7 files changed, 67 insertions, 26 deletions

diff --git a/include/net/dst.h b/include/net/dst.h
index 29e255796ce1..13d507d69ddb 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -37,7 +37,7 @@ struct dst_entry {
         unsigned long           _metrics;
         unsigned long           expires;
         struct dst_entry        *path;
-        struct neighbour        *_neighbour;
+        struct neighbour __rcu  *_neighbour;
 #ifdef CONFIG_XFRM
         struct xfrm_state       *xfrm;
 #else
@@ -88,12 +88,17 @@ struct dst_entry {
 
 static inline struct neighbour *dst_get_neighbour(struct dst_entry *dst)
 {
-        return dst->_neighbour;
+        return rcu_dereference(dst->_neighbour);
+}
+
+static inline struct neighbour *dst_get_neighbour_raw(struct dst_entry *dst)
+{
+        return rcu_dereference_raw(dst->_neighbour);
 }
 
 static inline void dst_set_neighbour(struct dst_entry *dst, struct neighbour *neigh)
 {
-        dst->_neighbour = neigh;
+        rcu_assign_pointer(dst->_neighbour, neigh);
 }
 
 extern u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
@@ -382,8 +387,12 @@ static inline void dst_rcu_free(struct rcu_head *head)
 static inline void dst_confirm(struct dst_entry *dst)
 {
         if (dst) {
-                struct neighbour *n = dst_get_neighbour(dst);
+                struct neighbour *n;
+
+                rcu_read_lock();
+                n = dst_get_neighbour(dst);
                 neigh_confirm(n);
+                rcu_read_unlock();
         }
 }
 
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index ccaaa851ab42..77d3eded665a 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -204,9 +204,15 @@ static inline int ip_finish_output2(struct sk_buff *skb)
                 skb = skb2;
         }
 
+        rcu_read_lock();
         neigh = dst_get_neighbour(dst);
-        if (neigh)
-                return neigh_output(neigh, skb);
+        if (neigh) {
+                int res = neigh_output(neigh, skb);
+
+                rcu_read_unlock();
+                return res;
+        }
+        rcu_read_unlock();
 
         if (net_ratelimit())
                 printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n");
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 1730689f560e..6afc4eb50591 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1628,16 +1628,18 @@ static int check_peer_redir(struct dst_entry *dst, struct inet_peer *peer)
 {
         struct rtable *rt = (struct rtable *) dst;
         __be32 orig_gw = rt->rt_gateway;
-        struct neighbour *n;
+        struct neighbour *n, *old_n;
 
         dst_confirm(&rt->dst);
 
-        neigh_release(dst_get_neighbour(&rt->dst));
-        dst_set_neighbour(&rt->dst, NULL);
-
         rt->rt_gateway = peer->redirect_learned.a4;
-        rt_bind_neighbour(rt);
-        n = dst_get_neighbour(&rt->dst);
+
+        n = ipv4_neigh_lookup(&rt->dst, &rt->rt_gateway);
+        if (IS_ERR(n))
+                return PTR_ERR(n);
+        old_n = xchg(&rt->dst._neighbour, n);
+        if (old_n)
+                neigh_release(old_n);
         if (!n || !(n->nud_state & NUD_VALID)) {
                 if (n)
                         neigh_event_send(n, NULL);
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index a55500cc0b29..f012ebd87b43 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -656,7 +656,7 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr, int pfxlen,
          * layer address of our nexhop router
          */
 
-        if (dst_get_neighbour(&rt->dst) == NULL)
+        if (dst_get_neighbour_raw(&rt->dst) == NULL)
                 ifa->flags &= ~IFA_F_OPTIMISTIC;
 
         ifa->idev = idev;
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 54a4678955bf..320d91d20ad7 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -1455,7 +1455,7 @@ static int fib6_age(struct rt6_info *rt, void *arg)
                         RT6_TRACE("aging clone %p\n", rt);
                         return -1;
                 } else if ((rt->rt6i_flags & RTF_GATEWAY) &&
-                           (!(dst_get_neighbour(&rt->dst)->flags & NTF_ROUTER))) {
+                           (!(dst_get_neighbour_raw(&rt->dst)->flags & NTF_ROUTER))) {
                         RT6_TRACE("purging route %p via non-router but gateway\n",
                                   rt);
                         return -1;
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 32e5339db0c8..4c882cf4e8a1 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -135,10 +135,15 @@ static int ip6_finish_output2(struct sk_buff *skb)
                                 skb->len);
         }
 
