Re: PATCH] filter: fix sk_filter rcu handling

David Miller
2010-12-06T17:29:32Z

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Sun, 05 Dec 2010 21:53:52 +0100

> [PATCH] filter: fix sk_filter rcu handling
>
> Pavel Emelyanov tried to fix a race between sk_filter_(de|at)tach and
> sk_clone() in commit 47e958eac280c263397
>
> Problem is we can have several clones sharing a common sk_filter, and
> these clones might want to sk_filter_attach() their own filters at the
> same time, and can overwrite old_filter->rcu, corrupting RCU queues.
>
> We can not use filter->rcu without being sure no other thread could do
> the same thing.
>
> Switch code to a more conventional ref-counting technique : Do the
> atomic decrement immediately and queue one rcu call back when last
> reference is released.
>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>

Applied, and queued up for -stable, thanks.