From: Harald Welte <laforge@netfilter.org>
Date: Mon, 30 May 2005 22:35:26 +0000 (-0700)
Subject: [NETFILTER]: Fix deadlock with ip_queue and tcp local input path.
X-Git-Tag: v2.6.12-rc6~33^2~5
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9bb7bc942d3da606f184ac6a4dfc7e4d470c831b;p=pandora-kernel.git

[NETFILTER]: Fix deadlock with ip_queue and tcp local input path.

When we have ip_queue being used from LOCAL_IN, then we end up with a
situation where the verdicts coming back from userspace traverse the TCP
input path from syscall context.  While this seems to work most of the
time, there's an ugly deadlock:

syscall context is interrupted by the timer interrupt.  When the timer
interrupt leaves, the timer softirq get's scheduled and calls
tcp_delack_timer() and alike.  They themselves do bh_lock_sock(sk),
which is already held from somewhere else -> boom.

I've now tested the suggested solution by Patrick McHardy and Herbert Xu to
simply use local_bh_{en,dis}able().

Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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