Re: [PATCH v7 3/7] media: uvcvideo: Add support for compound controls

Yunke Cao
2022-08-29T05:39:39Z

Hi Laurent,

Thanks for the review!

On Thu, Aug 25, 2022 at 4:56 AM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Yunke,
>
> Thank you for the patch.
>
> On Tue, Jun 28, 2022 at 04:57:01PM +0900, Yunke Cao wrote:
> > Supports getting/setting current value.
> > Supports getting default value.
> > Handles V4L2_CTRL_FLAG_NEXT_COMPOUND.
> >
> > Signed-off-by: Yunke Cao <yunkec@google.com>
> > ---
> > drivers/media/usb/uvc/uvc_ctrl.c | 279 ++++++++++++++++++++++++++-----
> > drivers/media/usb/uvc/uvcvideo.h | 4 +
> > 2 files changed, 238 insertions(+), 45 deletions(-)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> > index 772d9d28a520..508ee04afbcd 100644
> > --- a/drivers/media/usb/uvc/uvc_ctrl.c
> > +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> > @@ -815,6 +815,34 @@ static void uvc_set_le_value(struct uvc_control_mapping *mapping,
> > }
> > }
> >
> > +/* Extract the byte array specified by mapping->offset and mapping->size
> > + * stored at 'data' to the output array 'data_out'.
> > + */
>
> Please use the
>
> /*
> * multi
> * line
> */
>
> style instead of
>
> /* multi
> * line
> */
>
> The uvcvideo driver has recently switched to the former in commit
> 699b9a86a3f0 ("media: uvcvideo: Fix comment blocks style").
>
> > +static int uvc_get_array(struct uvc_control_mapping *mapping, const u8 *data,
> > + u8 *data_out)
> > +{
> > + // Only supports byte-aligned data.
>
> And no C++-style comments either please.
>

Will fix the comments style in the next version.

> > + if (WARN_ON(mapping->offset % 8 || mapping->size % 8))
> > + return -EINVAL;
> > +
> > + memcpy(data_out, data + mapping->offset / 8, mapping->size / 8);
> > + return 0;
> > +}
> > +
> > +/* Copy the byte array 'data_in' to the destination specified by mapping->offset
> > + * and mapping->size stored at 'data'.
> > + */
> > +static int uvc_set_array(struct uvc_control_mapping *mapping, const u8 *data_in,
> > + u8 *data)
> > +{
> > + // Only supports byte-aligned data.
> > + if (WARN_ON(mapping->offset % 8 || mapping->size % 8))
> > + return -EINVAL;
> > +
> > + memcpy(data + mapping->offset / 8, data_in, mapping->size / 8);
> > + return 0;
> > +}
> > +
>
> Could you add here a
>
> static bool
> uvc_ctrl_mapping_is_compound(const struct uvc_control_mapping *mapping)
> {
> return mapping->v4l2_type >= V4L2_CTRL_COMPOUND_TYPES;
> }
>
> and use it below ? That would be clearer I think.
>
> > /* ------------------------------------------------------------------------
> > * Terminal and unit management
> > */
> > @@ -831,7 +859,7 @@ static int uvc_entity_match_guid(const struct uvc_entity *entity,
> >
> > static void __uvc_find_control(struct uvc_entity *entity, u32 v4l2_id,
> > struct uvc_control_mapping **mapping, struct uvc_control **control,
> > - int next)
> > + int next, int next_compound)
> > {
> > struct uvc_control *ctrl;
> > struct uvc_control_mapping *map;
> > @@ -846,14 +874,18 @@ static void __uvc_find_control(struct uvc_entity *entity, u32 v4l2_id,
> > continue;
> >
> > list_for_each_entry(map, &ctrl->info.mappings, list) {
> > - if ((map->id == v4l2_id) && !next) {
> > + if (map->id == v4l2_id && !next && !next_compound) {
> > *control = ctrl;
> > *mapping = map;
> > return;
> > }
> >
> > if ((*mapping == NULL || (*mapping)->id > map->id) &&
> > - (map->id > v4l2_id) && next) {
> > + (map->id > v4l2_id) &&
> > + ((map->v4l2_type < V4L2_CTRL_COMPOUND_TYPES &&
> > + next) ||
> > + (map->v4l2_type >= V4L2_CTRL_COMPOUND_TYPES &&
> > + next_compound))) {
> > *control = ctrl;
> > *mapping = map;
> > }
>
> This could become for instance
>
> if ((*mapping == NULL || (*mapping)->id > map->id) &&
> (map->id > v4l2_id) &&
> ((!uvc_ctrl_mapping_is_compound(map) && next) ||
> (uvc_ctrl_mapping_is_compound(map) && next_compound))) {
> *control = ctrl;
> *mapping = map;
> }
>

