| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.18 30/84] dm thin: fix a race in thin_dtr | Date | Tue, 6 Jan 2015 17:49:33 -0800 |
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3.18-stable review patch. If anyone has any objections, please let me know.
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From: Mikulas Patocka <mpatocka@redhat.com>
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 <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/md/dm-thin.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -3266,14 +3266,14 @@ static void thin_dtr(struct dm_target *t 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);
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