[RFC][PATCH 4/5] mm/zpool: allow NULL `zpool' pointer in zpool_destroy_pool()

[Sergey Senozhatsky]

zpool_destroy_pool() does not tolerate a NULL zpool pointer
argument and performs a NULL-pointer dereference. Although
there is only one zpool_destroy_pool() user (as of 4.1),
still update it to be coherent with the corresponding
destroy() functions of the remainig pool-allocators (slab,
mempool, etc.), which now allow NULL pool-pointers.

For consistency, tweak zpool_destroy_pool() and NULL-check the
pointer there.

Proposed by Andrew Morton.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Reported-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
LKML-reference: https://lkml.org/lkml/2015/6/8/583
---
 mm/zpool.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/zpool.c b/mm/zpool.c
index bacdab6..2f59b90 100644
--- a/mm/zpool.c
+++ b/mm/zpool.c
@@ -202,6 +202,9 @@ struct zpool *zpool_create_pool(char *type, char *name, gfp_t gfp,
  */
 void zpool_destroy_pool(struct zpool *zpool)
 {
+	if (unlikely(!zpool))
+		return;
+
 	pr_info("destroying pool type %s\n", zpool->type);
 
 	spin_lock(&pools_lock);
-- 
2.4.3.368.g7974889

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