ipv6: mcast: RCU conversions

- ipv6_sock_mc_join() : doesnt touch dev refcount

- ipv6_sock_mc_drop() : doesnt touch dev/idev refcounts

- ip6_mc_find_dev() becomes ip6_mc_find_dev_rcu() (called from rcu),
                    and doesnt touch dev/idev refcounts

- ipv6_sock_mc_close() : doesnt touch dev/idev refcounts

- ip6_mc_source() uses ip6_mc_find_dev_rcu()

- ip6_mc_msfilter() uses ip6_mc_find_dev_rcu()

- ip6_mc_msfget() uses ip6_mc_find_dev_rcu()

- ipv6_dev_mc_dec(), ipv6_chk_mcast_addr(),
  igmp6_event_query(), igmp6_event_report(),
  mld_sendpack(), igmp6_send() dont touch idev refcount

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 8752e80..3e36d15 100644 (file)
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -152,18 +152,19 @@ int ipv6_sock_mc_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
        mc_lst->next = NULL;
        ipv6_addr_copy(&mc_lst->addr, addr);
 
+       rcu_read_lock();
        if (ifindex == 0) {
                struct rt6_info *rt;
                rt = rt6_lookup(net, addr, NULL, 0, 0);
                if (rt) {
                        dev = rt->rt6i_dev;
-                       dev_hold(dev);
                        dst_release(&rt->u.dst);
                }
        } else
-               dev = dev_get_by_index(net, ifindex);
+               dev = dev_get_by_index_rcu(net, ifindex);
 
        if (dev == NULL) {
+               rcu_read_unlock();
                sock_kfree_s(sk, mc_lst, sizeof(*mc_lst));
                return -ENODEV;
        }
@@ -180,8 +181,8 @@ int ipv6_sock_mc_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
        err = ipv6_dev_mc_inc(dev, addr);
 
        if (err) {
+               rcu_read_unlock();
                sock_kfree_s(sk, mc_lst, sizeof(*mc_lst));
-               dev_put(dev);
                return err;
        }
 
@@ -190,7 +191,7 @@ int ipv6_sock_mc_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
        np->ipv6_mc_list = mc_lst;
        write_unlock_bh(&ipv6_sk_mc_lock);
 
-       dev_put(dev);
+       rcu_read_unlock();
 
        return 0;
 }
@@ -213,18 +214,17 @@ int ipv6_sock_mc_drop(struct sock *sk, int ifindex, const struct in6_addr *addr)
                        *lnk = mc_lst->next;
                        write_unlock_bh(&ipv6_sk_mc_lock);
 
-                       dev = dev_get_by_index(net, mc_lst->ifindex);
+                       rcu_read_lock();
+                       dev = dev_get_by_index_rcu(net, mc_lst->ifindex);
                        if (dev != NULL) {
-                               struct inet6_dev *idev = in6_dev_get(dev);
+                               struct inet6_dev *idev = __in6_dev_get(dev);
 
                                (void) ip6_mc_leave_src(sk, mc_lst, idev);
-                               if (idev) {
+                               if (idev)
                                        __ipv6_dev_mc_dec(idev, &mc_lst->addr);
-                                       in6_dev_put(idev);
-                               }
-                               dev_put(dev);
                        } else
                                (void) ip6_mc_leave_src(sk, mc_lst, NULL);
+                       rcu_read_unlock();
                        sock_kfree_s(sk, mc_lst, sizeof(*mc_lst));
                        return 0;
                }
@@ -234,43 +234,36 @@ int ipv6_sock_mc_drop(struct sock *sk, int ifindex, const struct in6_addr *addr)
        return -EADDRNOTAVAIL;
 }
 
-static struct inet6_dev *ip6_mc_find_dev(struct net *net,
-                                        struct in6_addr *group,
-                                        int ifindex)
+/* called with rcu_read_lock() */
+static struct inet6_dev *ip6_mc_find_dev_rcu(struct net *net,
+                                            struct in6_addr *group,
+                                            int ifindex)
 {
        struct net_device *dev = NULL;
        struct inet6_dev *idev = NULL;
 
        if (ifindex == 0) {
-               struct rt6_info *rt;
+               struct rt6_info *rt = rt6_lookup(net, group, NULL, 0, 0);
 
