        /* start new sublist */
                        INIT_LIST_HEAD(&sublist);
                        pt_curr = pt_prev;
                        od_curr = orig_dev;
                }
                list_add_tail(&skb->list, &sublist);
        }

        /* dispatch final sublist */
        __netif_receive_skb_list_ptype(&sublist, pt_curr, od_curr);
}

static int __netif_receive_skb(struct sk_buff *skb)
{
        int ret;

        if (sk_memalloc_socks() && skb_pfmemalloc(skb)) {
                unsigned int noreclaim_flag;

                /*
                 * PFMEMALLOC skbs are special, they should
                 * - be delivered to SOCK_MEMALLOC sockets only
                 * - stay away from userspace
                 * - have bounded memory usage
                 *
                 * Use PF_MEMALLOC as this saves us from propagating the allocation
                 * context down to all allocation sites.
                 */
                noreclaim_flag = memalloc_noreclaim_save();
                ret = __netif_receive_skb_one_core(skb, true);
                memalloc_noreclaim_restore(noreclaim_flag);
        } else
                ret = __netif_receive_skb_one_core(skb, false);

        return ret;
}

static void __netif_receive_skb_list(struct list_head *head)
{
        unsigned long noreclaim_flag = 0;
        struct sk_buff *skb, *next;
        bool pfmemalloc = false; /* Is current sublist PF_MEMALLOC? */

        list_for_each_entry_safe(skb, next, head, list) {
                if ((sk_memalloc_socks() && skb_pfmemalloc(skb)) != pfmemalloc) {
                        struct list_head sublist;

                        /* Handle the previous sublist */
                        list_cut_before(&sublist, head, &skb->list);
                        if (!list_empty(&sublist))
                                __netif_receive_skb_list_core(&sublist, pfmemalloc);
                        pfmemalloc = !pfmemalloc;
                        /* See comments in __netif_receive_skb */
                        if (pfmemalloc)
                                noreclaim_flag = memalloc_noreclaim_save();
                        else
                                memalloc_noreclaim_restore(noreclaim_flag);
                }
        }
        /* Handle the remaining sublist */
        if (!list_empty(head))
                __netif_receive_skb_list_core(head, pfmemalloc);
        /* Restore pflags */
        if (pfmemalloc)
                memalloc_noreclaim_restore(noreclaim_flag);
}

static int generic_xdp_install(struct net_device *dev, struct netdev_bpf *xdp)
{
        struct bpf_prog *old = rtnl_dereference(dev->xdp_prog);
        struct bpf_prog *new = xdp->prog;
        int ret = 0;

        switch (xdp->command) {
        case XDP_SETUP_PROG:
                rcu_assign_pointer(dev->xdp_prog, new);
                if (old)
                        bpf_prog_put(old);

                if (old && !new) {
                        static_branch_dec(&generic_xdp_needed_key);
                } else if (new && !old) {
                        static_branch_inc(&generic_xdp_needed_key);
                        dev_disable_lro(dev);
                        dev_disable_gro_hw(dev);
                }
                break;

        default:
                ret = -EINVAL;
                break;
        }

        return ret;
}

static int netif_receive_skb_internal(struct sk_buff *skb)
{
        int ret;

        net_timestamp_check(READ_ONCE(netdev_tstamp_prequeue), skb);

        if (skb_defer_rx_timestamp(skb))
                return NET_RX_SUCCESS;

        rcu_read_lock();
#ifdef CONFIG_RPS
        if (static_branch_unlikely(&rps_needed)) {
                struct rps_dev_flow voidflow, *rflow = &voidflow;
                int cpu = get_rps_cpu(skb->dev, skb, &rflow);

                if (cpu >= 0) {
                        ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
                        rcu_read_unlock();
                        return ret;
                }
        }
#endif
        ret = __netif_receive_skb(skb);
        rcu_read_unlock();
        return ret;
}

void netif_receive_skb_list_internal(struct list_head *head)
{
        struct sk_buff *skb, *next;
        struct list_head sublist;

        INIT_LIST_HEAD(&sublist);
        list_for_each_entry_safe(skb, next, head, list) {
                net_timestamp_check(READ_ONCE(netdev_tstamp_prequeue), skb);
                skb_list_del_init(skb);
                if (!skb_defer_rx_timestamp(skb))
                        list_add_tail(&skb->list, &sublist);
        }
        list_splice_init(&sublist, head);

        rcu_read_lock();
#ifdef CONFIG_RPS
        if (static_branch_unlikely(&rps_needed)) {
                list_for_each_entry_safe(skb, next, head, list) {
                        struct rps_dev_flow voidflow, *rflow = &voidflow;
                        int cpu = get_rps_cpu(skb->dev, skb, &rflow);

                        if (cpu >= 0) {
                                /* Will be handled, remove from list */
                                skb_list_del_init(skb);
                                enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
                        }
                }
        }
#endif
        __netif_receive_skb_list(head);
        rcu_read_unlock();
}

/**
 *      netif_receive_skb - process receive buffer from network
 *      @skb: buffer to process
 *
 *      netif_receive_skb() is the main receive data processing function.
 *      It always succeeds. The buffer may be dropped during processing
 *      for congestion control or by the protocol layers.
 *
 *      This function may only be called from softirq context and interrupts
 *      should be enabled.
 *
 *      Return values (usually ignored):
 *      NET_RX_SUCCESS: no congestion
 *      NET_RX_DROP: packet was dropped
 */
int netif_receive_skb(struct sk_buff *skb)
{
        int ret;

        trace_netif_receive_skb_entry(skb);

        ret = netif_receive_skb_internal(skb);
        trace_netif_receive_skb_exit(ret);

        return ret;
}
EXPORT_SYMBOL(netif_receive_skb);

/**
 *      netif_receive_skb_list - process many receive buffers from network
 *      @head: list of skbs to process.
 *
 *      Since return value of netif_receive_skb() is normally ignored, and
 *      wouldn't be meaningful for a list, this function returns void.
 *
 *      This function may only be called from softirq context and interrupts
 *      should be enabled.
 */
void netif_receive_skb_list(struct list_head *head)
{
        struct sk_buff *skb;

        if (list_empty(head))
                return;
        if (trace_netif_receive_skb_list_entry_enabled()) {
                list_for_each_entry(skb, head, list)
                        trace_netif_receive_skb_list_entry(skb);
        }
        netif_receive_skb_list_internal(head);
        trace_netif_receive_skb_list_exit(0);
}
EXPORT_SYMBOL(netif_receive_skb_list);

static DEFINE_PER_CPU(struct work_struct, flush_works);

/* Network device is going away, flush any packets still pending */
static void flush_backlog(struct work_struct *work)
{
        struct sk_buff *skb, *tmp;
        struct softnet_data *sd;

        local_bh_disable();
        sd = this_cpu_ptr(&softnet_data);

        rps_lock_irq_disable(sd);
        skb_queue_walk_safe(&sd->input_pkt_queue, skb, tmp) {
                if (skb->dev->reg_state == NETREG_UNREGISTERING) {
                        __skb_unlink(skb, &sd->input_pkt_queue);
                        dev_kfree_skb_irq(skb);
                        input_queue_head_incr(sd);
                }
        }
        rps_unlock_irq_enable(sd);

        skb_queue_walk_safe(&sd->process_queue, skb, tmp) {
                if (skb->dev->reg_state == NETREG_UNREGISTERING) {
                        __skb_unlink(skb, &sd->process_queue);
                        kfree_skb(skb);
                        input_queue_head_incr(sd);
                }
        }
        local_bh_enable();
}

static bool flush_required(int cpu)
{
#if IS_ENABLED(CONFIG_RPS)
        struct softnet_data *sd = &per_cpu(softnet_data, cpu);
        bool do_flush;

        rps_lock_irq_disable(sd);

        /* as insertion into process_queue happens with the rps lock held,
         * process_queue access may race only with dequeue
         */
        do_flush = !skb_queue_empty(&sd->input_pkt_queue) ||
                   !skb_queue_empty_lockless(&sd->process_queue);
        rps_unlock_irq_enable(sd);

        return do_flush;
#endif
        /* without RPS we can't safely check input_pkt_queue: during a
         * concurrent remote skb_queue_splice() we can detect as empty both
         * input_pkt_queue and process_queue even if the latter could end-up
         * containing a lot of packets.
         */
        return true;
}

static void flush_all_backlogs(void)
{
        static cpumask_t flush_cpus;
        unsigned int cpu;

        /* since we are under rtnl lock protection we can use static data
         * for the cpumask and avoid allocating on stack the possibly
         * large mask
         */
        ASSERT_RTNL();

        cpus_read_lock();

        cpumask_clear(&flush_cpus);
        for_each_online_cpu(cpu) {
                if (flush_required(cpu)) {
                        queue_work_on(cpu, system_highpri_wq,
                                      per_cpu_ptr(&flush_works, cpu));
                        cpumask_set_cpu(cpu, &flush_cpus);
                }
        }

        /* we can have in flight packet[s] on the cpus we are not flushing,
         * synchronize_net() in unregister_netdevice_many() will take care of
         * them
         */
        for_each_cpu(cpu, &flush_cpus)
                flush_work(per_cpu_ptr(&flush_works, cpu));

        cpus_read_unlock();
}

static void net_rps_send_ipi(struct softnet_data *remsd)
{
#ifdef CONFIG_RPS
        while (remsd) {
                struct softnet_data *next = remsd->rps_ipi_next;

                if (cpu_online(remsd->cpu))
                        smp_call_function_single_async(remsd->cpu, &remsd->csd);
                remsd = next;
        }
#endif
}

/*
 * net_rps_action_and_irq_enable sends any pending IPI's for rps.
 * Note: called with local irq disabled, but exits with local irq enabled.
 */
static void net_rps_action_and_irq_enable(struct softnet_data *sd)
{
#ifdef CONFIG_RPS
        struct softnet_data *remsd = sd->rps_ipi_list;

        if (remsd) {
                sd->rps_ipi_list = NULL;

                local_irq_enable();

                /* Send pending IPI's to kick RPS processing on remote cpus. */
                net_rps_send_ipi(remsd);
        } else
#endif
                local_irq_enable();
}

static bool sd_has_rps_ipi_waiting(struct softnet_data *sd)
{
#ifdef CONFIG_RPS
        return sd->rps_ipi_list != NULL;
#else
        return false;
#endif
}

static int process_backlog(struct napi_struct *napi, int quota)
{
        struct softnet_data *sd = container_of(napi, struct softnet_data, backlog);
        bool again = true;
        int work = 0;

        /* Check if we have pending ipi, its better to send them now,
         * not waiting net_rx_action() end.
         */
        if (sd_has_rps_ipi_waiting(sd)) {
                local_irq_disable();
                net_rps_action_and_irq_enable(sd);
        }

        napi->weight = READ_ONCE(dev_rx_weight);
        while (again) {
                struct sk_buff *skb;

                while ((skb = __skb_dequeue(&sd->process_queue))) {
                        rcu_read_lock();
                        __netif_receive_skb(skb);
                        rcu_read_unlock();
                        input_queue_head_incr(sd);
                        if (++work >= quota)
                                return work;

                }

                rps_lock_irq_disable(sd);
                if (skb_queue_empty(&sd->input_pkt_queue)) {
                        /*
                         * Inline a custom version of __napi_complete().
                         * only current cpu owns and manipulates this napi,
                         * and NAPI_STATE_SCHED is the only possible flag set
                         * on backlog.
                         * We can use a plain write instead of clear_bit(),
                         * and we dont need an smp_mb() memory barrier.
                         */
                        napi->state = 0;
                        again = false;
                } else {
                        skb_queue_splice_tail_init(&sd->input_pkt_queue,
                                                   &sd->process_queue);
                }
                rps_unlock_irq_enable(sd);
        }

        return work;
}

/**
 * __napi_schedule - schedule for receive
 * @n: entry to schedule
 *
 * The entry's receive function will be scheduled to run.
 * Consider using __napi_schedule_irqoff() if hard irqs are masked.
 */
void __napi_schedule(struct napi_struct *n)
{
        unsigned long flags;

        local_irq_save(flags);
        ____napi_schedule(this_cpu_ptr(&softnet_data), n);
        local_irq_restore(flags);
}
EXPORT_SYMBOL(__napi_schedule);

/**
 *      napi_schedule_prep - check if napi can be scheduled
 *      @n: napi context
 *
 * Test if NAPI routine is already running, and if not mark
 * it as running.  This is used as a condition variable to
 * insure only one NAPI poll instance runs.  We also make
 * sure there is no pending NAPI disable.
 */
bool napi_schedule_prep(struct napi_struct *n)
{
        unsigned long new, val = READ_ONCE(n->state);

        do {
                if (unlikely(val & NAPIF_STATE_DISABLE))
                        return false;
                new = val | NAPIF_STATE_SCHED;

                /* Sets STATE_MISSED bit if STATE_SCHED was already set
                 * This was suggested by Alexander Duyck, as compiler
                 * emits better code than :
                 * if (val & NAPIF_STATE_SCHED)
                 *     new |= NAPIF_STATE_MISSED;
                 */
                new |= (val & NAPIF_STATE_SCHED) / NAPIF_STATE_SCHED *
                                                   NAPIF_STATE_MISSED;
        } while (!try_cmpxchg(&n->state, &val, new));

        return !(val & NAPIF_STATE_SCHED);
}
EXPORT_SYMBOL(napi_schedule_prep);

/**
 * __napi_schedule_irqoff - schedule for receive
 * @n: entry to schedule
 *
 * Variant of __napi_schedule() assuming hard irqs are masked.
 *
 * On PREEMPT_RT enabled kernels this maps to __napi_schedule()
 * because the interrupt disabled assumption might not be true
 * due to force-threaded interrupts and spinlock substitution.
 */
void __napi_schedule_irqoff(struct napi_struct *n)
{
        if (!IS_ENABLED(CONFIG_PREEMPT_RT))
                ____napi_schedule(this_cpu_ptr(&softnet_data), n);
        else
                __napi_schedule(n);
}
EXPORT_SYMBOL(__napi_schedule_irqoff);

bool napi_complete_done(struct napi_struct *n, int work_done)
{
        unsigned long flags, val, new, timeout = 0;
        bool ret = true;

        /*
         * 1) Don't let napi dequeue from the cpu poll list
         *    just in case its running on a different cpu.
         * 2) If we are busy polling, do nothing here, we have
         *    the guarantee we will be called later.
         */
        if (unlikely(n->state & (NAPIF_STATE_NPSVC |
                                 NAPIF_STATE_IN_BUSY_POLL)))
                return false;

        if (work_done) {
                if (n->gro_bitmask)
                        timeout = READ_ONCE(n->dev->gro_flush_timeout);
                n->defer_hard_irqs_count = READ_ONCE(n->dev->napi_defer_hard_irqs);
        }
        if (n->defer_hard_irqs_count > 0) {
                n->defer_hard_irqs_count--;
                timeout = READ_ONCE(n->dev->gro_flush_timeout);
                if (timeout)
                        ret = false;
        }
        if (n->gro_bitmask) {
                /* When the NAPI instance uses a timeout and keeps postponing
                 * it, we need to bound somehow the time packets are kept in
                 * the GRO layer
                 */
                napi_gro_flush(n, !!timeout);
        }

        gro_normal_list(n);

        if (unlikely(!list_empty(&n->poll_list))) {
                /* If n->poll_list is not empty, we need to mask irqs */
                local_irq_save(flags);
                list_del_init(&n->poll_list);
                local_irq_restore(flags);
        }
        WRITE_ONCE(n->list_owner, -1);

        val = READ_ONCE(n->state);
        do {
                WARN_ON_ONCE(!(val & NAPIF_STATE_SCHED));

                new = val & ~(NAPIF_STATE_MISSED | NAPIF_STATE_SCHED |
                              NAPIF_STATE_SCHED_THREADED |
                              NAPIF_STATE_PREFER_BUSY_POLL);

                /* If STATE_MISSED was set, leave STATE_SCHED set,
                 * because we will call napi->poll() one more time.
                 * This C code was suggested by Alexander Duyck to help gcc.
                 */
                new |= (val & NAPIF_STATE_MISSED) / NAPIF_STATE_MISSED *
                                                    NAPIF_STATE_SCHED;
        } while (!try_cmpxchg(&n->state, &val, new));

        if (unlikely(val & NAPIF_STATE_MISSED)) {
                __napi_schedule(n);
                return false;
        }

        if (timeout)
                hrtimer_start(&n->timer, ns_to_ktime(timeout),
                              HRTIMER_MODE_REL_PINNED);
        return ret;
}
EXPORT_SYMBOL(napi_complete_done);

/* must be called under rcu_read_lock(), as we dont take a reference */
static struct napi_struct *napi_by_id(unsigned int napi_id)
{
        unsigned int hash = napi_id % HASH_SIZE(napi_hash);
        struct napi_struct *napi;

        hlist_for_each_entry_rcu(napi, &napi_hash[hash], napi_hash_node)
                if (napi->napi_id == napi_id)
                        return napi;

        return NULL;
}

#if defined(CONFIG_NET_RX_BUSY_POLL)

static void __busy_poll_stop(struct napi_struct *napi, bool skip_schedule)
{
        if (!skip_schedule) {
                gro_normal_list(napi);
                __napi_schedule(napi);
                return;
        }

        if (napi->gro_bitmask) {
                /* flush too old packets
                 * If HZ < 1000, flush all packets.
                 */
                napi_gro_flush(napi, HZ >= 1000);
        }

        gro_normal_list(napi);
        clear_bit(NAPI_STATE_SCHED, &napi->state);
}

static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock, bool prefer_busy_poll,
                           u16 budget)
{
        bool skip_schedule = false;
        unsigned long timeout;
        int rc;

        /* Busy polling means there is a high chance device driver hard irq
         * could not grab NAPI_STATE_SCHED, and that NAPI_STATE_MISSED was
         * set in napi_schedule_prep().
         * Since we are about to call napi->poll() once more, we can safely
         * clear NAPI_STATE_MISSED.
         *
         * Note: x86 could use a single "lock and ..." instruction
         * to perform these two clear_bit()
         */
        clear_bit(NAPI_STATE_MISSED, &napi->state);
        clear_bit(NAPI_STATE_IN_BUSY_POLL, &napi->state);

        local_bh_disable();

        if (prefer_busy_poll) {
                napi->defer_hard_irqs_count = READ_ONCE(napi->dev->napi_defer_hard_irqs);
                timeout = READ_ONCE(napi->dev->gro_flush_timeout);
                if (napi->defer_hard_irqs_count && timeout) {
                        hrtimer_start(&napi->timer, ns_to_ktime(timeout), HRTIMER_MODE_REL_PINNED);
                        skip_schedule = true;
                }
        }

        /* All we really want here is to re-enable device interrupts.
         * Ideally, a new ndo_busy_poll_stop() could avoid another round.
         */
        rc = napi->poll(napi, budget);
        /* We can't gro_normal_list() here, because napi->poll() might have
         * rearmed the napi (napi_complete_done()) in which case it could
         * already be running on another CPU.
         */
        trace_napi_poll(napi, rc, budget);
        netpoll_poll_unlock(have_poll_lock);
        if (rc == budget)
                __busy_poll_stop(napi, skip_schedule);
        local_bh_enable();
}

void napi_busy_loop(unsigned int napi_id,
                    bool (*loop_end)(void *, unsigned long),
                    void *loop_end_arg, bool prefer_busy_poll, u16 budget)
{
        unsigned long start_time = loop_end ? busy_loop_current_time() : 0;
        int (*napi_poll)(struct napi_struct *napi, int budget);
        void *have_poll_lock = NULL;
        struct napi_struct *napi;

restart:
        napi_poll = NULL;

        rcu_read_lock();

        napi = napi_by_id(napi_id);
        if (!napi)
                goto out;

        if (!IS_ENABLED(CONFIG_PREEMPT_RT))
                preempt_disable();
        for (;;) {
                int work = 0;

                local_bh_disable();
                if (!napi_poll) {
                        unsigned long val = READ_ONCE(napi->state);

                        /* If multiple threads are competing for this napi,
                         * we avoid dirtying napi->state as much as we can.
                         */
                        if (val & (NAPIF_STATE_DISABLE | NAPIF_STATE_SCHED |
                                   NAPIF_STATE_IN_BUSY_POLL)) {
                                if (prefer_busy_poll)
                                        set_bit(NAPI_STATE_PREFER_BUSY_POLL, &napi->state);
                                goto count;
                        }
                        if (cmpxchg(&napi->state, val,
                                    val | NAPIF_STATE_IN_BUSY_POLL |
                                          NAPIF_STATE_SCHED) != val) {
                                if (prefer_busy_poll)
                                        set_bit(NAPI_STATE_PREFER_BUSY_POLL, &napi->state);
                                goto count;
                        }
                        have_poll_lock = netpoll_poll_lock(napi);
                        napi_poll = napi->poll;
                }
                work = napi_poll(napi, budget);
                trace_napi_poll(napi, work, budget);
                gro_normal_list(napi);
count:
                if (work > 0)
                        __NET_ADD_STATS(dev_net(napi->dev),
                                        LINUX_MIB_BUSYPOLLRXPACKETS, work);
                local_bh_enable();

                if (!loop_end || loop_end(loop_end_arg, start_time))
                        break;

                if (unlikely(need_resched())) {
                        if (napi_poll)
                                busy_poll_stop(napi, have_poll_lock, prefer_busy_poll, budget);
                        if (!IS_ENABLED(CONFIG_PREEMPT_RT))
                                preempt_enable();
                        rcu_read_unlock();
                        cond_resched();
                        if (loop_end(loop_end_arg, start_time))
                                return;
                        goto restart;
                }
                cpu_relax();
        }
        if (napi_poll)
                busy_poll_stop(napi, have_poll_lock, prefer_busy_poll, budget);
        if (!IS_ENABLED(CONFIG_PREEMPT_RT))
                preempt_enable();
out:
        rcu_read_unlock();
}
EXPORT_SYMBOL(napi_busy_loop);

#endif /* CONFIG_NET_RX_BUSY_POLL */

static void napi_hash_add(struct napi_struct *napi)
{
        if (test_bit(NAPI_STATE_NO_BUSY_POLL, &napi->state))
                return;

        spin_lock(&napi_hash_lock);

        /* 0..NR_CPUS range is reserved for sender_cpu use */
        do {
                if (unlikely(++napi_gen_id < MIN_NAPI_ID))
                        napi_gen_id = MIN_NAPI_ID;
        } while (napi_by_id(napi_gen_id));
        napi->napi_id = napi_gen_id;

        hlist_add_head_rcu(&napi->napi_hash_node,
                           &napi_hash[napi->napi_id % HASH_SIZE(napi_hash)]);

        spin_unlock(&napi_hash_lock);
}

/* Warning : caller is responsible to make sure rcu grace period
 * is respected before freeing memory containing @napi
 */
static void napi_hash_del(struct napi_struct *napi)
{
        spin_lock(&napi_hash_lock);

        hlist_del_init_rcu(&napi->napi_hash_node);

        spin_unlock(&napi_hash_lock);
}

static enum hrtimer_restart napi_watchdog(struct hrtimer *timer)
{
        struct napi_struct *napi;

        napi = container_of(timer, struct napi_struct, timer);

