Re: [PATCH v2 07/22] media: Amend media graph walk API by init and cleanup functions

[Mauro Carvalho Chehab <mchehab@osg.samsung.com>]

Em Sun, 29 Nov 2015 21:20:08 +0200
Sakari Ailus <sakari.ailus@iki.fi> escreveu:

> Add media_entity_graph_walk_init() and media_entity_graph_walk_cleanup()
> functions in order to dynamically allocate memory for the graph. This is
> not done in media_entity_graph_walk_start() as there are situations where
> e.g. correct error handling, that itself may not fail, requires successful
> graph walk.

looks ok to me.

> 
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
>  drivers/media/media-entity.c | 39 ++++++++++++++++++++++++++++++++++-----
>  include/media/media-entity.h |  5 ++++-
>  2 files changed, 38 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
> index 667ab32..bf3c31f 100644
> --- a/drivers/media/media-entity.c
> +++ b/drivers/media/media-entity.c
> @@ -353,14 +353,44 @@ static struct media_entity *stack_pop(struct media_entity_graph *graph)
>  #define stack_top(en)	((en)->stack[(en)->top].entity)
>  
>  /**
> + * media_entity_graph_walk_init - Allocate resources for graph walk
> + * @graph: Media graph structure that will be used to walk the graph
> + * @mdev: Media device
> + *
> + * Reserve resources for graph walk in media device's current
> + * state. The memory must be released using
> + * media_entity_graph_walk_free().
> + *
> + * Returns error on failure, zero on success.
> + */
> +__must_check int media_entity_graph_walk_init(
> +	struct media_entity_graph *graph, struct media_device *mdev)
> +{
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(media_entity_graph_walk_init);
> +
> +/**
> + * media_entity_graph_walk_cleanup - Release resources related to graph walking
> + * @graph: Media graph structure that was used to walk the graph
> + */
> +void media_entity_graph_walk_cleanup(struct media_entity_graph *graph)
> +{
> +}
> +EXPORT_SYMBOL_GPL(media_entity_graph_walk_cleanup);
> +
> +/**
>   * media_entity_graph_walk_start - Start walking the media graph at a given entity
>   * @graph: Media graph structure that will be used to walk the graph
>   * @entity: Starting entity
>   *
> - * This function initializes the graph traversal structure to walk the entities
> - * graph starting at the given entity. The traversal structure must not be
> - * modified by the caller during graph traversal. When done the structure can
> - * safely be freed.
> + * Before using this function, media_entity_graph_walk_init() must be
> + * used to allocate resources used for walking the graph. This
> + * function initializes the graph traversal structure to walk the
> + * entities graph starting at the given entity. The traversal
> + * structure must not be modified by the caller during graph
> + * traversal. After the graph walk, the resources must be released
> + * using media_entity_graph_walk_cleanup().
>   */
>  void media_entity_graph_walk_start(struct media_entity_graph *graph,
>  				   struct media_entity *entity)
> @@ -377,7 +407,6 @@ void media_entity_graph_walk_start(struct media_entity_graph *graph,
>  }
>  EXPORT_SYMBOL_GPL(media_entity_graph_walk_start);
>  
> -
>  /**
>   * media_entity_graph_walk_next - Get the next entity in the graph
>   * @graph: Media graph structure
> diff --git a/include/media/media-entity.h b/include/media/media-entity.h
> index 4b5ca39..f0652e2 100644
> --- a/include/media/media-entity.h
> +++ b/include/media/media-entity.h
> @@ -506,8 +506,11 @@ struct media_pad *media_entity_remote_pad(struct media_pad *pad);
>  struct media_entity *media_entity_get(struct media_entity *entity);
>  void media_entity_put(struct media_entity *entity);
>  
> +__must_check int media_entity_graph_walk_init(
> +	struct media_entity_graph *graph, struct media_device *mdev);
> +void media_entity_graph_walk_cleanup(struct media_entity_graph *graph);
>  void media_entity_graph_walk_start(struct media_entity_graph *graph,
> -		struct media_entity *entity);
> +				   struct media_entity *entity);
>  struct media_entity *
>  media_entity_graph_walk_next(struct media_entity_graph *graph);
>  __must_check int media_entity_pipeline_start(struct media_entity *entity,