[media] media: Add support for circular graph traversal (5c7b25b9) · Commits · 戴 / test

drivers/media/media-entity.c

+11 −3

Original line number	Diff line number	Diff line
		@@ -20,6 +20,7 @@
		* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
		*/

		#include <linux/bitmap.h>
		#include <linux/module.h>
		#include <linux/slab.h>
		#include <media/media-entity.h>
		@@ -121,7 +122,6 @@ static struct media_entity stack_pop(struct media_entity_graph graph)
		return entity;
		}

		#define stack_peek(en) ((en)->stack[(en)->top - 1].entity)
		#define link_top(en) ((en)->stack[(en)->top].link)
		#define stack_top(en) ((en)->stack[(en)->top].entity)

		@@ -140,6 +140,12 @@ void media_entity_graph_walk_start(struct media_entity_graph *graph,
		{
		graph->top = 0;
		graph->stack[graph->top].entity = NULL;
		bitmap_zero(graph->entities, MEDIA_ENTITY_ENUM_MAX_ID);

		if (WARN_ON(entity->id >= MEDIA_ENTITY_ENUM_MAX_ID))
		return;

		__set_bit(entity->id, graph->entities);
		stack_push(graph, entity);
		}
		EXPORT_SYMBOL_GPL(media_entity_graph_walk_start);
		@@ -180,9 +186,11 @@ media_entity_graph_walk_next(struct media_entity_graph *graph)

		/* Get the entity in the other end of the link . */
		next = media_entity_other(entity, link);
		if (WARN_ON(next->id >= MEDIA_ENTITY_ENUM_MAX_ID))
		return NULL;

		/* Was it the entity we came here from? */
		if (next == stack_peek(graph)) {
		/* Has the entity already been visited? */
		if (__test_and_set_bit(next->id, graph->entities)) {
		link_top(graph)++;
		continue;
		}

+4 −0

Original line number	Diff line number	Diff line
		@@ -23,6 +23,7 @@
		#ifndef _MEDIA_ENTITY_H
		#define _MEDIA_ENTITY_H

		#include <linux/bitops.h>
		#include <linux/list.h>
		#include <linux/media.h>

		@@ -113,12 +114,15 @@ static inline u32 media_entity_subtype(struct media_entity *entity)
		}

		#define MEDIA_ENTITY_ENUM_MAX_DEPTH 16
		#define MEDIA_ENTITY_ENUM_MAX_ID 64

		struct media_entity_graph {
		struct {
		struct media_entity *entity;
		int link;
		} stack[MEDIA_ENTITY_ENUM_MAX_DEPTH];

		DECLARE_BITMAP(entities, MEDIA_ENTITY_ENUM_MAX_ID);
		int top;
		};