On 6/29/19 2:57 PM, Hans Verkuil wrote:
> 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 <hverkuil-ci...@xs4all.nl>
>>> Reported-by: Niklas Söderlund <niklas.soderlund+rene...@ragnatech.se>
>>> 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.
Sakari, do you think it is ever possible that an entity may have pad ops,
but num_pads goes at some point to 0?
If so, then we can check for sd->entity.function != 0. All MC subdevs must
set that to a non-0 value, otherwise the core will issue a WARN_ON. I think
it is the only reliable indicator that can be used.
Regards,
Hans
>
>>
>> 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)
>>
>>
>>
>>
>
