Hi Kieran, On Wed, May 17, 2017 at 04:38:14PM +0100, Kieran Bingham wrote: > From: Kieran Bingham <kieran.bingham+rene...@ideasonboard.com> > > Return NULL, if a null entity is parsed for it's v4l2_subdev > > Signed-off-by: Kieran Bingham <kieran.bingham+rene...@ideasonboard.com> > --- > include/media/v4l2-subdev.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h > index 5f1669c45642..72d7f28f38dc 100644 > --- a/include/media/v4l2-subdev.h > +++ b/include/media/v4l2-subdev.h > @@ -829,7 +829,7 @@ struct v4l2_subdev { > }; > > #define media_entity_to_v4l2_subdev(ent) \ > - container_of(ent, struct v4l2_subdev, entity) > + (ent ? container_of(ent, struct v4l2_subdev, entity) : NULL) > #define vdev_to_v4l2_subdev(vdev) \ > ((struct v4l2_subdev *)video_get_drvdata(vdev)) >
The problem with this is that ent is now referenced twice. If the ent macro argument has side effect, this would introduce bugs. It's unlikely, but worth avoiding. Either use a macro or a function. I think I'd use function for there's little use for supporting for const and non-const arguments presumably. A simple static inline function should do. -- Regards, Sakari Ailus e-mail: sakari.ai...@iki.fi XMPP: sai...@retiisi.org.uk