linux-kernel - [PATCH] blk-mq: set BLK_MQ_S_STOPPED first to avoid unexpected queue work

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Date:   Wed, 29 Jun 2022 13:18:20 +0800
From:   Liu Song <liusong@...ux.alibaba.com>
To:     axboe@...nel.dk
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] blk-mq: set BLK_MQ_S_STOPPED first to avoid unexpected queue work

From: Liu Song <liusong@...ux.alibaba.com>

In "__blk_mq_delay_run_hw_queue", BLK_MQ_S_STOPPED is checked first,
and then queue work, but in "blk_mq_stop_hw_queue", execute cancel
work first and then set BLK_MQ_S_STOPPED, so there is a risk of
queue work after setting BLK_MQ_S_STOPPED, which can be solved by
adjusting the order.

Signed-off-by: Liu Song <liusong@...ux.alibaba.com>
---
 block/blk-mq.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 93d9d60..865915e 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2258,9 +2258,9 @@ bool blk_mq_queue_stopped(struct request_queue *q)
  */
 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
 {
-	cancel_delayed_work(&hctx->run_work);
-
 	set_bit(BLK_MQ_S_STOPPED, &hctx->state);
+
+	cancel_delayed_work(&hctx->run_work);
 }
 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
 
-- 
1.8.3.1