Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Thu, 16 Apr 2020 22:12:16 +0800
From:   Ming Lei <ming.lei@redhat.com>
To:     John Garry <john.garry@huawei.com>
Cc:     axboe@kernel.dk, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] blk-mq: Put driver tag in blk_mq_dispatch_rq_list() when
 no budget
Message-ID: <20200416141216.GA2907988@T590>
References: <1587035931-125028-1-git-send-email-john.garry@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1587035931-125028-1-git-send-email-john.garry@huawei.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, Apr 16, 2020 at 07:18:51PM +0800, John Garry wrote:
> If in blk_mq_dispatch_rq_list() we find no budget, then we break of the
> dispatch loop, but the request may keep the driver tag, evaulated
> in 'nxt' in the previous loop iteration.
> 
> Fix by putting the driver tag for that request.
> 
> Signed-off-by: John Garry <john.garry@huawei.com>
> 
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 8e56884fd2e9..a7785df2c944 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -1222,8 +1222,10 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
>  		rq = list_first_entry(list, struct request, queuelist);
>  
>  		hctx = rq->mq_hctx;
> -		if (!got_budget && !blk_mq_get_dispatch_budget(hctx))
> +		if (!got_budget && !blk_mq_get_dispatch_budget(hctx)) {
> +			blk_mq_put_driver_tag(rq);
>  			break;
> +		}
>  
>  		if (!blk_mq_get_driver_tag(rq)) {
>  			/*
> -- 
> 2.16.4
> 

Reviewed-by: Ming Lei <ming.lei@redhat.com>

-- 
Ming