Sure! That does look much better.

> > @@ -867,6 +899,7 @@ static struct uvc_control *uvc_find_control(struct uvc_video_chain *chain,
> > struct uvc_control *ctrl = NULL;
> > struct uvc_entity *entity;
> > int next = v4l2_id & V4L2_CTRL_FLAG_NEXT_CTRL;
> > + int next_compound = v4l2_id & V4L2_CTRL_FLAG_NEXT_COMPOUND;
> >
> > *mapping = NULL;
> >
> > @@ -875,12 +908,13 @@ static struct uvc_control *uvc_find_control(struct uvc_video_chain *chain,
> >
> > /* Find the control. */
> > list_for_each_entry(entity, &chain->entities, chain) {
> > - __uvc_find_control(entity, v4l2_id, mapping, &ctrl, next);
> > - if (ctrl && !next)
> > + __uvc_find_control(entity, v4l2_id, mapping, &ctrl, next,
> > + next_compound);
> > + if (ctrl && !next && !next_compound)
> > return ctrl;
> > }
> >
> > - if (ctrl == NULL && !next)
> > + if (!ctrl && !next && !next_compound)
> > uvc_dbg(chain->dev, CONTROL, "Control 0x%08x not found\n",
> > v4l2_id);
> >
> > @@ -943,6 +977,39 @@ static int uvc_ctrl_populate_cache(struct uvc_video_chain *chain,
> > return 0;
> > }
> >
> > +static int __uvc_ctrl_load_cur(struct uvc_video_chain *chain,
> > + struct uvc_control *ctrl)
> > +{
>
> I would declare
>
> u8 data;
>
> here, and
>
> > + int ret = 0;
> > +
> > + if ((ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR) == 0)
> > + return -EACCES;
> > +
> > + if (ctrl->loaded)
> > + return 0;
> > +
>
> set
>
> data = uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT);
>
> here, and
>
> > + if (ctrl->entity->get_cur) {
> > + ret = ctrl->entity->get_cur(chain->dev,
> > + ctrl->entity,
> > + ctrl->info.selector,
> > + uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
> > + ctrl->info.size);
>
> improve indentation here
>
> ret = ctrl->entity->get_cur(chain->dev, ctrl->entity,
> ctrl->info.selector, data,
> ctrl->info.size);
>
>
> > + } else {
>
> and also use data here
>
> > + ret = uvc_query_ctrl(chain->dev, UVC_GET_CUR,
> > + ctrl->entity->id, chain->dev->intfnum,
> > + ctrl->info.selector,
> > + uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
> > + ctrl->info.size);
>
> ret = uvc_query_ctrl(chain->dev, UVC_GET_CUR,
> ctrl->entity->id, chain->dev->intfnum,
> ctrl->info.selector, data,
> ctrl->info.size);
>
> > + }
> > +
> > + if (ret < 0)
> > + return ret;
> > +
> > + ctrl->loaded = 1;
> > +
> > + return ret;
> > +}
> > +
> > static s32 __uvc_ctrl_get_value(struct uvc_control_mapping *mapping,
> > const u8 *data)
> > {
> > @@ -963,35 +1030,19 @@ static s32 __uvc_ctrl_get_value(struct uvc_control_mapping *mapping,
> > return value;
> > }
> >
> > -static int __uvc_ctrl_get(struct uvc_video_chain *chain,
> > - struct uvc_control *ctrl, struct uvc_control_mapping *mapping,
> > - s32 *value)
> > +static int __uvc_ctrl_get_std(struct uvc_video_chain *chain,
> > + struct uvc_control *ctrl,
> > + struct uvc_control_mapping *mapping,
> > + s32 *value)
> > {
> > int ret;
> >
> > - if ((ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR) == 0)
> > - return -EACCES;
> > -
> > - if (!ctrl->loaded) {
> > - if (ctrl->entity->get_cur) {
> > - ret = ctrl->entity->get_cur(chain->dev,
> > - ctrl->entity,
> > - ctrl->info.selector,
> > - uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
> > - ctrl->info.size);
> > - } else {
> > - ret = uvc_query_ctrl(chain->dev, UVC_GET_CUR,
