net_sched: reintroduce dev->qdisc for use by sch_api

Currently the multiqueue integration with the qdisc API suffers from
a few problems:

- with multiple queues, all root qdiscs use the same handle. This means
  they can't be exposed to userspace in a backwards compatible fashion.

- all API operations always refer to queue number 0. Newly created
  qdiscs are automatically shared between all queues, its not possible
  to address individual queues or restore multiqueue behaviour once a
  shared qdisc has been attached.

- Dumps only contain the root qdisc of queue 0, in case of non-shared
  qdiscs this means the statistics are incomplete.

This patch reintroduces dev->qdisc, which points to the (single) root qdisc
from userspace's point of view. Currently it either points to the first
(non-shared) default qdisc, or a qdisc shared between all queues. The
following patches will introduce a classful dummy qdisc, which will be used
as root qdisc and contain the per-queue qdiscs as children.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 121cbad..a44118b 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -832,6 +832,9 @@ struct net_device
        /* Number of TX queues currently active in device  */
        unsigned int            real_num_tx_queues;
 
+       /* root qdisc from userspace point of view */
+       struct Qdisc            *qdisc;
+
        unsigned long           tx_queue_len;   /* Max frames per queue allowed */
        spinlock_t              tx_global_lock;
 /*

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index bbcba2a..eb42873 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -606,7 +606,6 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev,
                            int type, u32 pid, u32 seq, u32 change,
                            unsigned int flags)
 {
-       struct netdev_queue *txq;
        struct ifinfomsg *ifm;
        struct nlmsghdr *nlh;
        const struct net_device_stats *stats;
@@ -637,9 +636,8 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev,
        if (dev->master)
                NLA_PUT_U32(skb, IFLA_MASTER, dev->master->ifindex);
 
-       txq = netdev_get_tx_queue(dev, 0);
-       if (txq->qdisc_sleeping)
-               NLA_PUT_STRING(skb, IFLA_QDISC, txq->qdisc_sleeping->ops->id);
+       if (dev->qdisc)
+               NLA_PUT_STRING(skb, IFLA_QDISC, dev->qdisc->ops->id);
 
        if (dev->ifalias)
                NLA_PUT_STRING(skb, IFLA_IFALIAS, dev->ifalias);

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index bcfbdb4..6a53694 100644 (file)
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -168,8 +168,7 @@ replay:
 
        /* Find qdisc */
        if (!parent) {
-               struct netdev_queue *dev_queue = netdev_get_tx_queue(dev, 0);
-               q = dev_queue->qdisc_sleeping;
+               q = dev->qdisc;
                parent = q->handle;
        } else {
                q = qdisc_lookup(dev, TC_H_MAJ(t->tcm_parent));
@@ -408,7 +407,6 @@ static int tcf_node_dump(struct tcf_proto *tp, unsigned long n,
 static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb)
 {
        struct net *net = sock_net(skb->sk);
-       struct netdev_queue *dev_queue;
        int t;
        int s_t;
        struct net_device *dev;
@@ -427,9 +425,8 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb)
        if ((dev = dev_get_by_index(&init_net, tcm->tcm_ifindex)) == NULL)
                return skb->len;
 
-       dev_queue = netdev_get_tx_queue(dev, 0);
        if (!tcm->tcm_parent)
-               q = dev_queue->qdisc_sleeping;
+               q = dev->qdisc;
        else
                q = qdisc_lookup(dev, TC_H_MAJ(tcm->tcm_parent));
        if (!q)

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 166fcca..8aa9a0c 100644 (file)
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -207,7 +207,7 @@ static struct Qdisc *qdisc_match_from_root(struct Qdisc *root, u32 handle)
 static void qdisc_list_add(struct Qdisc *q)
 {
        if ((q->parent != TC_H_ROOT) && !(q->flags & TCQ_F_INGRESS))
-               list_add_tail(&q->list, &qdisc_root_sleeping(q)->list);
+               list_add_tail(&q->list, &qdisc_dev(q)->qdisc->list);
 }
 
 void qdisc_list_del(struct Qdisc *q)
@@ -219,17 +219,11 @@ EXPORT_SYMBOL(qdisc_list_del);
 
 struct Qdisc *qdisc_lookup(struct net_device *dev, u32 handle)
 {
-       unsigned int i;
        struct Qdisc *q;
 
-       for (i = 0; i < dev->num_tx_queues; i++) {
-               struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
-               struct Qdisc *txq_root = txq->qdisc_sleeping;
-
-               q = qdisc_match_from_root(txq_root, handle);
-               if (q)
-                       goto out;
-       }
+       q = qdisc_match_from_root(dev->qdisc, handle);
+       if (q)
+               goto out;
 
        q = qdisc_match_from_root(dev->rx_queue.qdisc_sleeping, handle);
 out:
@@ -720,9 +714,14 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent,
                        if (new && i > 0)
                                atomic_inc(&new->refcnt);
 
-                       notify_and_destroy(skb, n, classid, old, new);
+                       qdisc_destroy(old);
                }
 
