On 6/29/19 2:06 PM, Janusz Krzysztofik wrote:
> Hi Hans,
>
> On Saturday, June 29, 2019 12:00:24 P.M. CEST Hans Verkuil wrote:
>> sd->entity.graph_obj.mdev can be NULL when this function is called, and
>> that breaks existing drivers (rcar-vin, but probably others as well).
>>
>> Check if sd->entity.num_pads is non-zero instead since that doesn't depend
>> on mdev.
>>
>> Signed-off-by: Hans Verkuil <[email protected]>
>> Reported-by: Niklas Söderlund <[email protected]>
>> Fixes: a8fa55078a77 ("media: v4l2-subdev: Verify arguments in
>> v4l2_subdev_call()") ---
>> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c
>> b/drivers/media/v4l2-core/v4l2-subdev.c index 21fb90d66bfc..bc32fc1e0c0b
>> 100644
>> --- a/drivers/media/v4l2-core/v4l2-subdev.c
>> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
>> @@ -124,16 +124,11 @@ static inline int check_which(__u32 which)
>> static inline int check_pad(struct v4l2_subdev *sd, __u32 pad)
>> {
>> #if defined(CONFIG_MEDIA_CONTROLLER)
>> - if (sd->entity.graph_obj.mdev) {
>> - if (pad >= sd->entity.num_pads)
>> - return -EINVAL;
>> - return 0;
>> - }
>> + if (sd->entity.num_pads)
>
> This reverts a change introduced on Sakari's request in v7 of the series
> which
> is the source of the regression. The intention was to fail if num_pads == 0
> on a valid media entity. Maybe we should still keep that restriction and fail
> in case mdev is not NULL? In other words:
>
> - if (sd->entity.num_pads)
> + if (sd->entity.num_pads || sd->entity.graph_obj.mdev)
If an entity has no pads, then it doesn't have pad ops either and this function
would never be called.
>
> Thanks,
> Janusz
>
>> + return pad >= sd->entity.num_pads ? -EINVAL : 0;
>
> This and below look like coding style changes, not related strictly to the
> merit. Shouldn't they rather be split into a separate patch?
I'll post a v2, the diff is a lot smaller. I might post a follow-up patch
to use ? : since that's a lot shorter code.
Regards,
Hans
>
> BTW, the current coding style follows original implementation of check_*
> functions present before that series was introduced. Maybe it would be
> better
> to keep them unified, i.e., either as is or all updated with the new style.
>
> Thanks,
> Janusz
>
>> #endif
>> /* allow pad 0 on subdevices not registered as media entities */
>> - if (pad > 0)
>> - return -EINVAL;
>> - return 0;
>> + return pad ? -EINVAL : 0;
>> }
>>
>> static int check_cfg(__u32 which, struct v4l2_subdev_pad_config *cfg)
>
>
>
>