        /* Note : we use a relaxed variant of napi_schedule_prep() not setting
         * NAPI_STATE_MISSED, since we do not react to a device IRQ.
         */
        if (!napi_disable_pending(napi) &&
            !test_and_set_bit(NAPI_STATE_SCHED, &napi->state)) {
                clear_bit(NAPI_STATE_PREFER_BUSY_POLL, &napi->state);
                __napi_schedule_irqoff(napi);
        }

        return HRTIMER_NORESTART;
}

static void init_gro_hash(struct napi_struct *napi)
{
        int i;

        for (i = 0; i < GRO_HASH_BUCKETS; i++) {
                INIT_LIST_HEAD(&napi->gro_hash[i].list);
                napi->gro_hash[i].count = 0;
        }
        napi->gro_bitmask = 0;
}

int dev_set_threaded(struct net_device *dev, bool threaded)
{
        struct napi_struct *napi;
        int err = 0;

        if (dev->threaded == threaded)
                return 0;

        if (threaded) {
                list_for_each_entry(napi, &dev->napi_list, dev_list) {
                        if (!napi->thread) {
                                err = napi_kthread_create(napi);
                                if (err) {
                                        threaded = false;
                                        break;
                                }
                        }
                }
        }

        dev->threaded = threaded;

        /* Make sure kthread is created before THREADED bit
         * is set.
         */
        smp_mb__before_atomic();

        /* Setting/unsetting threaded mode on a napi might not immediately
         * take effect, if the current napi instance is actively being
         * polled. In this case, the switch between threaded mode and
         * softirq mode will happen in the next round of napi_schedule().
         * This should not cause hiccups/stalls to the live traffic.
         */
        list_for_each_entry(napi, &dev->napi_list, dev_list)
                assign_bit(NAPI_STATE_THREADED, &napi->state, threaded);

        return err;
}
EXPORT_SYMBOL(dev_set_threaded);

void netif_napi_add_weight(struct net_device *dev, struct napi_struct *napi,
                           int (*poll)(struct napi_struct *, int), int weight)
{
        if (WARN_ON(test_and_set_bit(NAPI_STATE_LISTED, &napi->state)))
                return;

        INIT_LIST_HEAD(&napi->poll_list);
        INIT_HLIST_NODE(&napi->napi_hash_node);
        hrtimer_init(&napi->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_PINNED);
        napi->timer.function = napi_watchdog;
        init_gro_hash(napi);
        napi->skb = NULL;
        INIT_LIST_HEAD(&napi->rx_list);
        napi->rx_count = 0;
        napi->poll = poll;
        if (weight > NAPI_POLL_WEIGHT)
                netdev_err_once(dev, "%s() called with weight %d\n", __func__,
                                weight);
        napi->weight = weight;
        napi->dev = dev;
#ifdef CONFIG_NETPOLL
        napi->poll_owner = -1;
#endif
        napi->list_owner = -1;
        set_bit(NAPI_STATE_SCHED, &napi->state);
        set_bit(NAPI_STATE_NPSVC, &napi->state);
        list_add_rcu(&napi->dev_list, &dev->napi_list);
        napi_hash_add(napi);
        napi_get_frags_check(napi);
        /* Create kthread for this napi if dev->threaded is set.
         * Clear dev->threaded if kthread creation failed so that
         * threaded mode will not be enabled in napi_enable().
         */
        if (dev->threaded && napi_kthread_create(napi))
                dev->threaded = 0;
}
EXPORT_SYMBOL(netif_napi_add_weight);

void napi_disable(struct napi_struct *n)
{
        unsigned long val, new;

        might_sleep();
        set_bit(NAPI_STATE_DISABLE, &n->state);

        val = READ_ONCE(n->state);
        do {
                while (val & (NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC)) {
                        usleep_range(20, 200);
                        val = READ_ONCE(n->state);
                }

                new = val | NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC;
                new &= ~(NAPIF_STATE_THREADED | NAPIF_STATE_PREFER_BUSY_POLL);
        } while (!try_cmpxchg(&n->state, &val, new));

        hrtimer_cancel(&n->timer);

        clear_bit(NAPI_STATE_DISABLE, &n->state);
}
EXPORT_SYMBOL(napi_disable);

/**
 *      napi_enable - enable NAPI scheduling
 *      @n: NAPI context
 *
 * Resume NAPI from being scheduled on this context.
 * Must be paired with napi_disable.
 */
void napi_enable(struct napi_struct *n)
{
        unsigned long new, val = READ_ONCE(n->state);

        do {
                BUG_ON(!test_bit(NAPI_STATE_SCHED, &val));

                new = val & ~(NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC);
                if (n->dev->threaded && n->thread)
                        new |= NAPIF_STATE_THREADED;
        } while (!try_cmpxchg(&n->state, &val, new));
}
EXPORT_SYMBOL(napi_enable);

static void flush_gro_hash(struct napi_struct *napi)
{
        int i;

        for (i = 0; i < GRO_HASH_BUCKETS; i++) {
                struct sk_buff *skb, *n;

                list_for_each_entry_safe(skb, n, &napi->gro_hash[i].list, list)
                        kfree_skb(skb);
                napi->gro_hash[i].count = 0;
        }
}

/* Must be called in process context */
void __netif_napi_del(struct napi_struct *napi)
{
        if (!test_and_clear_bit(NAPI_STATE_LISTED, &napi->state))
                return;

        napi_hash_del(napi);
        list_del_rcu(&napi->dev_list);
        napi_free_frags(napi);

        flush_gro_hash(napi);
        napi->gro_bitmask = 0;

        if (napi->thread) {
                kthread_stop(napi->thread);
                napi->thread = NULL;
        }
}
EXPORT_SYMBOL(__netif_napi_del);

static int __napi_poll(struct napi_struct *n, bool *repoll)
{
        int work, weight;

        weight = n->weight;

        /* This NAPI_STATE_SCHED test is for avoiding a race
         * with netpoll's poll_napi().  Only the entity which
         * obtains the lock and sees NAPI_STATE_SCHED set will
         * actually make the ->poll() call.  Therefore we avoid
         * accidentally calling ->poll() when NAPI is not scheduled.
         */
        work = 0;
        if (test_bit(NAPI_STATE_SCHED, &n->state)) {
                work = n->poll(n, weight);
                trace_napi_poll(n, work, weight);
        }

        if (unlikely(work > weight))
                netdev_err_once(n->dev, "NAPI poll function %pS returned %d, exceeding its budget of %d.\n",
                                n->poll, work, weight);

        if (likely(work < weight))
                return work;

        /* Drivers must not modify the NAPI state if they
         * consume the entire weight.  In such cases this code
         * still "owns" the NAPI instance and therefore can
         * move the instance around on the list at-will.
         */
        if (unlikely(napi_disable_pending(n))) {
                napi_complete(n);
                return work;
        }

        /* The NAPI context has more processing work, but busy-polling
         * is preferred. Exit early.
         */
        if (napi_prefer_busy_poll(n)) {
                if (napi_complete_done(n, work)) {
                        /* If timeout is not set, we need to make sure
                         * that the NAPI is re-scheduled.
                         */
                        napi_schedule(n);
                }
                return work;
        }

        if (n->gro_bitmask) {
                /* flush too old packets
                 * If HZ < 1000, flush all packets.
                 */
                napi_gro_flush(n, HZ >= 1000);
        }

        gro_normal_list(n);

        /* Some drivers may have called napi_schedule
         * prior to exhausting their budget.
         */
        if (unlikely(!list_empty(&n->poll_list))) {
                pr_warn_once("%s: Budget exhausted after napi rescheduled\n",
                             n->dev ? n->dev->name : "backlog");
                return work;
        }

        *repoll = true;

        return work;
}

static int napi_poll(struct napi_struct *n, struct list_head *repoll)
{
        bool do_repoll = false;
        void *have;
        int work;

        list_del_init(&n->poll_list);

        have = netpoll_poll_lock(n);

        work = __napi_poll(n, &do_repoll);

        if (do_repoll)
                list_add_tail(&n->poll_list, repoll);

        netpoll_poll_unlock(have);

        return work;
}

static int napi_thread_wait(struct napi_struct *napi)
{
        bool woken = false;

        set_current_state(TASK_INTERRUPTIBLE);

        while (!kthread_should_stop()) {
                /* Testing SCHED_THREADED bit here to make sure the current
                 * kthread owns this napi and could poll on this napi.
                 * Testing SCHED bit is not enough because SCHED bit might be
                 * set by some other busy poll thread or by napi_disable().
                 */
                if (test_bit(NAPI_STATE_SCHED_THREADED, &napi->state) || woken) {
                        WARN_ON(!list_empty(&napi->poll_list));
                        __set_current_state(TASK_RUNNING);
                        return 0;
                }

                schedule();
                /* woken being true indicates this thread owns this napi. */
                woken = true;
                set_current_state(TASK_INTERRUPTIBLE);
        }
        __set_current_state(TASK_RUNNING);

        return -1;
}

static void skb_defer_free_flush(struct softnet_data *sd)
{
        struct sk_buff *skb, *next;

        /* Paired with WRITE_ONCE() in skb_attempt_defer_free() */
        if (!READ_ONCE(sd->defer_list))
                return;

        spin_lock(&sd->defer_lock);
        skb = sd->defer_list;
        sd->defer_list = NULL;
        sd->defer_count = 0;
        spin_unlock(&sd->defer_lock);

        while (skb != NULL) {
                next = skb->next;
                napi_consume_skb(skb, 1);
                skb = next;
        }
}

static int napi_threaded_poll(void *data)
{
        struct napi_struct *napi = data;
        struct softnet_data *sd;
        void *have;

        while (!napi_thread_wait(napi)) {
                for (;;) {
                        bool repoll = false;

                        local_bh_disable();
                        sd = this_cpu_ptr(&softnet_data);
                        sd->in_napi_threaded_poll = true;

                        have = netpoll_poll_lock(napi);
                        __napi_poll(napi, &repoll);
                        netpoll_poll_unlock(have);

                        sd->in_napi_threaded_poll = false;
                        barrier();

                        if (sd_has_rps_ipi_waiting(sd)) {
                                local_irq_disable();
                                net_rps_action_and_irq_enable(sd);
                        }
                        skb_defer_free_flush(sd);
                        local_bh_enable();

                        if (!repoll)
                                break;

                        cond_resched();
                }
        }
        return 0;
}

static __latent_entropy void net_rx_action(struct softirq_action *h)
{
        struct softnet_data *sd = this_cpu_ptr(&softnet_data);
        unsigned long time_limit = jiffies +
                usecs_to_jiffies(READ_ONCE(netdev_budget_usecs));
        int budget = READ_ONCE(netdev_budget);
        LIST_HEAD(list);
        LIST_HEAD(repoll);

start:
        sd->in_net_rx_action = true;
        local_irq_disable();
        list_splice_init(&sd->poll_list, &list);
        local_irq_enable();

        for (;;) {
                struct napi_struct *n;

                skb_defer_free_flush(sd);

                if (list_empty(&list)) {
                        if (list_empty(&repoll)) {
                                sd->in_net_rx_action = false;
                                barrier();
                                /* We need to check if ____napi_schedule()
                                 * had refilled poll_list while
                                 * sd->in_net_rx_action was true.
                                 */
                                if (!list_empty(&sd->poll_list))
                                        goto start;
                                if (!sd_has_rps_ipi_waiting(sd))
                                        goto end;
                        }
                        break;
                }

                n = list_first_entry(&list, struct napi_struct, poll_list);
                budget -= napi_poll(n, &repoll);

                /* If softirq window is exhausted then punt.
                 * Allow this to run for 2 jiffies since which will allow
                 * an average latency of 1.5/HZ.
                 */
                if (unlikely(budget <= 0 ||
                             time_after_eq(jiffies, time_limit))) {
                        sd->time_squeeze++;
                        break;
                }
        }

        local_irq_disable();

        list_splice_tail_init(&sd->poll_list, &list);
        list_splice_tail(&repoll, &list);
        list_splice(&list, &sd->poll_list);
        if (!list_empty(&sd->poll_list))
                __raise_softirq_irqoff(NET_RX_SOFTIRQ);
        else
                sd->in_net_rx_action = false;

        net_rps_action_and_irq_enable(sd);
end:;
}

struct netdev_adjacent {
        struct net_device *dev;
        netdevice_tracker dev_tracker;

        /* upper master flag, there can only be one master device per list */
        bool master;

        /* lookup ignore flag */
        bool ignore;

        /* counter for the number of times this device was added to us */
        u16 ref_nr;

        /* private field for the users */
        void *private;

        struct list_head list;
        struct rcu_head rcu;
};

static struct netdev_adjacent *__netdev_find_adj(struct net_device *adj_dev,
                                                 struct list_head *adj_list)
{
        struct netdev_adjacent *adj;

        list_for_each_entry(adj, adj_list, list) {
                if (adj->dev == adj_dev)
                        return adj;
        }
        return NULL;
}

static int ____netdev_has_upper_dev(struct net_device *upper_dev,
                                    struct netdev_nested_priv *priv)
{
        struct net_device *dev = (struct net_device *)priv->data;

        return upper_dev == dev;
}

/**
 * netdev_has_upper_dev - Check if device is linked to an upper device
 * @dev: device
 * @upper_dev: upper device to check
 *
 * Find out if a device is linked to specified upper device and return true
 * in case it is. Note that this checks only immediate upper device,
 * not through a complete stack of devices. The caller must hold the RTNL lock.
 */
bool netdev_has_upper_dev(struct net_device *dev,
                          struct net_device *upper_dev)
{
        struct netdev_nested_priv priv = {
                .data = (void *)upper_dev,
        };

        ASSERT_RTNL();

        return netdev_walk_all_upper_dev_rcu(dev, ____netdev_has_upper_dev,
                                             &priv);
}
EXPORT_SYMBOL(netdev_has_upper_dev);

/**
 * netdev_has_upper_dev_all_rcu - Check if device is linked to an upper device
 * @dev: device
 * @upper_dev: upper device to check
 *
 * Find out if a device is linked to specified upper device and return true
 * in case it is. Note that this checks the entire upper device chain.
 * The caller must hold rcu lock.
 */

bool netdev_has_upper_dev_all_rcu(struct net_device *dev,
                                  struct net_device *upper_dev)
{
        struct netdev_nested_priv priv = {
                .data = (void *)upper_dev,
        };

        return !!netdev_walk_all_upper_dev_rcu(dev, ____netdev_has_upper_dev,
                                               &priv);
}
EXPORT_SYMBOL(netdev_has_upper_dev_all_rcu);

/**
 * netdev_has_any_upper_dev - Check if device is linked to some device
 * @dev: device
 *
 * Find out if a device is linked to an upper device and return true in case
 * it is. The caller must hold the RTNL lock.
 */
bool netdev_has_any_upper_dev(struct net_device *dev)
{
        ASSERT_RTNL();

        return !list_empty(&dev->adj_list.upper);
}
EXPORT_SYMBOL(netdev_has_any_upper_dev);

/**
 * netdev_master_upper_dev_get - Get master upper device
 * @dev: device
 *
 * Find a master upper device and return pointer to it or NULL in case
 * it's not there. The caller must hold the RTNL lock.
 */
struct net_device *netdev_master_upper_dev_get(struct net_device *dev)
{
        struct netdev_adjacent *upper;

        ASSERT_RTNL();

        if (list_empty(&dev->adj_list.upper))
                return NULL;

        upper = list_first_entry(&dev->adj_list.upper,
                                 struct netdev_adjacent, list);
        if (likely(upper->master))
                return upper->dev;
        return NULL;
}
EXPORT_SYMBOL(netdev_master_upper_dev_get);

static struct net_device *__netdev_master_upper_dev_get(struct net_device *dev)
{
        struct netdev_adjacent *upper;

        ASSERT_RTNL();

        if (list_empty(&dev->adj_list.upper))
                return NULL;

        upper = list_first_entry(&dev->adj_list.upper,
                                 struct netdev_adjacent, list);
        if (likely(upper->master) && !upper->ignore)
                return upper->dev;
        return NULL;
}

/**
 * netdev_has_any_lower_dev - Check if device is linked to some device
 * @dev: device
 *
 * Find out if a device is linked to a lower device and return true in case
 * it is. The caller must hold the RTNL lock.
 */
static bool netdev_has_any_lower_dev(struct net_device *dev)
{
        ASSERT_RTNL();

        return !list_empty(&dev->adj_list.lower);
}

void *netdev_adjacent_get_private(struct list_head *adj_list)
{
        struct netdev_adjacent *adj;

        adj = list_entry(adj_list, struct netdev_adjacent, list);

        return adj->private;
}
EXPORT_SYMBOL(netdev_adjacent_get_private);

/**
 * netdev_upper_get_next_dev_rcu - Get the next dev from upper list
 * @dev: device
 * @iter: list_head ** of the current position
 *
 * Gets the next device from the dev's upper list, starting from iter
 * position. The caller must hold RCU read lock.
 */
struct net_device *netdev_upper_get_next_dev_rcu(struct net_device *dev,
                                                 struct list_head **iter)
{
        struct netdev_adjacent *upper;

        WARN_ON_ONCE(!rcu_read_lock_held() && !lockdep_rtnl_is_held());

        upper = list_entry_rcu((*iter)->next, struct netdev_adjacent, list);

        if (&upper->list == &dev->adj_list.upper)
                return NULL;

        *iter = &upper->list;

        return upper->dev;
}
EXPORT_SYMBOL(netdev_upper_get_next_dev_rcu);

static struct net_device *__netdev_next_upper_dev(struct net_device *dev,
                                                  struct list_head **iter,
                                                  bool *ignore)
{
        struct netdev_adjacent *upper;

        upper = list_entry((*iter)->next, struct netdev_adjacent, list);

        if (&upper->list == &dev->adj_list.upper)
                return NULL;

        *iter = &upper->list;
        *ignore = upper->ignore;

        return upper->dev;
}

static struct net_device *netdev_next_upper_dev_rcu(struct net_device *dev,
                                                    struct list_head **iter)
{
        struct netdev_adjacent *upper;

        WARN_ON_ONCE(!rcu_read_lock_held() && !lockdep_rtnl_is_held());

        upper = list_entry_rcu((*iter)->next, struct netdev_adjacent, list);

        if (&upper->list == &dev->adj_list.upper)
                return NULL;

        *iter = &upper->list;

        return upper->dev;
}

static int __netdev_walk_all_upper_dev(struct net_device *dev,
                                       int (*fn)(struct net_device *dev,
                                         struct netdev_nested_priv *priv),
                                       struct netdev_nested_priv *priv)
{
        struct net_device *udev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
        struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
        int ret, cur = 0;
        bool ignore;

        now = dev;
        iter = &dev->adj_list.upper;

        while (1) {
                if (now != dev) {
                        ret = fn(now, priv);
                        if (ret)
                                return ret;
                }

                next = NULL;
                while (1) {
                        udev = __netdev_next_upper_dev(now, &iter, &ignore);
                        if (!udev)
                                break;
                        if (ignore)
                                continue;

                        next = udev;
                        niter = &udev->adj_list.upper;
                        dev_stack[cur] = now;
                        iter_stack[cur++] = iter;
                        break;
                }

                if (!next) {
                        if (!cur)
                                return 0;
                        next = dev_stack[--cur];
                        niter = iter_stack[cur];
                }

                now = next;
                iter = niter;
        }

        return 0;
}

int netdev_walk_all_upper_dev_rcu(struct net_device *dev,
                                  int (*fn)(struct net_device *dev,
                                            struct netdev_nested_priv *priv),
                                  struct netdev_nested_priv *priv)
{
        struct net_device *udev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
        struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
        int ret, cur = 0;

        now = dev;
        iter = &dev->adj_list.upper;

        while (1) {
                if (now != dev) {
                        ret = fn(now, priv);
                        if (ret)
                                return ret;
                }

                next = NULL;
                while (1) {
                        udev = netdev_next_upper_dev_rcu(now, &iter);
                        if (!udev)
                                break;

                        next = udev;
                        niter = &udev->adj_list.upper;
                        dev_stack[cur] = now;
                        iter_stack[cur++] = iter;
                        break;
                }

                if (!next) {
                        if (!cur)
                                return 0;
                        next = dev_stack[--cur];
                        niter = iter_stack[cur];
                }

                now = next;
                iter = niter;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(netdev_walk_all_upper_dev_rcu);

static bool __netdev_has_upper_dev(struct net_device *dev,
                                   struct net_device *upper_dev)
{
        struct netdev_nested_priv priv = {
                .flags = 0,
                .data = (void *)upper_dev,
        };

        ASSERT_RTNL();

        return __netdev_walk_all_upper_dev(dev, ____netdev_has_upper_dev,
                                           &priv);
}

/**
 * netdev_lower_get_next_private - Get the next ->private from the
 *                                 lower neighbour list
 * @dev: device
 * @iter: list_head ** of the current position
 *
 * Gets the next netdev_adjacent->private from the dev's lower neighbour
 * list, starting from iter position. The caller must hold either hold the
 * RTNL lock or its own locking that guarantees that the neighbour lower
 * list will remain unchanged.
 */
void *netdev_lower_get_next_private(struct net_device *dev,
                                    struct list_head **iter)
{
        struct netdev_adjacent *lower;

        lower = list_entry(*iter, struct netdev_adjacent, list);

        if (&lower->list == &dev->adj_list.lower)
                return NULL;

        *iter = lower->list.next;

        return lower->private;
}
EXPORT_SYMBOL(netdev_lower_get_next_private);

/**
 * netdev_lower_get_next_private_rcu - Get the next ->private from the
 *                                     lower neighbour list, RCU
 *                                     variant
 * @dev: device
 * @iter: list_head ** of the current position
 *
 * Gets the next netdev_adjacent->private from the dev's lower neighbour
 * list, starting from iter position. The caller must hold RCU read lock.
 */
void *netdev_lower_get_next_private_rcu(struct net_device *dev,
                                        struct list_head **iter)
{
        struct netdev_adjacent *lower;

        WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_bh_held());

        lower = list_entry_rcu((*iter)->next, struct netdev_adjacent, list);

        if (&lower->list == &dev->adj_list.lower)
                return NULL;

        *iter = &lower->list;

        return lower->private;
}
EXPORT_SYMBOL(netdev_lower_get_next_private_rcu);

/**
 * netdev_lower_get_next - Get the next device from the lower neighbour
 *                         list
 * @dev: device
 * @iter: list_head ** of the current position
 *
 * Gets the next netdev_adjacent from the dev's lower neighbour
 * list, starting from iter position. The caller must hold RTNL lock or
 * its own locking that guarantees that the neighbour lower
 * list will remain unchanged.
 */
void *netdev_lower_get_next(struct net_device *dev, struct list_head **iter)
{
        struct netdev_adjacent *lower;

        lower = list_entry(*iter, struct netdev_adjacent, list);

        if (&lower->list == &dev->adj_list.lower)
                return NULL;

        *iter = lower->list.next;

        return lower->dev;
}
EXPORT_SYMBOL(netdev_lower_get_next);

static struct net_device *netdev_next_lower_dev(struct net_device *dev,
                                                struct list_head **iter)
{
        struct netdev_adjacent *lower;

        lower = list_entry((*iter)->next, struct netdev_adjacent, list);

        if (&lower->list == &dev->adj_list.lower)
                return NULL;

