The graph traversal API (media_entity_graph_walk_*) will fail to
correctly walk the graph when circular links exist. Fix it by checking
whether an entity is already present in the stack before pushing it.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
---
drivers/media/media-entity.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
index cb30ffb..c8aba5e 100644
--- a/drivers/media/media-entity.c
+++ b/drivers/media/media-entity.c
@@ -121,9 +121,9 @@ 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)
+#define stack_peek(en, i) ((en)->stack[i].entity)
+#define link_top(en) ((en)->stack[(en)->top].link)
+#define stack_top(en) ((en)->stack[(en)->top].entity)
/**
* media_entity_graph_walk_start - Start walking the media graph at a given entity
@@ -159,6 +159,8 @@ EXPORT_SYMBOL_GPL(media_entity_graph_walk_start);
struct media_entity *
media_entity_graph_walk_next(struct media_entity_graph *graph)
{
+ unsigned int i;
+
if (stack_top(graph) == NULL)
return NULL;
@@ -181,8 +183,13 @@ 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);
- /* Was it the entity we came here from? */
- if (next == stack_peek(graph)) {
+ /* Is the entity already in the path? */
+ for (i = 1; i < graph->top; ++i) {
+ if (next == stack_peek(graph, i))
+ break;
+ }
+
+ if (i < graph->top) {
link_top(graph)++;
continue;
}
--
1.8.1.5
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