-               rt = rt6_lookup(net, group, NULL, 0, 0);
                if (rt) {
                        dev = rt->rt6i_dev;
                        dev_hold(dev);
                        dst_release(&rt->u.dst);
                }
        } else
-               dev = dev_get_by_index(net, ifindex);
+               dev = dev_get_by_index_rcu(net, ifindex);
 
        if (!dev)
-               goto nodev;
-       idev = in6_dev_get(dev);
+               return NULL;
+       idev = __in6_dev_get(dev);
        if (!idev)
-               goto release;
+               return NULL;;
        read_lock_bh(&idev->lock);
-       if (idev->dead)
-               goto unlock_release;
-
+       if (idev->dead) {
+               read_unlock_bh(&idev->lock);
+               return NULL;
+       }
        return idev;
-
-unlock_release:
-       read_unlock_bh(&idev->lock);
-       in6_dev_put(idev);
-release:
-       dev_put(dev);
-nodev:
-       return NULL;
 }
 
 void ipv6_sock_mc_close(struct sock *sk)
@@ -286,19 +279,17 @@ void ipv6_sock_mc_close(struct sock *sk)
                np->ipv6_mc_list = mc_lst->next;
                write_unlock_bh(&ipv6_sk_mc_lock);
 
-               dev = dev_get_by_index(net, mc_lst->ifindex);
+               rcu_read_lock();
+               dev = dev_get_by_index_rcu(net, mc_lst->ifindex);
                if (dev) {
-                       struct inet6_dev *idev = in6_dev_get(dev);
+                       struct inet6_dev *idev = __in6_dev_get(dev);
 
                        (void) ip6_mc_leave_src(sk, mc_lst, idev);
-                       if (idev) {
+                       if (idev)
                                __ipv6_dev_mc_dec(idev, &mc_lst->addr);
-                               in6_dev_put(idev);
-                       }
-                       dev_put(dev);
                } else
                        (void) ip6_mc_leave_src(sk, mc_lst, NULL);
-
+               rcu_read_unlock();
                sock_kfree_s(sk, mc_lst, sizeof(*mc_lst));
 
                write_lock_bh(&ipv6_sk_mc_lock);
@@ -327,14 +318,17 @@ int ip6_mc_source(int add, int omode, struct sock *sk,
        if (!ipv6_addr_is_multicast(group))
                return -EINVAL;
 
-       idev = ip6_mc_find_dev(net, group, pgsr->gsr_interface);
-       if (!idev)
+       rcu_read_lock();
+       idev = ip6_mc_find_dev_rcu(net, group, pgsr->gsr_interface);
+       if (!idev) {
+               rcu_read_unlock();
                return -ENODEV;
+       }
        dev = idev->dev;
 
        err = -EADDRNOTAVAIL;
 
-       read_lock_bh(&ipv6_sk_mc_lock);
+       read_lock(&ipv6_sk_mc_lock);
        for (pmc=inet6->ipv6_mc_list; pmc; pmc=pmc->next) {
                if (pgsr->gsr_interface && pmc->ifindex != pgsr->gsr_interface)
                        continue;
@@ -358,7 +352,7 @@ int ip6_mc_source(int add, int omode, struct sock *sk,
                pmc->sfmode = omode;
        }
 