+        rcu_read_lock();
         neigh = dst_get_neighbour(dst);
-        if (neigh)
-                return neigh_output(neigh, skb);
+        if (neigh) {
+                int res = neigh_output(neigh, skb);
 
+                rcu_read_unlock();
+                return res;
+        }
+        rcu_read_unlock();
         IP6_INC_STATS_BH(dev_net(dst->dev),
                          ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
         kfree_skb(skb);
@@ -975,12 +980,14 @@ static int ip6_dst_lookup_tail(struct sock *sk,
          * dst entry and replace it instead with the
          * dst entry of the nexthop router
          */
+        rcu_read_lock();
         n = dst_get_neighbour(*dst);
         if (n && !(n->nud_state & NUD_VALID)) {
                 struct inet6_ifaddr *ifp;
                 struct flowi6 fl_gw6;
                 int redirect;
 
+                rcu_read_unlock();
                 ifp = ipv6_get_ifaddr(net, &fl6->saddr,
                                       (*dst)->dev, 1);
 
@@ -1000,6 +1007,8 @@ static int ip6_dst_lookup_tail(struct sock *sk,
                         if ((err = (*dst)->error))
                                 goto out_err_release;
                 }
+        } else {
+                rcu_read_unlock();
         }
 #endif
 
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index e8987da06667..9e69eb0ec6dd 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -364,7 +364,7 @@ out:
 #ifdef CONFIG_IPV6_ROUTER_PREF
 static void rt6_probe(struct rt6_info *rt)
 {
-        struct neighbour *neigh = rt ? dst_get_neighbour(&rt->dst) : NULL;
+        struct neighbour *neigh;
         /*
          * Okay, this does not seem to be appropriate
          * for now, however, we need to check if it
@@ -373,8 +373,10 @@ static void rt6_probe(struct rt6_info *rt)
          * Router Reachability Probe MUST be rate-limited
          * to no more than one per minute.
          */
+        rcu_read_lock();
+        neigh = rt ? dst_get_neighbour(&rt->dst) : NULL;
         if (!neigh || (neigh->nud_state & NUD_VALID))
-                return;
+                goto out;
         read_lock_bh(&neigh->lock);
         if (!(neigh->nud_state & NUD_VALID) &&
             time_after(jiffies, neigh->updated + rt->rt6i_idev->cnf.rtr_probe_interval)) {
@@ -387,8 +389,11 @@ static void rt6_probe(struct rt6_info *rt)
                 target = (struct in6_addr *)&neigh->primary_key;
                 addrconf_addr_solict_mult(target, &mcaddr);
                 ndisc_send_ns(rt->rt6i_dev, NULL, target, &mcaddr, NULL);
-        } else
+        } else {
                 read_unlock_bh(&neigh->lock);
+        }
+out:
+        rcu_read_unlock();
 }
 #else
 static inline void rt6_probe(struct rt6_info *rt)
@@ -412,8 +417,11 @@ static inline int rt6_check_dev(struct rt6_info *rt, int oif)
 
 static inline int rt6_check_neigh(struct rt6_info *rt)
 {
-        struct neighbour *neigh = dst_get_neighbour(&rt->dst);
+        struct neighbour *neigh;
         int m;
+
+        rcu_read_lock();
+        neigh = dst_get_neighbour(&rt->dst);
         if (rt->rt6i_flags & RTF_NONEXTHOP ||
             !(rt->rt6i_flags & RTF_GATEWAY))
                 m = 1;
@@ -430,6 +438,7 @@ static inline int rt6_check_neigh(struct rt6_info *rt)
                 read_unlock_bh(&neigh->lock);
         } else
                 m = 0;
+        rcu_read_unlock();
         return m;
 }
 
