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authorEric W. Biederman <ebiederm@xmission.com>2009-12-03 02:29:08 +0000
committerDavid S. Miller <davem@davemloft.net>2009-12-03 12:23:47 -0800
commit575f4cd5a5b639457747434dbe18d175fa767db4 (patch)
tree476224db152a2b5bef33046944cb77b5822fae26
parentnet: Allow fib_rule_unregister to batch (diff)
downloadlinux-dev-575f4cd5a5b639457747434dbe18d175fa767db4.tar.xz
linux-dev-575f4cd5a5b639457747434dbe18d175fa767db4.zip
net: Use rcu lookups in inet_twsk_purge.
While we are looking up entries to free there is no reason to take the lock in inet_twsk_purge. We have to drop locks and restart occassionally anyway so adding a few more in case we get on the wrong list because of a timewait move is no big deal. At the same time not taking the lock for long periods of time is much more polite to the rest of the users of the hash table. In my test configuration of killing 4k network namespaces this change causes 4k back to back runs of inet_twsk_purge on an empty hash table to go from roughly 20.7s to 3.3s, and the total time to destroy 4k network namespaces goes from roughly 44s to 3.3s. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/inet_timewait_sock.c39
1 files changed, 24 insertions, 15 deletions
diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index 1f5d508bb18b..d38ca7c77b93 100644
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -427,31 +427,40 @@ void inet_twsk_purge(struct net *net, struct inet_hashinfo *hashinfo,
struct inet_timewait_sock *tw;
struct sock *sk;
struct hlist_nulls_node *node;
- int h;
+ unsigned int slot;
- local_bh_disable();
- for (h = 0; h <= hashinfo->ehash_mask; h++) {
- struct inet_ehash_bucket *head =
- inet_ehash_bucket(hashinfo, h);
- spinlock_t *lock = inet_ehash_lockp(hashinfo, h);
+ for (slot = 0; slot <= hashinfo->ehash_mask; slot++) {
+ struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
+restart_rcu:
+ rcu_read_lock();
restart:
- spin_lock(lock);
- sk_nulls_for_each(sk, node, &head->twchain) {
-
+ sk_nulls_for_each_rcu(sk, node, &head->twchain) {
tw = inet_twsk(sk);
if (!net_eq(twsk_net(tw), net) ||
tw->tw_family != family)
continue;
- atomic_inc(&tw->tw_refcnt);
- spin_unlock(lock);
+ if (unlikely(!atomic_inc_not_zero(&tw->tw_refcnt)))
+ continue;
+
+ if (unlikely(!net_eq(twsk_net(tw), net) ||
+ tw->tw_family != family)) {
+ inet_twsk_put(tw);
+ goto restart;
+ }
+
+ rcu_read_unlock();
inet_twsk_deschedule(tw, twdr);
inet_twsk_put(tw);
-
- goto restart;
+ goto restart_rcu;
}
- spin_unlock(lock);
+ /* If the nulls value we got at the end of this lookup is
+ * not the expected one, we must restart lookup.
+ * We probably met an item that was moved to another chain.
+ */
+ if (get_nulls_value(node) != slot)
+ goto restart;
+ rcu_read_unlock();
}
- local_bh_enable();
}
EXPORT_SYMBOL_GPL(inet_twsk_purge);