From 0e1efe9d5e10921f1e2152b108e013605fca3c9f Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 5 Dec 2012 09:18:10 +0000 Subject: 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 Signed-off-by: David S. Miller --- net/ipv6/mcast.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'net/ipv6/mcast.c') diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c index b19ed51..28dfa5f 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) { -- cgit v1.1