Re: [PATCH] net: Fix sock_wfree() race
From: David Miller
Date: Fri Sep 11 2009 - 14:43:32 EST
From: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Date: 2009年9月09日 00:49:31 +0200
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[PATCH] net: Fix sock_wfree() race
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Commit 2b85a34e911bf483c27cfdd124aeb1605145dc80
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(net: No more expensive sock_hold()/sock_put() on each tx)
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opens a window in sock_wfree() where another cpu
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might free the socket we are working on.
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Fix is to call sk->sk_write_space(sk) only
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while still holding a reference on sk.
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Since doing this call is done before the
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atomic_sub(truesize, &sk->sk_wmem_alloc), we should pass truesize as
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a bias for possible sk_wmem_alloc evaluations.
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Reported-by: Jike Song <albcamus@xxxxxxxxx>
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Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Applied to net-next-2.6, thanks. I'll queue up your simpler
version for -stable.
BTW, if most if not all of the sock_writeable() calls are now
sock_writeable_bias(), it's probably better to just add the
bias argument to sock_writable().
And a quick grep shows that only a few plain sock_writeable()
calls remain in the less often used protocols.
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