mmc: block: fix read single on recovery logic

On reads with MMC_READ_MULTIPLE_BLOCK that fail,
the recovery handler will use MMC_READ_SINGLE_BLOCK for
each of the blocks, up to MMC_READ_SINGLE_RETRIES times each.
The logic for this is fixed to never report unsuccessful reads
as success to the block layer.

On command error with retries remaining, blk_update_request was
called with whatever value error was set last to.
In case it was last set to BLK_STS_OK (default), the read will be
reported as success, even though there was no data read from the device.
This could happen on a CRC mismatch for the response,
a card rejecting the command (e.g. again due to a CRC mismatch).
In case it was last set to BLK_STS_IOERR, the error is reported correctly,
but no retries will be attempted.

The patch now will count both command and data errors as retries and
send BLK_STS_IOERR if there are no retries remaining,
or BLK_STS_OK if the single read was successful in the meantime.

Signed-off-by: Christian Loehle <cloehle@hyperstone.com>
---
 drivers/mmc/core/block.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

+ Adrian

On Thu, 3 Feb 2022 at 11:09, Christian Löhle <CLoehle@hyperstone.com> wrote:
>
> So could anyone take a long at this so far?
>

Thanks for pinging. Apologize for the delay, it's on top of my "to-review" list.

I have added Adrian too, who knows this code very well too.

Kind regards
Uffe

>
>
> From: Christian Löhle
> Sent: Wednesday, January 5, 2022 5:43 PM
> To: ulf.hansson@linaro.org; Christian Löhle; linux-mmc@vger.kernel.org; linux-kernel@vger.kernel.org
> Cc: Avri Altman
> Subject: [PATCH] mmc: block: fix read single on recovery logic
>
> On reads with MMC_READ_MULTIPLE_BLOCK that fail,
> the recovery handler will use MMC_READ_SINGLE_BLOCK for
> each of the blocks, up to MMC_READ_SINGLE_RETRIES times each.
> The logic for this is fixed to never report unsuccessful reads
> as success to the block layer.
>
> On command error with retries remaining, blk_update_request was
> called with whatever value error was set last to.
> In case it was last set to BLK_STS_OK (default), the read will be
> reported as success, even though there was no data read from the device.
> This could happen on a CRC mismatch for the response,
> a card rejecting the command (e.g. again due to a CRC mismatch).
> In case it was last set to BLK_STS_IOERR, the error is reported correctly,
> but no retries will be attempted.
>
> The patch now will count both command and data errors as retries and
> send BLK_STS_IOERR if there are no retries remaining,
> or BLK_STS_OK if the single read was successful in the meantime.
>
> Signed-off-by: Christian Loehle <cloehle@hyperstone.com>
> ---
>  drivers/mmc/core/block.c | 28 ++++++++++++++--------------
>  1 file changed, 14 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index 90e1bcd03b46..d7d880ce0f8a 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -1682,31 +1682,31 @@ static void mmc_blk_read_single(struct mmc_queue *mq, struct request *req)
>          struct mmc_card *card = mq->card;
>          struct mmc_host *host = card->host;
>          blk_status_t error = BLK_STS_OK;
> -       int retries = 0;
>
>          do {
>                  u32 status;
>                  int err;
> +               int retries = 0;
>
> -               mmc_blk_rw_rq_prep(mqrq, card, 1, mq);
> +               while (retries++ < MMC_READ_SINGLE_RETRIES) {
> +                       mmc_blk_rw_rq_prep(mqrq, card, 1, mq);
>
> -               mmc_wait_for_req(host, mrq);
> +                       mmc_wait_for_req(host, mrq);
>
> -               err = mmc_send_status(card, &status);
> -               if (err)
> -                       goto error_exit;
> -
> -               if (!mmc_host_is_spi(host) &&
> -                   !mmc_ready_for_data(status)) {
> -                       err = mmc_blk_fix_state(card, req);
> +                       err = mmc_send_status(card, &status);
>                          if (err)
>                                  goto error_exit;
> -               }
>
> -               if (mrq->cmd->error && retries++ < MMC_READ_SINGLE_RETRIES)
> -                       continue;
> +                       if (!mmc_host_is_spi(host) &&
> +                           !mmc_ready_for_data(status)) {
> +                               err = mmc_blk_fix_state(card, req);
> +                               if (err)
> +                                       goto error_exit;
> +                       }
>
> -               retries = 0;
> +                       if (!mrq->cmd->error && !mrq->data->error)
> +                               break;
> +               }
>
>                  if (mrq->cmd->error ||
>                      mrq->data->error ||
> --
> 2.34.1
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