Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next

[sfrench/cifs-2.6.git] / block / blk-mq-sched.c

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 40905539afed347ebb7882d7e02c824c096e16ce..74c6bb871f7e6e299d7180720f2de05f0460b5af 100644 (file)
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * blk-mq scheduling framework
  *
@@ -413,6 +414,14 @@ void blk_mq_sched_insert_requests(struct blk_mq_hw_ctx *hctx,
                                  struct list_head *list, bool run_queue_async)
 {
        struct elevator_queue *e;
+       struct request_queue *q = hctx->queue;
+
+       /*
+        * blk_mq_sched_insert_requests() is called from flush plug
+        * context only, and hold one usage counter to prevent queue
+        * from being released.
+        */
+       percpu_ref_get(&q->q_usage_counter);
 
        e = hctx->queue->elevator;
        if (e && e->type->ops.insert_requests)
@@ -423,13 +432,17 @@ void blk_mq_sched_insert_requests(struct blk_mq_hw_ctx *hctx,
                 * busy in case of 'none' scheduler, and this way may save
                 * us one extra enqueue & dequeue to sw queue.
                 */
-               if (!hctx->dispatch_busy && !e && !run_queue_async)
+               if (!hctx->dispatch_busy && !e && !run_queue_async) {
                        blk_mq_try_issue_list_directly(hctx, list);
-               else
-                       blk_mq_insert_requests(hctx, ctx, list);
+                       if (list_empty(list))
+                               goto out;
+               }
+               blk_mq_insert_requests(hctx, ctx, list);
        }
 
        blk_mq_run_hw_queue(hctx, run_queue_async);
+ out:
+       percpu_ref_put(&q->q_usage_counter);
 }
 
 static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set,