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authorEric Dumazet <edumazet@google.com>2012-12-05 09:18:10 +0000
committerDavid S. Miller <davem@davemloft.net>2012-12-05 16:01:28 -0500
commit0e1efe9d5e10921f1e2152b108e013605fca3c9f (patch)
treec254570a9058345ea2eb1f319cc5c88cfe8c65ee
parentcc86802805b5d714a5dc80fe4edecaf1368b09ed (diff)
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ipv6: avoid taking locks at socket dismantle
ipv6_sock_mc_close() is called for ipv6 sockets at close time, and most of them don't use multicast. Add a test to avoid contention on a shared spinlock. Same heuristic applies for ipv6_sock_ac_close(), to avoid contention on a shared rwlock. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv6/anycast.c3
-rw-r--r--net/ipv6/mcast.c3
2 files changed, 6 insertions, 0 deletions
diff --git a/net/ipv6/anycast.c b/net/ipv6/anycast.c
index 2f4f584d796d..757a810d8f15 100644
--- a/net/ipv6/anycast.c
+++ b/net/ipv6/anycast.c
@@ -189,6 +189,9 @@ void ipv6_sock_ac_close(struct sock *sk)
struct net *net = sock_net(sk);
int prev_index;
+ if (!np->ipv6_ac_list)
+ return;
+
write_lock_bh(&ipv6_sk_ac_lock);
pac = np->ipv6_ac_list;
np->ipv6_ac_list = NULL;
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index b19ed51a45bb..28dfa5f3801f 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -284,6 +284,9 @@ void ipv6_sock_mc_close(struct sock *sk)
struct ipv6_mc_socklist *mc_lst;
struct net *net = sock_net(sk);
+ if (!rcu_access_pointer(np->ipv6_mc_list))
+ return;
+
spin_lock(&ipv6_sk_mc_lock);
while ((mc_lst = rcu_dereference_protected(np->ipv6_mc_list,
lockdep_is_held(&ipv6_sk_mc_lock))) != NULL) {