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Commit 0e1efe9d authored Dec 05, 2012 by Eric Dumazet Committed by David S. Miller Dec 05, 2012

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>

parent cc868028

net/ipv6/anycast.c

+3 −0

Original line number	Original line	Diff line number	Diff line
	@@ -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;

net/ipv6/mcast.c

+3 −0

Original line number	Original line	Diff line number	Diff line
	@@ -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) {