+               notify_and_destroy(skb, n, classid, dev->qdisc, new);
+               if (new)
+                       atomic_inc(&new->refcnt);
+               dev->qdisc = new ? : &noop_qdisc;
+
                if (dev->flags & IFF_UP)
                        dev_activate(dev);
        } else {
@@ -974,9 +973,7 @@ static int tc_get_qdisc(struct sk_buff *skb, struct nlmsghdr *n, void *arg)
                                q = dev->rx_queue.qdisc_sleeping;
                        }
                } else {
-                       struct netdev_queue *dev_queue;
-                       dev_queue = netdev_get_tx_queue(dev, 0);
-                       q = dev_queue->qdisc_sleeping;
+                       q = dev->qdisc;
                }
                if (!q)
                        return -ENOENT;
@@ -1044,9 +1041,7 @@ replay:
                                q = dev->rx_queue.qdisc_sleeping;
                        }
                } else {
-                       struct netdev_queue *dev_queue;
-                       dev_queue = netdev_get_tx_queue(dev, 0);
-                       q = dev_queue->qdisc_sleeping;
+                       q = dev->qdisc;
                }
 
                /* It may be default qdisc, ignore it */
@@ -1291,8 +1286,7 @@ static int tc_dump_qdisc(struct sk_buff *skb, struct netlink_callback *cb)
                        s_q_idx = 0;
                q_idx = 0;
 
-               dev_queue = netdev_get_tx_queue(dev, 0);
-               if (tc_dump_qdisc_root(dev_queue->qdisc_sleeping, skb, cb, &q_idx, s_q_idx) < 0)
+               if (tc_dump_qdisc_root(dev->qdisc, skb, cb, &q_idx, s_q_idx) < 0)
                        goto done;
 
                dev_queue = &dev->rx_queue;
@@ -1323,7 +1317,6 @@ done:
 static int tc_ctl_tclass(struct sk_buff *skb, struct nlmsghdr *n, void *arg)
 {
        struct net *net = sock_net(skb->sk);
-       struct netdev_queue *dev_queue;
        struct tcmsg *tcm = NLMSG_DATA(n);
        struct nlattr *tca[TCA_MAX + 1];
        struct net_device *dev;
@@ -1361,7 +1354,6 @@ static int tc_ctl_tclass(struct sk_buff *skb, struct nlmsghdr *n, void *arg)
 
        /* Step 1. Determine qdisc handle X:0 */
 
-       dev_queue = netdev_get_tx_queue(dev, 0);
        if (pid != TC_H_ROOT) {
                u32 qid1 = TC_H_MAJ(pid);
 
@@ -1372,7 +1364,7 @@ static int tc_ctl_tclass(struct sk_buff *skb, struct nlmsghdr *n, void *arg)
                } else if (qid1) {
                        qid = qid1;
                } else if (qid == 0)
-                       qid = dev_queue->qdisc_sleeping->handle;
+                       qid = dev->qdisc->handle;
 
                /* Now qid is genuine qdisc handle consistent
                   both with parent and child.
@@ -1383,7 +1375,7 @@ static int tc_ctl_tclass(struct sk_buff *skb, struct nlmsghdr *n, void *arg)
                        pid = TC_H_MAKE(qid, pid);
        } else {
                if (qid == 0)
-                       qid = dev_queue->qdisc_sleeping->handle;
+                       qid = dev->qdisc->handle;
        }
 
        /* OK. Locate qdisc */
@@ -1588,8 +1580,7 @@ static int tc_dump_tclass(struct sk_buff *skb, struct netlink_callback *cb)
        s_t = cb->args[0];
        t = 0;
 
-       dev_queue = netdev_get_tx_queue(dev, 0);
-       if (tc_dump_tclass_root(dev_queue->qdisc_sleeping, skb, tcm, cb, &t, s_t) < 0)
+       if (tc_dump_tclass_root(dev->qdisc, skb, tcm, cb, &t, s_t) < 0)
                goto done;
 
        dev_queue = &dev->rx_queue;

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 6128e6f..a91f079 100644 (file)
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -623,19 +623,6 @@ void qdisc_destroy(struct Qdisc *qdisc)
 }
 EXPORT_SYMBOL(qdisc_destroy);
 
-static bool dev_all_qdisc_sleeping_noop(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);
-
-               if (txq->qdisc_sleeping != &noop_qdisc)
-                       return false;
-       }
-       return true;
-}
-
 static void attach_one_default_qdisc(struct net_device *dev,
                                     struct netdev_queue *dev_queue,
                                     void *_unused)
@@ -677,6 +664,7 @@ static void transition_one_qdisc(struct net_device *dev,
 
 void dev_activate(struct net_device *dev)
 {
+       struct netdev_queue *txq;
        int need_watchdog;
 
        /* No queueing discipline is attached to device;
@@ -685,9 +673,14 @@ void dev_activate(struct net_device *dev)
           virtual interfaces
         */
 
-       if (dev_all_qdisc_sleeping_noop(dev))
+       if (dev->qdisc == &noop_qdisc) {
                netdev_for_each_tx_queue(dev, attach_one_default_qdisc, NULL);
 
+               txq = netdev_get_tx_queue(dev, 0);
+               dev->qdisc = txq->qdisc_sleeping;
+               atomic_inc(&dev->qdisc->refcnt);
+       }
+
        if (!netif_carrier_ok(dev))
                /* Delay activation until next carrier-on event */
                return;
@@ -777,6 +770,7 @@ static void dev_init_scheduler_queue(struct net_device *dev,
 
 void dev_init_scheduler(struct net_device *dev)
 {
+       dev->qdisc = &noop_qdisc;
        netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
        dev_init_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc);
 
@@ -802,5 +796,8 @@ void dev_shutdown(struct net_device *dev)
 {
        netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
        shutdown_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc);
+       qdisc_destroy(dev->qdisc);
+       dev->qdisc = &noop_qdisc;
+
        WARN_ON(timer_pending(&dev->watchdog_timer));
 }