Re: [PATCH v7 17/19] media: mc: Check pad flag validity

From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>,
	linux-media@vger.kernel.org, laurent.pinchart@ideasonboard.com,
	Tianshu Qiu <tian.shu.qiu@intel.com>,
	Bingbu Cao <bingbu.cao@intel.com>,
	Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>,
	Jacopo Mondi <jacopo+renesas@jmondi.org>,
	Rui Miguel Silva <rmfrfs@gmail.com>,
	Martin Kepplinger <martink@posteo.de>,
	Tomasz Figa <tomasz.figa@gmail.com>
Subject: Re: [PATCH v7 17/19] media: mc: Check pad flag validity
Date: Sat, 3 Feb 2024 14:28:34 +0900	[thread overview]
Message-ID: <20240203052834.GC69174@google.com> (raw)
In-Reply-To: <Zbt645NhD4Gv3t1c@kekkonen.localdomain>

On (24/02/01 11:05), Sakari Ailus wrote:
[..]
> > > > >  	if (num_pads >= MEDIA_ENTITY_MAX_PADS)
> > > > >  		return -E2BIG;
> > > > > @@ -210,15 +211,27 @@ 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;
> > > > 
> > > > Can we please have some sort of WARN_ON() or pr_err() here?
> > > > This is a pretty big change.
> > > 
> > > Doing proper input validation is hardly anything unusual, is it?
> > 
> > Well, function requirements change quite significantly, to the point
> > that drivers that worked before won't work after.
> > 
> > > I'm fine with a WARN_ON() though, I'll add that to v8.
> > 
> > Thanks!
> 
> Actually this was a patchset that was merged quite some time ago. I'll
> post separate patch on this.

Ack.

I just debugged a driver that miraculously stopped working, and it
turned out to be because of this media_entity_pads_init() change.
I think I would have benefited from WARN_ON() or pr_err() there.