[PATCH for stable branch 3.16.y] block: fix wrong error return in elevator_init()

From: Dinesh K B
Date: Sat May 06 2017 - 07:22:08 EST

3.16.y review patch. Please let me know if anybody has objections.

commit d32f6b57523b6e9b2e39e990e056f9882a6f099a
From: Sudip Mukherjee <sudipm.mukherjee@xxxxxxxxx>
Date: Thu, 23 Oct 2014 22:16:48 +0530
Subject: block: fix wrong error return in elevator_init()

while compiling integer err was showing as a set but unused variable.
elevator_init_fn can be either cfq_init_queue or deadline_init_queue
or noop_init_queue.
all three of these functions are returning -ENOMEM if they fail to
allocate the queue.
so we should actually be returning the error code rather than
returning 0 always.

Signed-off-by: Sudip Mukherjee <sudip@xxxxxxxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxx>

Backported to 3.16.y as is.
Signed-off-by: Dinesh K B <dineshkumarb@xxxxxxxxx>
block/elevator.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/block/elevator.c b/block/elevator.c
index 24c28b6..afa3b03 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -229,7 +229,9 @@ int elevator_init(struct request_queue *q, char *name)

err = e->ops.elevator_init_fn(q, e);
- return 0;
+ if (err)
+ elevator_put(e);
+ return err;