On 6/29/19 3:13 PM, Janusz Krzysztofik wrote:
> On Saturday, June 29, 2019 2:57:09 P.M. CEST 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 <[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.
>
> Unless this is a subdevice which doesn't support MC, was updated in the past
> to use pad ops instead of depreciated video ops, so it actually has pad ops
> even if it has num_pads == 0, and is built by a user with
> CONFIG_MEDIA_CONTROLLER=y for some reason.
That's fine. Then it just checks if pad == 0, which is OK for such drivers.
The issue here is a MC-enabled subdev with pad ops, but that really has no pads
for some reason, so check_pad() would always have to return -EINVAL.
Regards,
Hans
>
> Thanks,
> Janusz
>
>>
>>> 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)
>
>
>
>
