Re: [PATCH v2] mmc: core: don't initialize block size from ext_csd if not present

[Adrian Hunter <adrian.hunter@intel.com>]

On 14/01/21 10:14 pm, Peter Collingbourne wrote:
> If extended CSD was not available, the eMMC driver would incorrectly
> set the block size to 0, as the data_sector_size field of ext_csd
> was never initialized. This issue was exposed by commit 817046ecddbc
> ("block: Align max_hw_sectors to logical blocksize") which caused
> max_sectors and max_hw_sectors to be set to 0 after setting the block
> size to 0, resulting in a kernel panic in bio_split when attempting
> to read from the device. Fix it by only reading the block size from
> ext_csd if it is available.
> 
> Fixes: a5075eb94837 ("mmc: block: Allow disabling 512B sector size emulation")
> Signed-off-by: Peter Collingbourne <pcc@google.com>
> Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
> Link: https://linux-review.googlesource.com/id/If244d178da4d86b52034459438fec295b02d6e60

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

> ---
>  drivers/mmc/core/queue.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
> index de7cb0369c30..002426e3cf76 100644
> --- a/drivers/mmc/core/queue.c
> +++ b/drivers/mmc/core/queue.c
> @@ -384,8 +384,10 @@ static void mmc_setup_queue(struct mmc_queue *mq, struct mmc_card *card)
>  		     "merging was advertised but not possible");
>  	blk_queue_max_segments(mq->queue, mmc_get_max_segments(host));
>  
> -	if (mmc_card_mmc(card))
> +	if (mmc_card_mmc(card) && card->ext_csd.data_sector_size) {
>  		block_size = card->ext_csd.data_sector_size;
> +		WARN_ON(block_size != 512 && block_size != 4096);
> +	}
>  
>  	blk_queue_logical_block_size(mq->queue, block_size);
>  	/*
>