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When replacing del_timer() with del_timer_sync(), I introduced

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a deadlock condition :

reqsk_queue_unlink() is called from inet_csk_reqsk_queue_drop()

inet_csk_reqsk_queue_drop() can be called from many contexts,
one being the timer handler itself (reqsk_timer_handler()).

In this case, del_timer_sync() loops forever.

Simple fix is to test if timer is pending.

Fixes: 2235f2ac75 ("inet: fix races with reqsk timers")
Signed-off-by: Eric Dumazet <edumazet@google.com>
This commit is contained in:
Eric Dumazet
2015-10-09 14:32:55 +01:00
committed by popcornmix
parent 499958c660
commit 74328c7da3
1 changed files with 1 additions and 1 deletions
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2
net/ipv4/inet_connection_sock.c
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@@ -584,7 +584,7 @@ static bool reqsk_queue_unlink(struct request_sock_queue *queue,
}
spin_unlock(&queue->syn_wait_lock);
if (del_timer_sync(&req->rsk_timer))
if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
reqsk_put(req);
return found;
}