Re: [PATCH v2] v4l2-subdev: Return -EOPNOTSUPP for unsupported pad type in call_get_frame_desc()

[Sakari Ailus]

Hi Laurent,

On Mon, Oct 07, 2024 at 09:16:54PM +0300, Laurent Pinchart wrote:
> Hi Prabhakar,
> 
> Thank you for the patch.
> 
> On Mon, Oct 07, 2024 at 01:38:09PM +0100, Prabhakar wrote:
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> > 
> > The `get_frame_desc()` operation should always be called on a source pad,
> > which is indicated by the `MEDIA_PAD_FL_SOURCE` flag. This patch adds a
> > check in `call_get_frame_desc()` to ensure that the `MEDIA_PAD_FL_SOURCE`
> > flag is set for the pad before invoking `get_frame_desc()`. If the pad is
> > not a source pad, the function will return an `-EOPNOTSUPP` error,
> > signaling that the operation is not supported on non-source pads.
> > 
> > Suggested-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> > ---
> > v1->v2
> > - Added a check for CONFIG_MEDIA_CONTROLLER, as the `entity` member in 
> >   `struct v4l2_subdev` is only available when CONFIG_MEDIA_CONTROLLER
> >   is enabled.
> > ---
> >  drivers/media/v4l2-core/v4l2-subdev.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> > index de9ac67574bb..446fbc3805c7 100644
> > --- a/drivers/media/v4l2-core/v4l2-subdev.c
> > +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> > @@ -325,6 +325,11 @@ static int call_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
> >  	unsigned int i;
> >  	int ret;
> >  
> > +#if defined(CONFIG_MEDIA_CONTROLLER)
> > +	if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
> 
> As this should really not happen, I wonder if we shouldn't be more
> vocal:
> 
> 	if (WARN_ON(!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE)))
> 
> Sakari, what do you think ? Either way,

I wouldn't as this is probably going to be user-triggerable. The problem
shouldn't be too hard to find out either.

> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>

Thanks!

-- 
Kind regards,

Sakari Ailus