Re: [PATCH v16 19/32] v4l: async: Ensure only unique fwnodes are registered to notifiers

["Niklas Söderlund" <niklas.soderlund@ragnatech.se>]

Hi Sakari,

On 2017-10-27 13:06:09 +0300, Sakari Ailus wrote:
> Hi Niklas,
> 
> On Fri, Oct 27, 2017 at 11:52:27AM +0200, Niklas Söderlund wrote:
> > Hi Sakari,
> > 
> > Thanks for your patch.
> > 
> > On 2017-10-26 10:53:29 +0300, Sakari Ailus wrote:
> > > While registering a notifier, check that each newly added fwnode is
> > > unique, and return an error if it is not. Also check that a newly added
> > > notifier does not have the same fwnodes twice.
> > > 
> > > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > > Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
> > > ---
> > >  drivers/media/v4l2-core/v4l2-async.c | 82 +++++++++++++++++++++++++++++++++---
> > >  1 file changed, 77 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
> > > index ed539c4fd5dc..b4e88eef195f 100644
> > > --- a/drivers/media/v4l2-core/v4l2-async.c
> > > +++ b/drivers/media/v4l2-core/v4l2-async.c
> > > @@ -308,8 +308,71 @@ static void v4l2_async_notifier_unbind_all_subdevs(
> > >  	notifier->parent = NULL;
> > >  }
> > >  
> > > +/* See if an fwnode can be found in a notifier's lists. */
> > > +static bool __v4l2_async_notifier_fwnode_has_async_subdev(
> > > +	struct v4l2_async_notifier *notifier, struct fwnode_handle *fwnode)
> > > +{
> > > +	struct v4l2_async_subdev *asd;
> > > +	struct v4l2_subdev *sd;
> > > +
> > > +	list_for_each_entry(asd, &notifier->waiting, list) {
> > > +		if (asd->match_type != V4L2_ASYNC_MATCH_FWNODE)
> > > +			continue;
> > > +
> > > +		if (asd->match.fwnode.fwnode == fwnode)
> > > +			return true;
> > > +	}
> > > +
> > > +	list_for_each_entry(sd, &notifier->done, async_list) {
> > > +		if (WARN_ON(!sd->asd))
> > > +			continue;
> > > +
> > > +		if (sd->asd->match_type != V4L2_ASYNC_MATCH_FWNODE)
> > > +			continue;
> > > +
> > > +		if (sd->asd->match.fwnode.fwnode == fwnode)
> > > +			return true;
> > > +	}
> > > +
> > > +	return false;
> > > +}
> > > +
> > > +/*
> > > + * Find out whether an async sub-device was set up for an fwnode already or
> > > + * whether it exists in a given notifier before @this_index.
> > > + */
> > > +static bool v4l2_async_notifier_fwnode_has_async_subdev(
> > > +	struct v4l2_async_notifier *notifier, struct fwnode_handle *fwnode,
> > > +	unsigned int this_index)
> > > +{
> > > +	unsigned int j;
> > > +
> > > +	lockdep_assert_held(&list_lock);
> > > +
> > > +	/* Check that an fwnode is not being added more than once. */
> > > +	for (j = 0; j < this_index; j++) {
> > > +		struct v4l2_async_subdev *asd = notifier->subdevs[this_index];
> > > +		struct v4l2_async_subdev *other_asd = notifier->subdevs[j];
> > > +
> > > +		if (other_asd->match_type == V4L2_ASYNC_MATCH_FWNODE &&
> > > +		    asd->match.fwnode.fwnode ==
> > > +		    other_asd->match.fwnode.fwnode)
> > > +			return true;
> > > +	}
> > > +
> > > +	/* Check than an fwnode did not exist in other notifiers. */
> > > +	list_for_each_entry(notifier, &notifier_list, list)
> > > +		if (__v4l2_async_notifier_fwnode_has_async_subdev(
> > > +			    notifier, fwnode))
> > > +			return true;
> > > +
> > > +	return false;
> > > +}
> > > +
> > >  static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
> > >  {
> > > +	struct device *dev =
> > > +		notifier->v4l2_dev ? notifier->v4l2_dev->dev : NULL;
> > >  	struct v4l2_async_subdev *asd;
> > >  	int ret;
> > >  	int i;
> > > @@ -320,6 +383,8 @@ static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
> > >  	INIT_LIST_HEAD(&notifier->waiting);
> > >  	INIT_LIST_HEAD(&notifier->done);
> > >  
> > > +	mutex_lock(&list_lock);
> > > +
> > >  	for (i = 0; i < notifier->num_subdevs; i++) {
> > >  		asd = notifier->subdevs[i];
> > >  
> > > @@ -327,19 +392,25 @@ static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
> > >  		case V4L2_ASYNC_MATCH_CUSTOM:
> > >  		case V4L2_ASYNC_MATCH_DEVNAME:
> > >  		case V4L2_ASYNC_MATCH_I2C:
> > > +			break;
> > >  		case V4L2_ASYNC_MATCH_FWNODE:
> > > +			if (v4l2_async_notifier_fwnode_has_async_subdev(
> > > +				    notifier, asd->match.fwnode.fwnode, i)) {
> > > +				dev_err(dev,
> > > +					"fwnode has already been registered or in notifier's subdev list\n");
> > > +				ret = -EEXIST;
> > > +				goto out_unlock;
> > 
> > You store the error code in ret before the jump, but in the out_unlock 
> > path ret is not considered and 0 is always returned.
> > 
> > > +			}
> > >  			break;
> > >  		default:
> > > -			dev_err(notifier->v4l2_dev ? notifier->v4l2_dev->dev : NULL,
> > > -				"Invalid match type %u on %p\n",
> > > +			dev_err(dev, "Invalid match type %u on %p\n",
> > >  				asd->match_type, asd);
> > > -			return -EINVAL;
> > > +			ret = -EINVAL;
> > > +			goto out_unlock;
> > 
> > Same here.
> 
> Good catch! How about this change on top of the patch? It makes return
> value checks a little bit safer, too.

