dm rq: clear kworker_task if kthread_run() returned an error

cleanup_mapped_device() calls kthread_stop() if kworker_task is
non-NULL.  Currently the assigned value could be a valid task struct or
an error code (e.g -ENOMEM).  Reset md->kworker_task to NULL if
kthread_run() returned an erorr.

Fixes: 7193a9defc ("dm rq: check kthread_run return for .request_fn request-based DM")
Cc: stable@vger.kernel.org # 4.8
Reported-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
index 5eacce1..63e43f2 100644 (file)
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -856,8 +856,11 @@ int dm_old_init_request_queue(struct mapped_device *md)
        init_kthread_worker(&md->kworker);
        md->kworker_task = kthread_run(kthread_worker_fn, &md->kworker,
                                       "kdmwork-%s", dm_device_name(md));
-       if (IS_ERR(md->kworker_task))
-               return PTR_ERR(md->kworker_task);
+       if (IS_ERR(md->kworker_task)) {
+               int error = PTR_ERR(md->kworker_task);
+               md->kworker_task = NULL;
+               return error;
+       }
 
        elv_register_queue(md->queue);