@@ -769,7 +778,7 @@ static struct rt6_info *rt6_alloc_clone(struct rt6_info *ort,
                 rt->rt6i_dst.plen = 128;
                 rt->rt6i_flags |= RTF_CACHE;
                 rt->dst.flags |= DST_HOST;
-                dst_set_neighbour(&rt->dst, neigh_clone(dst_get_neighbour(&ort->dst)));
+                dst_set_neighbour(&rt->dst, neigh_clone(dst_get_neighbour_raw(&ort->dst)));
         }
         return rt;
 }
@@ -803,7 +812,7 @@ restart:
         dst_hold(&rt->dst);
         read_unlock_bh(&table->tb6_lock);
 
-        if (!dst_get_neighbour(&rt->dst) && !(rt->rt6i_flags & RTF_NONEXTHOP))
+        if (!dst_get_neighbour_raw(&rt->dst) && !(rt->rt6i_flags & RTF_NONEXTHOP))
                 nrt = rt6_alloc_cow(rt, &fl6->daddr, &fl6->saddr);
         else if (!(rt->dst.flags & DST_HOST))
                 nrt = rt6_alloc_clone(rt, &fl6->daddr);
@@ -1587,7 +1596,7 @@ void rt6_redirect(const struct in6_addr *dest, const struct in6_addr *src,
         dst_confirm(&rt->dst);
 
         /* Duplicate redirect: silently ignore. */
-        if (neigh == dst_get_neighbour(&rt->dst))
+        if (neigh == dst_get_neighbour_raw(&rt->dst))
                 goto out;
 
         nrt = ip6_rt_copy(rt, dest);
@@ -1682,7 +1691,7 @@ again:
            1. It is connected route. Action: COW
            2. It is gatewayed route or NONEXTHOP route. Action: clone it.
          */
-        if (!dst_get_neighbour(&rt->dst) && !(rt->rt6i_flags & RTF_NONEXTHOP))
+        if (!dst_get_neighbour_raw(&rt->dst) && !(rt->rt6i_flags & RTF_NONEXTHOP))
                 nrt = rt6_alloc_cow(rt, daddr, saddr);
         else
                 nrt = rt6_alloc_clone(rt, daddr);
@@ -2326,6 +2335,7 @@ static int rt6_fill_node(struct net *net,
         struct nlmsghdr *nlh;
         long expires;
         u32 table;
+        struct neighbour *n;
 
         if (prefix) {   /* user wants prefix routes only */
                 if (!(rt->rt6i_flags & RTF_PREFIX_RT)) {
@@ -2414,8 +2424,11 @@ static int rt6_fill_node(struct net *net,
         if (rtnetlink_put_metrics(skb, dst_metrics_ptr(&rt->dst)) < 0)
                 goto nla_put_failure;
 
-        if (dst_get_neighbour(&rt->dst))
-                NLA_PUT(skb, RTA_GATEWAY, 16, &dst_get_neighbour(&rt->dst)->primary_key);
+        rcu_read_lock();
+        n = dst_get_neighbour(&rt->dst);
+        if (n)
+                NLA_PUT(skb, RTA_GATEWAY, 16, &n->primary_key);
+        rcu_read_unlock();
 
         if (rt->dst.dev)
                 NLA_PUT_U32(skb, RTA_OIF, rt->rt6i_dev->ifindex);
@@ -2608,12 +2621,14 @@ static int rt6_info_route(struct rt6_info *rt, void *p_arg)
 #else
         seq_puts(m, "00000000000000000000000000000000 00 ");
 #endif
+        rcu_read_lock();
         n = dst_get_neighbour(&rt->dst);
         if (n) {
                 seq_printf(m, "%pi6", n->primary_key);
         } else {
                 seq_puts(m, "00000000000000000000000000000000");
         }
+        rcu_read_unlock();
         seq_printf(m, " %08x %08x %08x %08x %8s\n",
                    rt->rt6i_metric, atomic_read(&rt->dst.__refcnt),
                    rt->dst.__use, rt->rt6i_flags,