linux-kernel - Re: [PATCH] [media] v4l2-async: Always unregister the subdev on failure

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Date:	Wed, 11 May 2016 18:32:52 +0200
From:	Alban Bedel <alban.bedel@...onic-design.de>
To:	Javier Martinez Canillas <javier@....samsung.com>
Cc:	Alban Bedel <alban.bedel@...onic-design.de>,
	linux-media@...r.kernel.org,
	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	Sakari Ailus <sakari.ailus@....fi>,
	Bryan Wu <cooloney@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [media] v4l2-async: Always unregister the subdev on
 failure

On Wed, 11 May 2016 12:22:44 -0400
Javier Martinez Canillas <javier@....samsung.com> wrote:

> Hello Alban,
> 
> On 05/11/2016 11:40 AM, Alban Bedel wrote:
> > In v4l2_async_test_notify() if the registered_async callback or the
> > complete notifier returns an error the subdev is not unregistered.
> > This leave paths where v4l2_async_register_subdev() can fail but
> > leave the subdev still registered.
> > 
> > Add the required calls to v4l2_device_unregister_subdev() to plug
> > these holes.
> > 
> > Signed-off-by: Alban Bedel <alban.bedel@...onic-design.de>
> > ---
> >  drivers/media/v4l2-core/v4l2-async.c | 10 ++++++++--
> >  1 file changed, 8 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
> > index ceb28d4..43393f8 100644
> > --- a/drivers/media/v4l2-core/v4l2-async.c
> > +++ b/drivers/media/v4l2-core/v4l2-async.c
> > @@ -121,13 +121,19 @@ static int v4l2_async_test_notify(struct v4l2_async_notifier *notifier,
> >  
> >  	ret = v4l2_subdev_call(sd, core, registered_async);
> >  	if (ret < 0 && ret != -ENOIOCTLCMD) {
> > +		v4l2_device_unregister_subdev(sd);
> >  		if (notifier->unbind)
> >  			notifier->unbind(notifier, sd, asd);
> >  		return ret;
> >  	}
> >  
> > -	if (list_empty(&notifier->waiting) && notifier->complete)
> > -		return notifier->complete(notifier);
> > +	if (list_empty(&notifier->waiting) && notifier->complete) {
> > +		ret = notifier->complete(notifier);
> > +		if (ret < 0) {
> > +			v4l2_device_unregister_subdev(sd);
> 
> Isn't a call to notifier->unbind() missing here as well?
> 
> Also, I think the error path is becoming too duplicated and complex, so
> maybe we can have a single error path and use goto labels as is common
> in Linux? For example something like the following (not tested) can be
> squashed on top of your change:

Yes, that look better. I'll test it and report tomorrow.

Alban

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