Re: [PATCH v2 12/12] media: mc: Check pad flag validity

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

On Tue, Sep 19, 2023 at 10:24:32AM +0000, Sakari Ailus wrote:
> On Mon, Sep 18, 2023 at 04:48:02PM +0300, Laurent Pinchart wrote:
> > On Mon, Sep 18, 2023 at 03:51:38PM +0300, Sakari Ailus wrote:
> > > Check the validity of pad flags on entity init. Exactly one of the flags
> > > must be set.
> > > 
> > > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > > ---
> > >  drivers/media/mc/mc-entity.c | 20 ++++++++++++++++++--
> > >  1 file changed, 18 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
> > > index 83468d4a440b..38d5bbae33d7 100644
> > > --- a/drivers/media/mc/mc-entity.c
> > > +++ b/drivers/media/mc/mc-entity.c
> > > @@ -195,8 +195,9 @@ int media_entity_pads_init(struct media_entity *entity, u16 num_pads,
> > >  			   struct media_pad *pads)
> > >  {
> > >  	struct media_device *mdev = entity->graph_obj.mdev;
> > > -	struct media_pad *iter;
> > > +	struct media_pad *iter, *iter2;
> > >  	unsigned int i = 0;
> > > +	int ret = 0;
> > >  
> > >  	if (num_pads >= MEDIA_ENTITY_MAX_PADS)
> > >  		return -E2BIG;
> > > @@ -210,15 +211,30 @@ int media_entity_pads_init(struct media_entity *entity, u16 num_pads,
> > >  	media_entity_for_each_pad(entity, iter) {
> > >  		iter->entity = entity;
> > >  		iter->index = i++;
> > > +
> > > +		if (hweight32(iter->flags & (MEDIA_PAD_FL_SINK |
> > > +					     MEDIA_PAD_FL_SOURCE)) != 1) {
> > > +			ret = -EINVAL;
> > > +			break;
> > > +		}
> > > +
> > >  		if (mdev)
> > >  			media_gobj_create(mdev, MEDIA_GRAPH_PAD,
> > >  					  &iter->graph_obj);
> > >  	}
> > >  
> > > +	if (ret && mdev) {
> > > +		media_entity_for_each_pad(entity, iter2) {
> > > +			if (iter2 == iter)
> > > +				break;
> > > +			media_gobj_destroy(&iter->graph_obj);
> > 
> > Wrong iterator.
> > 
> > Instead of using a second iterator, which can be error-prone as shown
> > here, how about breaking when !iter->graph_obj.mdev, which indicates an
> > uninitialized object ?
> 
> media_gobj_destroy() is actually a no-op if it hasn't been initialised
> (created).

I'm fine calling it unconditionally too.

> It'd be still cleaner to make the pad flag checks first and only then call
> media_gobj_create() on them. But if someone needs something more in the
> future, then that doesn't mix as well anymore.
> 
> Both are fine IMO.
> 
> > > +		}
> > > +	}
> > > +
> > >  	if (mdev)
> > >  		mutex_unlock(&mdev->graph_mutex);
> > >  
> > > -	return 0;
> > > +	return ret;
> > >  }
> > >  EXPORT_SYMBOL_GPL(media_entity_pads_init);
> > >  

-- 
Regards,

Laurent Pinchart