From 5c7b25b90d36942c524d06522ebaf0510a75592a Mon Sep 17 00:00:00 2001
From: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Date: Fri, 7 Jun 2013 12:45:11 -0300
Subject: [media] media: Add support for circular graph traversal

The graph traversal API (media_entity_graph_walk_*) doesn't support
cyclic graphs and will fail to correctly walk a graph when circular
links exist. Support circular graph traversal by checking whether an
entity has already been visited before pushing it to the stack.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
---
 include/media/media-entity.h | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'include/media')

diff --git a/include/media/media-entity.h b/include/media/media-entity.h
index 06bacf937d61..10df55187981 100644
--- a/include/media/media-entity.h
+++ b/include/media/media-entity.h
@@ -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;
 };
 
-- 
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