From ec08e40bf044261a26ab53602d8a8c96a285da88 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 5 Nov 2014 17:00:13 -0500 Subject: [PATCH] dm thin: fix a race in thin_dtr commit 17181fb7a0c3a279196c0eeb2caba65a1519614b upstream. As long as struct thin_c is in the list, anyone can grab a reference of it. Consequently, we must wait for the reference count to drop to zero *after* we remove the structure from the list, not before. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer Signed-off-by: Luis Henriques --- drivers/md/dm-thin.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index df898e0db419..6f75083a81cc 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -3183,14 +3183,14 @@ static void thin_dtr(struct dm_target *ti) struct thin_c *tc = ti->private; unsigned long flags; - thin_put(tc); - wait_for_completion(&tc->can_destroy); - spin_lock_irqsave(&tc->pool->lock, flags); list_del_rcu(&tc->list); spin_unlock_irqrestore(&tc->pool->lock, flags); synchronize_rcu(); + thin_put(tc); + wait_for_completion(&tc->can_destroy); + mutex_lock(&dm_thin_pool_table.mutex); __pool_dec(tc->pool);