        *iter = &lower->list;

        return lower->dev;
}

static struct net_device *__netdev_next_lower_dev(struct net_device *dev,
                                                  struct list_head **iter,
                                                  bool *ignore)
{
        struct netdev_adjacent *lower;

        lower = list_entry((*iter)->next, struct netdev_adjacent, list);

        if (&lower->list == &dev->adj_list.lower)
                return NULL;

        *iter = &lower->list;
        *ignore = lower->ignore;

        return lower->dev;
}

int netdev_walk_all_lower_dev(struct net_device *dev,
                              int (*fn)(struct net_device *dev,
                                        struct netdev_nested_priv *priv),
                              struct netdev_nested_priv *priv)
{
        struct net_device *ldev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
        struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
        int ret, cur = 0;

        now = dev;
        iter = &dev->adj_list.lower;

        while (1) {
                if (now != dev) {
                        ret = fn(now, priv);
                        if (ret)
                                return ret;
                }

                next = NULL;
                while (1) {
                        ldev = netdev_next_lower_dev(now, &iter);
                        if (!ldev)
                                break;

                        next = ldev;
                        niter = &ldev->adj_list.lower;
                        dev_stack[cur] = now;
                        iter_stack[cur++] = iter;
                        break;
                }

                if (!next) {
                        if (!cur)
                                return 0;
                        next = dev_stack[--cur];
                        niter = iter_stack[cur];
                }

                now = next;
                iter = niter;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(netdev_walk_all_lower_dev);

static int __netdev_walk_all_lower_dev(struct net_device *dev,
                                       int (*fn)(struct net_device *dev,
                                         struct netdev_nested_priv *priv),
                                       struct netdev_nested_priv *priv)
{
        struct net_device *ldev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
        struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
        int ret, cur = 0;
        bool ignore;

        now = dev;
        iter = &dev->adj_list.lower;

        while (1) {
                if (now != dev) {
                        ret = fn(now, priv);
                        if (ret)
                                return ret;
                }

                next = NULL;
                while (1) {
                        ldev = __netdev_next_lower_dev(now, &iter, &ignore);
                        if (!ldev)
                                break;
                        if (ignore)
                                continue;

                        next = ldev;
                        niter = &ldev->adj_list.lower;
                        dev_stack[cur] = now;
                        iter_stack[cur++] = iter;
                        break;
                }

                if (!next) {
                        if (!cur)
                                return 0;
                        next = dev_stack[--cur];
                        niter = iter_stack[cur];
                }

                now = next;
                iter = niter;
        }

        return 0;
}

struct net_device *netdev_next_lower_dev_rcu(struct net_device *dev,
                                             struct list_head **iter)
{
        struct netdev_adjacent *lower;

        lower = list_entry_rcu((*iter)->next, struct netdev_adjacent, list);
        if (&lower->list == &dev->adj_list.lower)
                return NULL;

        *iter = &lower->list;

        return lower->dev;
}
EXPORT_SYMBOL(netdev_next_lower_dev_rcu);

static u8 __netdev_upper_depth(struct net_device *dev)
{
        struct net_device *udev;
        struct list_head *iter;
        u8 max_depth = 0;
        bool ignore;

        for (iter = &dev->adj_list.upper,
             udev = __netdev_next_upper_dev(dev, &iter, &ignore);
             udev;
             udev = __netdev_next_upper_dev(dev, &iter, &ignore)) {
                if (ignore)
                        continue;
                if (max_depth < udev->upper_level)
                        max_depth = udev->upper_level;
        }

        return max_depth;
}

static u8 __netdev_lower_depth(struct net_device *dev)
{
        struct net_device *ldev;
        struct list_head *iter;
        u8 max_depth = 0;
        bool ignore;

        for (iter = &dev->adj_list.lower,
             ldev = __netdev_next_lower_dev(dev, &iter, &ignore);
             ldev;
             ldev = __netdev_next_lower_dev(dev, &iter, &ignore)) {
                if (ignore)
                        continue;
                if (max_depth < ldev->lower_level)
                        max_depth = ldev->lower_level;
        }

        return max_depth;
}

static int __netdev_update_upper_level(struct net_device *dev,
                                       struct netdev_nested_priv *__unused)
{
        dev->upper_level = __netdev_upper_depth(dev) + 1;
        return 0;
}

#ifdef CONFIG_LOCKDEP
static LIST_HEAD(net_unlink_list);

static void net_unlink_todo(struct net_device *dev)
{
        if (list_empty(&dev->unlink_list))
                list_add_tail(&dev->unlink_list, &net_unlink_list);
}
#endif

static int __netdev_update_lower_level(struct net_device *dev,
                                       struct netdev_nested_priv *priv)
{
        dev->lower_level = __netdev_lower_depth(dev) + 1;

#ifdef CONFIG_LOCKDEP
        if (!priv)
                return 0;

        if (priv->flags & NESTED_SYNC_IMM)
                dev->nested_level = dev->lower_level - 1;
        if (priv->flags & NESTED_SYNC_TODO)
                net_unlink_todo(dev);
#endif
        return 0;
}

int netdev_walk_all_lower_dev_rcu(struct net_device *dev,
                                  int (*fn)(struct net_device *dev,
                                            struct netdev_nested_priv *priv),
                                  struct netdev_nested_priv *priv)
{
        struct net_device *ldev, *next, *now, *dev_stack[MAX_NEST_DEV + 1];
        struct list_head *niter, *iter, *iter_stack[MAX_NEST_DEV + 1];
        int ret, cur = 0;

        now = dev;
        iter = &dev->adj_list.lower;

        while (1) {
                if (now != dev) {
                        ret = fn(now, priv);
                        if (ret)
                                return ret;
                }

                next = NULL;
                while (1) {
                        ldev = netdev_next_lower_dev_rcu(now, &iter);
                        if (!ldev)
                                break;

                        next = ldev;
                        niter = &ldev->adj_list.lower;
                        dev_stack[cur] = now;
                        iter_stack[cur++] = iter;
                        break;
                }

                if (!next) {
                        if (!cur)
                                return 0;
                        next = dev_stack[--cur];
                        niter = iter_stack[cur];
                }

                now = next;
                iter = niter;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(netdev_walk_all_lower_dev_rcu);

/**
 * netdev_lower_get_first_private_rcu - Get the first ->private from the
 *                                     lower neighbour list, RCU
 *                                     variant
 * @dev: device
 *
 * Gets the first netdev_adjacent->private from the dev's lower neighbour
 * list. The caller must hold RCU read lock.
 */
void *netdev_lower_get_first_private_rcu(struct net_device *dev)
{
        struct netdev_adjacent *lower;

        lower = list_first_or_null_rcu(&dev->adj_list.lower,
                        struct netdev_adjacent, list);
        if (lower)
                return lower->private;
        return NULL;
}
EXPORT_SYMBOL(netdev_lower_get_first_private_rcu);

/**
 * netdev_master_upper_dev_get_rcu - Get master upper device
 * @dev: device
 *
 * Find a master upper device and return pointer to it or NULL in case
 * it's not there. The caller must hold the RCU read lock.
 */
struct net_device *netdev_master_upper_dev_get_rcu(struct net_device *dev)
{
        struct netdev_adjacent *upper;

        upper = list_first_or_null_rcu(&dev->adj_list.upper,
                                       struct netdev_adjacent, list);
        if (upper && likely(upper->master))
                return upper->dev;
        return NULL;
}
EXPORT_SYMBOL(netdev_master_upper_dev_get_rcu);

static int netdev_adjacent_sysfs_add(struct net_device *dev,
                              struct net_device *adj_dev,
                              struct list_head *dev_list)
{
        char linkname[IFNAMSIZ+7];

        sprintf(linkname, dev_list == &dev->adj_list.upper ?
                "upper_%s" : "lower_%s", adj_dev->name);
        return sysfs_create_link(&(dev->dev.kobj), &(adj_dev->dev.kobj),
                                 linkname);
}
static void netdev_adjacent_sysfs_del(struct net_device *dev,
                               char *name,
                               struct list_head *dev_list)
{
        char linkname[IFNAMSIZ+7];

        sprintf(linkname, dev_list == &dev->adj_list.upper ?
                "upper_%s" : "lower_%s", name);
        sysfs_remove_link(&(dev->dev.kobj), linkname);
}

static inline bool netdev_adjacent_is_neigh_list(struct net_device *dev,
                                                 struct net_device *adj_dev,
                                                 struct list_head *dev_list)
{
        return (dev_list == &dev->adj_list.upper ||
                dev_list == &dev->adj_list.lower) &&
                net_eq(dev_net(dev), dev_net(adj_dev));
}

static int __netdev_adjacent_dev_insert(struct net_device *dev,
                                        struct net_device *adj_dev,
                                        struct list_head *dev_list,
                                        void *private, bool master)
{
        struct netdev_adjacent *adj;
        int ret;

        adj = __netdev_find_adj(adj_dev, dev_list);

        if (adj) {
                adj->ref_nr += 1;
                pr_debug("Insert adjacency: dev %s adj_dev %s adj->ref_nr %d\n",
                         dev->name, adj_dev->name, adj->ref_nr);

                return 0;
        }

        adj = kmalloc(sizeof(*adj), GFP_KERNEL);
        if (!adj)
                return -ENOMEM;

        adj->dev = adj_dev;
        adj->master = master;
        adj->ref_nr = 1;
        adj->private = private;
        adj->ignore = false;
        netdev_hold(adj_dev, &adj->dev_tracker, GFP_KERNEL);

        pr_debug("Insert adjacency: dev %s adj_dev %s adj->ref_nr %d; dev_hold on %s\n",
                 dev->name, adj_dev->name, adj->ref_nr, adj_dev->name);

        if (netdev_adjacent_is_neigh_list(dev, adj_dev, dev_list)) {
                ret = netdev_adjacent_sysfs_add(dev, adj_dev, dev_list);
                if (ret)
                        goto free_adj;
        }

        /* Ensure that master link is always the first item in list. */
        if (master) {
                ret = sysfs_create_link(&(dev->dev.kobj),
                                        &(adj_dev->dev.kobj), "master");
                if (ret)
                        goto remove_symlinks;

                list_add_rcu(&adj->list, dev_list);
        } else {
                list_add_tail_rcu(&adj->list, dev_list);
        }

        return 0;

remove_symlinks:
        if (netdev_adjacent_is_neigh_list(dev, adj_dev, dev_list))
                netdev_adjacent_sysfs_del(dev, adj_dev->name, dev_list);
free_adj:
        netdev_put(adj_dev, &adj->dev_tracker);
        kfree(adj);

        return ret;
}

static void __netdev_adjacent_dev_remove(struct net_device *dev,
                                         struct net_device *adj_dev,
                                         u16 ref_nr,
                                         struct list_head *dev_list)
{
        struct netdev_adjacent *adj;

        pr_debug("Remove adjacency: dev %s adj_dev %s ref_nr %d\n",
                 dev->name, adj_dev->name, ref_nr);

        adj = __netdev_find_adj(adj_dev, dev_list);

        if (!adj) {
                pr_err("Adjacency does not exist for device %s from %s\n",
                       dev->name, adj_dev->name);
                WARN_ON(1);
                return;
        }

        if (adj->ref_nr > ref_nr) {
                pr_debug("adjacency: %s to %s ref_nr - %d = %d\n",
                         dev->name, adj_dev->name, ref_nr,
                         adj->ref_nr - ref_nr);
                adj->ref_nr -= ref_nr;
                return;
        }

        if (adj->master)
                sysfs_remove_link(&(dev->dev.kobj), "master");

        if (netdev_adjacent_is_neigh_list(dev, adj_dev, dev_list))
                netdev_adjacent_sysfs_del(dev, adj_dev->name, dev_list);

        list_del_rcu(&adj->list);
        pr_debug("adjacency: dev_put for %s, because link removed from %s to %s\n",
                 adj_dev->name, dev->name, adj_dev->name);
        netdev_put(adj_dev, &adj->dev_tracker);
        kfree_rcu(adj, rcu);
}

static int __netdev_adjacent_dev_link_lists(struct net_device *dev,
                                            struct net_device *upper_dev,
                                            struct list_head *up_list,
                                            struct list_head *down_list,
                                            void *private, bool master)
{
        int ret;

        ret = __netdev_adjacent_dev_insert(dev, upper_dev, up_list,
                                           private, master);
        if (ret)
                return ret;

        ret = __netdev_adjacent_dev_insert(upper_dev, dev, down_list,
                                           private, false);
        if (ret) {
                __netdev_adjacent_dev_remove(dev, upper_dev, 1, up_list);
                return ret;
        }

        return 0;
}

static void __netdev_adjacent_dev_unlink_lists(struct net_device *dev,
                                               struct net_device *upper_dev,
                                               u16 ref_nr,
                                               struct list_head *up_list,
                                               struct list_head *down_list)
{
        __netdev_adjacent_dev_remove(dev, upper_dev, ref_nr, up_list);
        __netdev_adjacent_dev_remove(upper_dev, dev, ref_nr, down_list);
}

static int __netdev_adjacent_dev_link_neighbour(struct net_device *dev,
                                                struct net_device *upper_dev,
                                                void *private, bool master)
{
        return __netdev_adjacent_dev_link_lists(dev, upper_dev,
                                                &dev->adj_list.upper,
                                                &upper_dev->adj_list.lower,
                                                private, master);
}

static void __netdev_adjacent_dev_unlink_neighbour(struct net_device *dev,
                                                   struct net_device *upper_dev)
{
        __netdev_adjacent_dev_unlink_lists(dev, upper_dev, 1,
                                           &dev->adj_list.upper,
                                           &upper_dev->adj_list.lower);
}

static int __netdev_upper_dev_link(struct net_device *dev,
                                   struct net_device *upper_dev, bool master,
                                   void *upper_priv, void *upper_info,
                                   struct netdev_nested_priv *priv,
                                   struct netlink_ext_ack *extack)
{
        struct netdev_notifier_changeupper_info changeupper_info = {
                .info = {
                        .dev = dev,
                        .extack = extack,
                },
                .upper_dev = upper_dev,
                .master = master,
                .linking = true,
                .upper_info = upper_info,
        };
        struct net_device *master_dev;
        int ret = 0;

        ASSERT_RTNL();

        if (dev == upper_dev)
                return -EBUSY;

        /* To prevent loops, check if dev is not upper device to upper_dev. */
        if (__netdev_has_upper_dev(upper_dev, dev))
                return -EBUSY;

        if ((dev->lower_level + upper_dev->upper_level) > MAX_NEST_DEV)
                return -EMLINK;

        if (!master) {
                if (__netdev_has_upper_dev(dev, upper_dev))
                        return -EEXIST;
        } else {
                master_dev = __netdev_master_upper_dev_get(dev);
                if (master_dev)
                        return master_dev == upper_dev ? -EEXIST : -EBUSY;
        }

        ret = call_netdevice_notifiers_info(NETDEV_PRECHANGEUPPER,
                                            &changeupper_info.info);
        ret = notifier_to_errno(ret);
        if (ret)
                return ret;

        ret = __netdev_adjacent_dev_link_neighbour(dev, upper_dev, upper_priv,
                                                   master);
        if (ret)
                return ret;

        ret = call_netdevice_notifiers_info(NETDEV_CHANGEUPPER,
                                            &changeupper_info.info);
        ret = notifier_to_errno(ret);
        if (ret)
                goto rollback;

        __netdev_update_upper_level(dev, NULL);
        __netdev_walk_all_lower_dev(dev, __netdev_update_upper_level, NULL);

        __netdev_update_lower_level(upper_dev, priv);
        __netdev_walk_all_upper_dev(upper_dev, __netdev_update_lower_level,
                                    priv);

        return 0;

rollback:
        __netdev_adjacent_dev_unlink_neighbour(dev, upper_dev);

        return ret;
}

/**
 * netdev_upper_dev_link - Add a link to the upper device
 * @dev: device
 * @upper_dev: new upper device
 * @extack: netlink extended ack
 *
 * Adds a link to device which is upper to this one. The caller must hold
 * the RTNL lock. On a failure a negative errno code is returned.
 * On success the reference counts are adjusted and the function
 * returns zero.
 */
int netdev_upper_dev_link(struct net_device *dev,
                          struct net_device *upper_dev,
                          struct netlink_ext_ack *extack)
{
        struct netdev_nested_priv priv = {
                .flags = NESTED_SYNC_IMM | NESTED_SYNC_TODO,
                .data = NULL,
        };

        return __netdev_upper_dev_link(dev, upper_dev, false,
                                       NULL, NULL, &priv, extack);
}
EXPORT_SYMBOL(netdev_upper_dev_link);

/**
 * netdev_master_upper_dev_link - Add a master link to the upper device
 * @dev: device
 * @upper_dev: new upper device
 * @upper_priv: upper device private
 * @upper_info: upper info to be passed down via notifier
 * @extack: netlink extended ack
 *
 * Adds a link to device which is upper to this one. In this case, only
 * one master upper device can be linked, although other non-master devices
 * might be linked as well. The caller must hold the RTNL lock.
 * On a failure a negative errno code is returned. On success the reference
 * counts are adjusted and the function returns zero.
 */
int netdev_master_upper_dev_link(struct net_device *dev,
                                 struct net_device *upper_dev,
                                 void *upper_priv, void *upper_info,
                                 struct netlink_ext_ack *extack)
{
        struct netdev_nested_priv priv = {
                .flags = NESTED_SYNC_IMM | NESTED_SYNC_TODO,
                .data = NULL,
        };

        return __netdev_upper_dev_link(dev, upper_dev, true,
                                       upper_priv, upper_info, &priv, extack);
}
EXPORT_SYMBOL(netdev_master_upper_dev_link);

static void __netdev_upper_dev_unlink(struct net_device *dev,
                                      struct net_device *upper_dev,
                                      struct netdev_nested_priv *priv)
{
        struct netdev_notifier_changeupper_info changeupper_info = {
                .info = {
                        .dev = dev,
                },
                .upper_dev = upper_dev,
                .linking = false,
        };

        ASSERT_RTNL();

        changeupper_info.master = netdev_master_upper_dev_get(dev) == upper_dev;

        call_netdevice_notifiers_info(NETDEV_PRECHANGEUPPER,
                                      &changeupper_info.info);

        __netdev_adjacent_dev_unlink_neighbour(dev, upper_dev);

        call_netdevice_notifiers_info(NETDEV_CHANGEUPPER,
                                      &changeupper_info.info);

        __netdev_update_upper_level(dev, NULL);
        __netdev_walk_all_lower_dev(dev, __netdev_update_upper_level, NULL);

        __netdev_update_lower_level(upper_dev, priv);
        __netdev_walk_all_upper_dev(upper_dev, __netdev_update_lower_level,
                                    priv);
}

/**
 * netdev_upper_dev_unlink - Removes a link to upper device
 * @dev: device
 * @upper_dev: new upper device
 *
 * Removes a link to device which is upper to this one. The caller must hold
 * the RTNL lock.
 */
void netdev_upper_dev_unlink(struct net_device *dev,
                             struct net_device *upper_dev)
{
        struct netdev_nested_priv priv = {
                .flags = NESTED_SYNC_TODO,
                .data = NULL,
        };

        __netdev_upper_dev_unlink(dev, upper_dev, &priv);
}
EXPORT_SYMBOL(netdev_upper_dev_unlink);

static void __netdev_adjacent_dev_set(struct net_device *upper_dev,
                                      struct net_device *lower_dev,
                                      bool val)
{
        struct netdev_adjacent *adj;

        adj = __netdev_find_adj(lower_dev, &upper_dev->adj_list.lower);
        if (adj)
                adj->ignore = val;

        adj = __netdev_find_adj(upper_dev, &lower_dev->adj_list.upper);
        if (adj)
                adj->ignore = val;
}

static void netdev_adjacent_dev_disable(struct net_device *upper_dev,
                                        struct net_device *lower_dev)
{
        __netdev_adjacent_dev_set(upper_dev, lower_dev, true);
}

static void netdev_adjacent_dev_enable(struct net_device *upper_dev,
                                       struct net_device *lower_dev)
{
        __netdev_adjacent_dev_set(upper_dev, lower_dev, false);
}

int netdev_adjacent_change_prepare(struct net_device *old_dev,
                                   struct net_device *new_dev,
                                   struct net_device *dev,
                                   struct netlink_ext_ack *extack)
{
        struct netdev_nested_priv priv = {
                .flags = 0,
                .data = NULL,
        };
        int err;

        if (!new_dev)
                return 0;

        if (old_dev && new_dev != old_dev)
                netdev_adjacent_dev_disable(dev, old_dev);
        err = __netdev_upper_dev_link(new_dev, dev, false, NULL, NULL, &priv,
                                      extack);
        if (err) {
                if (old_dev && new_dev != old_dev)
                        netdev_adjacent_dev_enable(dev, old_dev);
                return err;
        }

        return 0;
}
EXPORT_SYMBOL(netdev_adjacent_change_prepare);

void netdev_adjacent_change_commit(struct net_device *old_dev,
                                   struct net_device *new_dev,
                                   struct net_device *dev)
{
        struct netdev_nested_priv priv = {
                .flags = NESTED_SYNC_IMM | NESTED_SYNC_TODO,
                .data = NULL,
        };

        if (!new_dev || !old_dev)
                return;

        if (new_dev == old_dev)
                return;

        netdev_adjacent_dev_enable(dev, old_dev);
        __netdev_upper_dev_unlink(old_dev, dev, &priv);
}
EXPORT_SYMBOL(netdev_adjacent_change_commit);

void netdev_adjacent_change_abort(struct net_device *old_dev,
                                  struct net_device *new_dev,
                                  struct net_device *dev)
{
        struct netdev_nested_priv priv = {
                .flags = 0,
                .data = NULL,
        };

        if (!new_dev)
                return;

        if (old_dev && new_dev != old_dev)
                netdev_adjacent_dev_enable(dev, old_dev);

        __netdev_upper_dev_unlink(new_dev, dev, &priv);
}
EXPORT_SYMBOL(netdev_adjacent_change_abort);

/**
 * netdev_bonding_info_change - Dispatch event about slave change
 * @dev: device
 * @bonding_info: info to dispatch
 *
 * Send NETDEV_BONDING_INFO to netdev notifiers with info.
 * The caller must hold the RTNL lock.
 */
void netdev_bonding_info_change(struct net_device *dev,
                                struct netdev_bonding_info *bonding_info)
{
        struct netdev_notifier_bonding_info info = {
                .info.dev = dev,
        };

        memcpy(&info.bonding_info, bonding_info,
               sizeof(struct netdev_bonding_info));
        call_netdevice_notifiers_info(NETDEV_BONDING_INFO,
                                      &info.info);
}
EXPORT_SYMBOL(netdev_bonding_info_change);

static int netdev_offload_xstats_enable_l3(struct net_device *dev,
                                           struct netlink_ext_ack *extack)
{
        struct netdev_notifier_offload_xstats_info info = {
                .info.dev = dev,
                .info.extack = extack,
                .type = NETDEV_OFFLOAD_XSTATS_TYPE_L3,
        };
        int err;
        int rc;

        dev->offload_xstats_l3 = kzalloc(sizeof(*dev->offload_xstats_l3),
                                         GFP_KERNEL);
        if (!dev->offload_xstats_l3)
                return -ENOMEM;

        rc = call_netdevice_notifiers_info_robust(NETDEV_OFFLOAD_XSTATS_ENABLE,
                                                  NETDEV_OFFLOAD_XSTATS_DISABLE,
                                                  &info.info);
        err = notifier_to_errno(rc);
        if (err)
                goto free_stats;

        return 0;

free_stats:
        kfree(dev->offload_xstats_l3);
        dev->offload_xstats_l3 = NULL;
        return err;
}

int netdev_offload_xstats_enable(struct net_device *dev,
                                 enum netdev_offload_xstats_type type,
                                 struct netlink_ext_ack *extack)
{
        ASSERT_RTNL();

        if (netdev_offload_xstats_enabled(dev, type))
                return -EALREADY;

        switch (type) {
        case NETDEV_OFFLOAD_XSTATS_TYPE_L3:
                return netdev_offload_xstats_enable_l3(dev, extack);
        }

