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Date: Fri, 11 Sep 2015 09:17:30 -0700
From: Grant Grundler <grundler@...omium.org>
To: Jon Hunter <jonathanh@...dia.com>
Cc: Ulf Hansson <ulf.hansson@...aro.org>,
"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>,
Seshagiri Holi <sholi@...dia.com>,
Arnd Bergmann <arnd@...db.de>,
Olof Johansson <olofj@...omium.org>
Subject: Re: [PATCH V2] mmc: block: Add new ioctl to send multi commands
On Fri, Sep 11, 2015 at 5:22 AM, Jon Hunter <jonathanh@...dia.com> wrote:
> From: Seshagiri Holi <sholi@...dia.com>
>
> 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 pointer type to pass a
> pointer to the command list. The __u64 pointer type is used to ensure the
> pointer size is the same regardless of the address size used by user-space.
> The number of commands that can be passed is limited to 256 by the 8-bit
> type of the num_of_cmds member (which should be more than sufficient).
>
> Signed-off-by: Seshagiri Holi <sholi@...dia.com>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Grant Grundler <grundler@...gle.com>
Reviewed-by: Grant Grundler <grundler@...omium.org>
One comment below. two actually. ;)
> Cc: Olof Johansson <olofj@...omium.org>
> [ jonathanh@...dia.com: Rebased on linux-next from v3.18. Changed
> userspace pointer type for multi command to be a u64. Renamed
> from combo commands to multi commands. Updated patch based upon
> feedback review comments received. Updated commit message ]
I don't think the comment in '[]' needs to be in the commit message.
Ok to move it to where the V2 changes are listed?
> Signed-off-by: Jon Hunter <jonathanh@...dia.com>
> ---
>
> V2 changes:
> - Updated changelog per Arnd's feedback
> - Moved mmc_put/get_card() outside of __mmc_blk_ioctl_cmd()
>
> drivers/mmc/card/block.c | 218 ++++++++++++++++++++++++++++++-----------
> include/uapi/linux/mmc/ioctl.h | 22 ++++-
> 2 files changed, 184 insertions(+), 56 deletions(-)
>
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index c742cfd7674e..9bdbf1ea65ba 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 +586,50 @@ 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;
> +
> + /*
> + * 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;
> + }
> +
> + card = md->queue.card;
> + if (IS_ERR(card)) {
> + err = PTR_ERR(card);
> + goto cmd_done;
> + }
> +
> + mmc_get_card(card);
Yeah, the double call in the ioc_multi_cmd case was irritating me too.
> +
> + 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 +638,101 @@ cmd_err:
> return err;
> }
>
> +static int mmc_blk_ioctl_multi_cmd(struct block_device *bdev,
> + struct mmc_ioc_multi_cmd __user *user)
> +{
> + struct mmc_ioc_multi_cmd mcci = {0};
> + struct mmc_blk_ioc_data **idata = NULL;
> + struct mmc_ioc_cmd __user *cmds;
> + struct mmc_card *card;
> + struct mmc_blk_data *md;
> + int i, err = -EFAULT;
> + u8 n_cmds = 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;
> +
> + if (copy_from_user(&mcci, user, sizeof(struct mmc_ioc_multi_cmd)))
> + return -EFAULT;
> +
> + if (!mcci.num_of_cmds) {
> + err = -EINVAL;
> + goto cmd_err;
> + }
> +
> + idata = kcalloc(mcci.num_of_cmds, sizeof(*idata), GFP_KERNEL);
> + if (!idata) {
> + err = -ENOMEM;
> + goto cmd_err;
> + }
> +
> + cmds = (struct mmc_ioc_cmd __user *)(unsigned long)mcci.cmds_ptr;
> + for (n_cmds = 0; n_cmds < mcci.num_of_cmds; n_cmds++) {
> + idata[n_cmds] = mmc_blk_ioctl_copy_from_user(&cmds[n_cmds]);
> + if (IS_ERR(idata[n_cmds])) {
> + err = PTR_ERR(idata[n_cmds]);
> + 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 < n_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 < n_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 < n_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;
> + 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..420bd063ee45 100644
> --- a/include/uapi/linux/mmc/ioctl.h
> +++ b/include/uapi/linux/mmc/ioctl.h
> @@ -45,8 +45,28 @@ 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
> + * @cmds_ptr: Address of the location where the list of commands resides
> + * @num_of_cmds: number of commands to send
> + */
> +struct mmc_ioc_multi_cmd {
> + __u64 cmds_ptr;
> + __u8 num_of_cmds;
>
> + /*
> + * Pad struct so it's size is a multiple of it's alignment.
> + */
> + __u8 __pad[7];
> +};
Is this the final structure or we going to adopt Arnd's suggestion for:
struct mmc_ioc_multi_cmd {
__u64 num_of_cmds;
struct mmc_ioc_cmd cmds[0];
}
After having slept on it, I like this better (feels "cleaner").
And "fgrep -R '[0];' /usr/include/linux" tells me this non-standard
gcc feature is already widely "visible" to user space compilers.
cheers,
grant
> +
> +#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
> --
> 2.1.4
>
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