From e1b207dac13ddb2f8ddebc7dc9729a97421909bd Mon Sep 17 00:00:00 2001
From: Jesper Dangaard Brouer <brouer@redhat.com>
Date: Mon, 3 Mar 2014 14:45:39 +0100
Subject: [PATCH] netfilter: avoid race with exp->master ct

Preparation for disconnecting the nf_conntrack_lock from the
expectations code.  Once the nf_conntrack_lock is lifted, a race
condition is exposed.

The expectations master conntrack exp->master, can race with
delete operations, as the refcnt increment happens too late in
init_conntrack().  Race is against other CPUs invoking
->destroy() (destroy_conntrack()), or nf_ct_delete() (via timeout
or early_drop()).

Avoid this race in nf_ct_find_expectation() by using atomic_inc_not_zero(),
and checking if nf_ct_is_dying() (path via nf_ct_delete()).

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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