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From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: netdev@vger.kernel.org, paulmck@linux.vnet.ibm.com
Subject: Re: [PATCH net-next-2.6] net: sk_dst_cache RCUification
Date: Tue, 13 Apr 2010 01:52:32 -0700 (PDT)	[thread overview]
Message-ID: <20100413.015232.67916764.davem@davemloft.net> (raw)
In-Reply-To: <1270803809.2623.69.camel@edumazet-laptop>

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 09 Apr 2010 11:03:29 +0200

> 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>

Applied, thanks for doing this work Eric.

  reply	other threads:[~2010-04-13  8:52 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-04-09  9:03 [PATCH net-next-2.6] net: sk_dst_cache RCUification Eric Dumazet
2010-04-13  8:52 ` David Miller [this message]
2010-04-13 23:04   ` Eric Dumazet
2010-04-13 23:11     ` David Miller
2010-04-14  5:35       ` Eric Dumazet
2010-04-14  5:47         ` Eric Dumazet
2010-04-20 23:03     ` [PATCH net-next-2.6] net: sk_sleep() helper Eric Dumazet
2010-04-20 23:39       ` David Miller
2010-04-26  8:20         ` Eric Dumazet
2010-04-26 18:17           ` David Miller

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