On 4 August 2017 at 04:51, Shawn Lin <shawn.lin@xxxxxxxxxxxxxx> wrote:
> The intention for this patch is to help folks debug the failure
> like this:
>
> dwmmc_rockchip fe320000.dwmmc: IDMAC supports 32-bit address mode.
> dwmmc_rockchip fe320000.dwmmc: Using internal DMA controller.
> dwmmc_rockchip fe320000.dwmmc: Version ID is 270a
> dwmmc_rockchip fe320000.dwmmc: DW MMC controller at irq 28,32 bit
> host data width,256 deep fifo
> dwmmc_rockchip fe320000.dwmmc: Got CD GPIO
> mmc_host mmc0: Bus speed (slot 0) = 400000Hz (slot req 400000Hz, actual
> 400000HZ div = 0)
> mmc_host mmc0: Bus speed (slot 0) = 50000000Hz (slot req 50000000Hz,
> actual 50000000HZ div = 0)
> mmc0: new high speed SDHC card at address 0007
> mmcblk: probe of mmc0:0007 failed with error -28
>
> It's quite annoying that some buggy userspace deamon miss the disk remove
> uevent sometimes so it would finally make the SD card not work. So from
> the dmesg it only shows a errno of -28 but still don't understand what
> happened.
>
> For quick reproduce this, we could set max_devices to 8 and run
>
> for i in $(seq 1 9); do
> echo "========================" $i
> echo fe320000.dwmmc > /sys/bus/platform/drivers/dwmmc_rockchip/unbind
> sleep .5
> echo fe320000.dwmmc > /sys/bus/platform/drivers/dwmmc_rockchip/bind
> sleep .5
> mount -t vfat /dev/mmcblk0 /mnt
> sleep .5
> done
>
> Signed-off-by: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>
> ---
>
> drivers/mmc/core/block.c | 18 +++++++++++++++++-
> 1 file changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index a11bead..3ede32a 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -1985,8 +1985,24 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct mmc_card *card,
> int devidx, ret;
>
> devidx = ida_simple_get(&mmc_blk_ida, 0, max_devices, GFP_KERNEL);
> - if (devidx < 0)
> + if (devidx < 0) {
> + /*
> + * The reason for why we could get -ENOSPC here for
> + * removable devices is that probably userspace mount
> + * the partition but forget to umount it which makes
> + * it fail to release md->usage via mmc_blk_release,
> + * so as a result it leaks the device ID and finally
> + * breaks the reference counting for mmc block layer.
> + * It's uerspace's responsibility to guarantee it but
> + * we could cast an explcit error log here to clarify
> + * the situation.
> + */
I would re-phrase the above to something like this:
"We get -ENOSPC because there are no more any available devidx. The
reason may be that userspace haven't yet unmounted the partitions,
which postpones mmc_blk_release() from being called."
> + if (mmc_card_is_removable(card->host) && devidx == -ENOSPC)
Why not print this error for all type of cards, it seems like relevant
information for the user.
> + dev_err(mmc_dev(card->host),
> + "possible unblanced mount/umount detected\n");
> +
> return ERR_PTR(devidx);
> + }
>
> md = kzalloc(sizeof(struct mmc_blk_data), GFP_KERNEL);
> if (!md) {
> --
> 1.9.1
Kind regards
Uffe
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