Re: [PATCH V4] mmc: block: Add new ioctl to send multi commands

[Grant Grundler]

On Wed, Sep 23, 2015 at 2:42 PM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
> On 22 September 2015 at 11:27, Jon Hunter <jonathanh@xxxxxxxxxx> wrote:
>> Certain eMMC devices allow vendor specific device information to be read
>> via a sequence of vendor commands. These vendor commands must be issued
>> in sequence and an atomic fashion. One way to support this would be to
>> add an ioctl function for sending a sequence of commands to the device
>> atomically as proposed here. These multi commands are simple array of
>> the existing mmc_ioc_cmd structure.
>>
>> The structure passed via the ioctl uses a __u64 type to specify the number
>> of commands (so that the structure is aligned on a 64-bit boundary) and a
>> zero length array as a header for list of commands to be issued. The
>> maximum number of commands that can be sent is determined by
>> MMC_IOC_MAX_CMDS (which defaults to 255 and should be more than
>> sufficient).
>>
>> This based upon work by Seshagiri Holi <sholi@xxxxxxxxxx>.
>>
>> Signed-off-by: Seshagiri Holi <sholi@xxxxxxxxxx>
>> Signed-off-by: Jon Hunter <jonathanh@xxxxxxxxxx>
>
> Thanks, applied for next!

Awesome! Thanks Ulf! (and Jon for preparing the patches)

I'll prepare a patch to implement Gwendal's previous suggestion based
on this 3.18 patch:
    https://chromium-review.googlesource.com/#/c/299956/

cheers,
grant

>
> Kind regards
> Uffe
>
>> ---
>> V4 changes:
>> - Moved duplicated test in mmc_blk_ioc_cmd() and mmc_blk_ioc_multi_cmd()
>>   to mmc_blk_ioctl(). Changed author.
>> V3 changes:
>> - Updated mmc_ioc_multi_cmd structure per Grant's preference
>> V2 changes:
>> - Updated changelog and patch per Arnd's feedback
>> - Moved mmc_put/get_card() outside of __mmc_blk_ioctl_cmd()
>>
>>  drivers/mmc/card/block.c       | 206 ++++++++++++++++++++++++++++++-----------
>>  include/uapi/linux/mmc/ioctl.h |  19 +++-
>>  2 files changed, 169 insertions(+), 56 deletions(-)
>>
>> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
>> index c742cfd7674e..f6acf0f6c410 100644
>> --- a/drivers/mmc/card/block.c
>> +++ b/drivers/mmc/card/block.c
>> @@ -387,6 +387,24 @@ out:
>>         return ERR_PTR(err);
>>  }
>>
>> +static int mmc_blk_ioctl_copy_to_user(struct mmc_ioc_cmd __user *ic_ptr,
>> +                                     struct mmc_blk_ioc_data *idata)
>> +{
>> +       struct mmc_ioc_cmd *ic = &idata->ic;
>> +
>> +       if (copy_to_user(&(ic_ptr->response), ic->response,
>> +                        sizeof(ic->response)))
>> +               return -EFAULT;
>> +
>> +       if (!idata->ic.write_flag) {
>> +               if (copy_to_user((void __user *)(unsigned long)ic->data_ptr,
>> +                                idata->buf, idata->buf_bytes))
>> +                       return -EFAULT;
>> +       }
>> +
>> +       return 0;
>> +}
>> +
>>  static int ioctl_rpmb_card_status_poll(struct mmc_card *card, u32 *status,
>>                                        u32 retries_max)
>>  {
>> @@ -447,12 +465,9 @@ out:
>>         return err;
>>  }
>>
>> -static int mmc_blk_ioctl_cmd(struct block_device *bdev,
>> -       struct mmc_ioc_cmd __user *ic_ptr)
>> +static int __mmc_blk_ioctl_cmd(struct mmc_card *card, struct mmc_blk_data *md,
>> +                              struct mmc_blk_ioc_data *idata)
>>  {
>> -       struct mmc_blk_ioc_data *idata;
>> -       struct mmc_blk_data *md;
>> -       struct mmc_card *card;
>>         struct mmc_command cmd = {0};
>>         struct mmc_data data = {0};
>>         struct mmc_request mrq = {NULL};
>> @@ -461,33 +476,12 @@ static int mmc_blk_ioctl_cmd(struct block_device *bdev,
>>         int is_rpmb = false;
>>         u32 status = 0;
>>
>> -       /*
>> -        * The caller must have CAP_SYS_RAWIO, and must be calling this on the
>> -        * whole block device, not on a partition.  This prevents overspray
>> -        * between sibling partitions.