        WARN_ON(1);
        return -EINVAL;
}
EXPORT_SYMBOL(netdev_offload_xstats_enable);

static void netdev_offload_xstats_disable_l3(struct net_device *dev)
{
        struct netdev_notifier_offload_xstats_info info = {
                .info.dev = dev,
                .type = NETDEV_OFFLOAD_XSTATS_TYPE_L3,
        };

        call_netdevice_notifiers_info(NETDEV_OFFLOAD_XSTATS_DISABLE,
                                      &info.info);
        kfree(dev->offload_xstats_l3);
        dev->offload_xstats_l3 = NULL;
}

int netdev_offload_xstats_disable(struct net_device *dev,
                                  enum netdev_offload_xstats_type type)
{
        ASSERT_RTNL();

        if (!netdev_offload_xstats_enabled(dev, type))
                return -EALREADY;

        switch (type) {
        case NETDEV_OFFLOAD_XSTATS_TYPE_L3:
                netdev_offload_xstats_disable_l3(dev);
                return 0;
        }

        WARN_ON(1);
        return -EINVAL;
}
EXPORT_SYMBOL(netdev_offload_xstats_disable);

static void netdev_offload_xstats_disable_all(struct net_device *dev)
{
        netdev_offload_xstats_disable(dev, NETDEV_OFFLOAD_XSTATS_TYPE_L3);
}

static struct rtnl_hw_stats64 *
netdev_offload_xstats_get_ptr(const struct net_device *dev,
                              enum netdev_offload_xstats_type type)
{
        switch (type) {
        case NETDEV_OFFLOAD_XSTATS_TYPE_L3:
                return dev->offload_xstats_l3;
        }

        WARN_ON(1);
        return NULL;
}

bool netdev_offload_xstats_enabled(const struct net_device *dev,
                                   enum netdev_offload_xstats_type type)
{
        ASSERT_RTNL();

        return netdev_offload_xstats_get_ptr(dev, type);
}
EXPORT_SYMBOL(netdev_offload_xstats_enabled);

struct netdev_notifier_offload_xstats_ru {
        bool used;
};

struct netdev_notifier_offload_xstats_rd {
        struct rtnl_hw_stats64 stats;
        bool used;
};

static void netdev_hw_stats64_add(struct rtnl_hw_stats64 *dest,
                                  const struct rtnl_hw_stats64 *src)
{
        dest->rx_packets          += src->rx_packets;
        dest->tx_packets          += src->tx_packets;
        dest->rx_bytes            += src->rx_bytes;
        dest->tx_bytes            += src->tx_bytes;
        dest->rx_errors           += src->rx_errors;
        dest->tx_errors           += src->tx_errors;
        dest->rx_dropped          += src->rx_dropped;
        dest->tx_dropped          += src->tx_dropped;
        dest->multicast           += src->multicast;
}

static int netdev_offload_xstats_get_used(struct net_device *dev,
                                          enum netdev_offload_xstats_type type,
                                          bool *p_used,
                                          struct netlink_ext_ack *extack)
{
        struct netdev_notifier_offload_xstats_ru report_used = {};
        struct netdev_notifier_offload_xstats_info info = {
                .info.dev = dev,
                .info.extack = extack,
                .type = type,
                .report_used = &report_used,
        };
        int rc;

        WARN_ON(!netdev_offload_xstats_enabled(dev, type));
        rc = call_netdevice_notifiers_info(NETDEV_OFFLOAD_XSTATS_REPORT_USED,
                                           &info.info);
        *p_used = report_used.used;
        return notifier_to_errno(rc);
}

static int netdev_offload_xstats_get_stats(struct net_device *dev,
                                           enum netdev_offload_xstats_type type,
                                           struct rtnl_hw_stats64 *p_stats,
                                           bool *p_used,
                                           struct netlink_ext_ack *extack)
{
        struct netdev_notifier_offload_xstats_rd report_delta = {};
        struct netdev_notifier_offload_xstats_info info = {
                .info.dev = dev,
                .info.extack = extack,
                .type = type,
                .report_delta = &report_delta,
        };
        struct rtnl_hw_stats64 *stats;
        int rc;

        stats = netdev_offload_xstats_get_ptr(dev, type);
        if (WARN_ON(!stats))
                return -EINVAL;

        rc = call_netdevice_notifiers_info(NETDEV_OFFLOAD_XSTATS_REPORT_DELTA,
                                           &info.info);

        /* Cache whatever we got, even if there was an error, otherwise the
         * successful stats retrievals would get lost.
         */
        netdev_hw_stats64_add(stats, &report_delta.stats);

        if (p_stats)
                *p_stats = *stats;
        *p_used = report_delta.used;

        return notifier_to_errno(rc);
}

int netdev_offload_xstats_get(struct net_device *dev,
                              enum netdev_offload_xstats_type type,
                              struct rtnl_hw_stats64 *p_stats, bool *p_used,
                              struct netlink_ext_ack *extack)
{
        ASSERT_RTNL();

        if (p_stats)
                return netdev_offload_xstats_get_stats(dev, type, p_stats,
                                                       p_used, extack);
        else
                return netdev_offload_xstats_get_used(dev, type, p_used,
                                                      extack);
}
EXPORT_SYMBOL(netdev_offload_xstats_get);

void
netdev_offload_xstats_report_delta(struct netdev_notifier_offload_xstats_rd *report_delta,
                                   const struct rtnl_hw_stats64 *stats)
{
        report_delta->used = true;
        netdev_hw_stats64_add(&report_delta->stats, stats);
}
EXPORT_SYMBOL(netdev_offload_xstats_report_delta);

void
netdev_offload_xstats_report_used(struct netdev_notifier_offload_xstats_ru *report_used)
{
        report_used->used = true;
}
EXPORT_SYMBOL(netdev_offload_xstats_report_used);

void netdev_offload_xstats_push_delta(struct net_device *dev,
                                      enum netdev_offload_xstats_type type,
                                      const struct rtnl_hw_stats64 *p_stats)
{
        struct rtnl_hw_stats64 *stats;

        ASSERT_RTNL();

        stats = netdev_offload_xstats_get_ptr(dev, type);
        if (WARN_ON(!stats))
                return;

        netdev_hw_stats64_add(stats, p_stats);
}
EXPORT_SYMBOL(netdev_offload_xstats_push_delta);

/**
 * netdev_get_xmit_slave - Get the xmit slave of master device
 * @dev: device
 * @skb: The packet
 * @all_slaves: assume all the slaves are active
 *
 * The reference counters are not incremented so the caller must be
 * careful with locks. The caller must hold RCU lock.
 * %NULL is returned if no slave is found.
 */

struct net_device *netdev_get_xmit_slave(struct net_device *dev,
                                         struct sk_buff *skb,
                                         bool all_slaves)
{
        const struct net_device_ops *ops = dev->netdev_ops;

        if (!ops->ndo_get_xmit_slave)
                return NULL;
        return ops->ndo_get_xmit_slave(dev, skb, all_slaves);
}
EXPORT_SYMBOL(netdev_get_xmit_slave);

static struct net_device *netdev_sk_get_lower_dev(struct net_device *dev,
                                                  struct sock *sk)
{
        const struct net_device_ops *ops = dev->netdev_ops;

        if (!ops->ndo_sk_get_lower_dev)
                return NULL;
        return ops->ndo_sk_get_lower_dev(dev, sk);
}

/**
 * netdev_sk_get_lowest_dev - Get the lowest device in chain given device and socket
 * @dev: device
 * @sk: the socket
 *
 * %NULL is returned if no lower device is found.
 */

struct net_device *netdev_sk_get_lowest_dev(struct net_device *dev,
                                            struct sock *sk)
{
        struct net_device *lower;

        lower = netdev_sk_get_lower_dev(dev, sk);
        while (lower) {
                dev = lower;
                lower = netdev_sk_get_lower_dev(dev, sk);
        }

        return dev;
}
EXPORT_SYMBOL(netdev_sk_get_lowest_dev);

static void netdev_adjacent_add_links(struct net_device *dev)
{
        struct netdev_adjacent *iter;

        struct net *net = dev_net(dev);

        list_for_each_entry(iter, &dev->adj_list.upper, list) {
                if (!net_eq(net, dev_net(iter->dev)))
                        continue;
                netdev_adjacent_sysfs_add(iter->dev, dev,
                                          &iter->dev->adj_list.lower);
                netdev_adjacent_sysfs_add(dev, iter->dev,
                                          &dev->adj_list.upper);
        }

        list_for_each_entry(iter, &dev->adj_list.lower, list) {
                if (!net_eq(net, dev_net(iter->dev)))
                        continue;
                netdev_adjacent_sysfs_add(iter->dev, dev,
                                          &iter->dev->adj_list.upper);
                netdev_adjacent_sysfs_add(dev, iter->dev,
                                          &dev->adj_list.lower);
        }
}

static void netdev_adjacent_del_links(struct net_device *dev)
{
        struct netdev_adjacent *iter;

        struct net *net = dev_net(dev);

        list_for_each_entry(iter, &dev->adj_list.upper, list) {
                if (!net_eq(net, dev_net(iter->dev)))
                        continue;
                netdev_adjacent_sysfs_del(iter->dev, dev->name,
                                          &iter->dev->adj_list.lower);
                netdev_adjacent_sysfs_del(dev, iter->dev->name,
                                          &dev->adj_list.upper);
        }

        list_for_each_entry(iter, &dev->adj_list.lower, list) {
                if (!net_eq(net, dev_net(iter->dev)))
                        continue;
                netdev_adjacent_sysfs_del(iter->dev, dev->name,
                                          &iter->dev->adj_list.upper);
                netdev_adjacent_sysfs_del(dev, iter->dev->name,
                                          &dev->adj_list.lower);
        }
}

void netdev_adjacent_rename_links(struct net_device *dev, char *oldname)
{
        struct netdev_adjacent *iter;

        struct net *net = dev_net(dev);

        list_for_each_entry(iter, &dev->adj_list.upper, list) {
                if (!net_eq(net, dev_net(iter->dev)))
                        continue;
                netdev_adjacent_sysfs_del(iter->dev, oldname,
                                          &iter->dev->adj_list.lower);
                netdev_adjacent_sysfs_add(iter->dev, dev,
                                          &iter->dev->adj_list.lower);
        }

        list_for_each_entry(iter, &dev->adj_list.lower, list) {
                if (!net_eq(net, dev_net(iter->dev)))
                        continue;
                netdev_adjacent_sysfs_del(iter->dev, oldname,
                                          &iter->dev->adj_list.upper);
                netdev_adjacent_sysfs_add(iter->dev, dev,
                                          &iter->dev->adj_list.upper);
        }
}

void *netdev_lower_dev_get_private(struct net_device *dev,
                                   struct net_device *lower_dev)
{
        struct netdev_adjacent *lower;

        if (!lower_dev)
                return NULL;
        lower = __netdev_find_adj(lower_dev, &dev->adj_list.lower);
        if (!lower)
                return NULL;

        return lower->private;
}
EXPORT_SYMBOL(netdev_lower_dev_get_private);


/**
 * netdev_lower_state_changed - Dispatch event about lower device state change
 * @lower_dev: device
 * @lower_state_info: state to dispatch
 *
 * Send NETDEV_CHANGELOWERSTATE to netdev notifiers with info.
 * The caller must hold the RTNL lock.
 */
void netdev_lower_state_changed(struct net_device *lower_dev,
                                void *lower_state_info)
{
        struct netdev_notifier_changelowerstate_info changelowerstate_info = {
                .info.dev = lower_dev,
        };

        ASSERT_RTNL();
        changelowerstate_info.lower_state_info = lower_state_info;
        call_netdevice_notifiers_info(NETDEV_CHANGELOWERSTATE,
                                      &changelowerstate_info.info);
}
EXPORT_SYMBOL(netdev_lower_state_changed);

static void dev_change_rx_flags(struct net_device *dev, int flags)
{
        const struct net_device_ops *ops = dev->netdev_ops;

        if (ops->ndo_change_rx_flags)
                ops->ndo_change_rx_flags(dev, flags);
}

static int __dev_set_promiscuity(struct net_device *dev, int inc, bool notify)
{
        unsigned int old_flags = dev->flags;
        kuid_t uid;
        kgid_t gid;

        ASSERT_RTNL();

        dev->flags |= IFF_PROMISC;
        dev->promiscuity += inc;
        if (dev->promiscuity == 0) {
                /*
                 * Avoid overflow.
                 * If inc causes overflow, untouch promisc and return error.
                 */
                if (inc < 0)
                        dev->flags &= ~IFF_PROMISC;
                else {
                        dev->promiscuity -= inc;
                        netdev_warn(dev, "promiscuity touches roof, set promiscuity failed. promiscuity feature of device might be broken.\n");
                        return -EOVERFLOW;
                }
        }
        if (dev->flags != old_flags) {
                netdev_info(dev, "%s promiscuous mode\n",
                            dev->flags & IFF_PROMISC ? "entered" : "left");
                if (audit_enabled) {
                        current_uid_gid(&uid, &gid);
                        audit_log(audit_context(), GFP_ATOMIC,
                                  AUDIT_ANOM_PROMISCUOUS,
                                  "dev=%s prom=%d old_prom=%d auid=%u uid=%u gid=%u ses=%u",
                                  dev->name, (dev->flags & IFF_PROMISC),
                                  (old_flags & IFF_PROMISC),
                                  from_kuid(&init_user_ns, audit_get_loginuid(current)),
                                  from_kuid(&init_user_ns, uid),
                                  from_kgid(&init_user_ns, gid),
                                  audit_get_sessionid(current));
                }

                dev_change_rx_flags(dev, IFF_PROMISC);
        }
        if (notify)
                __dev_notify_flags(dev, old_flags, IFF_PROMISC, 0, NULL);
        return 0;
}

/**
 *      dev_set_promiscuity     - update promiscuity count on a device
 *      @dev: device
 *      @inc: modifier
 *
 *      Add or remove promiscuity from a device. While the count in the device
 *      remains above zero the interface remains promiscuous. Once it hits zero
 *      the device reverts back to normal filtering operation. A negative inc
 *      value is used to drop promiscuity on the device.
 *      Return 0 if successful or a negative errno code on error.
 */
int dev_set_promiscuity(struct net_device *dev, int inc)
{
        unsigned int old_flags = dev->flags;
        int err;

        err = __dev_set_promiscuity(dev, inc, true);
        if (err < 0)
                return err;
        if (dev->flags != old_flags)
                dev_set_rx_mode(dev);
        return err;
}
EXPORT_SYMBOL(dev_set_promiscuity);

static int __dev_set_allmulti(struct net_device *dev, int inc, bool notify)
{
        unsigned int old_flags = dev->flags, old_gflags = dev->gflags;

        ASSERT_RTNL();

        dev->flags |= IFF_ALLMULTI;
        dev->allmulti += inc;
        if (dev->allmulti == 0) {
                /*
                 * Avoid overflow.
                 * If inc causes overflow, untouch allmulti and return error.
                 */
                if (inc < 0)
                        dev->flags &= ~IFF_ALLMULTI;
                else {
                        dev->allmulti -= inc;
                        netdev_warn(dev, "allmulti touches roof, set allmulti failed. allmulti feature of device might be broken.\n");
                        return -EOVERFLOW;
                }
        }
        if (dev->flags ^ old_flags) {
                netdev_info(dev, "%s allmulticast mode\n",
                            dev->flags & IFF_ALLMULTI ? "entered" : "left");
                dev_change_rx_flags(dev, IFF_ALLMULTI);
                dev_set_rx_mode(dev);
                if (notify)
                        __dev_notify_flags(dev, old_flags,
                                           dev->gflags ^ old_gflags, 0, NULL);
        }
        return 0;
}

/**
 *      dev_set_allmulti        - update allmulti count on a device
 *      @dev: device
 *      @inc: modifier
 *
 *      Add or remove reception of all multicast frames to a device. While the
 *      count in the device remains above zero the interface remains listening
 *      to all interfaces. Once it hits zero the device reverts back to normal
 *      filtering operation. A negative @inc value is used to drop the counter
 *      when releasing a resource needing all multicasts.
 *      Return 0 if successful or a negative errno code on error.
 */

int dev_set_allmulti(struct net_device *dev, int inc)
{
        return __dev_set_allmulti(dev, inc, true);
}
EXPORT_SYMBOL(dev_set_allmulti);

/*
 *      Upload unicast and multicast address lists to device and
 *      configure RX filtering. When the device doesn't support unicast
 *      filtering it is put in promiscuous mode while unicast addresses
 *      are present.
 */
void __dev_set_rx_mode(struct net_device *dev)
{
        const struct net_device_ops *ops = dev->netdev_ops;

        /* dev_open will call this function so the list will stay sane. */
        if (!(dev->flags&IFF_UP))
                return;

        if (!netif_device_present(dev))
                return;

        if (!(dev->priv_flags & IFF_UNICAST_FLT)) {
                /* Unicast addresses changes may only happen under the rtnl,
                 * therefore calling __dev_set_promiscuity here is safe.
                 */
                if (!netdev_uc_empty(dev) && !dev->uc_promisc) {
                        __dev_set_promiscuity(dev, 1, false);
                        dev->uc_promisc = true;
                } else if (netdev_uc_empty(dev) && dev->uc_promisc) {
                        __dev_set_promiscuity(dev, -1, false);
                        dev->uc_promisc = false;
                }
        }

        if (ops->ndo_set_rx_mode)
                ops->ndo_set_rx_mode(dev);
}

void dev_set_rx_mode(struct net_device *dev)
{
        netif_addr_lock_bh(dev);
        __dev_set_rx_mode(dev);
        netif_addr_unlock_bh(dev);
}

/**
 *      dev_get_flags - get flags reported to userspace
 *      @dev: device
 *
 *      Get the combination of flag bits exported through APIs to userspace.
 */
unsigned int dev_get_flags(const struct net_device *dev)
{
        unsigned int flags;

        flags = (dev->flags & ~(IFF_PROMISC |
                                IFF_ALLMULTI |
                                IFF_RUNNING |
                                IFF_LOWER_UP |
                                IFF_DORMANT)) |
                (dev->gflags & (IFF_PROMISC |
                                IFF_ALLMULTI));

        if (netif_running(dev)) {
                if (netif_oper_up(dev))
                        flags |= IFF_RUNNING;
                if (netif_carrier_ok(dev))
                        flags |= IFF_LOWER_UP;
                if (netif_dormant(dev))
                        flags |= IFF_DORMANT;
        }

        return flags;
}
EXPORT_SYMBOL(dev_get_flags);

int __dev_change_flags(struct net_device *dev, unsigned int flags,
                       struct netlink_ext_ack *extack)
{
        unsigned int old_flags = dev->flags;
        int ret;

        ASSERT_RTNL();

        /*
         *      Set the flags on our device.
         */

        dev->flags = (flags & (IFF_DEBUG | IFF_NOTRAILERS | IFF_NOARP |
                               IFF_DYNAMIC | IFF_MULTICAST | IFF_PORTSEL |
                               IFF_AUTOMEDIA)) |
                     (dev->flags & (IFF_UP | IFF_VOLATILE | IFF_PROMISC |
                                    IFF_ALLMULTI));

        /*
         *      Load in the correct multicast list now the flags have changed.
         */

        if ((old_flags ^ flags) & IFF_MULTICAST)
                dev_change_rx_flags(dev, IFF_MULTICAST);

        dev_set_rx_mode(dev);

        /*
         *      Have we downed the interface. We handle IFF_UP ourselves
         *      according to user attempts to set it, rather than blindly
         *      setting it.
         */

        ret = 0;
        if ((old_flags ^ flags) & IFF_UP) {
                if (old_flags & IFF_UP)
                        __dev_close(dev);
                else
                        ret = __dev_open(dev, extack);
        }

        if ((flags ^ dev->gflags) & IFF_PROMISC) {
                int inc = (flags & IFF_PROMISC) ? 1 : -1;
                unsigned int old_flags = dev->flags;

                dev->gflags ^= IFF_PROMISC;

                if (__dev_set_promiscuity(dev, inc, false) >= 0)
                        if (dev->flags != old_flags)
                                dev_set_rx_mode(dev);
        }

        /* NOTE: order of synchronization of IFF_PROMISC and IFF_ALLMULTI
         * is important. Some (broken) drivers set IFF_PROMISC, when
         * IFF_ALLMULTI is requested not asking us and not reporting.
         */
        if ((flags ^ dev->gflags) & IFF_ALLMULTI) {
                int inc = (flags & IFF_ALLMULTI) ? 1 : -1;

                dev->gflags ^= IFF_ALLMULTI;
                __dev_set_allmulti(dev, inc, false);
        }

        return ret;
}

void __dev_notify_flags(struct net_device *dev, unsigned int old_flags,
                        unsigned int gchanges, u32 portid,
                        const struct nlmsghdr *nlh)
{
        unsigned int changes = dev->flags ^ old_flags;

        if (gchanges)
                rtmsg_ifinfo(RTM_NEWLINK, dev, gchanges, GFP_ATOMIC, portid, nlh);

        if (changes & IFF_UP) {
                if (dev->flags & IFF_UP)
                        call_netdevice_notifiers(NETDEV_UP, dev);
                else
                        call_netdevice_notifiers(NETDEV_DOWN, dev);
        }

        if (dev->flags & IFF_UP &&
            (changes & ~(IFF_UP | IFF_PROMISC | IFF_ALLMULTI | IFF_VOLATILE))) {
                struct netdev_notifier_change_info change_info = {
                        .info = {
                                .dev = dev,
                        },
                        .flags_changed = changes,
                };

                call_netdevice_notifiers_info(NETDEV_CHANGE, &change_info.info);
        }
}

/**
 *      dev_change_flags - change device settings
 *      @dev: device
 *      @flags: device state flags
 *      @extack: netlink extended ack
 *
 *      Change settings on device based state flags. The flags are
 *      in the userspace exported format.
 */
int dev_change_flags(struct net_device *dev, unsigned int flags,
                     struct netlink_ext_ack *extack)
{
        int ret;
        unsigned int changes, old_flags = dev->flags, old_gflags = dev->gflags;

        ret = __dev_change_flags(dev, flags, extack);
        if (ret < 0)
                return ret;

        changes = (old_flags ^ dev->flags) | (old_gflags ^ dev->gflags);
        __dev_notify_flags(dev, old_flags, changes, 0, NULL);
        return ret;
}
EXPORT_SYMBOL(dev_change_flags);

int __dev_set_mtu(struct net_device *dev, int new_mtu)
{
        const struct net_device_ops *ops = dev->netdev_ops;

        if (ops->ndo_change_mtu)
                return ops->ndo_change_mtu(dev, new_mtu);