> > - ctrl->entity->id,
> > - chain->dev->intfnum,
> > - ctrl->info.selector,
> > - uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
> > - ctrl->info.size);
> > - }
> > - if (ret < 0)
> > - return ret;
> > + if (mapping->v4l2_type >= V4L2_CTRL_COMPOUND_TYPES)
> > + return -EINVAL;
> >
> > - ctrl->loaded = 1;
> > - }
> > + ret = __uvc_ctrl_load_cur(chain, ctrl);
> > + if (ret < 0)
> > + return ret;
> >
> > *value = __uvc_ctrl_get_value(mapping,
> > uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT));
> > @@ -999,6 +1050,57 @@ static int __uvc_ctrl_get(struct uvc_video_chain *chain,
> > return 0;
> > }
> >
> > +static int __uvc_ctrl_get_compound_to_user(struct uvc_control_mapping *mapping,
>
> I don't like this name much. One option would be to rename the
> __uvc_ctrl_get_compound() function below to
> __uvc_ctrl_get_compound_cur() and call this function
> __uvc_ctrl_get_compound(). Better options are likely possible.
>
> > + struct uvc_control *ctrl,
> > + int id,
> > + struct v4l2_ext_control *xctrl)
> > +{
> > + int ret, size;
>
> size is never negative, make it an unsigned int.
>
> > + u8 *data;
> > +
> > + if (WARN_ON(!mapping->size % 8))
> > + return -EINVAL;
>
> This duplicates a check in the get_array function. Let's move all those
> checks to the function that adds mappings.
>
> > +
> > + size = mapping->size / 8;
> > + if (xctrl->size < size) {
> > + xctrl->size = size;
> > + return -ENOSPC;
> > + }
> > +
> > + data = kmalloc(size, GFP_KERNEL);
> > + if (!data)
> > + return -ENOMEM;
> > +
> > + ret = mapping->get_array(mapping, uvc_ctrl_data(ctrl, id), data);
> > + if (ret < 0)
> > + goto out;
> > +
> > + ret = copy_to_user(xctrl->ptr, data, size) ? -EFAULT : 0;
> > +
> > +out:
> > + kfree(data);
> > + return ret;
> > +}
> > +
> > +static int __uvc_ctrl_get_compound(struct uvc_video_chain *chain,
> > + struct uvc_control *ctrl,
> > + struct uvc_control_mapping *mapping,
> > + struct v4l2_ext_control *xctrl)
> > +{
> > + int ret;
> > +
> > + if (mapping->v4l2_type < V4L2_CTRL_COMPOUND_TYPES)
> > + return -EINVAL;
> > +
> > + ret = __uvc_ctrl_load_cur(chain, ctrl);
> > + if (ret < 0)
> > + return ret;
> > +
> > + return __uvc_ctrl_get_compound_to_user(mapping, ctrl,
> > + UVC_CTRL_DATA_CURRENT,
> > + xctrl);
> > +}
> > +
> > static int __uvc_query_v4l2_class(struct uvc_video_chain *chain, u32 req_id,
> > u32 found_id)
> > {
> > @@ -1102,10 +1204,15 @@ static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
> >
> > if (mapping->master_id)
> > __uvc_find_control(ctrl->entity, mapping->master_id,
> > - &master_map, &master_ctrl, 0);
> > + &master_map, &master_ctrl, 0, 0);
> > if (master_ctrl && (master_ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR)) {
> > - s32 val;
> > - int ret = __uvc_ctrl_get(chain, master_ctrl, master_map, &val);
> > + int ret;
> > + s32 val = 0;
>
> Move ret after val.
>
> > +
> > + if (master_map->v4l2_type >= V4L2_CTRL_COMPOUND_TYPES)
> > + return -EINVAL;
> > +
> > + ret = __uvc_ctrl_get_std(chain, master_ctrl, master_map, &val);
> > if (ret < 0)
> > return ret;
> >
> > @@ -1113,6 +1220,15 @@ static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
> > v4l2_ctrl->flags |= V4L2_CTRL_FLAG_INACTIVE;
> > }
> >
> > + if (v4l2_ctrl->type >= V4L2_CTRL_COMPOUND_TYPES) {