>> -        */
>> -       if ((!capable(CAP_SYS_RAWIO)) || (bdev != bdev->bd_contains))
>> -               return -EPERM;
>> -
>> -       idata = mmc_blk_ioctl_copy_from_user(ic_ptr);
>> -       if (IS_ERR(idata))
>> -               return PTR_ERR(idata);
>> -
>> -       md = mmc_blk_get(bdev->bd_disk);
>> -       if (!md) {
>> -               err = -EINVAL;
>> -               goto cmd_err;
>> -       }
>> +       if (!card || !md || !idata)
>> +               return -EINVAL;
>>
>>         if (md->area_type & MMC_BLK_DATA_AREA_RPMB)
>>                 is_rpmb = true;
>>
>> -       card = md->queue.card;
>> -       if (IS_ERR(card)) {
>> -               err = PTR_ERR(card);
>> -               goto cmd_done;
>> -       }
>> -
>>         cmd.opcode = idata->ic.opcode;
>>         cmd.arg = idata->ic.arg;
>>         cmd.flags = idata->ic.flags;
>> @@ -530,23 +524,21 @@ static int mmc_blk_ioctl_cmd(struct block_device *bdev,
>>
>>         mrq.cmd = &cmd;
>>
>> -       mmc_get_card(card);
>> -
>>         err = mmc_blk_part_switch(card, md);
>>         if (err)
>> -               goto cmd_rel_host;
>> +               return err;
>>
>>         if (idata->ic.is_acmd) {
>>                 err = mmc_app_cmd(card->host, card);
>>                 if (err)
>> -                       goto cmd_rel_host;
>> +                       return err;
>>         }
>>
>>         if (is_rpmb) {
>>                 err = mmc_set_blockcount(card, data.blocks,
>>                         idata->ic.write_flag & (1 << 31));
>>                 if (err)
>> -                       goto cmd_rel_host;
>> +                       return err;
>>         }
>>
>>         if ((MMC_EXTRACT_INDEX_FROM_ARG(cmd.arg) == EXT_CSD_SANITIZE_START) &&
>> @@ -557,7 +549,7 @@ static int mmc_blk_ioctl_cmd(struct block_device *bdev,
>>                         pr_err("%s: ioctl_do_sanitize() failed. err = %d",
>>                                __func__, err);
>>
>> -               goto cmd_rel_host;
>> +               return err;
>>         }
>>
>>         mmc_wait_for_req(card->host, &mrq);
>> @@ -565,14 +557,12 @@ static int mmc_blk_ioctl_cmd(struct block_device *bdev,
>>         if (cmd.error) {
>>                 dev_err(mmc_dev(card->host), "%s: cmd error %d\n",
>>                                                 __func__, cmd.error);
>> -               err = cmd.error;
>> -               goto cmd_rel_host;
>> +               return cmd.error;
>>         }
>>         if (data.error) {
>>                 dev_err(mmc_dev(card->host), "%s: data error %d\n",
>>                                                 __func__, data.error);
>> -               err = data.error;
>> -               goto cmd_rel_host;
>> +               return data.error;
>>         }
>>
>>         /*
>> @@ -582,18 +572,7 @@ static int mmc_blk_ioctl_cmd(struct block_device *bdev,
>>         if (idata->ic.postsleep_min_us)
>>                 usleep_range(idata->ic.postsleep_min_us, idata->ic.postsleep_max_us);
>>
>> -       if (copy_to_user(&(ic_ptr->response), cmd.resp, sizeof(cmd.resp))) {
>> -               err = -EFAULT;
>> -               goto cmd_rel_host;
>> -       }
>> -
>> -       if (!idata->ic.write_flag) {
>> -               if (copy_to_user((void __user *)(unsigned long) idata->ic.data_ptr,
>> -                                               idata->buf, idata->buf_bytes)) {
>> -                       err = -EFAULT;
>> -                       goto cmd_rel_host;
>> -               }
>> -       }
>> +       memcpy(&(idata->ic.response), cmd.resp, sizeof(cmd.resp));
>>
>>         if (is_rpmb) {
>>                 /*
>> @@ -607,9 +586,42 @@ static int mmc_blk_ioctl_cmd(struct block_device *bdev,