        /* Pairs with all the lockless reads of dev->mtu in the stack */
        WRITE_ONCE(dev->mtu, new_mtu);
        return 0;
}
EXPORT_SYMBOL(__dev_set_mtu);

int dev_validate_mtu(struct net_device *dev, int new_mtu,
                     struct netlink_ext_ack *extack)
{
        /* MTU must be positive, and in range */
        if (new_mtu < 0 || new_mtu < dev->min_mtu) {
                NL_SET_ERR_MSG(extack, "mtu less than device minimum");
                return -EINVAL;
        }

        if (dev->max_mtu > 0 && new_mtu > dev->max_mtu) {
                NL_SET_ERR_MSG(extack, "mtu greater than device maximum");
                return -EINVAL;
        }
        return 0;
}

/**
 *      dev_set_mtu_ext - Change maximum transfer unit
 *      @dev: device
 *      @new_mtu: new transfer unit
 *      @extack: netlink extended ack
 *
 *      Change the maximum transfer size of the network device.
 */
int dev_set_mtu_ext(struct net_device *dev, int new_mtu,
                    struct netlink_ext_ack *extack)
{
        int err, orig_mtu;

        if (new_mtu == dev->mtu)
                return 0;

        err = dev_validate_mtu(dev, new_mtu, extack);
        if (err)
                return err;

        if (!netif_device_present(dev))
                return -ENODEV;

        err = call_netdevice_notifiers(NETDEV_PRECHANGEMTU, dev);
        err = notifier_to_errno(err);
        if (err)
                return err;

        orig_mtu = dev->mtu;
        err = __dev_set_mtu(dev, new_mtu);

        if (!err) {
                err = call_netdevice_notifiers_mtu(NETDEV_CHANGEMTU, dev,
                                                   orig_mtu);
                err = notifier_to_errno(err);
                if (err) {
                        /* setting mtu back and notifying everyone again,
                         * so that they have a chance to revert changes.
                         */
                        __dev_set_mtu(dev, orig_mtu);
                        call_netdevice_notifiers_mtu(NETDEV_CHANGEMTU, dev,
                                                     new_mtu);
                }
        }
        return err;
}

int dev_set_mtu(struct net_device *dev, int new_mtu)
{
        struct netlink_ext_ack extack;
        int err;

        memset(&extack, 0, sizeof(extack));
        err = dev_set_mtu_ext(dev, new_mtu, &extack);
        if (err && extack._msg)
                net_err_ratelimited("%s: %s\n", dev->name, extack._msg);
        return err;
}
EXPORT_SYMBOL(dev_set_mtu);

/**
 *      dev_change_tx_queue_len - Change TX queue length of a netdevice
 *      @dev: device
 *      @new_len: new tx queue length
 */
int dev_change_tx_queue_len(struct net_device *dev, unsigned long new_len)
{
        unsigned int orig_len = dev->tx_queue_len;
        int res;

        if (new_len != (unsigned int)new_len)
                return -ERANGE;

        if (new_len != orig_len) {
                dev->tx_queue_len = new_len;
                res = call_netdevice_notifiers(NETDEV_CHANGE_TX_QUEUE_LEN, dev);
                res = notifier_to_errno(res);
                if (res)
                        goto err_rollback;
                res = dev_qdisc_change_tx_queue_len(dev);
                if (res)
                        goto err_rollback;
        }

        return 0;

err_rollback:
        netdev_err(dev, "refused to change device tx_queue_len\n");
        dev->tx_queue_len = orig_len;
        return res;
}

/**
 *      dev_set_group - Change group this device belongs to
 *      @dev: device
 *      @new_group: group this device should belong to
 */
void dev_set_group(struct net_device *dev, int new_group)
{
        dev->group = new_group;
}

/**
 *      dev_pre_changeaddr_notify - Call NETDEV_PRE_CHANGEADDR.
 *      @dev: device
 *      @addr: new address
 *      @extack: netlink extended ack
 */
int dev_pre_changeaddr_notify(struct net_device *dev, const char *addr,
                              struct netlink_ext_ack *extack)
{
        struct netdev_notifier_pre_changeaddr_info info = {
                .info.dev = dev,
                .info.extack = extack,
                .dev_addr = addr,
        };
        int rc;

        rc = call_netdevice_notifiers_info(NETDEV_PRE_CHANGEADDR, &info.info);
        return notifier_to_errno(rc);
}
EXPORT_SYMBOL(dev_pre_changeaddr_notify);

/**
 *      dev_set_mac_address - Change Media Access Control Address
 *      @dev: device
 *      @sa: new address
 *      @extack: netlink extended ack
 *
 *      Change the hardware (MAC) address of the device
 */
int dev_set_mac_address(struct net_device *dev, struct sockaddr *sa,
                        struct netlink_ext_ack *extack)
{
        const struct net_device_ops *ops = dev->netdev_ops;
        int err;

        if (!ops->ndo_set_mac_address)
                return -EOPNOTSUPP;
        if (sa->sa_family != dev->type)
                return -EINVAL;
        if (!netif_device_present(dev))
                return -ENODEV;
        err = dev_pre_changeaddr_notify(dev, sa->sa_data, extack);
        if (err)
                return err;
        if (memcmp(dev->dev_addr, sa->sa_data, dev->addr_len)) {
                err = ops->ndo_set_mac_address(dev, sa);
                if (err)
                        return err;
        }
        dev->addr_assign_type = NET_ADDR_SET;
        call_netdevice_notifiers(NETDEV_CHANGEADDR, dev);
        add_device_randomness(dev->dev_addr, dev->addr_len);
        return 0;
}
EXPORT_SYMBOL(dev_set_mac_address);

static DECLARE_RWSEM(dev_addr_sem);

int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,
                             struct netlink_ext_ack *extack)
{
        int ret;

        down_write(&dev_addr_sem);
        ret = dev_set_mac_address(dev, sa, extack);
        up_write(&dev_addr_sem);
        return ret;
}
EXPORT_SYMBOL(dev_set_mac_address_user);

int dev_get_mac_address(struct sockaddr *sa, struct net *net, char *dev_name)
{
        size_t size = sizeof(sa->sa_data_min);
        struct net_device *dev;
        int ret = 0;

        down_read(&dev_addr_sem);
        rcu_read_lock();

        dev = dev_get_by_name_rcu(net, dev_name);
        if (!dev) {
                ret = -ENODEV;
                goto unlock;
        }
        if (!dev->addr_len)
                memset(sa->sa_data, 0, size);
        else
                memcpy(sa->sa_data, dev->dev_addr,
                       min_t(size_t, size, dev->addr_len));
        sa->sa_family = dev->type;

unlock:
        rcu_read_unlock();
        up_read(&dev_addr_sem);
        return ret;
}
EXPORT_SYMBOL(dev_get_mac_address);

/**
 *      dev_change_carrier - Change device carrier
 *      @dev: device
 *      @new_carrier: new value
 *
 *      Change device carrier
 */
int dev_change_carrier(struct net_device *dev, bool new_carrier)
{
        const struct net_device_ops *ops = dev->netdev_ops;

        if (!ops->ndo_change_carrier)
                return -EOPNOTSUPP;
        if (!netif_device_present(dev))
                return -ENODEV;
        return ops->ndo_change_carrier(dev, new_carrier);
}

/**
 *      dev_get_phys_port_id - Get device physical port ID
 *      @dev: device
 *      @ppid: port ID
 *
 *      Get device physical port ID
 */
int dev_get_phys_port_id(struct net_device *dev,
                         struct netdev_phys_item_id *ppid)
{
        const struct net_device_ops *ops = dev->netdev_ops;

        if (!ops->ndo_get_phys_port_id)
                return -EOPNOTSUPP;
        return ops->ndo_get_phys_port_id(dev, ppid);
}

/**
 *      dev_get_phys_port_name - Get device physical port name
 *      @dev: device
 *      @name: port name
 *      @len: limit of bytes to copy to name
 *
 *      Get device physical port name
 */
int dev_get_phys_port_name(struct net_device *dev,
                           char *name, size_t len)
{
        const struct net_device_ops *ops = dev->netdev_ops;
        int err;

        if (ops->ndo_get_phys_port_name) {
                err = ops->ndo_get_phys_port_name(dev, name, len);
                if (err != -EOPNOTSUPP)
                        return err;
        }
        return devlink_compat_phys_port_name_get(dev, name, len);
}

/**
 *      dev_get_port_parent_id - Get the device's port parent identifier
 *      @dev: network device
 *      @ppid: pointer to a storage for the port's parent identifier
 *      @recurse: allow/disallow recursion to lower devices
 *
 *      Get the devices's port parent identifier
 */
int dev_get_port_parent_id(struct net_device *dev,
                           struct netdev_phys_item_id *ppid,
                           bool recurse)
{
        const struct net_device_ops *ops = dev->netdev_ops;
        struct netdev_phys_item_id first = { };
        struct net_device *lower_dev;
        struct list_head *iter;
        int err;

        if (ops->ndo_get_port_parent_id) {
                err = ops->ndo_get_port_parent_id(dev, ppid);
                if (err != -EOPNOTSUPP)
                        return err;
        }

        err = devlink_compat_switch_id_get(dev, ppid);
        if (!recurse || err != -EOPNOTSUPP)
                return err;

        netdev_for_each_lower_dev(dev, lower_dev, iter) {
                err = dev_get_port_parent_id(lower_dev, ppid, true);
                if (err)
                        break;
                if (!first.id_len)
                        first = *ppid;
                else if (memcmp(&first, ppid, sizeof(*ppid)))
                        return -EOPNOTSUPP;
        }

        return err;
}
EXPORT_SYMBOL(dev_get_port_parent_id);

/**
 *      netdev_port_same_parent_id - Indicate if two network devices have
 *      the same port parent identifier
 *      @a: first network device
 *      @b: second network device
 */
bool netdev_port_same_parent_id(struct net_device *a, struct net_device *b)
{
        struct netdev_phys_item_id a_id = { };
        struct netdev_phys_item_id b_id = { };

        if (dev_get_port_parent_id(a, &a_id, true) ||
            dev_get_port_parent_id(b, &b_id, true))
                return false;

        return netdev_phys_item_id_same(&a_id, &b_id);
}
EXPORT_SYMBOL(netdev_port_same_parent_id);

/**
 *      dev_change_proto_down - set carrier according to proto_down.
 *
 *      @dev: device
 *      @proto_down: new value
 */
int dev_change_proto_down(struct net_device *dev, bool proto_down)
{
        if (!(dev->priv_flags & IFF_CHANGE_PROTO_DOWN))
                return -EOPNOTSUPP;
        if (!netif_device_present(dev))
                return -ENODEV;
        if (proto_down)
                netif_carrier_off(dev);
        else
                netif_carrier_on(dev);
        dev->proto_down = proto_down;
        return 0;
}

/**
 *      dev_change_proto_down_reason - proto down reason
 *
 *      @dev: device
 *      @mask: proto down mask
 *      @value: proto down value
 */
void dev_change_proto_down_reason(struct net_device *dev, unsigned long mask,
                                  u32 value)
{
        int b;

        if (!mask) {
                dev->proto_down_reason = value;
        } else {
                for_each_set_bit(b, &mask, 32) {
                        if (value & (1 << b))
                                dev->proto_down_reason |= BIT(b);
                        else
                                dev->proto_down_reason &= ~BIT(b);
                }
        }
}

struct bpf_xdp_link {
        struct bpf_link link;
        struct net_device *dev; /* protected by rtnl_lock, no refcnt held */
        int flags;
};

static enum bpf_xdp_mode dev_xdp_mode(struct net_device *dev, u32 flags)
{
        if (flags & XDP_FLAGS_HW_MODE)
                return XDP_MODE_HW;
        if (flags & XDP_FLAGS_DRV_MODE)
                return XDP_MODE_DRV;
        if (flags & XDP_FLAGS_SKB_MODE)
                return XDP_MODE_SKB;
        return dev->netdev_ops->ndo_bpf ? XDP_MODE_DRV : XDP_MODE_SKB;
}

static bpf_op_t dev_xdp_bpf_op(struct net_device *dev, enum bpf_xdp_mode mode)
{
        switch (mode) {
        case XDP_MODE_SKB:
                return generic_xdp_install;
        case XDP_MODE_DRV:
        case XDP_MODE_HW:
                return dev->netdev_ops->ndo_bpf;
        default:
                return NULL;
        }
}

static struct bpf_xdp_link *dev_xdp_link(struct net_device *dev,
                                         enum bpf_xdp_mode mode)
{
        return dev->xdp_state[mode].link;
}

static struct bpf_prog *dev_xdp_prog(struct net_device *dev,
                                     enum bpf_xdp_mode mode)
{
        struct bpf_xdp_link *link = dev_xdp_link(dev, mode);

        if (link)
                return link->link.prog;
        return dev->xdp_state[mode].prog;
}

u8 dev_xdp_prog_count(struct net_device *dev)
{
        u8 count = 0;
        int i;

        for (i = 0; i < __MAX_XDP_MODE; i++)
                if (dev->xdp_state[i].prog || dev->xdp_state[i].link)
                        count++;
        return count;
}
EXPORT_SYMBOL_GPL(dev_xdp_prog_count);

u32 dev_xdp_prog_id(struct net_device *dev, enum bpf_xdp_mode mode)
{
        struct bpf_prog *prog = dev_xdp_prog(dev, mode);

        return prog ? prog->aux->id : 0;
}

static void dev_xdp_set_link(struct net_device *dev, enum bpf_xdp_mode mode,
                             struct bpf_xdp_link *link)
{
        dev->xdp_state[mode].link = link;
        dev->xdp_state[mode].prog = NULL;
}

static void dev_xdp_set_prog(struct net_device *dev, enum bpf_xdp_mode mode,
                             struct bpf_prog *prog)
{
        dev->xdp_state[mode].link = NULL;
        dev->xdp_state[mode].prog = prog;
}

static int dev_xdp_install(struct net_device *dev, enum bpf_xdp_mode mode,
                           bpf_op_t bpf_op, struct netlink_ext_ack *extack,
                           u32 flags, struct bpf_prog *prog)
{
        struct netdev_bpf xdp;
        int err;

        memset(&xdp, 0, sizeof(xdp));
        xdp.command = mode == XDP_MODE_HW ? XDP_SETUP_PROG_HW : XDP_SETUP_PROG;
        xdp.extack = extack;
        xdp.flags = flags;
        xdp.prog = prog;

        /* Drivers assume refcnt is already incremented (i.e, prog pointer is
         * "moved" into driver), so they don't increment it on their own, but
         * they do decrement refcnt when program is detached or replaced.
         * Given net_device also owns link/prog, we need to bump refcnt here
         * to prevent drivers from underflowing it.
         */
        if (prog)
                bpf_prog_inc(prog);
        err = bpf_op(dev, &xdp);
        if (err) {
                if (prog)
                        bpf_prog_put(prog);
                return err;
        }

        if (mode != XDP_MODE_HW)
                bpf_prog_change_xdp(dev_xdp_prog(dev, mode), prog);

        return 0;
}

static void dev_xdp_uninstall(struct net_device *dev)
{
        struct bpf_xdp_link *link;
        struct bpf_prog *prog;
        enum bpf_xdp_mode mode;
        bpf_op_t bpf_op;

        ASSERT_RTNL();

        for (mode = XDP_MODE_SKB; mode < __MAX_XDP_MODE; mode++) {
                prog = dev_xdp_prog(dev, mode);
                if (!prog)
                        continue;

                bpf_op = dev_xdp_bpf_op(dev, mode);
                if (!bpf_op)
                        continue;

                WARN_ON(dev_xdp_install(dev, mode, bpf_op, NULL, 0, NULL));

                /* auto-detach link from net device */
                link = dev_xdp_link(dev, mode);
                if (link)
                        link->dev = NULL;
                else
                        bpf_prog_put(prog);

                dev_xdp_set_link(dev, mode, NULL);
        }
}

static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack,
                          struct bpf_xdp_link *link, struct bpf_prog *new_prog,
                          struct bpf_prog *old_prog, u32 flags)
{
        unsigned int num_modes = hweight32(flags & XDP_FLAGS_MODES);
        struct bpf_prog *cur_prog;
        struct net_device *upper;
        struct list_head *iter;
        enum bpf_xdp_mode mode;
        bpf_op_t bpf_op;
        int err;

        ASSERT_RTNL();

        /* either link or prog attachment, never both */
        if (link && (new_prog || old_prog))
                return -EINVAL;
        /* link supports only XDP mode flags */
        if (link && (flags & ~XDP_FLAGS_MODES)) {
                NL_SET_ERR_MSG(extack, "Invalid XDP flags for BPF link attachment");
                return -EINVAL;
        }
        /* just one XDP mode bit should be set, zero defaults to drv/skb mode */
        if (num_modes > 1) {
                NL_SET_ERR_MSG(extack, "Only one XDP mode flag can be set");
                return -EINVAL;
        }
        /* avoid ambiguity if offload + drv/skb mode progs are both loaded */
        if (!num_modes && dev_xdp_prog_count(dev) > 1) {
                NL_SET_ERR_MSG(extack,
                               "More than one program loaded, unset mode is ambiguous");
                return -EINVAL;
        }
        /* old_prog != NULL implies XDP_FLAGS_REPLACE is set */
        if (old_prog && !(flags & XDP_FLAGS_REPLACE)) {
                NL_SET_ERR_MSG(extack, "XDP_FLAGS_REPLACE is not specified");
                return -EINVAL;
        }

        mode = dev_xdp_mode(dev, flags);
        /* can't replace attached link */
        if (dev_xdp_link(dev, mode)) {
                NL_SET_ERR_MSG(extack, "Can't replace active BPF XDP link");
                return -EBUSY;
        }

        /* don't allow if an upper device already has a program */
        netdev_for_each_upper_dev_rcu(dev, upper, iter) {
                if (dev_xdp_prog_count(upper) > 0) {
                        NL_SET_ERR_MSG(extack, "Cannot attach when an upper device already has a program");
                        return -EEXIST;
                }
        }

        cur_prog = dev_xdp_prog(dev, mode);
        /* can't replace attached prog with link */
        if (link && cur_prog) {
                NL_SET_ERR_MSG(extack, "Can't replace active XDP program with BPF link");
                return -EBUSY;
        }
        if ((flags & XDP_FLAGS_REPLACE) && cur_prog != old_prog) {
                NL_SET_ERR_MSG(extack, "Active program does not match expected");
                return -EEXIST;
        }

        /* put effective new program into new_prog */
        if (link)
                new_prog = link->link.prog;

        if (new_prog) {
                bool offload = mode == XDP_MODE_HW;
                enum bpf_xdp_mode other_mode = mode == XDP_MODE_SKB
                                               ? XDP_MODE_DRV : XDP_MODE_SKB;

                if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && cur_prog) {
                        NL_SET_ERR_MSG(extack, "XDP program already attached");
                        return -EBUSY;
                }
                if (!offload && dev_xdp_prog(dev, other_mode)) {
                        NL_SET_ERR_MSG(extack, "Native and generic XDP can't be active at the same time");
                        return -EEXIST;
                }
                if (!offload && bpf_prog_is_offloaded(new_prog->aux)) {
                        NL_SET_ERR_MSG(extack, "Using offloaded program without HW_MODE flag is not supported");
                        return -EINVAL;
                }
                if (bpf_prog_is_dev_bound(new_prog->aux) && !bpf_offload_dev_match(new_prog, dev)) {
                        NL_SET_ERR_MSG(extack, "Program bound to different device");
                        return -EINVAL;
                }
                if (new_prog->expected_attach_type == BPF_XDP_DEVMAP) {
                        NL_SET_ERR_MSG(extack, "BPF_XDP_DEVMAP programs can not be attached to a device");
                        return -EINVAL;
                }
                if (new_prog->expected_attach_type == BPF_XDP_CPUMAP) {
                        NL_SET_ERR_MSG(extack, "BPF_XDP_CPUMAP programs can not be attached to a device");
                        return -EINVAL;
                }
        }

        /* don't call drivers if the effective program didn't change */
        if (new_prog != cur_prog) {
                bpf_op = dev_xdp_bpf_op(dev, mode);
                if (!bpf_op) {
                        NL_SET_ERR_MSG(extack, "Underlying driver does not support XDP in native mode");
                        return -EOPNOTSUPP;
                }

                err = dev_xdp_install(dev, mode, bpf_op, extack, flags, new_prog);
                if (err)
                        return err;
        }

        if (link)
                dev_xdp_set_link(dev, mode, link);
        else
                dev_xdp_set_prog(dev, mode, new_prog);
        if (cur_prog)
                bpf_prog_put(cur_prog);

        return 0;
}

static int dev_xdp_attach_link(struct net_device *dev,
                               struct netlink_ext_ack *extack,
                               struct bpf_xdp_link *link)
{
        return dev_xdp_attach(dev, extack, link, NULL, NULL, link->flags);
}

static int dev_xdp_detach_link(struct net_device *dev,
                               struct netlink_ext_ack *extack,
                               struct bpf_xdp_link *link)
{
        enum bpf_xdp_mode mode;
        bpf_op_t bpf_op;

        ASSERT_RTNL();

        mode = dev_xdp_mode(dev, link->flags);
        if (dev_xdp_link(dev, mode) != link)
                return -EINVAL;

        bpf_op = dev_xdp_bpf_op(dev, mode);
        WARN_ON(dev_xdp_install(dev, mode, bpf_op, NULL, 0, NULL));
        dev_xdp_set_link(dev, mode, NULL);
        return 0;
}

static void bpf_xdp_link_release(struct bpf_link *link)
{
        struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);

        rtnl_lock();

        /* if racing with net_device's tear down, xdp_link->dev might be
         * already NULL, in which case link was already auto-detached
         */
        if (xdp_link->dev) {
                WARN_ON(dev_xdp_detach_link(xdp_link->dev, NULL, xdp_link));
                xdp_link->dev = NULL;
        }

        rtnl_unlock();
}

static int bpf_xdp_link_detach(struct bpf_link *link)
{
        bpf_xdp_link_release(link);
        return 0;
}

static void bpf_xdp_link_dealloc(struct bpf_link *link)
{
        struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);

        kfree(xdp_link);
}

static void bpf_xdp_link_show_fdinfo(const struct bpf_link *link,
                                     struct seq_file *seq)
{
        struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
        u32 ifindex = 0;

        rtnl_lock();
        if (xdp_link->dev)
                ifindex = xdp_link->dev->ifindex;
        rtnl_unlock();

        seq_printf(seq, "ifindex:\t%u\n", ifindex);
}

static int bpf_xdp_link_fill_link_info(const struct bpf_link *link,
                                       struct bpf_link_info *info)
{
        struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
        u32 ifindex = 0;

        rtnl_lock();
        if (xdp_link->dev)
                ifindex = xdp_link->dev->ifindex;
        rtnl_unlock();

        info->xdp.ifindex = ifindex;
        return 0;
}

static int bpf_xdp_link_update(struct bpf_link *link, struct bpf_prog *new_prog,
                               struct bpf_prog *old_prog)
{
        struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
        enum bpf_xdp_mode mode;
        bpf_op_t bpf_op;
        int err = 0;

        rtnl_lock();

