Re: [PATCH v16.1 19/32] v4l: async: Ensure only unique fwnodes are registered to notifiers

[Sebastian Reichel]

Hi,

On Fri, Oct 27, 2017 at 01:53:09PM +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.ai...@linux.intel.com>
> Acked-by: Hans Verkuil <hans.verk...@cisco.com>
> Acked-by: Niklas Söderlund <niklas.soderlund+rene...@ragnatech.se>
> ---
>  drivers/media/v4l2-core/v4l2-async.c | 89 
> ++++++++++++++++++++++++++++++++----
>  1 file changed, 81 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-async.c 
> b/drivers/media/v4l2-core/v4l2-async.c
> index ed539c4fd5dc..a33a68e5417b 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];
>  
> @@ -327,33 +392,41 @@ 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;
> +                     }
>                       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;
>               }
>               list_add_tail(&asd->list, &notifier->waiting);
>       }
>  
> -     mutex_lock(&list_lock);
> -
>       ret = v4l2_async_notifier_try_all_subdevs(notifier);
> -     if (ret)
> +     if (ret < 0)
>               goto err_unbind;

the error path does no unlock?

>       ret = v4l2_async_notifier_try_complete(notifier);
> -     if (ret)
> +     if (ret < 0)
>               goto err_unbind;

dito

> +     ret = 0;
>  
>       /* Keep also completed notifiers on the list */
>       list_add(&notifier->list, &notifier_list);
>  
> +out_unlock:
>       mutex_unlock(&list_lock);
>  
> -     return 0;
> +     return ret;
>  
>  err_unbind:
>       /*

Otherwise:

Reviewed-by: Sebastian Reichel <sebastian.reic...@collabora.co.uk>

-- Sebastian

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