>>                                         __func__, status, err);
>>         }
>>
>> -cmd_rel_host:
>> +       return err;
>> +}
>> +
>> +static int mmc_blk_ioctl_cmd(struct block_device *bdev,
>> +                            struct mmc_ioc_cmd __user *ic_ptr)
>> +{
>> +       struct mmc_blk_ioc_data *idata;
>> +       struct mmc_blk_data *md;
>> +       struct mmc_card *card;
>> +       int err;
>> +
>> +       idata = mmc_blk_ioctl_copy_from_user(ic_ptr);
>> +       if (IS_ERR(idata))
>> +               return PTR_ERR(idata);
>> +
>> +       md = mmc_blk_get(bdev->bd_disk);
>> +       if (!md) {
>> +               err = -EINVAL;
>> +               goto cmd_err;
>> +       }
>> +
>> +       card = md->queue.card;
>> +       if (IS_ERR(card)) {
>> +               err = PTR_ERR(card);
>> +               goto cmd_done;
>> +       }
>> +
>> +       mmc_get_card(card);
>> +
>> +       err = __mmc_blk_ioctl_cmd(card, md, idata);
>> +
>>         mmc_put_card(card);
>>
>> +       if (!err)
>> +               err = mmc_blk_ioctl_copy_to_user(ic_ptr, idata);
>> +
>>  cmd_done:
>>         mmc_blk_put(md);
>>  cmd_err:
>> @@ -618,13 +630,97 @@ cmd_err:
>>         return err;
>>  }
>>
>> +static int mmc_blk_ioctl_multi_cmd(struct block_device *bdev,
>> +                                  struct mmc_ioc_multi_cmd __user *user)
>> +{
>> +       struct mmc_blk_ioc_data **idata = NULL;
>> +       struct mmc_ioc_cmd __user *cmds = user->cmds;
>> +       struct mmc_card *card;
>> +       struct mmc_blk_data *md;
>> +       int i, err = -EFAULT;
>> +       __u64 num_of_cmds;
>> +
>> +       if (copy_from_user(&num_of_cmds, &user->num_of_cmds,
>> +                          sizeof(num_of_cmds)))
>> +               return -EFAULT;
>> +
>> +       if (num_of_cmds > MMC_IOC_MAX_CMDS)
>> +               return -EINVAL;
>> +
>> +       idata = kcalloc(num_of_cmds, sizeof(*idata), GFP_KERNEL);
>> +       if (!idata)
>> +               return -ENOMEM;
>> +
>> +       for (i = 0; i < num_of_cmds; i++) {
>> +               idata[i] = mmc_blk_ioctl_copy_from_user(&cmds[i]);
>> +               if (IS_ERR(idata[i])) {
>> +                       err = PTR_ERR(idata[i]);
>> +                       num_of_cmds = i;
>> +                       goto cmd_err;
>> +               }
>> +       }
>> +
>> +       md = mmc_blk_get(bdev->bd_disk);
>> +       if (!md)
>> +               goto cmd_err;
>> +
>> +       card = md->queue.card;
>> +       if (IS_ERR(card)) {
>> +               err = PTR_ERR(card);
>> +               goto cmd_done;
>> +       }
>> +
>> +       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;
>> +               }
>> +       }
>> +
>> +       mmc_put_card(card);
>> +
>> +       /* copy to user if data and response */
>> +       for (i = 0; i < num_of_cmds; i++) {
>> +               err = mmc_blk_ioctl_copy_to_user(&cmds[i], idata[i]);
>> +               if (err)
>> +                       break;
>> +       }
>> +
>> +cmd_done:
>> +       mmc_blk_put(md);
>> +cmd_err:
>> +       for (i = 0; i < num_of_cmds; i++) {
>> +               kfree(idata[i]->buf);
>> +               kfree(idata[i]);
>> +       }
>> +       kfree(idata);
>> +       return err;
>> +}
>> +
>>  static int mmc_blk_ioctl(struct block_device *bdev, fmode_t mode,
>>         unsigned int cmd, unsigned long arg)
>>  {
>> -       int ret = -EINVAL;
>> -       if (cmd == MMC_IOC_CMD)
>> -               ret = mmc_blk_ioctl_cmd(bdev, (struct mmc_ioc_cmd __user *)arg);
>> -       return ret;
>> +       /*
>> +        * The caller must have CAP_SYS_RAWIO, and must be calling this on the
>> +        * whole block device, not on a partition.  This prevents overspray
>> +        * between sibling partitions.