        /* link might have been auto-released already, so fail */
        if (!xdp_link->dev) {
                err = -ENOLINK;
                goto out_unlock;
        }

        if (old_prog && link->prog != old_prog) {
                err = -EPERM;
                goto out_unlock;
        }
        old_prog = link->prog;
        if (old_prog->type != new_prog->type ||
            old_prog->expected_attach_type != new_prog->expected_attach_type) {
                err = -EINVAL;
                goto out_unlock;
        }

        if (old_prog == new_prog) {
                /* no-op, don't disturb drivers */
                bpf_prog_put(new_prog);
                goto out_unlock;
        }

        mode = dev_xdp_mode(xdp_link->dev, xdp_link->flags);
        bpf_op = dev_xdp_bpf_op(xdp_link->dev, mode);
        err = dev_xdp_install(xdp_link->dev, mode, bpf_op, NULL,
                              xdp_link->flags, new_prog);
        if (err)
                goto out_unlock;

        old_prog = xchg(&link->prog, new_prog);
        bpf_prog_put(old_prog);

out_unlock:
        rtnl_unlock();
        return err;
}

static const struct bpf_link_ops bpf_xdp_link_lops = {
        .release = bpf_xdp_link_release,
        .dealloc = bpf_xdp_link_dealloc,
        .detach = bpf_xdp_link_detach,
        .show_fdinfo = bpf_xdp_link_show_fdinfo,
        .fill_link_info = bpf_xdp_link_fill_link_info,
        .update_prog = bpf_xdp_link_update,
};

int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
{
        struct net *net = current->nsproxy->net_ns;
        struct bpf_link_primer link_primer;
        struct netlink_ext_ack extack = {};
        struct bpf_xdp_link *link;
        struct net_device *dev;
        int err, fd;

        rtnl_lock();
        dev = dev_get_by_index(net, attr->link_create.target_ifindex);
        if (!dev) {
                rtnl_unlock();
                return -EINVAL;
        }

        link = kzalloc(sizeof(*link), GFP_USER);
        if (!link) {
                err = -ENOMEM;
                goto unlock;
        }

        bpf_link_init(&link->link, BPF_LINK_TYPE_XDP, &bpf_xdp_link_lops, prog);
        link->dev = dev;
        link->flags = attr->link_create.flags;

        err = bpf_link_prime(&link->link, &link_primer);
        if (err) {
                kfree(link);
                goto unlock;
        }

        err = dev_xdp_attach_link(dev, &extack, link);
        rtnl_unlock();

        if (err) {
                link->dev = NULL;
                bpf_link_cleanup(&link_primer);
                trace_bpf_xdp_link_attach_failed(extack._msg);
                goto out_put_dev;
        }

        fd = bpf_link_settle(&link_primer);
        /* link itself doesn't hold dev's refcnt to not complicate shutdown */
        dev_put(dev);
        return fd;

unlock:
        rtnl_unlock();

out_put_dev:
        dev_put(dev);
        return err;
}

/**
 *      dev_change_xdp_fd - set or clear a bpf program for a device rx path
 *      @dev: device
 *      @extack: netlink extended ack
 *      @fd: new program fd or negative value to clear
 *      @expected_fd: old program fd that userspace expects to replace or clear
 *      @flags: xdp-related flags
 *
 *      Set or clear a bpf program for a device
 */
int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
                      int fd, int expected_fd, u32 flags)
{
        enum bpf_xdp_mode mode = dev_xdp_mode(dev, flags);
        struct bpf_prog *new_prog = NULL, *old_prog = NULL;
        int err;

        ASSERT_RTNL();

        if (fd >= 0) {
                new_prog = bpf_prog_get_type_dev(fd, BPF_PROG_TYPE_XDP,
                                                 mode != XDP_MODE_SKB);
                if (IS_ERR(new_prog))
                        return PTR_ERR(new_prog);
        }

        if (expected_fd >= 0) {
                old_prog = bpf_prog_get_type_dev(expected_fd, BPF_PROG_TYPE_XDP,
                                                 mode != XDP_MODE_SKB);
                if (IS_ERR(old_prog)) {
                        err = PTR_ERR(old_prog);
                        old_prog = NULL;
                        goto err_out;
                }
        }

        err = dev_xdp_attach(dev, extack, NULL, new_prog, old_prog, flags);

err_out:
        if (err && new_prog)
                bpf_prog_put(new_prog);
        if (old_prog)
                bpf_prog_put(old_prog);
        return err;
}

/**
 * dev_index_reserve() - allocate an ifindex in a namespace
 * @net: the applicable net namespace
 * @ifindex: requested ifindex, pass %0 to get one allocated
 *
 * Allocate a ifindex for a new device. Caller must either use the ifindex
 * to store the device (via list_netdevice()) or call dev_index_release()
 * to give the index up.
 *
 * Return: a suitable unique value for a new device interface number or -errno.
 */
static int dev_index_reserve(struct net *net, u32 ifindex)
{
        int err;

        if (ifindex > INT_MAX) {
                DEBUG_NET_WARN_ON_ONCE(1);
                return -EINVAL;
        }

        if (!ifindex)
                err = xa_alloc_cyclic(&net->dev_by_index, &ifindex, NULL,
                                      xa_limit_31b, &net->ifindex, GFP_KERNEL);
        else
                err = xa_insert(&net->dev_by_index, ifindex, NULL, GFP_KERNEL);
        if (err < 0)
                return err;

        return ifindex;
}

static void dev_index_release(struct net *net, int ifindex)
{
        /* Expect only unused indexes, unlist_netdevice() removes the used */
        WARN_ON(xa_erase(&net->dev_by_index, ifindex));
}

/* Delayed registration/unregisteration */
LIST_HEAD(net_todo_list);
DECLARE_WAIT_QUEUE_HEAD(netdev_unregistering_wq);

static void net_set_todo(struct net_device *dev)
{
        list_add_tail(&dev->todo_list, &net_todo_list);
        atomic_inc(&dev_net(dev)->dev_unreg_count);
}

static netdev_features_t netdev_sync_upper_features(struct net_device *lower,
        struct net_device *upper, netdev_features_t features)
{
        netdev_features_t upper_disables = NETIF_F_UPPER_DISABLES;
        netdev_features_t feature;
        int feature_bit;

        for_each_netdev_feature(upper_disables, feature_bit) {
                feature = __NETIF_F_BIT(feature_bit);
                if (!(upper->wanted_features & feature)
                    && (features & feature)) {
                        netdev_dbg(lower, "Dropping feature %pNF, upper dev %s has it off.\n",
                                   &feature, upper->name);
                        features &= ~feature;
                }
        }

        return features;
}

static void netdev_sync_lower_features(struct net_device *upper,
        struct net_device *lower, netdev_features_t features)
{
        netdev_features_t upper_disables = NETIF_F_UPPER_DISABLES;
        netdev_features_t feature;
        int feature_bit;

        for_each_netdev_feature(upper_disables, feature_bit) {
                feature = __NETIF_F_BIT(feature_bit);
                if (!(features & feature) && (lower->features & feature)) {
                        netdev_dbg(upper, "Disabling feature %pNF on lower dev %s.\n",
                                   &feature, lower->name);
                        lower->wanted_features &= ~feature;
                        __netdev_update_features(lower);

                        if (unlikely(lower->features & feature))
                                netdev_WARN(upper, "failed to disable %pNF on %s!\n",
                                            &feature, lower->name);
                        else
                                netdev_features_change(lower);
                }
        }
}

static netdev_features_t netdev_fix_features(struct net_device *dev,
        netdev_features_t features)
{
        /* Fix illegal checksum combinations */
        if ((features & NETIF_F_HW_CSUM) &&
            (features & (NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM))) {
                netdev_warn(dev, "mixed HW and IP checksum settings.\n");
                features &= ~(NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM);
        }

        /* TSO requires that SG is present as well. */
        if ((features & NETIF_F_ALL_TSO) && !(features & NETIF_F_SG)) {
                netdev_dbg(dev, "Dropping TSO features since no SG feature.\n");
                features &= ~NETIF_F_ALL_TSO;
        }

        if ((features & NETIF_F_TSO) && !(features & NETIF_F_HW_CSUM) &&
                                        !(features & NETIF_F_IP_CSUM)) {
                netdev_dbg(dev, "Dropping TSO features since no CSUM feature.\n");
                features &= ~NETIF_F_TSO;
                features &= ~NETIF_F_TSO_ECN;
        }

        if ((features & NETIF_F_TSO6) && !(features & NETIF_F_HW_CSUM) &&
                                         !(features & NETIF_F_IPV6_CSUM)) {
                netdev_dbg(dev, "Dropping TSO6 features since no CSUM feature.\n");
                features &= ~NETIF_F_TSO6;
        }

        /* TSO with IPv4 ID mangling requires IPv4 TSO be enabled */
        if ((features & NETIF_F_TSO_MANGLEID) && !(features & NETIF_F_TSO))
                features &= ~NETIF_F_TSO_MANGLEID;

        /* TSO ECN requires that TSO is present as well. */
        if ((features & NETIF_F_ALL_TSO) == NETIF_F_TSO_ECN)
                features &= ~NETIF_F_TSO_ECN;

        /* Software GSO depends on SG. */
        if ((features & NETIF_F_GSO) && !(features & NETIF_F_SG)) {
                netdev_dbg(dev, "Dropping NETIF_F_GSO since no SG feature.\n");
                features &= ~NETIF_F_GSO;
        }

        /* GSO partial features require GSO partial be set */
        if ((features & dev->gso_partial_features) &&
            !(features & NETIF_F_GSO_PARTIAL)) {
                netdev_dbg(dev,
                           "Dropping partially supported GSO features since no GSO partial.\n");
                features &= ~dev->gso_partial_features;
        }

        if (!(features & NETIF_F_RXCSUM)) {
                /* NETIF_F_GRO_HW implies doing RXCSUM since every packet
                 * successfully merged by hardware must also have the
                 * checksum verified by hardware.  If the user does not
                 * want to enable RXCSUM, logically, we should disable GRO_HW.
                 */
                if (features & NETIF_F_GRO_HW) {
                        netdev_dbg(dev, "Dropping NETIF_F_GRO_HW since no RXCSUM feature.\n");
                        features &= ~NETIF_F_GRO_HW;
                }
        }

        /* LRO/HW-GRO features cannot be combined with RX-FCS */
        if (features & NETIF_F_RXFCS) {
                if (features & NETIF_F_LRO) {
                        netdev_dbg(dev, "Dropping LRO feature since RX-FCS is requested.\n");
                        features &= ~NETIF_F_LRO;
                }

                if (features & NETIF_F_GRO_HW) {
                        netdev_dbg(dev, "Dropping HW-GRO feature since RX-FCS is requested.\n");
                        features &= ~NETIF_F_GRO_HW;
                }
        }

        if ((features & NETIF_F_GRO_HW) && (features & NETIF_F_LRO)) {
                netdev_dbg(dev, "Dropping LRO feature since HW-GRO is requested.\n");
                features &= ~NETIF_F_LRO;
        }

        if (features & NETIF_F_HW_TLS_TX) {
                bool ip_csum = (features & (NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM)) ==
                        (NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM);
                bool hw_csum = features & NETIF_F_HW_CSUM;

                if (!ip_csum && !hw_csum) {
                        netdev_dbg(dev, "Dropping TLS TX HW offload feature since no CSUM feature.\n");
                        features &= ~NETIF_F_HW_TLS_TX;
                }
        }

        if ((features & NETIF_F_HW_TLS_RX) && !(features & NETIF_F_RXCSUM)) {
                netdev_dbg(dev, "Dropping TLS RX HW offload feature since no RXCSUM feature.\n");
                features &= ~NETIF_F_HW_TLS_RX;
        }

        return features;
}

int __netdev_update_features(struct net_device *dev)
{
        struct net_device *upper, *lower;
        netdev_features_t features;
        struct list_head *iter;
        int err = -1;

        ASSERT_RTNL();

        features = netdev_get_wanted_features(dev);

        if (dev->netdev_ops->ndo_fix_features)
                features = dev->netdev_ops->ndo_fix_features(dev, features);

        /* driver might be less strict about feature dependencies */
        features = netdev_fix_features(dev, features);

        /* some features can't be enabled if they're off on an upper device */
        netdev_for_each_upper_dev_rcu(dev, upper, iter)
                features = netdev_sync_upper_features(dev, upper, features);

        if (dev->features == features)
                goto sync_lower;

        netdev_dbg(dev, "Features changed: %pNF -> %pNF\n",
                &dev->features, &features);

        if (dev->netdev_ops->ndo_set_features)
                err = dev->netdev_ops->ndo_set_features(dev, features);
        else
                err = 0;

        if (unlikely(err < 0)) {
                netdev_err(dev,
                        "set_features() failed (%d); wanted %pNF, left %pNF\n",
                        err, &features, &dev->features);
                /* return non-0 since some features might have changed and
                 * it's better to fire a spurious notification than miss it
                 */
                return -1;
        }

sync_lower:
        /* some features must be disabled on lower devices when disabled
         * on an upper device (think: bonding master or bridge)
         */
        netdev_for_each_lower_dev(dev, lower, iter)
                netdev_sync_lower_features(dev, lower, features);

        if (!err) {
                netdev_features_t diff = features ^ dev->features;

                if (diff & NETIF_F_RX_UDP_TUNNEL_PORT) {
                        /* udp_tunnel_{get,drop}_rx_info both need
                         * NETIF_F_RX_UDP_TUNNEL_PORT enabled on the
                         * device, or they won't do anything.
                         * Thus we need to update dev->features
                         * *before* calling udp_tunnel_get_rx_info,
                         * but *after* calling udp_tunnel_drop_rx_info.
                         */
                        if (features & NETIF_F_RX_UDP_TUNNEL_PORT) {
                                dev->features = features;
                                udp_tunnel_get_rx_info(dev);
                        } else {
                                udp_tunnel_drop_rx_info(dev);
                        }
                }

                if (diff & NETIF_F_HW_VLAN_CTAG_FILTER) {
                        if (features & NETIF_F_HW_VLAN_CTAG_FILTER) {
                                dev->features = features;
                                err |= vlan_get_rx_ctag_filter_info(dev);
                        } else {
                                vlan_drop_rx_ctag_filter_info(dev);
                        }
                }

                if (diff & NETIF_F_HW_VLAN_STAG_FILTER) {
                        if (features & NETIF_F_HW_VLAN_STAG_FILTER) {
                                dev->features = features;
                                err |= vlan_get_rx_stag_filter_info(dev);
                        } else {
                                vlan_drop_rx_stag_filter_info(dev);
                        }
                }

                dev->features = features;
        }

        return err < 0 ? 0 : 1;
}

/**
 *      netdev_update_features - recalculate device features
 *      @dev: the device to check
 *
 *      Recalculate dev->features set and send notifications if it
 *      has changed. Should be called after driver or hardware dependent
 *      conditions might have changed that influence the features.
 */
void netdev_update_features(struct net_device *dev)
{
        if (__netdev_update_features(dev))
                netdev_features_change(dev);
}
EXPORT_SYMBOL(netdev_update_features);

/**
 *      netdev_change_features - recalculate device features
 *      @dev: the device to check
 *
 *      Recalculate dev->features set and send notifications even
 *      if they have not changed. Should be called instead of
 *      netdev_update_features() if also dev->vlan_features might
 *      have changed to allow the changes to be propagated to stacked
 *      VLAN devices.
 */
void netdev_change_features(struct net_device *dev)
{
        __netdev_update_features(dev);
        netdev_features_change(dev);
}
EXPORT_SYMBOL(netdev_change_features);

/**
 *      netif_stacked_transfer_operstate -      transfer operstate
 *      @rootdev: the root or lower level device to transfer state from
 *      @dev: the device to transfer operstate to
 *
 *      Transfer operational state from root to device. This is normally
 *      called when a stacking relationship exists between the root
 *      device and the device(a leaf device).
 */
void netif_stacked_transfer_operstate(const struct net_device *rootdev,
                                        struct net_device *dev)
{
        if (rootdev->operstate == IF_OPER_DORMANT)
                netif_dormant_on(dev);
        else
                netif_dormant_off(dev);

        if (rootdev->operstate == IF_OPER_TESTING)
                netif_testing_on(dev);
        else
                netif_testing_off(dev);

        if (netif_carrier_ok(rootdev))
                netif_carrier_on(dev);
        else
                netif_carrier_off(dev);
}
EXPORT_SYMBOL(netif_stacked_transfer_operstate);

static int netif_alloc_rx_queues(struct net_device *dev)
{
        unsigned int i, count = dev->num_rx_queues;
        struct netdev_rx_queue *rx;
        size_t sz = count * sizeof(*rx);
        int err = 0;

        BUG_ON(count < 1);

        rx = kvzalloc(sz, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
        if (!rx)
                return -ENOMEM;

        dev->_rx = rx;

        for (i = 0; i < count; i++) {
                rx[i].dev = dev;

                /* XDP RX-queue setup */
                err = xdp_rxq_info_reg(&rx[i].xdp_rxq, dev, i, 0);
                if (err < 0)
                        goto err_rxq_info;
        }
        return 0;

err_rxq_info:
        /* Rollback successful reg's and free other resources */
        while (i--)
                xdp_rxq_info_unreg(&rx[i].xdp_rxq);
        kvfree(dev->_rx);
        dev->_rx = NULL;
        return err;
}

static void netif_free_rx_queues(struct net_device *dev)
{
        unsigned int i, count = dev->num_rx_queues;

        /* netif_alloc_rx_queues alloc failed, resources have been unreg'ed */
        if (!dev->_rx)
                return;

        for (i = 0; i < count; i++)
                xdp_rxq_info_unreg(&dev->_rx[i].xdp_rxq);

        kvfree(dev->_rx);
}

static void netdev_init_one_queue(struct net_device *dev,
                                  struct netdev_queue *queue, void *_unused)
{
        /* Initialize queue lock */
        spin_lock_init(&queue->_xmit_lock);
        netdev_set_xmit_lockdep_class(&queue->_xmit_lock, dev->type);
        queue->xmit_lock_owner = -1;
        netdev_queue_numa_node_write(queue, NUMA_NO_NODE);
        queue->dev = dev;
#ifdef CONFIG_BQL
        dql_init(&queue->dql, HZ);
#endif
}

static void netif_free_tx_queues(struct net_device *dev)
{
        kvfree(dev->_tx);
}

static int netif_alloc_netdev_queues(struct net_device *dev)
{
        unsigned int count = dev->num_tx_queues;
        struct netdev_queue *tx;
        size_t sz = count * sizeof(*tx);

        if (count < 1 || count > 0xffff)
                return -EINVAL;

        tx = kvzalloc(sz, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
        if (!tx)
                return -ENOMEM;

        dev->_tx = tx;

        netdev_for_each_tx_queue(dev, netdev_init_one_queue, NULL);
        spin_lock_init(&dev->tx_global_lock);

        return 0;
}

void netif_tx_stop_all_queues(struct net_device *dev)
{
        unsigned int i;

        for (i = 0; i < dev->num_tx_queues; i++) {
                struct netdev_queue *txq = netdev_get_tx_queue(dev, i);

                netif_tx_stop_queue(txq);
        }
}
EXPORT_SYMBOL(netif_tx_stop_all_queues);

/**
 * register_netdevice() - register a network device
 * @dev: device to register
 *
 * Take a prepared network device structure and make it externally accessible.
 * A %NETDEV_REGISTER message is sent to the netdev notifier chain.
 * Callers must hold the rtnl lock - you may want register_netdev()
 * instead of this.
 */
int register_netdevice(struct net_device *dev)
{
        int ret;
        struct net *net = dev_net(dev);

        BUILD_BUG_ON(sizeof(netdev_features_t) * BITS_PER_BYTE <
                     NETDEV_FEATURE_COUNT);
        BUG_ON(dev_boot_phase);
        ASSERT_RTNL();

        might_sleep();

        /* When net_device's are persistent, this will be fatal. */
        BUG_ON(dev->reg_state != NETREG_UNINITIALIZED);
        BUG_ON(!net);

        ret = ethtool_check_ops(dev->ethtool_ops);
        if (ret)
                return ret;

        spin_lock_init(&dev->addr_list_lock);
        netdev_set_addr_lockdep_class(dev);

        ret = dev_get_valid_name(net, dev, dev->name);
        if (ret < 0)
                goto out;

        ret = -ENOMEM;
        dev->name_node = netdev_name_node_head_alloc(dev);
        if (!dev->name_node)
                goto out;

        /* Init, if this function is available */
        if (dev->netdev_ops->ndo_init) {
                ret = dev->netdev_ops->ndo_init(dev);
                if (ret) {
                        if (ret > 0)
                                ret = -EIO;
                        goto err_free_name;
                }
        }

        if (((dev->hw_features | dev->features) &
             NETIF_F_HW_VLAN_CTAG_FILTER) &&
            (!dev->netdev_ops->ndo_vlan_rx_add_vid ||
             !dev->netdev_ops->ndo_vlan_rx_kill_vid)) {
                netdev_WARN(dev, "Buggy VLAN acceleration in driver!\n");
                ret = -EINVAL;
                goto err_uninit;
        }

        ret = dev_index_reserve(net, dev->ifindex);
        if (ret < 0)
                goto err_uninit;
        dev->ifindex = ret;

        /* Transfer changeable features to wanted_features and enable
         * software offloads (GSO and GRO).
         */
        dev->hw_features |= (NETIF_F_SOFT_FEATURES | NETIF_F_SOFT_FEATURES_OFF);
        dev->features |= NETIF_F_SOFT_FEATURES;

        if (dev->udp_tunnel_nic_info) {
                dev->features |= NETIF_F_RX_UDP_TUNNEL_PORT;
                dev->hw_features |= NETIF_F_RX_UDP_TUNNEL_PORT;
        }

        dev->wanted_features = dev->features & dev->hw_features;

        if (!(dev->flags & IFF_LOOPBACK))
                dev->hw_features |= NETIF_F_NOCACHE_COPY;

        /* If IPv4 TCP segmentation offload is supported we should also
         * allow the device to enable segmenting the frame with the option
         * of ignoring a static IP ID value.  This doesn't enable the
         * feature itself but allows the user to enable it later.
         */
        if (dev->hw_features & NETIF_F_TSO)
                dev->hw_features |= NETIF_F_TSO_MANGLEID;
        if (dev->vlan_features & NETIF_F_TSO)
                dev->vlan_features |= NETIF_F_TSO_MANGLEID;
        if (dev->mpls_features & NETIF_F_TSO)
                dev->mpls_features |= NETIF_F_TSO_MANGLEID;
        if (dev->hw_enc_features & NETIF_F_TSO)
                dev->hw_enc_features |= NETIF_F_TSO_MANGLEID;