> > + v4l2_ctrl->flags |= V4L2_CTRL_FLAG_HAS_PAYLOAD;
> > + v4l2_ctrl->default_value = 0;
> > + v4l2_ctrl->minimum = 0;
> > + v4l2_ctrl->maximum = 0;
> > + v4l2_ctrl->step = 0;
> > + return 0;
> > + }
> > +
> > if (!ctrl->cached) {
> > int ret = uvc_ctrl_populate_cache(chain, ctrl);
> > if (ret < 0)
> > @@ -1346,11 +1462,12 @@ static void uvc_ctrl_send_slave_event(struct uvc_video_chain *chain,
> > u32 changes = V4L2_EVENT_CTRL_CH_FLAGS;
> > s32 val = 0;
> >
> > - __uvc_find_control(master->entity, slave_id, &mapping, &ctrl, 0);
> > + __uvc_find_control(master->entity, slave_id, &mapping, &ctrl, 0, 0);
> > if (ctrl == NULL)
> > return;
> >
> > - if (__uvc_ctrl_get(chain, ctrl, mapping, &val) == 0)
> > + if (mapping->v4l2_type >= V4L2_CTRL_COMPOUND_TYPES ||
> > + __uvc_ctrl_get_std(chain, ctrl, mapping, &val) == 0)
> > changes |= V4L2_EVENT_CTRL_CH_VALUE;
> >
> > uvc_ctrl_send_event(chain, handle, ctrl, mapping, val, changes);
> > @@ -1517,7 +1634,8 @@ static int uvc_ctrl_add_event(struct v4l2_subscribed_event *sev, unsigned elems)
> > u32 changes = V4L2_EVENT_CTRL_CH_FLAGS;
> > s32 val = 0;
> >
> > - if (__uvc_ctrl_get(handle->chain, ctrl, mapping, &val) == 0)
> > + if (mapping->v4l2_type >= V4L2_CTRL_COMPOUND_TYPES ||
> > + __uvc_ctrl_get_std(handle->chain, ctrl, mapping, &val) == 0)
> > changes |= V4L2_EVENT_CTRL_CH_VALUE;
> >
> > uvc_ctrl_fill_event(handle->chain, &ev, ctrl, mapping, val,
> > @@ -1647,7 +1765,7 @@ static int uvc_ctrl_find_ctrl_idx(struct uvc_entity *entity,
> >
> > for (i = 0; i < ctrls->count; i++) {
> > __uvc_find_control(entity, ctrls->controls[i].id, &mapping,
> > - &ctrl_found, 0);
> > + &ctrl_found, 0, 0);
> > if (uvc_control == ctrl_found)
> > return i;
> > }
> > @@ -1694,11 +1812,14 @@ int uvc_ctrl_get(struct uvc_video_chain *chain,
> > if (ctrl == NULL)
> > return -EINVAL;
> >
> > - return __uvc_ctrl_get(chain, ctrl, mapping, &xctrl->value);
> > + if (mapping->v4l2_type < V4L2_CTRL_COMPOUND_TYPES)
> > + return __uvc_ctrl_get_std(chain, ctrl, mapping, &xctrl->value);
> > + else
> > + return __uvc_ctrl_get_compound(chain, ctrl, mapping, xctrl);
> > }
> >
> > -int uvc_ctrl_get_fixed(struct uvc_video_chain *chain,
> > - struct v4l2_ext_control *xctrl)
> > +int __uvc_ctrl_get_fixed_std(struct uvc_video_chain *chain,
> > + struct v4l2_ext_control *xctrl)
> > {
> > struct v4l2_queryctrl qc = { .id = xctrl->id };
> > int ret = uvc_query_v4l2_ctrl(chain, &qc);
> > @@ -1710,6 +1831,56 @@ int uvc_ctrl_get_fixed(struct uvc_video_chain *chain,
> > return 0;
> > }
> >
> > +int uvc_ctrl_get_fixed(struct uvc_video_chain *chain,
> > + struct v4l2_ext_control *xctrl)
> > +{
> > + struct uvc_control *ctrl;
> > + struct uvc_control_mapping *mapping;
> > + int ret;
> > +
> > + if (__uvc_query_v4l2_class(chain, xctrl->id, 0) >= 0)
> > + return -EACCES;
> > +
>
> This check comes a bit out of the blue, I think it belongs to another
> patch, with a commit message that clearly explain the rationale.
>
> > + ctrl = uvc_find_control(chain, xctrl->id, &mapping);
> > + if (!ctrl)
> > + return -EINVAL;
>
> And here, you're duplicating the uvc_find_control() call from
> uvc_query_v4l2_ctrl(), called in __uvc_ctrl_get_fixed_std().
> Furthermore, you're not holding the ctrl_mutex lock here, which I think
> is wrong.
>

