linux-kernel - Re: [PATCH] blk-mq-sched: Remove redundant code in blk_mq_sched_mark_restart

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Message-Id: <1cf65d49-995a-462a-b355-cd28c093592c@fnnas.com>
Date: Fri, 16 Jan 2026 15:32:00 +0800
From: "Yu Kuai" <yukuai@...as.com>
To: "Chaohai Chen" <wdhh6@...yun.com>, <axboe@...nel.dk>, 
	<linux-block@...r.kernel.org>, <linux-kernel@...r.kernel.org>, 
	<yukuai@...as.com>
Subject: Re: [PATCH] blk-mq-sched: Remove redundant code in blk_mq_sched_mark_restart_hctx().

Hi,

在 2026/1/16 14:19, Chaohai Chen 写道:
> The current purpose of the blk_mq_sched_mark_restart_hctx() function
> is to set the BLK_MQ_S_SCHED_RESTART flag in hctx->state. Just remove
> the redundant judgement.

I don't think this is just redundant. This function is called from IO hot path,
and test_bit() should have less performance overhead than set_bit() if the
state is already set.

>
> Signed-off-by: Chaohai Chen <wdhh6@...yun.com>
> ---
>   block/blk-mq-sched.c | 3 ---
>   1 file changed, 3 deletions(-)
>
> diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
> index e26898128a7e..2f6c353cb6d0 100644
> --- a/block/blk-mq-sched.c
> +++ b/block/blk-mq-sched.c
> @@ -21,9 +21,6 @@
>    */
>   void blk_mq_sched_mark_restart_hctx(struct blk_mq_hw_ctx *hctx)
>   {
> -	if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
> -		return;
> -
>   	set_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
>   }
>   EXPORT_SYMBOL_GPL(blk_mq_sched_mark_restart_hctx);

-- 
Thansk,
Kuai