[PATCH 4.4 070/104] loop: Fix double mutex_unlock(&loop_ctl_mutex) in loop_control_ioctl()

[Greg Kroah-Hartman]

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

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

From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>

commit 628bd85947091830a8c4872adfd5ed1d515a9cf2 upstream.

Commit 0a42e99b58a20883 ("loop: Get rid of loop_index_mutex") forgot to
remove mutex_unlock(&loop_ctl_mutex) from loop_control_ioctl() when
replacing loop_index_mutex with loop_ctl_mutex.

Fixes: 0a42e99b58a20883 ("loop: Get rid of loop_index_mutex")
Reported-by: syzbot <syzbot+c0138741c2290fc5e63f@xxxxxxxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/block/loop.c |    2 --
 1 file changed, 2 deletions(-)

--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1936,12 +1936,10 @@ static long loop_control_ioctl(struct fi
 			break;
 		if (lo->lo_state != Lo_unbound) {
 			ret = -EBUSY;
-			mutex_unlock(&loop_ctl_mutex);
 			break;
 		}
 		if (atomic_read(&lo->lo_refcnt) > 0) {
 			ret = -EBUSY;
-			mutex_unlock(&loop_ctl_mutex);
 			break;
 		}
 		lo->lo_disk->private_data = NULL;