Re: [PATCH 2/2] media: v4l: async: Properly check for a notifier initialised or registered

[Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>]

Hi Alexander,

On Thu, Mar 14, 2024 at 03:04:44PM +0100, Alexander Stein wrote:
> Hi Sakari,
> 
> I suppose on of your intentions of this series is to replace my patch, no?

No, these are somewhat unrelated issues.

> 
> Am Montag, 11. März 2024, 13:17:41 CET schrieb Sakari Ailus:
> > Properly check that a notifier was never initialised or register. This can
> > now be done by looking at the entry in the notifier list, not the V4L2
> > device or sub-device that are set in the initialiser now.
> > 
> > Fixes: b8ec754ae4c5 ("media: v4l: async: Set v4l2_device and subdev in async notifier init")
> > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> > ---
> >  drivers/media/v4l2-core/v4l2-async.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
> > index 2ff35d5d60f2..3b43d6285dfe 100644
> > --- a/drivers/media/v4l2-core/v4l2-async.c
> > +++ b/drivers/media/v4l2-core/v4l2-async.c
> > @@ -630,12 +630,14 @@ EXPORT_SYMBOL(v4l2_async_nf_register);
> >  static void
> >  __v4l2_async_nf_unregister(struct v4l2_async_notifier *notifier)
> >  {
> > -	if (!notifier || (!notifier->v4l2_dev && !notifier->sd))
> > +	/* Return here if the notifier is never initialised or registered. */
> > +	if (!notifier->notifier_entry.next ||
> 
> I don't like the idea checking the next pointer of a list.
> Despite that it's not even necessary.

Actually I think we can drop the above change. But the list_del_init()
below is still necessary.

> 
> Best regards,
> Alexander
> 
> > +	    list_empty(&notifier->notifier_entry))
> >  		return;
> >  
> >  	v4l2_async_nf_unbind_all_subdevs(notifier);
> >  
> > -	list_del(&notifier->notifier_entry);
> > +	list_del_init(&notifier->notifier_entry);
> >  }
> >  
> >  void v4l2_async_nf_unregister(struct v4l2_async_notifier *notifier)
> > 
> 
> 

-- 
Regards,

Sakari Ailus