-       write_lock_bh(&pmc->sflock);
+       write_lock(&pmc->sflock);
        pmclocked = 1;
 
        psl = pmc->sflist;
@@ -433,11 +427,10 @@ int ip6_mc_source(int add, int omode, struct sock *sk,
        ip6_mc_add_src(idev, group, omode, 1, source, 1);
 done:
        if (pmclocked)
-               write_unlock_bh(&pmc->sflock);
-       read_unlock_bh(&ipv6_sk_mc_lock);
+               write_unlock(&pmc->sflock);
+       read_unlock(&ipv6_sk_mc_lock);
        read_unlock_bh(&idev->lock);
-       in6_dev_put(idev);
-       dev_put(dev);
+       rcu_read_unlock();
        if (leavegroup)
                return ipv6_sock_mc_drop(sk, pgsr->gsr_interface, group);
        return err;
@@ -463,14 +456,17 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf)
            gsf->gf_fmode != MCAST_EXCLUDE)
                return -EINVAL;
 
-       idev = ip6_mc_find_dev(net, group, gsf->gf_interface);
+       rcu_read_lock();
+       idev = ip6_mc_find_dev_rcu(net, group, gsf->gf_interface);
 
-       if (!idev)
+       if (!idev) {
+               rcu_read_unlock();
                return -ENODEV;
+       }
        dev = idev->dev;
 
        err = 0;
-       read_lock_bh(&ipv6_sk_mc_lock);
+       read_lock(&ipv6_sk_mc_lock);
 
        if (gsf->gf_fmode == MCAST_INCLUDE && gsf->gf_numsrc == 0) {
                leavegroup = 1;
@@ -512,7 +508,7 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf)
                (void) ip6_mc_add_src(idev, group, gsf->gf_fmode, 0, NULL, 0);
        }
 
-       write_lock_bh(&pmc->sflock);
+       write_lock(&pmc->sflock);
        psl = pmc->sflist;
        if (psl) {
                (void) ip6_mc_del_src(idev, group, pmc->sfmode,
@@ -522,13 +518,12 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf)
                (void) ip6_mc_del_src(idev, group, pmc->sfmode, 0, NULL, 0);
        pmc->sflist = newpsl;
        pmc->sfmode = gsf->gf_fmode;
-       write_unlock_bh(&pmc->sflock);
+       write_unlock(&pmc->sflock);
        err = 0;
 done:
-       read_unlock_bh(&ipv6_sk_mc_lock);
+       read_unlock(&ipv6_sk_mc_lock);
        read_unlock_bh(&idev->lock);
-       in6_dev_put(idev);
-       dev_put(dev);
+       rcu_read_unlock();
        if (leavegroup)
                err = ipv6_sock_mc_drop(sk, gsf->gf_interface, group);
        return err;
@@ -551,11 +546,13 @@ int ip6_mc_msfget(struct sock *sk, struct group_filter *gsf,
        if (!ipv6_addr_is_multicast(group))
                return -EINVAL;
 
-       idev = ip6_mc_find_dev(net, group, gsf->gf_interface);
+       rcu_read_lock();
+       idev = ip6_mc_find_dev_rcu(net, group, gsf->gf_interface);
 
-       if (!idev)
+       if (!idev) {
+               rcu_read_unlock();
                return -ENODEV;
-
+       }
        dev = idev->dev;
 
        err = -EADDRNOTAVAIL;
@@ -577,8 +574,7 @@ int ip6_mc_msfget(struct sock *sk, struct group_filter *gsf,
        psl = pmc->sflist;
        count = psl ? psl->sl_count : 0;
        read_unlock_bh(&idev->lock);
-       in6_dev_put(idev);
-       dev_put(dev);
+       rcu_read_unlock();
 
        copycount = count < gsf->gf_numsrc ? count : gsf->gf_numsrc;
        gsf->gf_numsrc = count;
@@ -604,8 +600,7 @@ int ip6_mc_msfget(struct sock *sk, struct group_filter *gsf,
        return 0;
 done:
        read_unlock_bh(&idev->lock);
-       in6_dev_put(idev);
-       dev_put(dev);
+       rcu_read_unlock();
        return err;
 }
 
@@ -822,6 +817,7 @@ int ipv6_dev_mc_inc(struct net_device *dev, const struct in6_addr *addr)
        struct ifmcaddr6 *mc;
        struct inet6_dev *idev;
 
