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net: fix possible deadlock in sum_frag_mem_limit

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Dave Jones reported a lockdep splat occurring in IP defrag code.

commit 6d7b857d54 (net: use lib/percpu_counter API for
fragmentation mem accounting) added a possible deadlock.

Because percpu_counter_sum_positive() needs to acquire
a lock that can be used from softirq, we need to disable BH
in sum_frag_mem_limit()

Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2013-02-22 07:43:35 +00:00 committed by David S. Miller
parent e2f8d555ec
commit 4cfb04854d
1 changed files with 7 additions and 1 deletions
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8
include/net/inet_frag.h
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@ -114,7 +114,13 @@ static inline void init_frag_mem_limit(struct netns_frags *nf)
static inline int sum_frag_mem_limit(struct netns_frags *nf)
{
return percpu_counter_sum_positive(&nf->mem);
int res;
local_bh_disable();
res = percpu_counter_sum_positive(&nf->mem);
local_bh_enable();
return res;
}
static inline void inet_frag_lru_move(struct inet_frag_queue *q)