block: don't kick empty queue in blk_drain_queue()

[mirror_ubuntu-artful-kernel.git] / block / blk-core.c

diff --git a/block/blk-core.c b/block/blk-core.c
index 20d69f6beb6ba165cfa601aa176071bde3a10555..15de223c7f9371a9da852825ea8857789d94ae70 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -366,7 +366,14 @@ void blk_drain_queue(struct request_queue *q, bool drain_all)
                if (drain_all)
                        blk_throtl_drain(q);
 
-               __blk_run_queue(q);
+               /*
+                * This function might be called on a queue which failed
+                * driver init after queue creation.  Some drivers
+                * (e.g. fd) get unhappy in such cases.  Kick queue iff
+                * dispatch queue has something on it.
+                */
+               if (!list_empty(&q->queue_head))
+                       __blk_run_queue(q);
 
                if (drain_all)
                        nr_rqs = q->rq.count[0] + q->rq.count[1];