From: Slava Pestov <sp@daterainc.com>
Date: Tue, 20 May 2014 19:20:28 +0000 (-0700)
Subject: bcache: fix crash on shutdown in passthrough mode
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=a664d0f05a2ec02c8f042db536d84d15d6e19e81;p=deliverable%2Flinux.git

bcache: fix crash on shutdown in passthrough mode

We never started the writeback thread in this case, so don't stop it.
---

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 09573c2bcb5d..6ceaec35b871 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1071,7 +1071,8 @@ static void cached_dev_free(struct closure *cl)
 	struct cached_dev *dc = container_of(cl, struct cached_dev, disk.cl);
 
 	cancel_delayed_work_sync(&dc->writeback_rate_update);
-	kthread_stop(dc->writeback_thread);
+	if (!IS_ERR_OR_NULL(dc->writeback_thread))
+		kthread_stop(dc->writeback_thread);
 
 	mutex_lock(&bch_register_lock);