+       /* we need to take a reference on idev */
        idev = in6_dev_get(dev);
 
        if (idev == NULL)
@@ -860,7 +856,7 @@ int ipv6_dev_mc_inc(struct net_device *dev, const struct in6_addr *addr)
        setup_timer(&mc->mca_timer, igmp6_timer_handler, (unsigned long)mc);
 
        ipv6_addr_copy(&mc->mca_addr, addr);
-       mc->idev = idev;
+       mc->idev = idev; /* (reference taken) */
        mc->mca_users = 1;
        /* mca_stamp should be updated upon changes */
        mc->mca_cstamp = mc->mca_tstamp = jiffies;
@@ -915,16 +911,18 @@ int __ipv6_dev_mc_dec(struct inet6_dev *idev, const struct in6_addr *addr)
 
 int ipv6_dev_mc_dec(struct net_device *dev, const struct in6_addr *addr)
 {
-       struct inet6_dev *idev = in6_dev_get(dev);
+       struct inet6_dev *idev;
        int err;
 
-       if (!idev)
-               return -ENODEV;
-
-       err = __ipv6_dev_mc_dec(idev, addr);
+       rcu_read_lock();
 
-       in6_dev_put(idev);
+       idev = __in6_dev_get(dev);
+       if (!idev)
+               err = -ENODEV;
+       else
+               err = __ipv6_dev_mc_dec(idev, addr);
 
+       rcu_read_unlock();
        return err;
 }
 
@@ -965,7 +963,8 @@ int ipv6_chk_mcast_addr(struct net_device *dev, const struct in6_addr *group,
        struct ifmcaddr6 *mc;
        int rv = 0;
 
-       idev = in6_dev_get(dev);
+       rcu_read_lock();
+       idev = __in6_dev_get(dev);
        if (idev) {
                read_lock_bh(&idev->lock);
                for (mc = idev->mc_list; mc; mc=mc->next) {
@@ -992,8 +991,8 @@ int ipv6_chk_mcast_addr(struct net_device *dev, const struct in6_addr *group,
                                rv = 1; /* don't filter unspecified source */
                }
                read_unlock_bh(&idev->lock);
-               in6_dev_put(idev);
        }
+       rcu_read_unlock();
        return rv;
 }
 
@@ -1104,6 +1103,7 @@ static int mld_marksources(struct ifmcaddr6 *pmc, int nsrcs,
        return 1;
 }
 
+/* called with rcu_read_lock() */
 int igmp6_event_query(struct sk_buff *skb)
 {
        struct mld2_query *mlh2 = NULL;
@@ -1127,7 +1127,7 @@ int igmp6_event_query(struct sk_buff *skb)
        if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL))
                return -EINVAL;
 
-       idev = in6_dev_get(skb->dev);
+       idev = __in6_dev_get(skb->dev);
 
        if (idev == NULL)
                return 0;
@@ -1137,10 +1137,8 @@ int igmp6_event_query(struct sk_buff *skb)
        group_type = ipv6_addr_type(group);
 
        if (group_type != IPV6_ADDR_ANY &&
-           !(group_type&IPV6_ADDR_MULTICAST)) {
-               in6_dev_put(idev);
+           !(group_type&IPV6_ADDR_MULTICAST))
                return -EINVAL;
-       }
 
