netdev - Re: [PATCH resend] tcp: tcp_release_cb() should release socket ownership

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Message-Id: <20140311.164644.516273403169764933.davem@davemloft.net>
Date:	Tue, 11 Mar 2014 16:46:44 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	lars.persson@...s.com, netdev@...r.kernel.org
Subject: Re: [PATCH resend] tcp: tcp_release_cb() should release socket
 ownership

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Mon, 10 Mar 2014 09:50:11 -0700

> Lars Persson reported following deadlock :
 ...
> Bug occurs because __tcp_checksum_complete_user() enables BH, assuming
> it is running from softirq context.
> 
> Lars trace involved a NIC without RX checksum support but other points
> are problematic as well, like the prequeue stuff.
> 
> Problem is triggered by a timer, that found socket being owned by user.
> 
> tcp_release_cb() should call tcp_write_timer_handler() or
> tcp_delack_timer_handler() in the appropriate context :
> 
> BH disabled and socket lock held, but 'owned' field cleared,
> as if they were running from timer handlers.
> 
> Fixes: 6f458dfb4092 ("tcp: improve latencies of timer triggered events")
> Reported-by: Lars Persson <lars.persson@...s.com>
> Tested-by: Lars Persson <lars.persson@...s.com>
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

Applied and queued up for -stable, thanks!
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