linux-kernel - Re: [PATCH] mmc: block: Fix in_flight[issue

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Date:   Tue, 1 Aug 2023 19:48:44 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Yunlong Xing <yunlong.xing@...soc.com>, CLoehle@...erstone.com,
        hare@...e.de, jinpu.wang@...os.com, asuk4.q@...il.com,
        avri.altman@....com, f.fainelli@...il.com
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        hongyu.jin@...soc.com, zhiguo.niu@...soc.com,
        yunlong.xing23@...il.com, Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH] mmc: block: Fix in_flight[issue_type] value error

On 1/08/23 11:13, Yunlong Xing wrote:
> From: Yibin Ding <yibin.ding@...soc.com>
> 
> For a completed request, after the mmc_blk_mq_complete_rq(mq, req)
> function is executed, the bitmap_tags corresponding to the
> request will be cleared, that is, the request will be regarded as
> idle. If the request is acquired by a different type of process at
> this time, the issue_type of the request may change. It further
> caused the value of mq->in_flight[issue_type] to be abnormal,
> and a large number of requests could not be sent.
> 
> p1:					      p2:
> mmc_blk_mq_complete_rq
>   blk_mq_free_request
> 					      blk_mq_get_request
> 					        blk_mq_rq_ctx_init
> mmc_blk_mq_dec_in_flight
>   mmc_issue_type(mq, req)
> 
> This strategy can ensure the consistency of issue_type
> before and after executing mmc_blk_mq_complete_rq.
> 
> Signed-off-by: Yibin Ding <yibin.ding@...soc.com>

One cosmetic comment below, otherwise:

Fixes: 81196976ed94 ("mmc: block: Add blk-mq support")
Cc: stable@...r.kernel.org
Acked-by: Adrian Hunter <adrian.hunter@...el.com>

Thank you!

> ---
>  drivers/mmc/core/block.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index f701efb1fa78..5b750311f638 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -2097,14 +2097,14 @@ static void mmc_blk_mq_poll_completion(struct mmc_queue *mq,
>  	mmc_blk_urgent_bkops(mq, mqrq);
>  }
>  
> -static void mmc_blk_mq_dec_in_flight(struct mmc_queue *mq, struct request *req)
> +static void mmc_blk_mq_dec_in_flight(struct mmc_queue *mq, enum mmc_issue_type issue_type)
>  {
>  	unsigned long flags;
>  	bool put_card;
>  
>  	spin_lock_irqsave(&mq->lock, flags);
>  
> -	mq->in_flight[mmc_issue_type(mq, req)] -= 1;
> +	mq->in_flight[issue_type] -= 1;
>  
>  	put_card = (mmc_tot_in_flight(mq) == 0);
>  
> @@ -2120,6 +2120,7 @@ static void mmc_blk_mq_post_req(struct mmc_queue *mq, struct request *req,
>  	struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
>  	struct mmc_request *mrq = &mqrq->brq.mrq;
>  	struct mmc_host *host = mq->card->host;
> +	enum mmc_issue_type issue_type = mmc_issue_type(mq, req);

It looks slightly neater to put the local declarations in
descending order of line length if possible e.g.

+	enum mmc_issue_type issue_type = mmc_issue_type(mq, req);
	struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
	struct mmc_request *mrq = &mqrq->brq.mrq;
	struct mmc_host *host = mq->card->host;

>  
>  	mmc_post_req(host, mrq, 0);
>  
> @@ -2136,7 +2137,7 @@ static void mmc_blk_mq_post_req(struct mmc_queue *mq, struct request *req,
>  			blk_mq_complete_request(req);
>  	}
>  
> -	mmc_blk_mq_dec_in_flight(mq, req);
> +	mmc_blk_mq_dec_in_flight(mq, issue_type);
>  }
>  
>  void mmc_blk_mq_recovery(struct mmc_queue *mq)