linux-kernel - Re: [PATCH] mmc: dw_mmc: Only inject fault before done/error

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Date:   Mon, 6 Sep 2021 19:09:08 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Vincent Whitchurch <vincent.whitchurch@...s.com>
Cc:     Jaehoon Chung <jh80.chung@...sung.com>, kernel <kernel@...s.com>,
        linux-mmc <linux-mmc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mmc: dw_mmc: Only inject fault before done/error

On Wed, 25 Aug 2021 at 13:42, Vincent Whitchurch
<vincent.whitchurch@...s.com> wrote:
>
> The fault injection function can set EVENT_DATA_ERROR but skip the
> setting of ->data_status to an error status if it hits just after a data
> over interrupt.  This confuses the tasklet which can later end up
> triggering the WARN_ON(host->cmd || ..) in dw_mci_request_end() since
> dw_mci_data_complete() would return success.
>
> Prevent the fault injection function from doing this since this is not a
> real case, and ensure that the fault injection doesn't race with a real
> error either.
>
> Signed-off-by: Vincent Whitchurch <vincent.whitchurch@...s.com>

Applied for fixes and by adding a fixes tag, thanks!

Kind regards
Uffe


> ---
>  drivers/mmc/host/dw_mmc.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 6578cc64ae9e..380f9aa56eb2 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -1802,10 +1802,15 @@ static enum hrtimer_restart dw_mci_fault_timer(struct hrtimer *t)
>
>         spin_lock_irqsave(&host->irq_lock, flags);
>
> -       if (!host->data_status)
> +       /*
> +        * Only inject an error if we haven't already got an error or data over
> +        * interrupt.
> +        */
> +       if (!host->data_status) {
>                 host->data_status = SDMMC_INT_DCRC;
> -       set_bit(EVENT_DATA_ERROR, &host->pending_events);
> -       tasklet_schedule(&host->tasklet);
> +               set_bit(EVENT_DATA_ERROR, &host->pending_events);
> +               tasklet_schedule(&host->tasklet);
> +       }
>
>         spin_unlock_irqrestore(&host->irq_lock, flags);
>
> @@ -2721,12 +2726,16 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)
>                 }
>
>                 if (pending & DW_MCI_DATA_ERROR_FLAGS) {
> +                       spin_lock(&host->irq_lock);
> +
>                         /* if there is an error report DATA_ERROR */
>                         mci_writel(host, RINTSTS, DW_MCI_DATA_ERROR_FLAGS);
>                         host->data_status = pending;
>                         smp_wmb(); /* drain writebuffer */
>                         set_bit(EVENT_DATA_ERROR, &host->pending_events);
>                         tasklet_schedule(&host->tasklet);
> +
> +                       spin_unlock(&host->irq_lock);
>                 }
>
>                 if (pending & SDMMC_INT_DATA_OVER) {
> --
> 2.28.0
>