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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>
This commit is contained in:
Eric Dumazet 2012-12-05 09:18:10 +00:00 committed by David S. Miller
parent cc86802805
commit 0e1efe9d5e
2 changed files with 6 additions and 0 deletions
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3
net/ipv6/anycast.c
View File

@ -189,6 +189,9 @@ void ipv6_sock_ac_close(struct sock *sk)
struct net *net = sock_net(sk); struct net *net = sock_net(sk);
int prev_index; int prev_index;
if (!np->ipv6_ac_list)
return;
write_lock_bh(&ipv6_sk_ac_lock); write_lock_bh(&ipv6_sk_ac_lock);
pac = np->ipv6_ac_list; pac = np->ipv6_ac_list;
np->ipv6_ac_list = NULL; np->ipv6_ac_list = NULL;

3
net/ipv6/mcast.c
View File

@ -284,6 +284,9 @@ void ipv6_sock_mc_close(struct sock *sk)
struct ipv6_mc_socklist *mc_lst; struct ipv6_mc_socklist *mc_lst;
struct net *net = sock_net(sk); struct net *net = sock_net(sk);
if (!rcu_access_pointer(np->ipv6_mc_list))
return;
spin_lock(&ipv6_sk_mc_lock); spin_lock(&ipv6_sk_mc_lock);
while ((mc_lst = rcu_dereference_protected(np->ipv6_mc_list, while ((mc_lst = rcu_dereference_protected(np->ipv6_mc_list,
lockdep_is_held(&ipv6_sk_mc_lock))) != NULL) { lockdep_is_held(&ipv6_sk_mc_lock))) != NULL) {