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authorEric Dumazet <edumazet@google.com>2012-12-05 13:18:10 +0400
committerDavid S. Miller <davem@davemloft.net>2012-12-06 01:01:28 +0400
commit0e1efe9d5e10921f1e2152b108e013605fca3c9f (patch)
treec254570a9058345ea2eb1f319cc5c88cfe8c65ee /net/ipv6/mcast.c
parentcc86802805b5d714a5dc80fe4edecaf1368b09ed (diff)
downloadlinux-0e1efe9d5e10921f1e2152b108e013605fca3c9f.tar.xz
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>
Diffstat (limited to 'net/ipv6/mcast.c')
-rw-r--r--net/ipv6/mcast.c3
1 files changed, 3 insertions, 0 deletions
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) {