Thanks for catching this!
I'm thinking of fixing it by calling __uvc_query_v4l2_ctrl()
in __uvc_ctrl_get_fixed_std(). And acquire the ctrl_mutex lock here
in uvc_ctrl_get_fixed(). Does that sound right to you?

> I'd like to see a patch before this one that refactors what needs to be
> refactored first, and then the introduction of compound types support
> without any extra change like this. Splitting code out to
> __uvc_ctrl_load_cur() could also be moved to a preparatory patch to
> simplify this one, it's quite hard to review.
>

I see. For __uvc_ctrl_load_cur(), I guess I can cherry-pick
"[PATCH v4] media: uvcvideo: Use entity get_cur in uvc_ctrl_set"
before this.

I am trying to split the refactoring in 2/7. Should I introduce the
"get/set_std()" functions before this as well?

> > +
> > + if (mapping->v4l2_type < V4L2_CTRL_COMPOUND_TYPES)
> > + return __uvc_ctrl_get_fixed_std(chain, xctrl);
> > +
> > + if (!ctrl->cached) {
> > + ret = uvc_ctrl_populate_cache(chain, ctrl);
> > + if (ret < 0)
> > + return ret;
> > + }
> > +
> > + return __uvc_ctrl_get_compound_to_user(mapping, ctrl, UVC_CTRL_DATA_DEF,
> > + xctrl);
> > +}
> > +
> > +int __uvc_ctrl_set_compound(struct uvc_control_mapping *mapping,
> > + struct v4l2_ext_control *xctrl,
> > + struct uvc_control *ctrl)
> > +{
> > + int ret;
> > + u8 *data;
>
> Please move ret after data.
>
> > +
> > + data = kmalloc(xctrl->size, GFP_KERNEL);
>
> A limit on the size is needed to avoid denial of service attacks.
>
> > + if (!data)
> > + return -ENOMEM;
> > +
> > + ret = copy_from_user(data, xctrl->ptr, xctrl->size);
> > + if (ret < 0)
> > + goto out;
> > +
> > + ret = mapping->set_array(mapping, data,
> > + uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT));
>
> ret = mapping->set_array(mapping, data,
> uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT));
>
> The V4L2 control model is that the kernel can update the value of a
> control if the requested value is out of range or otherwise not
> acceptable. You should here copy the data back to the user.

