linux-kernel - Re: [PATCH V2] mmc: block: Fix in_flight[issue

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Date:   Tue, 8 Aug 2023 12:52:39 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Yunlong Xing <yunlong.xing@...soc.com>
Cc:     adrian.hunter@...el.com, CLoehle@...erstone.com,
        brauner@...nel.org, hare@...e.de, asuk4.q@...il.com,
        avri.altman@....com, beanhuo@...ron.com, linus.walleij@...aro.org,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, hongyu.jin@...soc.com,
        zhiguo.niu@...soc.com, yunlong.xing23@...il.com,
        yibin.ding@...soc.com, dongliang.cui@...soc.com
Subject: Re: [PATCH V2] mmc: block: Fix in_flight[issue_type] value error

On Wed, 2 Aug 2023 at 04:33, Yunlong Xing <yunlong.xing@...soc.com> 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.
>
> Fixes: 81196976ed94 ("mmc: block: Add blk-mq support")
> Cc: stable@...r.kernel.org
> Signed-off-by: Yibin Ding <yibin.ding@...soc.com>
> Acked-by: Adrian Hunter <adrian.hunter@...el.com>

Applied for fixes, thanks!

Kind regards
Uffe


> ---
> changes of v2: Sort local declarations in descending order of
> line length
> ---
>  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..b6f4be25b31b 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);
>
> @@ -2117,6 +2117,7 @@ static void mmc_blk_mq_dec_in_flight(struct mmc_queue *mq, struct request *req)
>  static void mmc_blk_mq_post_req(struct mmc_queue *mq, struct request *req,
>                                 bool can_sleep)
>  {
> +       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;
> @@ -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)
> --
> 2.25.1
>