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

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Date:   Wed, 24 Aug 2016 15:49:34 +0200
From:   Alban Bedel <alban.bedel@...onic-design.de>
To:     Hans Verkuil <hverkuil@...all.nl>
Cc:     Alban Bedel <alban.bedel@...onic-design.de>,
        Javier Martinez Canillas <javier@....samsung.com>,
        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 Fri, 1 Jul 2016 13:55:44 +0200
Hans Verkuil <hverkuil@...all.nl> wrote:

> On 05/11/2016 06:32 PM, Alban Bedel wrote:
> > 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.  
> 
> I haven't heard anything back about this. Did you manage to test it?

Yes, that's working fine. Sorry for the delay, I'm sending the v2 patch.

Alban


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