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-rw-r--r--block/blk-mq-sched.c15
1 files changed, 12 insertions, 3 deletions
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 4ee7cb043812..9e8d6795a8c1 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -175,6 +175,8 @@ void blk_mq_sched_put_request(struct request *rq)
void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
{
struct elevator_queue *e = hctx->queue->elevator;
+ const bool has_sched_dispatch = e && e->type->ops.mq.dispatch_request;
+ bool did_work = false;
LIST_HEAD(rq_list);
if (unlikely(blk_mq_hctx_stopped(hctx)))
@@ -204,11 +206,18 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
*/
if (!list_empty(&rq_list)) {
blk_mq_sched_mark_restart(hctx);
- blk_mq_dispatch_rq_list(hctx, &rq_list);
- } else if (!e || !e->type->ops.mq.dispatch_request) {
+ did_work = blk_mq_dispatch_rq_list(hctx, &rq_list);
+ } else if (!has_sched_dispatch) {
blk_mq_flush_busy_ctxs(hctx, &rq_list);
blk_mq_dispatch_rq_list(hctx, &rq_list);
- } else {
+ }
+
+ /*
+ * We want to dispatch from the scheduler if we had no work left
+ * on the dispatch list, OR if we did have work but weren't able
+ * to make progress.
+ */
+ if (!did_work && has_sched_dispatch) {
do {
struct request *rq;