>> +        */
>> +       if ((!capable(CAP_SYS_RAWIO)) || (bdev != bdev->bd_contains))
>> +               return -EPERM;
>> +
>> +       switch (cmd) {
>> +       case MMC_IOC_CMD:
>> +               return mmc_blk_ioctl_cmd(bdev,
>> +                               (struct mmc_ioc_cmd __user *)arg);
>> +       case MMC_IOC_MULTI_CMD:
>> +               return mmc_blk_ioctl_multi_cmd(bdev,
>> +                               (struct mmc_ioc_multi_cmd __user *)arg);
>> +       default:
>> +               return -EINVAL;
>> +       }
>>  }
>>
>>  #ifdef CONFIG_COMPAT
>> diff --git a/include/uapi/linux/mmc/ioctl.h b/include/uapi/linux/mmc/ioctl.h
>> index 1f5e68923929..7e385b83b9d8 100644
>> --- a/include/uapi/linux/mmc/ioctl.h
>> +++ b/include/uapi/linux/mmc/ioctl.h
>> @@ -45,8 +45,24 @@ struct mmc_ioc_cmd {
>>  };
>>  #define mmc_ioc_cmd_set_data(ic, ptr) ic.data_ptr = (__u64)(unsigned long) ptr
>>
>> -#define MMC_IOC_CMD _IOWR(MMC_BLOCK_MAJOR, 0, struct mmc_ioc_cmd)
>> +/**
>> + * struct mmc_ioc_multi_cmd - multi command information
>> + * @num_of_cmds: Number of commands to send. Must be equal to or less than
>> + *     MMC_IOC_MAX_CMDS.
>> + * @cmds: Array of commands with length equal to 'num_of_cmds'
>> + */
>> +struct mmc_ioc_multi_cmd {
>> +       __u64 num_of_cmds;
>> +       struct mmc_ioc_cmd cmds[0];
>> +};
>>
>> +#define MMC_IOC_CMD _IOWR(MMC_BLOCK_MAJOR, 0, struct mmc_ioc_cmd)
>> +/*
>> + * MMC_IOC_MULTI_CMD: Used to send an array of MMC commands described by
>> + *     the structure mmc_ioc_multi_cmd. The MMC driver will issue all
>> + *     commands in array in sequence to card.
>> + */
>> +#define MMC_IOC_MULTI_CMD _IOWR(MMC_BLOCK_MAJOR, 1, struct mmc_ioc_multi_cmd)
>>  /*
>>   * Since this ioctl is only meant to enhance (and not replace) normal access
>>   * to the mmc bus device, an upper data transfer limit of MMC_IOC_MAX_BYTES
>> @@ -54,4 +70,5 @@ struct mmc_ioc_cmd {
>>   * block device operations.
>>   */
>>  #define MMC_IOC_MAX_BYTES  (512L * 256)
>> +#define MMC_IOC_MAX_CMDS    255
>>  #endif /* LINUX_MMC_IOCTL_H */
>> --
>> 2.1.4
>>
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