Merge tag 'dmaengine-fix-5.2-rc4' of git://git.infradead.org/users/vkoul/slave-dma

[linux.git] / block / blk-mq-sched.c

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index aa6bc5c0264388a549956c3f8acb57c1d144fb5f..500cb04901cc12906a8108c0795c5e3119e23d2c 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)
@@ -426,12 +435,14 @@ void blk_mq_sched_insert_requests(struct blk_mq_hw_ctx *hctx,
                if (!hctx->dispatch_busy && !e && !run_queue_async) {
                        blk_mq_try_issue_list_directly(hctx, list);
                        if (list_empty(list))
-                               return;
+                               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,
@@ -464,14 +475,18 @@ static int blk_mq_sched_alloc_tags(struct request_queue *q,
        return ret;
 }
 
+/* called in queue's release handler, tagset has gone away */
 static void blk_mq_sched_tags_teardown(struct request_queue *q)
 {
-       struct blk_mq_tag_set *set = q->tag_set;
        struct blk_mq_hw_ctx *hctx;
        int i;
 
-       queue_for_each_hw_ctx(q, hctx, i)
-               blk_mq_sched_free_tags(set, hctx, i);
+       queue_for_each_hw_ctx(q, hctx, i) {
+               if (hctx->sched_tags) {
+                       blk_mq_free_rq_map(hctx->sched_tags);
+                       hctx->sched_tags = NULL;
+               }
+       }
 }
 
 int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
@@ -512,6 +527,7 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
                        ret = e->ops.init_hctx(hctx, i);
                        if (ret) {
                                eq = q->elevator;
+                               blk_mq_sched_free_requests(q);
                                blk_mq_exit_sched(q, eq);
                                kobject_put(&eq->kobj);
                                return ret;
@@ -523,11 +539,30 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
        return 0;
 
 err:
+       blk_mq_sched_free_requests(q);
        blk_mq_sched_tags_teardown(q);
        q->elevator = NULL;
        return ret;
 }
 
+/*
+ * called in either blk_queue_cleanup or elevator_switch, tagset
+ * is required for freeing requests
+ */
+void blk_mq_sched_free_requests(struct request_queue *q)
+{
+       struct blk_mq_hw_ctx *hctx;
+       int i;
+
+       lockdep_assert_held(&q->sysfs_lock);
+       WARN_ON(!q->elevator);
+
+       queue_for_each_hw_ctx(q, hctx, i) {
+               if (hctx->sched_tags)
+                       blk_mq_free_rqs(q->tag_set, hctx->sched_tags, i);
+       }
+}
+
 void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e)
 {
        struct blk_mq_hw_ctx *hctx;