mmc: block: copy resp[] data on err for MMC_IOC_MULTI_CMD

MMC_IOC_CMD and MMC_IOC_MULTI_CMD ioctl() code currently bails on
any eMMC errors. However, in case there is any resp[] data, we
should attempt to copy resp[] back to user space. The user app
can then determine which command(s) failed in the MMC_IOC_MULTI_CMD
case AND/OR report better diagnostics in both cases.

Gwendal Grignou provided the idea and it was previously implemented
and tested on v3.18 ChromeOS kernel:
    https://chromium-review.googlesource.com/#/c/299956

Signed-off-by: Grant Grundler <grundler@chromium.org>
Reviewed-by: Hyung Taek Ryoo <hryoo@nvidia.com>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Tested-by: David Riley <davidriley@chromium.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index f6acf0f6c4106f06bfe6c1300dc939aa534e9f3f..23b6c8e8701ccd6e3ec57c85483276de4b02f51b 100644 (file)
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -595,7 +595,7 @@ static int mmc_blk_ioctl_cmd(struct block_device *bdev,
        struct mmc_blk_ioc_data *idata;
        struct mmc_blk_data *md;
        struct mmc_card *card;
-       int err;
+       int err = 0, ioc_err = 0;
 
        idata = mmc_blk_ioctl_copy_from_user(ic_ptr);
        if (IS_ERR(idata))
@@ -615,19 +615,18 @@ static int mmc_blk_ioctl_cmd(struct block_device *bdev,
 
        mmc_get_card(card);
 
-       err = __mmc_blk_ioctl_cmd(card, md, idata);
+       ioc_err = __mmc_blk_ioctl_cmd(card, md, idata);
 
        mmc_put_card(card);
 
-       if (!err)
-               err = mmc_blk_ioctl_copy_to_user(ic_ptr, idata);
+       err = mmc_blk_ioctl_copy_to_user(ic_ptr, idata);
 
 cmd_done:
        mmc_blk_put(md);
 cmd_err:
        kfree(idata->buf);
        kfree(idata);
-       return err;
+       return ioc_err ? ioc_err : err;
 }
 
 static int mmc_blk_ioctl_multi_cmd(struct block_device *bdev,
@@ -637,7 +636,7 @@ static int mmc_blk_ioctl_multi_cmd(struct block_device *bdev,
        struct mmc_ioc_cmd __user *cmds = user->cmds;
        struct mmc_card *card;
        struct mmc_blk_data *md;
-       int i, err = -EFAULT;
+       int i, err = 0, ioc_err = 0;
        __u64 num_of_cmds;
 
        if (copy_from_user(&num_of_cmds, &user->num_of_cmds,
@@ -672,22 +671,14 @@ static int mmc_blk_ioctl_multi_cmd(struct block_device *bdev,
 
        mmc_get_card(card);
 
-       for (i = 0; i < num_of_cmds; i++) {
-               err = __mmc_blk_ioctl_cmd(card, md, idata[i]);
-               if (err) {
-                       mmc_put_card(card);
-                       goto cmd_done;
-               }
-       }
+       for (i = 0; i < num_of_cmds && !ioc_err; i++)
+               ioc_err = __mmc_blk_ioctl_cmd(card, md, idata[i]);
 
        mmc_put_card(card);
 
        /* copy to user if data and response */
-       for (i = 0; i < num_of_cmds; i++) {
+       for (i = 0; i < num_of_cmds && !err; i++)
                err = mmc_blk_ioctl_copy_to_user(&cmds[i], idata[i]);
-               if (err)
-                       break;
-       }
 
 cmd_done:
        mmc_blk_put(md);
@@ -697,7 +688,7 @@ cmd_err:
                kfree(idata[i]);
        }
        kfree(idata);
-       return err;
+       return ioc_err ? ioc_err : err;
 }
 
 static int mmc_blk_ioctl(struct block_device *bdev, fmode_t mode,