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 09573c2bcb5d30bc15c15a32f1fcb5653db3e07f..6ceaec35b8719152d3decdb3e7a0da3bfdcb029e 100644 (file)
--- 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);