Re: [PATCH v4] mmc: core: Return correct emmc response in case of ioctl error

[Ulf Hansson]

On Tue, 24 Aug 2021 at 21:17, Nishad Kamdar <nishadkamdar@xxxxxxxxx> wrote:
>
> When a read/write command is sent via ioctl to the kernel,
> and the command fails, the actual error response of the emmc
> is not sent to the user.
>
> IOCTL read/write tests are carried out using commands
> 17 (Single BLock Read), 24 (Single Block Write),
> 18 (Multi Block Read), 25 (Multi Block Write)
>
> The tests are carried out on a 64Gb emmc device. All of these
> tests try to access an "out of range" sector address (0x09B2FFFF).
>
> It is seen that without the patch the response received by the user
> is not OUT_OF_RANGE error (R1 response 31st bit is not set) as per
> JEDEC specification. After applying the patch proper response is seen.
> This is because the function returns without copying the response to
> the user in case of failure. This patch fixes the issue.
>
> Hence, this memcpy is required whether we get an error response or not.
> Therefor it is moved up from the current position up to immediately
> after we have called mmc_wait_for_req().
>
> The test code and the output of only the CMD17 is included in the
> commit to limit the message length.
>
> CMD17 (Test Code Snippet):
> ==========================
>         printf("Forming CMD%d\n", opt_idx);
>         /*  single block read */
>         cmd.blksz = 512;
>         cmd.blocks = 1;
>         cmd.write_flag = 0;
>         cmd.opcode = 17;
>         //cmd.arg = atoi(argv[3]);
>         cmd.arg = 0x09B2FFFF;
>         /* Expecting response R1B */
>         cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_ADTC;
>
>         memset(data, 0, sizeof(__u8) * 512);
>         mmc_ioc_cmd_set_data(cmd, data);
>
>         printf("Sending CMD%d: ARG[0x%08x]\n", opt_idx, cmd.arg);
>         if(ioctl(fd, MMC_IOC_CMD, &cmd))
>                 perror("Error");
>
>         printf("\nResponse: %08x\n", cmd.response[0]);
>
> CMD17 (Output without patch):
> =============================
> test@test-LIVA-Z:~$ sudo ./mmc cmd_test /dev/mmcblk0 17
> Entering the do_mmc_commands:Device: /dev/mmcblk0 nargs:4
> Entering the do_mmc_commands:Device: /dev/mmcblk0 options[17, 0x09B2FFF]
> Forming CMD17
> Sending CMD17: ARG[0x09b2ffff]
> Error: Connection timed out
>
> Response: 00000000
> (Incorrect response)
>
> CMD17 (Output with patch):
> ==========================
> test@test-LIVA-Z:~$ sudo ./mmc cmd_test /dev/mmcblk0 17
> [sudo] password for test:
> Entering the do_mmc_commands:Device: /dev/mmcblk0 nargs:4
> Entering the do_mmc_commands:Device: /dev/mmcblk0 options[17, 09B2FFFF]
> Forming CMD17
> Sending CMD17: ARG[0x09b2ffff]
> Error: Connection timed out
>
> Response: 80000900
> (Correct OUT_OF_ERROR response as per JEDEC specification)
>
> Signed-off-by: Nishad Kamdar <nishadkamdar@xxxxxxxxx>
> Reviewed-by: Avri Altman <avri.altman@xxxxxxx>

Applied for next, thanks!

Kind regards
Uffe


> ---
> Changes in v4:
>   - Moved the existing
>     "memcpy(&(idata->ic.response), cmd.resp, sizeof(cmd.resp));"
>     from a couple of lines further down in the code, up to
>     immediately after we have called mmc_wait_for_req().
>   - Modified the commit message to explain this change
> Changes in v3:
>   - Shorten the commit message to include only CMD17 related
>     code and test.
> Changes in v2:
>   - Make commit message clearer by adding test cases as outputs.
>
>  drivers/mmc/core/block.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index 672cc505ce378..94bb8b4cd6a4e 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -557,6 +557,7 @@ static int __mmc_blk_ioctl_cmd(struct mmc_card *card, struct mmc_blk_data *md,
>                 return mmc_sanitize(card, idata->ic.cmd_timeout_ms);
>
>         mmc_wait_for_req(card->host, &mrq);
> +       memcpy(&idata->ic.response, cmd.resp, sizeof(cmd.resp));
>
>         if (cmd.error) {
>                 dev_err(mmc_dev(card->host), "%s: cmd error %d\n",
> @@ -606,8 +607,6 @@ static int __mmc_blk_ioctl_cmd(struct mmc_card *card, struct mmc_blk_data *md,
>         if (idata->ic.postsleep_min_us)
>                 usleep_range(idata->ic.postsleep_min_us, idata->ic.postsleep_max_us);
>
> -       memcpy(&(idata->ic.response), cmd.resp, sizeof(cmd.resp));
> -
>         if (idata->rpmb || (cmd.flags & MMC_RSP_R1B) == MMC_RSP_R1B) {
>                 /*
>                  * Ensure RPMB/R1B command has completed by polling CMD13
> --
> 2.17.1
>