[v3,07/23] media: Amend media graph walk API by init and cleanup functions
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Message ID 1450272758-29446-8-git-send-email-sakari.ailus@iki.fi
State New
Headers show

Commit Message

Sakari Ailus Dec. 16, 2015, 1:32 p.m. UTC
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.

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(-)

Patch
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diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
index 786a01f..d63204e 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 9315158..eaddcba 100644
--- a/include/media/media-entity.h
+++ b/include/media/media-entity.h
@@ -511,8 +511,11 @@  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,