I'm happy whit this change, feel free to add

Acked-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

> 
> diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
> index b4e88eef195f..a33a68e5417b 100644
> --- a/drivers/media/v4l2-core/v4l2-async.c
> +++ b/drivers/media/v4l2-core/v4l2-async.c
> @@ -412,12 +412,13 @@ static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
>  	}
>  
>  	ret = v4l2_async_notifier_try_all_subdevs(notifier);
> -	if (ret)
> +	if (ret < 0)
>  		goto err_unbind;
>  
>  	ret = v4l2_async_notifier_try_complete(notifier);
> -	if (ret)
> +	if (ret < 0)
>  		goto err_unbind;
> +	ret = 0;
>  
>  	/* Keep also completed notifiers on the list */
>  	list_add(&notifier->list, &notifier_list);
> @@ -425,7 +426,7 @@ static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
>  out_unlock:
>  	mutex_unlock(&list_lock);
>  
> -	return 0;
> +	return ret;
>  
>  err_unbind:
>  	/*
> 
> > 
> > >  		}
> > >  		list_add_tail(&asd->list, &notifier->waiting);
> > >  	}
> > >  
> > > -	mutex_lock(&list_lock);
> > > -
> > >  	ret = v4l2_async_notifier_try_all_subdevs(notifier);
> > >  	if (ret)
> > >  		goto err_unbind;
> > > @@ -351,6 +422,7 @@ static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
> > >  	/* Keep also completed notifiers on the list */
> > >  	list_add(&notifier->list, &notifier_list);
> > >  
> > > +out_unlock:
> > >  	mutex_unlock(&list_lock);
> > >  
> > >  	return 0;
> 
> -- 
> Sakari Ailus
> e-mail: sakari.ailus@iki.fi

-- 
Regards,
Niklas Söderlund