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authorLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>2013-06-07 12:45:11 -0300
committerMauro Carvalho Chehab <m.chehab@samsung.com>2013-08-18 07:16:48 -0300
commit5c7b25b90d36942c524d06522ebaf0510a75592a (patch)
tree979e3f88bf6e507021c28ac3e9236f7d5cc3bfa9 /drivers/media/media-entity.c
parent3a9677063f00a61b6067a07df3d7ee12eace79b7 (diff)
downloadlinux-5c7b25b90d36942c524d06522ebaf0510a75592a.tar.bz2
[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>
Diffstat (limited to 'drivers/media/media-entity.c')
-rw-r--r--drivers/media/media-entity.c14
1 files changed, 11 insertions, 3 deletions
diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
index cb30ffbd5ba8..2c286c307145 100644
--- a/drivers/media/media-entity.c
+++ b/drivers/media/media-entity.c
@@ -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;
}