Eric Dumazet b6c6712a42 net: sk_dst_cache RCUification
With latest CONFIG_PROVE_RCU stuff, I felt more comfortable to make this
work.

sk->sk_dst_cache is currently protected by a rwlock (sk_dst_lock)

This rwlock is readlocked for a very small amount of time, and dst
entries are already freed after RCU grace period. This calls for RCU
again :)

This patch converts sk_dst_lock to a spinlock, and use RCU for readers.

__sk_dst_get() is supposed to be called with rcu_read_lock() or if
socket locked by user, so use appropriate rcu_dereference_check()
condition (rcu_read_lock_held() || sock_owned_by_user(sk))

This patch avoids two atomic ops per tx packet on UDP connected sockets,
for example, and permits sk_dst_lock to be much less dirtied.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-04-13 01:41:33 -07:00
..
2010-01-07 00:24:55 -08:00
2010-03-21 18:34:16 -07:00
2009-11-04 05:06:25 -08:00
2009-09-01 17:40:57 -07:00
2009-11-04 05:06:25 -08:00
2009-03-21 19:06:54 -07:00
2009-09-01 17:40:31 -07:00
2010-04-13 01:41:33 -07:00
2008-07-05 21:26:57 -07:00
2009-11-04 05:06:25 -08:00
2009-11-04 05:06:25 -08:00
2009-11-13 20:46:58 -08:00
2010-04-13 01:41:33 -07:00
2008-06-11 21:00:38 -07:00
2009-11-04 05:06:25 -08:00
2009-11-04 05:06:25 -08:00
2009-12-26 20:46:28 -08:00
2010-03-12 15:52:40 -08:00
2009-01-06 11:38:15 -07:00
2009-11-20 15:35:04 -08:00
2010-04-01 18:38:48 -07:00
2009-03-21 19:06:50 -07:00
2009-11-04 05:06:25 -08:00
2009-07-26 19:11:14 -07:00
2010-04-01 18:38:48 -07:00
2009-11-04 05:06:25 -08:00
2010-03-21 18:34:16 -07:00
2010-04-13 01:41:33 -07:00
2008-07-05 21:25:39 -07:00
2009-11-10 20:54:38 -08:00
2009-10-07 16:39:43 -04:00