        /* Make NETIF_F_HIGHDMA inheritable to VLAN devices.
         */
        dev->vlan_features |= NETIF_F_HIGHDMA;

        /* Make NETIF_F_SG inheritable to tunnel devices.
         */
        dev->hw_enc_features |= NETIF_F_SG | NETIF_F_GSO_PARTIAL;

        /* Make NETIF_F_SG inheritable to MPLS.
         */
        dev->mpls_features |= NETIF_F_SG;

        ret = call_netdevice_notifiers(NETDEV_POST_INIT, dev);
        ret = notifier_to_errno(ret);
        if (ret)
                goto err_ifindex_release;

        ret = netdev_register_kobject(dev);
        write_lock(&dev_base_lock);
        dev->reg_state = ret ? NETREG_UNREGISTERED : NETREG_REGISTERED;
        write_unlock(&dev_base_lock);
        if (ret)
                goto err_uninit_notify;

        __netdev_update_features(dev);

        /*
         *      Default initial state at registry is that the
         *      device is present.
         */

        set_bit(__LINK_STATE_PRESENT, &dev->state);

        linkwatch_init_dev(dev);

        dev_init_scheduler(dev);

        netdev_hold(dev, &dev->dev_registered_tracker, GFP_KERNEL);
        list_netdevice(dev);

        add_device_randomness(dev->dev_addr, dev->addr_len);

        /* If the device has permanent device address, driver should
         * set dev_addr and also addr_assign_type should be set to
         * NET_ADDR_PERM (default value).
         */
        if (dev->addr_assign_type == NET_ADDR_PERM)
                memcpy(dev->perm_addr, dev->dev_addr, dev->addr_len);

        /* Notify protocols, that a new device appeared. */
        ret = call_netdevice_notifiers(NETDEV_REGISTER, dev);
        ret = notifier_to_errno(ret);
        if (ret) {
                /* Expect explicit free_netdev() on failure */
                dev->needs_free_netdev = false;
                unregister_netdevice_queue(dev, NULL);
                goto out;
        }
        /*
         *      Prevent userspace races by waiting until the network
         *      device is fully setup before sending notifications.
         */
        if (!dev->rtnl_link_ops ||
            dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
                rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL, 0, NULL);

out:
        return ret;

err_uninit_notify:
        call_netdevice_notifiers(NETDEV_PRE_UNINIT, dev);
err_ifindex_release:
        dev_index_release(net, dev->ifindex);
err_uninit:
        if (dev->netdev_ops->ndo_uninit)
                dev->netdev_ops->ndo_uninit(dev);
        if (dev->priv_destructor)
                dev->priv_destructor(dev);
err_free_name:
        netdev_name_node_free(dev->name_node);
        goto out;
}
EXPORT_SYMBOL(register_netdevice);

/**
 *      init_dummy_netdev       - init a dummy network device for NAPI
 *      @dev: device to init
 *
 *      This takes a network device structure and initialize the minimum
 *      amount of fields so it can be used to schedule NAPI polls without
 *      registering a full blown interface. This is to be used by drivers
 *      that need to tie several hardware interfaces to a single NAPI
 *      poll scheduler due to HW limitations.
 */
int init_dummy_netdev(struct net_device *dev)
{
        /* Clear everything. Note we don't initialize spinlocks
         * are they aren't supposed to be taken by any of the
         * NAPI code and this dummy netdev is supposed to be
         * only ever used for NAPI polls
         */
        memset(dev, 0, sizeof(struct net_device));

        /* make sure we BUG if trying to hit standard
         * register/unregister code path
         */
        dev->reg_state = NETREG_DUMMY;

        /* NAPI wants this */
        INIT_LIST_HEAD(&dev->napi_list);

        /* a dummy interface is started by default */
        set_bit(__LINK_STATE_PRESENT, &dev->state);
        set_bit(__LINK_STATE_START, &dev->state);

        /* napi_busy_loop stats accounting wants this */
        dev_net_set(dev, &init_net);

        /* Note : We dont allocate pcpu_refcnt for dummy devices,
         * because users of this 'device' dont need to change
         * its refcount.
         */

        return 0;
}
EXPORT_SYMBOL_GPL(init_dummy_netdev);


/**
 *      register_netdev - register a network device
 *      @dev: device to register
 *
 *      Take a completed network device structure and add it to the kernel
 *      interfaces. A %NETDEV_REGISTER message is sent to the netdev notifier
 *      chain. 0 is returned on success. A negative errno code is returned
 *      on a failure to set up the device, or if the name is a duplicate.
 *
 *      This is a wrapper around register_netdevice that takes the rtnl semaphore
 *      and expands the device name if you passed a format string to
 *      alloc_netdev.
 */
int register_netdev(struct net_device *dev)
{
        int err;

        if (rtnl_lock_killable())
                return -EINTR;
        err = register_netdevice(dev);
        rtnl_unlock();
        return err;
}
EXPORT_SYMBOL(register_netdev);

int netdev_refcnt_read(const struct net_device *dev)
{
#ifdef CONFIG_PCPU_DEV_REFCNT
        int i, refcnt = 0;

        for_each_possible_cpu(i)
                refcnt += *per_cpu_ptr(dev->pcpu_refcnt, i);
        return refcnt;
#else
        return refcount_read(&dev->dev_refcnt);
#endif
}
EXPORT_SYMBOL(netdev_refcnt_read);

int netdev_unregister_timeout_secs __read_mostly = 10;

#define WAIT_REFS_MIN_MSECS 1
#define WAIT_REFS_MAX_MSECS 250
/**
 * netdev_wait_allrefs_any - wait until all references are gone.
 * @list: list of net_devices to wait on
 *
 * This is called when unregistering network devices.
 *
 * Any protocol or device that holds a reference should register
 * for netdevice notification, and cleanup and put back the
 * reference if they receive an UNREGISTER event.
 * We can get stuck here if buggy protocols don't correctly
 * call dev_put.
 */
static struct net_device *netdev_wait_allrefs_any(struct list_head *list)
{
        unsigned long rebroadcast_time, warning_time;
        struct net_device *dev;
        int wait = 0;

        rebroadcast_time = warning_time = jiffies;

        list_for_each_entry(dev, list, todo_list)
                if (netdev_refcnt_read(dev) == 1)
                        return dev;

        while (true) {
                if (time_after(jiffies, rebroadcast_time + 1 * HZ)) {
                        rtnl_lock();

                        /* Rebroadcast unregister notification */
                        list_for_each_entry(dev, list, todo_list)
                                call_netdevice_notifiers(NETDEV_UNREGISTER, dev);

                        __rtnl_unlock();
                        rcu_barrier();
                        rtnl_lock();

                        list_for_each_entry(dev, list, todo_list)
                                if (test_bit(__LINK_STATE_LINKWATCH_PENDING,
                                             &dev->state)) {
                                        /* We must not have linkwatch events
                                         * pending on unregister. If this
                                         * happens, we simply run the queue
                                         * unscheduled, resulting in a noop
                                         * for this device.
                                         */
                                        linkwatch_run_queue();
                                        break;
                                }

                        __rtnl_unlock();

                        rebroadcast_time = jiffies;
                }

                if (!wait) {
                        rcu_barrier();
                        wait = WAIT_REFS_MIN_MSECS;
                } else {
                        msleep(wait);
                        wait = min(wait << 1, WAIT_REFS_MAX_MSECS);
                }

                list_for_each_entry(dev, list, todo_list)
                        if (netdev_refcnt_read(dev) == 1)
                                return dev;

                if (time_after(jiffies, warning_time +
                               READ_ONCE(netdev_unregister_timeout_secs) * HZ)) {
                        list_for_each_entry(dev, list, todo_list) {
                                pr_emerg("unregister_netdevice: waiting for %s to become free. Usage count = %d\n",
                                         dev->name, netdev_refcnt_read(dev));
                                ref_tracker_dir_print(&dev->refcnt_tracker, 10);
                        }

                        warning_time = jiffies;
                }
        }
}

/* The sequence is:
 *
 *      rtnl_lock();
 *      ...
 *      register_netdevice(x1);
 *      register_netdevice(x2);
 *      ...
 *      unregister_netdevice(y1);
 *      unregister_netdevice(y2);
 *      ...
 *      rtnl_unlock();
 *      free_netdev(y1);
 *      free_netdev(y2);
 *
 * We are invoked by rtnl_unlock().
 * This allows us to deal with problems:
 * 1) We can delete sysfs objects which invoke hotplug
 *    without deadlocking with linkwatch via keventd.
 * 2) Since we run with the RTNL semaphore not held, we can sleep
 *    safely in order to wait for the netdev refcnt to drop to zero.
 *
 * We must not return until all unregister events added during
 * the interval the lock was held have been completed.
 */
void netdev_run_todo(void)
{
        struct net_device *dev, *tmp;
        struct list_head list;
#ifdef CONFIG_LOCKDEP
        struct list_head unlink_list;

        list_replace_init(&net_unlink_list, &unlink_list);

        while (!list_empty(&unlink_list)) {
                struct net_device *dev = list_first_entry(&unlink_list,
                                                          struct net_device,
                                                          unlink_list);
                list_del_init(&dev->unlink_list);
                dev->nested_level = dev->lower_level - 1;
        }
#endif

        /* Snapshot list, allow later requests */
        list_replace_init(&net_todo_list, &list);

        __rtnl_unlock();

        /* Wait for rcu callbacks to finish before next phase */
        if (!list_empty(&list))
                rcu_barrier();

        list_for_each_entry_safe(dev, tmp, &list, todo_list) {
                if (unlikely(dev->reg_state != NETREG_UNREGISTERING)) {
                        netdev_WARN(dev, "run_todo but not unregistering\n");
                        list_del(&dev->todo_list);
                        continue;
                }

                write_lock(&dev_base_lock);
                dev->reg_state = NETREG_UNREGISTERED;
                write_unlock(&dev_base_lock);
                linkwatch_forget_dev(dev);
        }

        while (!list_empty(&list)) {
                dev = netdev_wait_allrefs_any(&list);
                list_del(&dev->todo_list);

                /* paranoia */
                BUG_ON(netdev_refcnt_read(dev) != 1);
                BUG_ON(!list_empty(&dev->ptype_all));
                BUG_ON(!list_empty(&dev->ptype_specific));
                WARN_ON(rcu_access_pointer(dev->ip_ptr));
                WARN_ON(rcu_access_pointer(dev->ip6_ptr));

                if (dev->priv_destructor)
                        dev->priv_destructor(dev);
                if (dev->needs_free_netdev)
                        free_netdev(dev);

                if (atomic_dec_and_test(&dev_net(dev)->dev_unreg_count))
                        wake_up(&netdev_unregistering_wq);

                /* Free network device */
                kobject_put(&dev->dev.kobj);
        }
}

/* Convert net_device_stats to rtnl_link_stats64. rtnl_link_stats64 has
 * all the same fields in the same order as net_device_stats, with only
 * the type differing, but rtnl_link_stats64 may have additional fields
 * at the end for newer counters.
 */
void netdev_stats_to_stats64(struct rtnl_link_stats64 *stats64,
                             const struct net_device_stats *netdev_stats)
{
        size_t i, n = sizeof(*netdev_stats) / sizeof(atomic_long_t);
        const atomic_long_t *src = (atomic_long_t *)netdev_stats;
        u64 *dst = (u64 *)stats64;

        BUILD_BUG_ON(n > sizeof(*stats64) / sizeof(u64));
        for (i = 0; i < n; i++)
                dst[i] = (unsigned long)atomic_long_read(&src[i]);
        /* zero out counters that only exist in rtnl_link_stats64 */
        memset((char *)stats64 + n * sizeof(u64), 0,
               sizeof(*stats64) - n * sizeof(u64));
}
EXPORT_SYMBOL(netdev_stats_to_stats64);

struct net_device_core_stats __percpu *netdev_core_stats_alloc(struct net_device *dev)
{
        struct net_device_core_stats __percpu *p;

        p = alloc_percpu_gfp(struct net_device_core_stats,
                             GFP_ATOMIC | __GFP_NOWARN);

        if (p && cmpxchg(&dev->core_stats, NULL, p))
                free_percpu(p);

        /* This READ_ONCE() pairs with the cmpxchg() above */
        return READ_ONCE(dev->core_stats);
}
EXPORT_SYMBOL(netdev_core_stats_alloc);

/**
 *      dev_get_stats   - get network device statistics
 *      @dev: device to get statistics from
 *      @storage: place to store stats
 *
 *      Get network statistics from device. Return @storage.
 *      The device driver may provide its own method by setting
 *      dev->netdev_ops->get_stats64 or dev->netdev_ops->get_stats;
 *      otherwise the internal statistics structure is used.
 */
struct rtnl_link_stats64 *dev_get_stats(struct net_device *dev,
                                        struct rtnl_link_stats64 *storage)
{
        const struct net_device_ops *ops = dev->netdev_ops;
        const struct net_device_core_stats __percpu *p;

        if (ops->ndo_get_stats64) {
                memset(storage, 0, sizeof(*storage));
                ops->ndo_get_stats64(dev, storage);
        } else if (ops->ndo_get_stats) {
                netdev_stats_to_stats64(storage, ops->ndo_get_stats(dev));
        } else {
                netdev_stats_to_stats64(storage, &dev->stats);
        }

        /* This READ_ONCE() pairs with the write in netdev_core_stats_alloc() */
        p = READ_ONCE(dev->core_stats);
        if (p) {
                const struct net_device_core_stats *core_stats;
                int i;

                for_each_possible_cpu(i) {
                        core_stats = per_cpu_ptr(p, i);
                        storage->rx_dropped += READ_ONCE(core_stats->rx_dropped);
                        storage->tx_dropped += READ_ONCE(core_stats->tx_dropped);
                        storage->rx_nohandler += READ_ONCE(core_stats->rx_nohandler);
                        storage->rx_otherhost_dropped += READ_ONCE(core_stats->rx_otherhost_dropped);
                }
        }
        return storage;
}
EXPORT_SYMBOL(dev_get_stats);

/**
 *      dev_fetch_sw_netstats - get per-cpu network device statistics
 *      @s: place to store stats
 *      @netstats: per-cpu network stats to read from
 *
 *      Read per-cpu network statistics and populate the related fields in @s.
 */
void dev_fetch_sw_netstats(struct rtnl_link_stats64 *s,
                           const struct pcpu_sw_netstats __percpu *netstats)
{
        int cpu;

        for_each_possible_cpu(cpu) {
                u64 rx_packets, rx_bytes, tx_packets, tx_bytes;
                const struct pcpu_sw_netstats *stats;
                unsigned int start;

                stats = per_cpu_ptr(netstats, cpu);
                do {
                        start = u64_stats_fetch_begin(&stats->syncp);
                        rx_packets = u64_stats_read(&stats->rx_packets);
                        rx_bytes   = u64_stats_read(&stats->rx_bytes);
                        tx_packets = u64_stats_read(&stats->tx_packets);
                        tx_bytes   = u64_stats_read(&stats->tx_bytes);
                } while (u64_stats_fetch_retry(&stats->syncp, start));

                s->rx_packets += rx_packets;
                s->rx_bytes   += rx_bytes;
                s->tx_packets += tx_packets;
                s->tx_bytes   += tx_bytes;
        }
}
EXPORT_SYMBOL_GPL(dev_fetch_sw_netstats);

/**
 *      dev_get_tstats64 - ndo_get_stats64 implementation
 *      @dev: device to get statistics from
 *      @s: place to store stats
 *
 *      Populate @s from dev->stats and dev->tstats. Can be used as
 *      ndo_get_stats64() callback.
 */
void dev_get_tstats64(struct net_device *dev, struct rtnl_link_stats64 *s)
{
        netdev_stats_to_stats64(s, &dev->stats);
        dev_fetch_sw_netstats(s, dev->tstats);
}
EXPORT_SYMBOL_GPL(dev_get_tstats64);

struct netdev_queue *dev_ingress_queue_create(struct net_device *dev)
{
        struct netdev_queue *queue = dev_ingress_queue(dev);

#ifdef CONFIG_NET_CLS_ACT
        if (queue)
                return queue;
        queue = kzalloc(sizeof(*queue), GFP_KERNEL);
        if (!queue)
                return NULL;
        netdev_init_one_queue(dev, queue, NULL);
        RCU_INIT_POINTER(queue->qdisc, &noop_qdisc);
        RCU_INIT_POINTER(queue->qdisc_sleeping, &noop_qdisc);
        rcu_assign_pointer(dev->ingress_queue, queue);
#endif
        return queue;
}

static const struct ethtool_ops default_ethtool_ops;

void netdev_set_default_ethtool_ops(struct net_device *dev,
                                    const struct ethtool_ops *ops)
{
        if (dev->ethtool_ops == &default_ethtool_ops)
                dev->ethtool_ops = ops;
}
EXPORT_SYMBOL_GPL(netdev_set_default_ethtool_ops);

/**
 * netdev_sw_irq_coalesce_default_on() - enable SW IRQ coalescing by default
 * @dev: netdev to enable the IRQ coalescing on
 *
 * Sets a conservative default for SW IRQ coalescing. Users can use
 * sysfs attributes to override the default values.
 */
void netdev_sw_irq_coalesce_default_on(struct net_device *dev)
{
        WARN_ON(dev->reg_state == NETREG_REGISTERED);

        if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
                dev->gro_flush_timeout = 20000;
                dev->napi_defer_hard_irqs = 1;
        }
}
EXPORT_SYMBOL_GPL(netdev_sw_irq_coalesce_default_on);

void netdev_freemem(struct net_device *dev)
{
        char *addr = (char *)dev - dev->padded;

        kvfree(addr);
}

/**
 * alloc_netdev_mqs - allocate network device
 * @sizeof_priv: size of private data to allocate space for
 * @name: device name format string
 * @name_assign_type: origin of device name
 * @setup: callback to initialize device
 * @txqs: the number of TX subqueues to allocate
 * @rxqs: the number of RX subqueues to allocate
 *
 * Allocates a struct net_device with private data area for driver use
 * and performs basic initialization.  Also allocates subqueue structs
 * for each queue on the device.
 */
struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
                unsigned char name_assign_type,
                void (*setup)(struct net_device *),
                unsigned int txqs, unsigned int rxqs)
{
        struct net_device *dev;
        unsigned int alloc_size;
        struct net_device *p;

        BUG_ON(strlen(name) >= sizeof(dev->name));

        if (txqs < 1) {
                pr_err("alloc_netdev: Unable to allocate device with zero queues\n");
                return NULL;
        }

        if (rxqs < 1) {
                pr_err("alloc_netdev: Unable to allocate device with zero RX queues\n");
                return NULL;
        }

        alloc_size = sizeof(struct net_device);
        if (sizeof_priv) {
                /* ensure 32-byte alignment of private area */
                alloc_size = ALIGN(alloc_size, NETDEV_ALIGN);
                alloc_size += sizeof_priv;
        }
        /* ensure 32-byte alignment of whole construct */
        alloc_size += NETDEV_ALIGN - 1;

        p = kvzalloc(alloc_size, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
        if (!p)
                return NULL;

        dev = PTR_ALIGN(p, NETDEV_ALIGN);
        dev->padded = (char *)dev - (char *)p;

        ref_tracker_dir_init(&dev->refcnt_tracker, 128, name);
#ifdef CONFIG_PCPU_DEV_REFCNT
        dev->pcpu_refcnt = alloc_percpu(int);
        if (!dev->pcpu_refcnt)
                goto free_dev;
        __dev_hold(dev);
#else
        refcount_set(&dev->dev_refcnt, 1);
#endif

        if (dev_addr_init(dev))
                goto free_pcpu;

        dev_mc_init(dev);
        dev_uc_init(dev);

        dev_net_set(dev, &init_net);

        dev->gso_max_size = GSO_LEGACY_MAX_SIZE;
        dev->xdp_zc_max_segs = 1;
        dev->gso_max_segs = GSO_MAX_SEGS;
        dev->gro_max_size = GRO_LEGACY_MAX_SIZE;
        dev->gso_ipv4_max_size = GSO_LEGACY_MAX_SIZE;
        dev->gro_ipv4_max_size = GRO_LEGACY_MAX_SIZE;
        dev->tso_max_size = TSO_LEGACY_MAX_SIZE;
        dev->tso_max_segs = TSO_MAX_SEGS;
        dev->upper_level = 1;
        dev->lower_level = 1;
#ifdef CONFIG_LOCKDEP
        dev->nested_level = 0;
        INIT_LIST_HEAD(&dev->unlink_list);
#endif

        INIT_LIST_HEAD(&dev->napi_list);
        INIT_LIST_HEAD(&dev->unreg_list);
        INIT_LIST_HEAD(&dev->close_list);
        INIT_LIST_HEAD(&dev->link_watch_list);
        INIT_LIST_HEAD(&dev->adj_list.upper);
        INIT_LIST_HEAD(&dev->adj_list.lower);
        INIT_LIST_HEAD(&dev->ptype_all);
        INIT_LIST_HEAD(&dev->ptype_specific);
        INIT_LIST_HEAD(&dev->net_notifier_list);
#ifdef CONFIG_NET_SCHED
        hash_init(dev->qdisc_hash);
#endif
        dev->priv_flags = IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM;
        setup(dev);

        if (!dev->tx_queue_len) {
                dev->priv_flags |= IFF_NO_QUEUE;
                dev->tx_queue_len = DEFAULT_TX_QUEUE_LEN;
        }

        dev->num_tx_queues = txqs;
        dev->real_num_tx_queues = txqs;
        if (netif_alloc_netdev_queues(dev))
                goto free_all;

        dev->num_rx_queues = rxqs;
        dev->real_num_rx_queues = rxqs;
        if (netif_alloc_rx_queues(dev))
                goto free_all;

        strcpy(dev->name, name);
        dev->name_assign_type = name_assign_type;
        dev->group = INIT_NETDEV_GROUP;
        if (!dev->ethtool_ops)
                dev->ethtool_ops = &default_ethtool_ops;

        nf_hook_netdev_init(dev);

        return dev;

free_all:
        free_netdev(dev);
        return NULL;

free_pcpu:
#ifdef CONFIG_PCPU_DEV_REFCNT
        free_percpu(dev->pcpu_refcnt);
free_dev:
#endif
        netdev_freemem(dev);
        return NULL;
}
EXPORT_SYMBOL(alloc_netdev_mqs);

/**
 * free_netdev - free network device
 * @dev: device
 *
 * This function does the last stage of destroying an allocated device
 * interface. The reference to the device object is released. If this
 * is the last reference then it will be freed.Must be called in process
 * context.
 */
void free_netdev(struct net_device *dev)
{
        struct napi_struct *p, *n;

        might_sleep();

        /* When called immediately after register_netdevice() failed the unwind
         * handling may still be dismantling the device. Handle that case by
         * deferring the free.
         */
        if (dev->reg_state == NETREG_UNREGISTERING) {
                ASSERT_RTNL();
                dev->needs_free_netdev = true;
                return;
        }

        netif_free_tx_queues(dev);
        netif_free_rx_queues(dev);

        kfree(rcu_dereference_protected(dev->ingress_queue, 1));

