[media] media: Move media graph state for streamon/off to the pipeline

The struct media_entity_graph was allocated in the stack, limiting the
number of entities that could be reasonably allocated. Instead, move the
struct to struct media_pipeline which is typically allocated using
kmalloc() instead.

The intent is to keep the enumeration around for later use for the
duration of the streaming. As streaming is eventually stopped, an
unfortunate memory allocation failure would prevent stopping the
streaming. As no memory will need to be allocated, the problem is avoided
altogether.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/media-entity.c

@@ -349,16 +349,16 @@ __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_graph *graph = &pipe->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);
+	media_entity_graph_walk_start(graph, entity);
 
-	while ((entity = media_entity_graph_walk_next(&graph))) {
+	while ((entity = media_entity_graph_walk_next(graph))) {
 		DECLARE_BITMAP(active, MEDIA_ENTITY_MAX_PADS);
 		DECLARE_BITMAP(has_no_links, MEDIA_ENTITY_MAX_PADS);
 
@@ -439,9 +439,9 @@ error:
 	 * Link validation on graph failed. We revert what we did and
 	 * return the error.
 	 */
-	media_entity_graph_walk_start(&graph, entity_err);
+	media_entity_graph_walk_start(graph, entity_err);
 
-	while ((entity_err = media_entity_graph_walk_next(&graph))) {
+	while ((entity_err = media_entity_graph_walk_next(graph))) {
 		entity_err->stream_count--;
 		if (entity_err->stream_count == 0)
 			entity_err->pipe = NULL;
@@ -463,13 +463,13 @@ EXPORT_SYMBOL_GPL(media_entity_pipeline_start);
 void media_entity_pipeline_stop(struct media_entity *entity)
 {
 	struct media_device *mdev = entity->graph_obj.mdev;
-	struct media_entity_graph graph;
+	struct media_entity_graph *graph = &entity->pipe->graph;
 
 	mutex_lock(&mdev->graph_mutex);
 
-	media_entity_graph_walk_start(&graph, entity);
+	media_entity_graph_walk_start(graph, entity);
 
-	while ((entity = media_entity_graph_walk_next(&graph))) {
+	while ((entity = media_entity_graph_walk_next(graph))) {
 		entity->stream_count--;
 		if (entity->stream_count == 0)
 			entity->pipe = NULL;

include/media/media-entity.h

@@ -116,7 +116,13 @@ struct media_entity_graph {
 	int top;
 };
 
+/*
+ * struct media_pipeline - Media pipeline related information
+ *
+ * @graph:	Media graph walk during pipeline start / stop
+ */
 struct media_pipeline {
+	struct media_entity_graph graph;
 };
 
 /**