Re: [PATCHv4 1/2] mmc: block: Remove error check of hw_reset on reset

Adrian Hunter
2022-10-13T10:38:34Z

On 12/10/22 21:37, Christian Löhle wrote:
> Before switching back to the right partition in mmc_blk_reset there used
> to be a check if hw_reset was even supported. This return value
> was removed, so there is no reason to check. Furthermore ensure
> part_curr is not falsely set to a valid value on reset or
> partition switch error.
>
> As part of this change the code paths of mmc_blk_reset calls were checked
> to ensure no commands are issued after a failed mmc_blk_reset directly
> without going through the block layer.
>
> Fixes: fefdd3c91e0a ("mmc: core: Drop superfluous validations in mmc_hw|sw_reset()")
> Cc: stable@vger.kernel.org
>
> Signed-off-by: Christian Loehle <cloehle@hyperstone.com>

One minor comment, otherwise:

Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>

> ---
> -v4: Only partition switch if necessary and fix one mmc_blk_reset call
> -v3: Ensure invalid part_curr on error
> -v2: Do not attempt to switch partitions if reset failed
>
> drivers/mmc/core/block.c | 42 ++++++++++++++++++++++++----------------
> 1 file changed, 25 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index ce89611a136e..2619cc47b97c 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -134,6 +134,7 @@ struct mmc_blk_data {
> * track of the current selected device partition.
> */
> unsigned int part_curr;
> +#define MMC_BLK_PART_INVALID UINT_MAX /* Unknown partition active */
> int area_type;
>
> /* debugfs files (only in main mmc_blk_data) */
> @@ -987,33 +988,39 @@ static unsigned int mmc_blk_data_timeout_ms(struct mmc_host *host,
> return ms;
> }
>
> +/*
> + * Attempts to reset the card and get back to the requested partition.
> + * Therefore any error here must result in cancelling the block layer
> + * request, it must not be reattempted without going through the mmc_blk
> + * partition sanity checks.
> + */
> static int mmc_blk_reset(struct mmc_blk_data *md, struct mmc_host *host,
> int type)
> {
> int err;
> + struct mmc_blk_data *main_md = dev_get_drvdata(&host->card->dev);
>
> if (md->reset_done & type)
> return -EEXIST;
>
> md->reset_done |= type;
> err = mmc_hw_reset(host->card);
> + /*
> + * A successful reset will leave the card in the main partition, but
> + * upon failure it might not be, so set it to MMC_BLK_PART_INVALID
> + * in that case.
> + */
> + main_md->part_curr = err ? MMC_BLK_PART_INVALID : main_md->part_type;
> + if (err)
> + return err;
> /* Ensure we switch back to the correct partition */
> - if (err) {
> - struct mmc_blk_data *main_md =
> - dev_get_drvdata(&host->card->dev);
> - int part_err;
> -
> - main_md->part_curr = main_md->part_type;
> - part_err = mmc_blk_part_switch(host->card, md->part_type);
> - if (part_err) {
> - /*
> - * We have failed to get back into the correct
> - * partition, so we need to abort the whole request.
> - */
> - return -ENODEV;
> - }
> - }
> - return err;
> + if (mmc_blk_part_switch(host->card, md->part_type))
> + /*
> + * We have failed to get back into the correct
> + * partition, so we need to abort the whole request.
> + */
> + return -ENODEV;
> + return 0;
> }
>
> static inline void mmc_blk_reset_success(struct mmc_blk_data *md, int type)
> @@ -1868,7 +1875,8 @@ static void mmc_blk_mq_rw_recovery(struct mmc_queue *mq, struct request *req)
>
> /* Reset before last retry */
> if (mqrq->retries + 1 == MMC_MAX_RETRIES)
> - mmc_blk_reset(md, card->host, type);
> + if (mmc_blk_reset(md, card->host, type))

Kernel style is to avoid nested "if" statements, so it should be like this:

if (mqrq->retries + 1 == MMC_MAX_RETRIES &&
mmc_blk_reset(md, card->host, type)
return;

> + return;
>
> /* Command errors fail fast, so use all MMC_MAX_RETRIES */
> if (brq->sbc.error || brq->cmd.error)