Ah okay. Will call "__uvc_ctrl_get_compound_to_user()" here.

>
> > +
> > +out:
> > + kfree(data);
> > + return ret;
> > +}
> > +
> > int uvc_ctrl_set(struct uvc_fh *handle,
> > struct v4l2_ext_control *xctrl)
> > {
> > @@ -1820,8 +1991,14 @@ int uvc_ctrl_set(struct uvc_fh *handle,
> > ctrl->info.size);
> > }
> >
> > - mapping->set(mapping, value,
> > - uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT));
> > + if (mapping->v4l2_type < V4L2_CTRL_COMPOUND_TYPES) {
> > + mapping->set(mapping, value,
> > + uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT));
> > + } else {
> > + ret = __uvc_ctrl_set_compound(mapping, xctrl, ctrl);
> > + if (ret < 0)
> > + return ret;
> > + }
> >
> > if (ctrl->info.flags & UVC_CTRL_FLAG_ASYNCHRONOUS)
> > ctrl->handle = handle;
> > @@ -2220,10 +2397,14 @@ static int __uvc_ctrl_add_mapping(struct uvc_video_chain *chain,
> > return -ENOMEM;
> > }
> >
> > - if (map->get == NULL)
> > + if (!map->get && map->v4l2_type < V4L2_CTRL_COMPOUND_TYPES)
> > map->get = uvc_get_le_value;
> > - if (map->set == NULL)
> > + if (!map->set && map->v4l2_type < V4L2_CTRL_COMPOUND_TYPES)
> > map->set = uvc_set_le_value;
> > + if (!map->get_array && map->v4l2_type >= V4L2_CTRL_COMPOUND_TYPES)
> > + map->get_array = uvc_get_array;
> > + if (!map->set_array && map->v4l2_type >= V4L2_CTRL_COMPOUND_TYPES)
> > + map->set_array = uvc_set_array;
> >
> > for (i = 0; i < ARRAY_SIZE(uvc_control_classes); i++) {
> > if (V4L2_CTRL_ID2WHICH(uvc_control_classes[i]) ==
> > @@ -2233,6 +2414,14 @@ static int __uvc_ctrl_add_mapping(struct uvc_video_chain *chain,
> > }
> > }
> >
> > + if (map->v4l2_type < V4L2_CTRL_COMPOUND_TYPES &&
> > + WARN_ON(!map->get || !map->set))
> > + return -EINVAL;
> > +
> > + if (map->v4l2_type >= V4L2_CTRL_COMPOUND_TYPES &&
> > + WARN_ON(!map->get_array || !map->set_array))
> > + return -EINVAL;
> > +
>
> Can this happen, given that you set them above if they're null ?
>

It cannot happen. Will remove this in v8.

> > list_add_tail(&map->list, &ctrl->info.mappings);
> > uvc_dbg(chain->dev, CONTROL, "Adding mapping '%s' to control %pUl/%u\n",
> > uvc_map_get_name(map), ctrl->info.entity,
> > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> > index ba028ba7c34e..2f9b75faae83 100644
> > --- a/drivers/media/usb/uvc/uvcvideo.h
> > +++ b/drivers/media/usb/uvc/uvcvideo.h
> > @@ -262,8 +262,12 @@ struct uvc_control_mapping {
> >
> > s32 (*get)(struct uvc_control_mapping *mapping, u8 query,
> > const u8 *data);
> > + int (*get_array)(struct uvc_control_mapping *mapping, const u8 *data,
> > + u8 *data_out);
> > void (*set)(struct uvc_control_mapping *mapping, s32 value,
> > u8 *data);
> > + int (*set_array)(struct uvc_control_mapping *mapping, const u8 *data_in,
> > + u8 *data);
>
> Wouldn't those operations be better names get_compound and set_compound ?
>

Agreed. Will rename to get_compound and set_compound.

Best,
Yunke

> > };
> >
> > struct uvc_control {
>
> --
> Regards,
>
> Laurent Pinchart