On Wed, Jan 13, 2021 at 10:11 PM Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
>
> On 13/01/21 9:46 pm, Peter Collingbourne wrote:
> > On Wed, Jan 13, 2021 at 2:43 AM Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
> >>
> >> On 12/01/21 11:09 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: 817046ecddbc ("block: Align max_hw_sectors to logical blocksize")
> >>
> >> I would go with the original commit i.e.
> >>
> >> Fixes: a5075eb94837 ("mmc: block: Allow disabling 512B sector size emulation")
> >
> > Sure, makes sense.
> >
> >>> Signed-off-by: Peter Collingbourne <pcc@xxxxxxxxxx>
> >>> Link: https://linux-review.googlesource.com/id/If244d178da4d86b52034459438fec295b02d6e60
> >>> ---
> >>> drivers/mmc/core/queue.c | 3 ++-
> >>> 1 file changed, 2 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
> >>> index de7cb0369c30..735cdbf1145c 100644
> >>> --- a/drivers/mmc/core/queue.c
> >>> +++ b/drivers/mmc/core/queue.c
> >>> @@ -20,6 +20,7 @@
> >>> #include "core.h"
> >>> #include "card.h"
> >>> #include "host.h"
> >>> +#include "mmc_ops.h"
> >>>
> >>> #define MMC_DMA_MAP_MERGE_SEGMENTS 512
> >>>
> >>> @@ -384,7 +385,7 @@ 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) && mmc_can_ext_csd(card))
> >>> block_size = card->ext_csd.data_sector_size;
> >>
> >> Might as well be:
> >>
> >> if (mmc_card_mmc(card) && card->ext_csd.data_sector_size)
> >> block_size = card->ext_csd.data_sector_size;
> >
> > Can we rely on this data structure to be zero initialized? I suppose
> > so, provided that it was allocated with mmc_alloc_card which uses
> > kzalloc. But it isn't entirely obvious and I figure it may be a little
> > better to be explicit in our intent here. But either way works for me.
>
> The only valid values are 512 and 4096, so you could add WARN_ON(block_size
> != 512 && block_size != 4096) if you want.
Okay, I did that in v2.
Peter
