[alsa-devel] [PATCH MC Next Gen 06/20] media: Media Controller non-locking __media_entity_pipeline_start/stop()

[Shuah Khan]

Add non-locking __media_entity_pipeline_start/stop() interfaces
to be called from code paths that hold the graph_mutex. For this
change, the media_entity_pipeline_start() routine is renamed to
__media_entity_pipeline_start() minus the graph_mutex lock and
unlock. media_entity_pipeline_start() now calls the non-locking
__media_entity_pipeline_start() holding the graph_lock. The stop
interface, media_entity_pipeline_stop() routine is renamed to
__media_entity_pipeline_stop() minus the graph_mutex lock and
unlock. media_entity_pipeline_stop() now calls the non-locking
__media_entity_pipeline_stop() holding the graph_lock.

Signed-off-by: Shuah Khan <shuahkh at osg.samsung.com>
---
 drivers/media/media-entity.c | 45 +++++++++++++++++++++++++++++---------------
 include/media/media-entity.h |  3 +++
 2 files changed, 33 insertions(+), 15 deletions(-)

diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
index 49a8755..4bb824b 100644
--- a/drivers/media/media-entity.c
+++ b/drivers/media/media-entity.c
@@ -397,7 +397,7 @@ EXPORT_SYMBOL_GPL(media_entity_graph_walk_next);
  */
 
 /**
- * media_entity_pipeline_start - Mark a pipeline as streaming
+ * __media_entity_pipeline_start - Mark a pipeline as streaming
  * @entity: Starting entity
  * @pipe: Media pipeline to be assigned to all entities in the pipeline.
  *
@@ -408,19 +408,18 @@ EXPORT_SYMBOL_GPL(media_entity_graph_walk_next);
  * Calls to this function can be nested, in which case the same number of
  * media_entity_pipeline_stop() calls will be required to stop streaming. The
  * pipeline pointer must be identical for all nested calls to
- * media_entity_pipeline_start().
+ * __media_entity_pipeline_start().
+ * User is expected to hold the graph_mutex. If not user can call
+ * media_entity_pipeline_start()
  */
-__must_check int media_entity_pipeline_start(struct media_entity *entity,
-					     struct media_pipeline *pipe)
+__must_check int __media_entity_pipeline_start(struct media_entity *entity,
+						struct media_pipeline *pipe)
 {
-	struct media_device *mdev = entity->graph_obj.mdev;
 	struct media_entity_graph graph;
 	struct media_entity *entity_err = entity;
 	struct media_link *link;
 	int ret;
 
-	mutex_lock(&mdev->graph_mutex);
-
 	media_entity_graph_walk_start(&graph, entity);
 
 	while ((entity = media_entity_graph_walk_next(&graph))) {
@@ -490,8 +489,6 @@ __must_check int media_entity_pipeline_start(struct media_entity *entity,
 		}
 	}
 
-	mutex_unlock(&mdev->graph_mutex);
-
 	return 0;
 
 error:
@@ -517,14 +514,25 @@ error:
 			break;
 	}
 
-	mutex_unlock(&mdev->graph_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__media_entity_pipeline_start);
+
+__must_check int media_entity_pipeline_start(struct media_entity *entity,
+					     struct media_pipeline *pipe)
+{
+	struct media_device *mdev = entity->graph_obj.mdev;
+	int ret;
 
+	mutex_lock(&mdev->graph_mutex);
+	ret = __media_entity_pipeline_start(entity, pipe);
+	mutex_unlock(&mdev->graph_mutex);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(media_entity_pipeline_start);
 
 /**
- * media_entity_pipeline_stop - Mark a pipeline as not streaming
+ * __media_entity_pipeline_stop - Mark a pipeline as not streaming
  * @entity: Starting entity
  *
  * Mark all entities connected to a given entity through enabled links, either
@@ -534,14 +542,13 @@ EXPORT_SYMBOL_GPL(media_entity_pipeline_start);
  * If multiple calls to media_entity_pipeline_start() have been made, the same
  * number of calls to this function are required to mark the pipeline as not
  * streaming.
+ * User is expected to hold the graph_mutex. If not user can call
+ * media_entity_pipeline_stop()
  */
-void media_entity_pipeline_stop(struct media_entity *entity)
+void __media_entity_pipeline_stop(struct media_entity *entity)
 {
-	struct media_device *mdev = entity->graph_obj.mdev;
 	struct media_entity_graph graph;
 
-	mutex_lock(&mdev->graph_mutex);
-
 	media_entity_graph_walk_start(&graph, entity);
 
 	while ((entity = media_entity_graph_walk_next(&graph))) {
@@ -552,7 +559,15 @@ void media_entity_pipeline_stop(struct media_entity *entity)
 				entity->pipe = NULL;
 		}
 	}
+}
+EXPORT_SYMBOL_GPL(__media_entity_pipeline_stop);
 
+void media_entity_pipeline_stop(struct media_entity *entity)
+{
+	struct media_device *mdev = entity->graph_obj.mdev;
+
+	mutex_lock(&mdev->graph_mutex);
+	__media_entity_pipeline_stop(entity);
 	mutex_unlock(&mdev->graph_mutex);
 }
 EXPORT_SYMBOL_GPL(media_entity_pipeline_stop);
diff --git a/include/media/media-entity.h b/include/media/media-entity.h
index 44ab153..3b971f2 100644
--- a/include/media/media-entity.h
+++ b/include/media/media-entity.h
@@ -365,8 +365,11 @@ void media_entity_graph_walk_start(struct media_entity_graph *graph,
 		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,
+						struct media_pipeline *pipe);
 __must_check int media_entity_pipeline_start(struct media_entity *entity,
 					     struct media_pipeline *pipe);
+void __media_entity_pipeline_stop(struct media_entity *entity);
 void media_entity_pipeline_stop(struct media_entity *entity);
 
 struct media_intf_devnode *
-- 
2.1.4