Re: [PATCH v16 17/32] v4l: async: Prepare for async sub-device notifiers

[Niklas Söderlund]

Hi Sakari,

On 2017-10-27 00:10:51 +0200, Niklas Söderlund wrote:
> On 2017-10-26 10:53:27 +0300, Sakari Ailus wrote:
> > Refactor the V4L2 async framework a little in preparation for async
> > sub-device notifiers. This avoids making some structural changes in the
> > patch actually implementing sub-device notifiers, making that patch easier
> > to review.
> > 
> > Signed-off-by: Sakari Ailus <sakari.ai...@linux.intel.com>
> > Acked-by: Hans Verkuil <hans.verk...@cisco.com>
> 
> Acked-by: Niklas Söderlund <niklas.soderlund+rene...@ragnatech.se>

I'm sorry I acted to soon, I think I found a small issue with this 
patch, see bellow. With that fixed feel free to attach my ack.

> 
> > ---
> >  drivers/media/v4l2-core/v4l2-async.c | 71 
> > ++++++++++++++++++++++++++----------
> >  1 file changed, 52 insertions(+), 19 deletions(-)
> > 
> > diff --git a/drivers/media/v4l2-core/v4l2-async.c 
> > b/drivers/media/v4l2-core/v4l2-async.c
> > index 1b536d68cedf..eb31d96254d1 100644
> > --- a/drivers/media/v4l2-core/v4l2-async.c
> > +++ b/drivers/media/v4l2-core/v4l2-async.c
> > @@ -125,12 +125,13 @@ static struct v4l2_async_subdev 
> > *v4l2_async_find_match(
> >  }
> >  
> >  static int v4l2_async_match_notify(struct v4l2_async_notifier *notifier,
> > +                              struct v4l2_device *v4l2_dev,
> >                                struct v4l2_subdev *sd,
> >                                struct v4l2_async_subdev *asd)
> >  {
> >     int ret;
> >  
> > -   ret = v4l2_device_register_subdev(notifier->v4l2_dev, sd);
> > +   ret = v4l2_device_register_subdev(v4l2_dev, sd);
> >     if (ret < 0)
> >             return ret;
> >  
> > @@ -151,6 +152,31 @@ static int v4l2_async_match_notify(struct 
> > v4l2_async_notifier *notifier,
> >     return 0;
> >  }
> >  
> > +/* Test all async sub-devices in a notifier for a match. */
> > +static int v4l2_async_notifier_try_all_subdevs(
> > +   struct v4l2_async_notifier *notifier)
> > +{
> > +   struct v4l2_device *v4l2_dev = notifier->v4l2_dev;
> > +   struct v4l2_subdev *sd, *tmp;
> > +
> > +   list_for_each_entry_safe(sd, tmp, &subdev_list, async_list) {
> > +           struct v4l2_async_subdev *asd;
> > +           int ret;
> > +
> > +           asd = v4l2_async_find_match(notifier, sd);
> > +           if (!asd)
> > +                   continue;
> > +
> > +           ret = v4l2_async_match_notify(notifier, v4l2_dev, sd, asd);
> > +           if (ret < 0) {
> > +                   mutex_unlock(&list_lock);

The mutex should not be unlocked here, as the caller will also unlock it 
if ret is none zero. You fix this in 18/32 so the end result is OK but I 
think its better to fix this in this patch.

> > +                   return ret;
> > +           }
> > +   }
> > +
> > +   return 0;
> > +}
> > +
> >  static void v4l2_async_cleanup(struct v4l2_subdev *sd)
> >  {
> >     v4l2_device_unregister_subdev(sd);
> > @@ -172,18 +198,15 @@ static void v4l2_async_notifier_unbind_all_subdevs(
> >     }
> >  }
> >  
> > -int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
> > -                            struct v4l2_async_notifier *notifier)
> > +static int __v4l2_async_notifier_register(struct v4l2_async_notifier 
> > *notifier)
> >  {
> > -   struct v4l2_subdev *sd, *tmp;
> >     struct v4l2_async_subdev *asd;
> >     int ret;
> >     int i;
> >  
> > -   if (!v4l2_dev || notifier->num_subdevs > V4L2_MAX_SUBDEVS)
> > +   if (notifier->num_subdevs > V4L2_MAX_SUBDEVS)
> >             return -EINVAL;
> >  
> > -   notifier->v4l2_dev = v4l2_dev;
> >     INIT_LIST_HEAD(&notifier->waiting);
> >     INIT_LIST_HEAD(&notifier->done);
> >  
> > @@ -216,18 +239,10 @@ int v4l2_async_notifier_register(struct v4l2_device 
> > *v4l2_dev,
> >  
> >     mutex_lock(&list_lock);
> >  
> > -   list_for_each_entry_safe(sd, tmp, &subdev_list, async_list) {
> > -           int ret;
> > -
> > -           asd = v4l2_async_find_match(notifier, sd);
> > -           if (!asd)
> > -                   continue;
> > -
> > -           ret = v4l2_async_match_notify(notifier, sd, asd);
> > -           if (ret < 0) {
> > -                   mutex_unlock(&list_lock);
> > -                   return ret;
> > -           }
> > +   ret = v4l2_async_notifier_try_all_subdevs(notifier);
> > +   if (ret) {
> > +           mutex_unlock(&list_lock);
> > +           return ret;
> >     }
> >  
> >     if (list_empty(&notifier->waiting)) {
> > @@ -250,6 +265,23 @@ int v4l2_async_notifier_register(struct v4l2_device 
> > *v4l2_dev,
> >  
> >     return ret;
> >  }
> > +
> > +int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
> > +                            struct v4l2_async_notifier *notifier)
> > +{
> > +   int ret;
> > +
> > +   if (WARN_ON(!v4l2_dev))
> > +           return -EINVAL;
> > +
> > +   notifier->v4l2_dev = v4l2_dev;
> > +
> > +   ret = __v4l2_async_notifier_register(notifier);
> > +   if (ret)
> > +           notifier->v4l2_dev = NULL;
> > +
> > +   return ret;
> > +}
> >  EXPORT_SYMBOL(v4l2_async_notifier_register);
> >  
> >  void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier)
> > @@ -324,7 +356,8 @@ int v4l2_async_register_subdev(struct v4l2_subdev *sd)
> >             if (!asd)
> >                     continue;
> >  
> > -           ret = v4l2_async_match_notify(notifier, sd, asd);
> > +           ret = v4l2_async_match_notify(notifier, notifier->v4l2_dev, sd,
> > +                                         asd);
> >             if (ret)
> >                     goto err_unlock;
> >  
> > -- 
> > 2.11.0
> > 
> 
> -- 
> Regards,
> Niklas Söderlund

-- 
Regards,
Niklas Söderlund