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dm thin: fix a race in thin_dtr

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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>
This commit is contained in:
Mikulas Patocka 2014-11-05 17:00:13 -05:00 committed by Mike Snitzer
parent d1d9220cba
commit 17181fb7a0
1 changed files with 3 additions and 3 deletions
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6
drivers/md/dm-thin.c
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@ -3622,14 +3622,14 @@ static void thin_dtr(struct dm_target *ti)
struct thin_c *tc = ti->private; struct thin_c *tc = ti->private;
unsigned long flags; unsigned long flags;
thin_put(tc);
wait_for_completion(&tc->can_destroy);
spin_lock_irqsave(&tc->pool->lock, flags); spin_lock_irqsave(&tc->pool->lock, flags);
list_del_rcu(&tc->list); list_del_rcu(&tc->list);
spin_unlock_irqrestore(&tc->pool->lock, flags); spin_unlock_irqrestore(&tc->pool->lock, flags);
synchronize_rcu(); synchronize_rcu();
thin_put(tc);
wait_for_completion(&tc->can_destroy);
mutex_lock(&dm_thin_pool_table.mutex); mutex_lock(&dm_thin_pool_table.mutex);
__pool_dec(tc->pool); __pool_dec(tc->pool);