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>

1 files changed, 87 insertions, 96 deletions

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 8752e8084806..3e36d1538b6e 100644
--- 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: