[PATCH 3.16 306/328] dm cache: destroy migration_cache if cache target registration failed

[Ben Hutchings]

3.16.62-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Shenghui Wang <shhuiw@xxxxxxxxxxx>

commit c7cd55504a5b0fc826a2cd9540845979d24ae542 upstream.

Commit 7e6358d244e47 ("dm: fix various targets to dm_register_target
after module __init resources created") inadvertently introduced this
bug when it moved dm_register_target() after the call to KMEM_CACHE().

Fixes: 7e6358d244e47 ("dm: fix various targets to dm_register_target after module __init resources created")
Signed-off-by: Shenghui Wang <shhuiw@xxxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/md/dm-cache-target.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -3109,14 +3109,13 @@ static int __init dm_cache_init(void)
 	int r;
 
 	migration_cache = KMEM_CACHE(dm_cache_migration, 0);
-	if (!migration_cache) {
-		dm_unregister_target(&cache_target);
+	if (!migration_cache)
 		return -ENOMEM;
-	}
 
 	r = dm_register_target(&cache_target);
 	if (r) {
 		DMERR("cache target registration failed: %d", r);
+		kmem_cache_destroy(migration_cache);
 		return r;
 	}