        if (len == 24) {
                int switchback;
@@ -1161,10 +1159,9 @@ int igmp6_event_query(struct sk_buff *skb)
        } else if (len >= 28) {
                int srcs_offset = sizeof(struct mld2_query) -
                                  sizeof(struct icmp6hdr);
-               if (!pskb_may_pull(skb, srcs_offset)) {
-                       in6_dev_put(idev);
+               if (!pskb_may_pull(skb, srcs_offset))
                        return -EINVAL;
-               }
+
                mlh2 = (struct mld2_query *)skb_transport_header(skb);
                max_delay = (MLDV2_MRC(ntohs(mlh2->mld2q_mrc))*HZ)/1000;
                if (!max_delay)
@@ -1173,28 +1170,23 @@ int igmp6_event_query(struct sk_buff *skb)
                if (mlh2->mld2q_qrv)
                        idev->mc_qrv = mlh2->mld2q_qrv;
                if (group_type == IPV6_ADDR_ANY) { /* general query */
-                       if (mlh2->mld2q_nsrcs) {
-                               in6_dev_put(idev);
+                       if (mlh2->mld2q_nsrcs)
                                return -EINVAL; /* no sources allowed */
-                       }
+
                        mld_gq_start_timer(idev);
-                       in6_dev_put(idev);
                        return 0;
                }
                /* mark sources to include, if group & source-specific */
                if (mlh2->mld2q_nsrcs != 0) {
                        if (!pskb_may_pull(skb, srcs_offset +
-                           ntohs(mlh2->mld2q_nsrcs) * sizeof(struct in6_addr))) {
-                               in6_dev_put(idev);
+                           ntohs(mlh2->mld2q_nsrcs) * sizeof(struct in6_addr)))
                                return -EINVAL;
-                       }
+
                        mlh2 = (struct mld2_query *)skb_transport_header(skb);
                        mark = 1;
                }
-       } else {
-               in6_dev_put(idev);
+       } else
                return -EINVAL;
-       }
 
        read_lock_bh(&idev->lock);
        if (group_type == IPV6_ADDR_ANY) {
@@ -1227,12 +1219,11 @@ int igmp6_event_query(struct sk_buff *skb)
                }
        }
        read_unlock_bh(&idev->lock);
-       in6_dev_put(idev);
 
        return 0;
 }
 
-
+/* called with rcu_read_lock() */
 int igmp6_event_report(struct sk_buff *skb)
 {
        struct ifmcaddr6 *ma;
@@ -1260,7 +1251,7 @@ int igmp6_event_report(struct sk_buff *skb)
            !(addr_type&IPV6_ADDR_LINKLOCAL))
                return -EINVAL;
 
-       idev = in6_dev_get(skb->dev);
+       idev = __in6_dev_get(skb->dev);
        if (idev == NULL)
                return -ENODEV;
 
@@ -1280,7 +1271,6 @@ int igmp6_event_report(struct sk_buff *skb)
                }
        }
        read_unlock_bh(&idev->lock);
-       in6_dev_put(idev);
        return 0;
 }
 
@@ -1396,12 +1386,14 @@ static void mld_sendpack(struct sk_buff *skb)
        struct mld2_report *pmr =
                              (struct mld2_report *)skb_transport_header(skb);
        int payload_len, mldlen;
-       struct inet6_dev *idev = in6_dev_get(skb->dev);
+       struct inet6_dev *idev;
        struct net *net = dev_net(skb->dev);
        int err;
        struct flowi fl;
        struct dst_entry *dst;
 
+       rcu_read_lock();
+       idev = __in6_dev_get(skb->dev);
        IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, skb->len);
 
        payload_len = (skb->tail - skb->network_header) - sizeof(*pip6);
@@ -1441,8 +1433,7 @@ out:
        } else
                IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_OUTDISCARDS);
 
-       if (likely(idev != NULL))
-               in6_dev_put(idev);
+       rcu_read_unlock();
        return;
 
 err_out:
@@ -1779,7 +1770,8 @@ static void igmp6_send(struct in6_addr *addr, struct net_device *dev, int type)
                                         IPPROTO_ICMPV6,
                                         csum_partial(hdr, len, 0));
 
-       idev = in6_dev_get(skb->dev);
+       rcu_read_lock();
+       idev = __in6_dev_get(skb->dev);
 
        dst = icmp6_dst_alloc(skb->dev, NULL, &ipv6_hdr(skb)->daddr);
        if (!dst) {
@@ -1806,8 +1798,7 @@ out:
        } else
                IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS);
 
-       if (likely(idev != NULL))
-               in6_dev_put(idev);
+       rcu_read_unlock();
        return;
 
 err_out: