From: Gao feng <gaofeng@cn•fujitsu.com>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: David Miller <davem@davemloft•net>,
netdev@vger•kernel.org, maheshb@google•com, therbert@google•com,
ebiederm@xmission•com
Subject: Re: [PATCH net-next v3] net: remove delay at device dismantle
Date: Thu, 23 Aug 2012 12:33:03 +0800 [thread overview]
Message-ID: <5035B27F.9060002@cn.fujitsu.com> (raw)
In-Reply-To: <1345691986.5904.40.camel@edumazet-glaptop>
于 2012年08月23日 11:19, Eric Dumazet 写道:
> From: Eric Dumazet <edumazet@google•com>
>
> I noticed extra one second delay in device dismantle, tracked down to
> a call to dst_dev_event() while some call_rcu() are still in RCU queues.
>
> These call_rcu() were posted by rt_free(struct rtable *rt) calls.
>
> We then wait a little (but one second) in netdev_wait_allrefs() before
> kicking again NETDEV_UNREGISTER.
>
> As the call_rcu() are now completed, dst_dev_event() can do the needed
> device swap on busy dst.
>
> To solve this problem, add a new NETDEV_UNREGISTER_FINAL, called
> after a rcu_barrier(), but outside of RTNL lock.
>
> Use NETDEV_UNREGISTER_FINAL with care !
>
> Change dst_dev_event() handler to react to NETDEV_UNREGISTER_FINAL
>
> Also remove NETDEV_UNREGISTER_BATCH, as its not used anymore after
> IP cache removal.
>
> With help from Gao feng
>
> Signed-off-by: Eric Dumazet <edumazet@google•com>
> Cc: Tom Herbert <therbert@google•com>
> Cc: Mahesh Bandewar <maheshb@google•com>
> Cc: "Eric W. Biederman" <ebiederm@xmission•com>
> Cc: Gao feng <gaofeng@cn•fujitsu.com>
looks good to me, the lockdep warning message disappeared.
next prev parent reply other threads:[~2012-08-23 4:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-23 3:19 [PATCH net-next v3] net: remove delay at device dismantle Eric Dumazet
2012-08-23 4:33 ` Gao feng [this message]
2012-08-23 4:50 ` David Miller
2012-08-23 6:34 ` Eric W. Biederman
2012-08-23 7:00 ` Eric Dumazet
2012-08-23 18:21 ` Ben Hutchings
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