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 <hverkuil-cisco@xxxxxxxxx>
> >> Reported-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> >> 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.
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)
