[PATCH 4.18 013/158] block: bfq: swap puts in bfqg_and_blkg_put

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

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

From: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>

commit d5274b3cd6a814ccb2f56d81ee87cbbf51bd4cf7 upstream.

Fix trivial use-after-free. This could be last reference to bfqg.

Fixes: 8f9bebc33dd7 ("block, bfq: access and cache blkg data only when safe")
Acked-by: Paolo Valente <paolo.valente@xxxxxxxxxx>
Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 block/bfq-cgroup.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -275,9 +275,9 @@ static void bfqg_and_blkg_get(struct bfq
 
 void bfqg_and_blkg_put(struct bfq_group *bfqg)
 {
-	bfqg_put(bfqg);
-
 	blkg_put(bfqg_to_blkg(bfqg));
+
+	bfqg_put(bfqg);
 }
 
 /* @stats = 0 */