linux-kernel - [PATCH] blk-mq: mark hctx RESTART when get budget fails

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Message-Id: <1523865336-17326-1-git-send-email-jianchao.w.wang@oracle.com>
Date:   Mon, 16 Apr 2018 15:55:36 +0800
From:   Jianchao Wang <jianchao.w.wang@...cle.com>
To:     axboe@...nel.dk, ming.lei@...hat.com
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] blk-mq: mark hctx RESTART when get budget fails

When get budget fails, blk_mq_sched_dispatch_requests does not do
anything to ensure the hctx to be restarted. We can survive from
this, because only the scsi implements .get_budget and it always
runs the hctx queues when request is completed.

Signed-off-by: Jianchao Wang <jianchao.w.wang@...cle.com>
---
 block/blk-mq-sched.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 25c14c5..49e7cd9 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -102,8 +102,10 @@ static void blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
 				!e->type->ops.mq.has_work(hctx))
 			break;
 
-		if (!blk_mq_get_dispatch_budget(hctx))
+		if (!blk_mq_get_dispatch_budget(hctx)) {
+			blk_mq_sched_mark_restart_hctx(hctx);
 			break;
+		}
 
 		rq = e->type->ops.mq.dispatch_request(hctx);
 		if (!rq) {
@@ -148,8 +150,10 @@ static void blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx)
 		if (!sbitmap_any_bit_set(&hctx->ctx_map))
 			break;
 
-		if (!blk_mq_get_dispatch_budget(hctx))
+		if (!blk_mq_get_dispatch_budget(hctx)) {
+			blk_mq_sched_mark_restart_hctx(hctx);
 			break;
+		}
 
 		rq = blk_mq_dequeue_from_ctx(hctx, ctx);
 		if (!rq) {
-- 
2.7.4