        /* Flush device addresses */
        dev_addr_flush(dev);

        list_for_each_entry_safe(p, n, &dev->napi_list, dev_list)
                netif_napi_del(p);

        ref_tracker_dir_exit(&dev->refcnt_tracker);
#ifdef CONFIG_PCPU_DEV_REFCNT
        free_percpu(dev->pcpu_refcnt);
        dev->pcpu_refcnt = NULL;
#endif
        free_percpu(dev->core_stats);
        dev->core_stats = NULL;
        free_percpu(dev->xdp_bulkq);
        dev->xdp_bulkq = NULL;

        /*  Compatibility with error handling in drivers */
        if (dev->reg_state == NETREG_UNINITIALIZED) {
                netdev_freemem(dev);
                return;
        }

        BUG_ON(dev->reg_state != NETREG_UNREGISTERED);
        dev->reg_state = NETREG_RELEASED;

        /* will free via device release */
        put_device(&dev->dev);
}
EXPORT_SYMBOL(free_netdev);

/**
 *      synchronize_net -  Synchronize with packet receive processing
 *
 *      Wait for packets currently being received to be done.
 *      Does not block later packets from starting.
 */
void synchronize_net(void)
{
        might_sleep();
        if (rtnl_is_locked())
                synchronize_rcu_expedited();
        else
                synchronize_rcu();
}
EXPORT_SYMBOL(synchronize_net);

/**
 *      unregister_netdevice_queue - remove device from the kernel
 *      @dev: device
 *      @head: list
 *
 *      This function shuts down a device interface and removes it
 *      from the kernel tables.
 *      If head not NULL, device is queued to be unregistered later.
 *
 *      Callers must hold the rtnl semaphore.  You may want
 *      unregister_netdev() instead of this.
 */

void unregister_netdevice_queue(struct net_device *dev, struct list_head *head)
{
        ASSERT_RTNL();

        if (head) {
                list_move_tail(&dev->unreg_list, head);
        } else {
                LIST_HEAD(single);

                list_add(&dev->unreg_list, &single);
                unregister_netdevice_many(&single);
        }
}
EXPORT_SYMBOL(unregister_netdevice_queue);

void unregister_netdevice_many_notify(struct list_head *head,
                                      u32 portid, const struct nlmsghdr *nlh)
{
        struct net_device *dev, *tmp;
        LIST_HEAD(close_head);

        BUG_ON(dev_boot_phase);
        ASSERT_RTNL();

        if (list_empty(head))
                return;

        list_for_each_entry_safe(dev, tmp, head, unreg_list) {
                /* Some devices call without registering
                 * for initialization unwind. Remove those
                 * devices and proceed with the remaining.
                 */
                if (dev->reg_state == NETREG_UNINITIALIZED) {
                        pr_debug("unregister_netdevice: device %s/%p never was registered\n",
                                 dev->name, dev);

                        WARN_ON(1);
                        list_del(&dev->unreg_list);
                        continue;
                }
                dev->dismantle = true;
                BUG_ON(dev->reg_state != NETREG_REGISTERED);
        }

        /* If device is running, close it first. */
        list_for_each_entry(dev, head, unreg_list)
                list_add_tail(&dev->close_list, &close_head);
        dev_close_many(&close_head, true);

        list_for_each_entry(dev, head, unreg_list) {
                /* And unlink it from device chain. */
                write_lock(&dev_base_lock);
                unlist_netdevice(dev, false);
                dev->reg_state = NETREG_UNREGISTERING;
                write_unlock(&dev_base_lock);
        }
        flush_all_backlogs();

        synchronize_net();

        list_for_each_entry(dev, head, unreg_list) {
                struct sk_buff *skb = NULL;

                /* Shutdown queueing discipline. */
                dev_shutdown(dev);
                dev_tcx_uninstall(dev);
                dev_xdp_uninstall(dev);
                bpf_dev_bound_netdev_unregister(dev);

                netdev_offload_xstats_disable_all(dev);

                /* Notify protocols, that we are about to destroy
                 * this device. They should clean all the things.
                 */
                call_netdevice_notifiers(NETDEV_UNREGISTER, dev);

                if (!dev->rtnl_link_ops ||
                    dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
                        skb = rtmsg_ifinfo_build_skb(RTM_DELLINK, dev, ~0U, 0,
                                                     GFP_KERNEL, NULL, 0,
                                                     portid, nlh);

                /*
                 *      Flush the unicast and multicast chains
                 */
                dev_uc_flush(dev);
                dev_mc_flush(dev);

                netdev_name_node_alt_flush(dev);
                netdev_name_node_free(dev->name_node);

                call_netdevice_notifiers(NETDEV_PRE_UNINIT, dev);

                if (dev->netdev_ops->ndo_uninit)
                        dev->netdev_ops->ndo_uninit(dev);

                if (skb)
                        rtmsg_ifinfo_send(skb, dev, GFP_KERNEL, portid, nlh);

                /* Notifier chain MUST detach us all upper devices. */
                WARN_ON(netdev_has_any_upper_dev(dev));
                WARN_ON(netdev_has_any_lower_dev(dev));

                /* Remove entries from kobject tree */
                netdev_unregister_kobject(dev);
#ifdef CONFIG_XPS
                /* Remove XPS queueing entries */
                netif_reset_xps_queues_gt(dev, 0);
#endif
        }

        synchronize_net();

        list_for_each_entry(dev, head, unreg_list) {
                netdev_put(dev, &dev->dev_registered_tracker);
                net_set_todo(dev);
        }

        list_del(head);
}

/**
 *      unregister_netdevice_many - unregister many devices
 *      @head: list of devices
 *
 *  Note: As most callers use a stack allocated list_head,
 *  we force a list_del() to make sure stack wont be corrupted later.
 */
void unregister_netdevice_many(struct list_head *head)
{
        unregister_netdevice_many_notify(head, 0, NULL);
}
EXPORT_SYMBOL(unregister_netdevice_many);

/**
 *      unregister_netdev - remove device from the kernel
 *      @dev: device
 *
 *      This function shuts down a device interface and removes it
 *      from the kernel tables.
 *
 *      This is just a wrapper for unregister_netdevice that takes
 *      the rtnl semaphore.  In general you want to use this and not
 *      unregister_netdevice.
 */
void unregister_netdev(struct net_device *dev)
{
        rtnl_lock();
        unregister_netdevice(dev);
        rtnl_unlock();
}
EXPORT_SYMBOL(unregister_netdev);

/**
 *      __dev_change_net_namespace - move device to different nethost namespace
 *      @dev: device
 *      @net: network namespace
 *      @pat: If not NULL name pattern to try if the current device name
 *            is already taken in the destination network namespace.
 *      @new_ifindex: If not zero, specifies device index in the target
 *                    namespace.
 *
 *      This function shuts down a device interface and moves it
 *      to a new network namespace. On success 0 is returned, on
 *      a failure a netagive errno code is returned.
 *
 *      Callers must hold the rtnl semaphore.
 */

int __dev_change_net_namespace(struct net_device *dev, struct net *net,
                               const char *pat, int new_ifindex)
{
        struct netdev_name_node *name_node;
        struct net *net_old = dev_net(dev);
        char new_name[IFNAMSIZ] = {};
        int err, new_nsid;

        ASSERT_RTNL();

        /* Don't allow namespace local devices to be moved. */
        err = -EINVAL;
        if (dev->features & NETIF_F_NETNS_LOCAL)
                goto out;

        /* Ensure the device has been registrered */
        if (dev->reg_state != NETREG_REGISTERED)
                goto out;

        /* Get out if there is nothing todo */
        err = 0;
        if (net_eq(net_old, net))
                goto out;

        /* Pick the destination device name, and ensure
         * we can use it in the destination network namespace.
         */
        err = -EEXIST;
        if (netdev_name_in_use(net, dev->name)) {
                /* We get here if we can't use the current device name */
                if (!pat)
                        goto out;
                err = dev_prep_valid_name(net, dev, pat, new_name);
                if (err < 0)
                        goto out;
        }
        /* Check that none of the altnames conflicts. */
        err = -EEXIST;
        netdev_for_each_altname(dev, name_node)
                if (netdev_name_in_use(net, name_node->name))
                        goto out;

        /* Check that new_ifindex isn't used yet. */
        if (new_ifindex) {
                err = dev_index_reserve(net, new_ifindex);
                if (err < 0)
                        goto out;
        } else {
                /* If there is an ifindex conflict assign a new one */
                err = dev_index_reserve(net, dev->ifindex);
                if (err == -EBUSY)
                        err = dev_index_reserve(net, 0);
                if (err < 0)
                        goto out;
                new_ifindex = err;
        }

        /*
         * And now a mini version of register_netdevice unregister_netdevice.
         */

        /* If device is running close it first. */
        dev_close(dev);

        /* And unlink it from device chain */
        unlist_netdevice(dev, true);

        synchronize_net();

        /* Shutdown queueing discipline. */
        dev_shutdown(dev);

        /* Notify protocols, that we are about to destroy
         * this device. They should clean all the things.
         *
         * Note that dev->reg_state stays at NETREG_REGISTERED.
         * This is wanted because this way 8021q and macvlan know
         * the device is just moving and can keep their slaves up.
         */
        call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
        rcu_barrier();

        new_nsid = peernet2id_alloc(dev_net(dev), net, GFP_KERNEL);

        rtmsg_ifinfo_newnet(RTM_DELLINK, dev, ~0U, GFP_KERNEL, &new_nsid,
                            new_ifindex);

        /*
         *      Flush the unicast and multicast chains
         */
        dev_uc_flush(dev);
        dev_mc_flush(dev);

        /* Send a netdev-removed uevent to the old namespace */
        kobject_uevent(&dev->dev.kobj, KOBJ_REMOVE);
        netdev_adjacent_del_links(dev);

        /* Move per-net netdevice notifiers that are following the netdevice */
        move_netdevice_notifiers_dev_net(dev, net);

        /* Actually switch the network namespace */
        dev_net_set(dev, net);
        dev->ifindex = new_ifindex;

        /* Send a netdev-add uevent to the new namespace */
        kobject_uevent(&dev->dev.kobj, KOBJ_ADD);
        netdev_adjacent_add_links(dev);

        if (new_name[0]) /* Rename the netdev to prepared name */
                strscpy(dev->name, new_name, IFNAMSIZ);

        /* Fixup kobjects */
        err = device_rename(&dev->dev, dev->name);
        WARN_ON(err);

        /* Adapt owner in case owning user namespace of target network
         * namespace is different from the original one.
         */
        err = netdev_change_owner(dev, net_old, net);
        WARN_ON(err);

        /* Add the device back in the hashes */
        list_netdevice(dev);

        /* Notify protocols, that a new device appeared. */
        call_netdevice_notifiers(NETDEV_REGISTER, dev);

        /*
         *      Prevent userspace races by waiting until the network
         *      device is fully setup before sending notifications.
         */
        rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL, 0, NULL);

        synchronize_net();
        err = 0;
out:
        return err;
}
EXPORT_SYMBOL_GPL(__dev_change_net_namespace);

static int dev_cpu_dead(unsigned int oldcpu)
{
        struct sk_buff **list_skb;
        struct sk_buff *skb;
        unsigned int cpu;
        struct softnet_data *sd, *oldsd, *remsd = NULL;

        local_irq_disable();
        cpu = smp_processor_id();
        sd = &per_cpu(softnet_data, cpu);
        oldsd = &per_cpu(softnet_data, oldcpu);

        /* Find end of our completion_queue. */
        list_skb = &sd->completion_queue;
        while (*list_skb)
                list_skb = &(*list_skb)->next;
        /* Append completion queue from offline CPU. */
        *list_skb = oldsd->completion_queue;
        oldsd->completion_queue = NULL;

        /* Append output queue from offline CPU. */
        if (oldsd->output_queue) {
                *sd->output_queue_tailp = oldsd->output_queue;
                sd->output_queue_tailp = oldsd->output_queue_tailp;
                oldsd->output_queue = NULL;
                oldsd->output_queue_tailp = &oldsd->output_queue;
        }
        /* Append NAPI poll list from offline CPU, with one exception :
         * process_backlog() must be called by cpu owning percpu backlog.
         * We properly handle process_queue & input_pkt_queue later.
         */
        while (!list_empty(&oldsd->poll_list)) {
                struct napi_struct *napi = list_first_entry(&oldsd->poll_list,
                                                            struct napi_struct,
                                                            poll_list);

                list_del_init(&napi->poll_list);
                if (napi->poll == process_backlog)
                        napi->state = 0;
                else
                        ____napi_schedule(sd, napi);
        }

        raise_softirq_irqoff(NET_TX_SOFTIRQ);
        local_irq_enable();

#ifdef CONFIG_RPS
        remsd = oldsd->rps_ipi_list;
        oldsd->rps_ipi_list = NULL;
#endif
        /* send out pending IPI's on offline CPU */
        net_rps_send_ipi(remsd);

        /* Process offline CPU's input_pkt_queue */
        while ((skb = __skb_dequeue(&oldsd->process_queue))) {
                netif_rx(skb);
                input_queue_head_incr(oldsd);
        }
        while ((skb = skb_dequeue(&oldsd->input_pkt_queue))) {
                netif_rx(skb);
                input_queue_head_incr(oldsd);
        }

        return 0;
}

/**
 *      netdev_increment_features - increment feature set by one
 *      @all: current feature set
 *      @one: new feature set
 *      @mask: mask feature set
 *
 *      Computes a new feature set after adding a device with feature set
 *      @one to the master device with current feature set @all.  Will not
 *      enable anything that is off in @mask. Returns the new feature set.
 */
netdev_features_t netdev_increment_features(netdev_features_t all,
        netdev_features_t one, netdev_features_t mask)
{
        if (mask & NETIF_F_HW_CSUM)
                mask |= NETIF_F_CSUM_MASK;
        mask |= NETIF_F_VLAN_CHALLENGED;

        all |= one & (NETIF_F_ONE_FOR_ALL | NETIF_F_CSUM_MASK) & mask;
        all &= one | ~NETIF_F_ALL_FOR_ALL;

        /* If one device supports hw checksumming, set for all. */
        if (all & NETIF_F_HW_CSUM)
                all &= ~(NETIF_F_CSUM_MASK & ~NETIF_F_HW_CSUM);

        return all;
}
EXPORT_SYMBOL(netdev_increment_features);

static struct hlist_head * __net_init netdev_create_hash(void)
{
        int i;
        struct hlist_head *hash;

        hash = kmalloc_array(NETDEV_HASHENTRIES, sizeof(*hash), GFP_KERNEL);
        if (hash != NULL)
                for (i = 0; i < NETDEV_HASHENTRIES; i++)
                        INIT_HLIST_HEAD(&hash[i]);

        return hash;
}

/* Initialize per network namespace state */
static int __net_init netdev_init(struct net *net)
{
        BUILD_BUG_ON(GRO_HASH_BUCKETS >
                     8 * sizeof_field(struct napi_struct, gro_bitmask));

        INIT_LIST_HEAD(&net->dev_base_head);

        net->dev_name_head = netdev_create_hash();
        if (net->dev_name_head == NULL)
                goto err_name;

        net->dev_index_head = netdev_create_hash();
        if (net->dev_index_head == NULL)
                goto err_idx;

        xa_init_flags(&net->dev_by_index, XA_FLAGS_ALLOC1);

        RAW_INIT_NOTIFIER_HEAD(&net->netdev_chain);

        return 0;

err_idx:
        kfree(net->dev_name_head);
err_name:
        return -ENOMEM;
}

/**
 *      netdev_drivername - network driver for the device
 *      @dev: network device
 *
 *      Determine network driver for device.
 */
const char *netdev_drivername(const struct net_device *dev)
{
        const struct device_driver *driver;
        const struct device *parent;
        const char *empty = "";

        parent = dev->dev.parent;
        if (!parent)
                return empty;

        driver = parent->driver;
        if (driver && driver->name)
                return driver->name;
        return empty;
}

static void __netdev_printk(const char *level, const struct net_device *dev,
                            struct va_format *vaf)
{
        if (dev && dev->dev.parent) {
                dev_printk_emit(level[1] - '0',
                                dev->dev.parent,
                                "%s %s %s%s: %pV",
                                dev_driver_string(dev->dev.parent),
                                dev_name(dev->dev.parent),
                                netdev_name(dev), netdev_reg_state(dev),
                                vaf);
        } else if (dev) {
                printk("%s%s%s: %pV",
                       level, netdev_name(dev), netdev_reg_state(dev), vaf);
        } else {
                printk("%s(NULL net_device): %pV", level, vaf);
        }
}

void netdev_printk(const char *level, const struct net_device *dev,
                   const char *format, ...)
{
        struct va_format vaf;
        va_list args;

        va_start(args, format);

        vaf.fmt = format;
        vaf.va = &args;

        __netdev_printk(level, dev, &vaf);

        va_end(args);
}
EXPORT_SYMBOL(netdev_printk);

#define define_netdev_printk_level(func, level)                 \
void func(const struct net_device *dev, const char *fmt, ...)   \
{                                                               \
        struct va_format vaf;                                   \
        va_list args;                                           \
                                                                \
        va_start(args, fmt);                                    \
                                                                \
        vaf.fmt = fmt;                                          \
        vaf.va = &args;                                         \
                                                                \
        __netdev_printk(level, dev, &vaf);                      \
                                                                \
        va_end(args);                                           \
}                                                               \
EXPORT_SYMBOL(func);

define_netdev_printk_level(netdev_emerg, KERN_EMERG);
define_netdev_printk_level(netdev_alert, KERN_ALERT);
define_netdev_printk_level(netdev_crit, KERN_CRIT);
define_netdev_printk_level(netdev_err, KERN_ERR);
define_netdev_printk_level(netdev_warn, KERN_WARNING);
define_netdev_printk_level(netdev_notice, KERN_NOTICE);
define_netdev_printk_level(netdev_info, KERN_INFO);

static void __net_exit netdev_exit(struct net *net)
{
        kfree(net->dev_name_head);
        kfree(net->dev_index_head);
        xa_destroy(&net->dev_by_index);
        if (net != &init_net)
                WARN_ON_ONCE(!list_empty(&net->dev_base_head));
}

static struct pernet_operations __net_initdata netdev_net_ops = {
        .init = netdev_init,
        .exit = netdev_exit,
};

static void __net_exit default_device_exit_net(struct net *net)
{
        struct net_device *dev, *aux;
        /*
         * Push all migratable network devices back to the
         * initial network namespace
         */
        ASSERT_RTNL();
        for_each_netdev_safe(net, dev, aux) {
                int err;
                char fb_name[IFNAMSIZ];

                /* Ignore unmoveable devices (i.e. loopback) */
                if (dev->features & NETIF_F_NETNS_LOCAL)
                        continue;

                /* Leave virtual devices for the generic cleanup */
                if (dev->rtnl_link_ops && !dev->rtnl_link_ops->netns_refund)
                        continue;

                /* Push remaining network devices to init_net */
                snprintf(fb_name, IFNAMSIZ, "dev%d", dev->ifindex);
                if (netdev_name_in_use(&init_net, fb_name))
                        snprintf(fb_name, IFNAMSIZ, "dev%%d");
                err = dev_change_net_namespace(dev, &init_net, fb_name);
                if (err) {
                        pr_emerg("%s: failed to move %s to init_net: %d\n",
                                 __func__, dev->name, err);
                        BUG();
                }
        }
}

static void __net_exit default_device_exit_batch(struct list_head *net_list)
{
        /* At exit all network devices most be removed from a network
         * namespace.  Do this in the reverse order of registration.
         * Do this across as many network namespaces as possible to
         * improve batching efficiency.
         */
        struct net_device *dev;
        struct net *net;
        LIST_HEAD(dev_kill_list);

        rtnl_lock();
        list_for_each_entry(net, net_list, exit_list) {
                default_device_exit_net(net);
                cond_resched();
        }

        list_for_each_entry(net, net_list, exit_list) {
                for_each_netdev_reverse(net, dev) {
                        if (dev->rtnl_link_ops && dev->rtnl_link_ops->dellink)
                                dev->rtnl_link_ops->dellink(dev, &dev_kill_list);
                        else
                                unregister_netdevice_queue(dev, &dev_kill_list);
                }
        }
        unregister_netdevice_many(&dev_kill_list);
        rtnl_unlock();
}

static struct pernet_operations __net_initdata default_device_ops = {
        .exit_batch = default_device_exit_batch,
};

/*
 *      Initialize the DEV module. At boot time this walks the device list and
 *      unhooks any devices that fail to initialise (normally hardware not
 *      present) and leaves us with a valid list of present and active devices.
 *
 */

/*
 *       This is called single threaded during boot, so no need
 *       to take the rtnl semaphore.
 */
static int __init net_dev_init(void)
{
        int i, rc = -ENOMEM;

        BUG_ON(!dev_boot_phase);

        if (dev_proc_init())
                goto out;

        if (netdev_kobject_init())
                goto out;

        INIT_LIST_HEAD(&ptype_all);
        for (i = 0; i < PTYPE_HASH_SIZE; i++)
                INIT_LIST_HEAD(&ptype_base[i]);

        if (register_pernet_subsys(&netdev_net_ops))
                goto out;

        /*
         *      Initialise the packet receive queues.
         */

        for_each_possible_cpu(i) {
                struct work_struct *flush = per_cpu_ptr(&flush_works, i);
                struct softnet_data *sd = &per_cpu(softnet_data, i);

                INIT_WORK(flush, flush_backlog);

                skb_queue_head_init(&sd->input_pkt_queue);
                skb_queue_head_init(&sd->process_queue);
#ifdef CONFIG_XFRM_OFFLOAD
                skb_queue_head_init(&sd->xfrm_backlog);
#endif
                INIT_LIST_HEAD(&sd->poll_list);
                sd->output_queue_tailp = &sd->output_queue;
#ifdef CONFIG_RPS
                INIT_CSD(&sd->csd, rps_trigger_softirq, sd);
                sd->cpu = i;
#endif
                INIT_CSD(&sd->defer_csd, trigger_rx_softirq, sd);
                spin_lock_init(&sd->defer_lock);

                init_gro_hash(&sd->backlog);
                sd->backlog.poll = process_backlog;
                sd->backlog.weight = weight_p;
        }

        dev_boot_phase = 0;

        /* The loopback device is special if any other network devices
         * is present in a network namespace the loopback device must
         * be present. Since we now dynamically allocate and free the
         * loopback device ensure this invariant is maintained by
         * keeping the loopback device as the first device on the
         * list of network devices.  Ensuring the loopback devices
         * is the first device that appears and the last network device
         * that disappears.
         */
        if (register_pernet_device(&loopback_net_ops))
                goto out;

        if (register_pernet_device(&default_device_ops))
                goto out;

        open_softirq(NET_TX_SOFTIRQ, net_tx_action);
        open_softirq(NET_RX_SOFTIRQ, net_rx_action);

        rc = cpuhp_setup_state_nocalls(CPUHP_NET_DEV_DEAD, "net/dev:dead",
                                       NULL, dev_cpu_dead);
        WARN_ON(rc < 0);
        rc = 0;
out:
        return rc;
}

subsys_initcall(net_dev_init);