Doug / smarc-fsl-linux-kernel

Download as
Browse Code ยป

Commit 5c7b25b90d36942c524d06522ebaf0510a75592a

Authored by Laurent Pinchart
Committed by Mauro Carvalho Chehab
1 parent 3a9677063f
Exists in smarc-imx_3.14.28_1.0.0_ga and in 1 other branch imx_3.14.28_1.0.0_ga

[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>

Showing 2 changed files with 15 additions and 3 deletions Side-by-side Diff

drivers/media/media-entity.c
Diff comments   View file @ 5c7b25b
... ... @@ -20,6 +20,7 @@
20 20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 21 */
22 22  
  23 +#include <linux/bitmap.h>
23 24 #include <linux/module.h>
24 25 #include <linux/slab.h>
25 26 #include <media/media-entity.h>
... ... @@ -121,7 +122,6 @@
121 122 return entity;
122 123 }
123 124  
124   -#define stack_peek(en) ((en)->stack[(en)->top - 1].entity)
125 125 #define link_top(en) ((en)->stack[(en)->top].link)
126 126 #define stack_top(en) ((en)->stack[(en)->top].entity)
127 127  
... ... @@ -140,6 +140,12 @@
140 140 {
141 141 graph->top = 0;
142 142 graph->stack[graph->top].entity = NULL;
  143 + bitmap_zero(graph->entities, MEDIA_ENTITY_ENUM_MAX_ID);
  144 +
  145 + if (WARN_ON(entity->id >= MEDIA_ENTITY_ENUM_MAX_ID))
  146 + return;
  147 +
  148 + __set_bit(entity->id, graph->entities);
143 149 stack_push(graph, entity);
144 150 }
145 151 EXPORT_SYMBOL_GPL(media_entity_graph_walk_start);
146 152  
... ... @@ -180,9 +186,11 @@
180 186  
181 187 /* Get the entity in the other end of the link . */
182 188 next = media_entity_other(entity, link);
  189 + if (WARN_ON(next->id >= MEDIA_ENTITY_ENUM_MAX_ID))
  190 + return NULL;
183 191  
184   - /* Was it the entity we came here from? */
185   - if (next == stack_peek(graph)) {
  192 + /* Has the entity already been visited? */
  193 + if (__test_and_set_bit(next->id, graph->entities)) {
186 194 link_top(graph)++;
187 195 continue;
188 196 }
include/media/media-entity.h
Diff comments   View file @ 5c7b25b
... ... @@ -23,6 +23,7 @@
23 23 #ifndef _MEDIA_ENTITY_H
24 24 #define _MEDIA_ENTITY_H
25 25  
  26 +#include <linux/bitops.h>
26 27 #include <linux/list.h>
27 28 #include <linux/media.h>
28 29  
29 30  
... ... @@ -113,12 +114,15 @@
113 114 }
114 115  
115 116 #define MEDIA_ENTITY_ENUM_MAX_DEPTH 16
  117 +#define MEDIA_ENTITY_ENUM_MAX_ID 64
116 118  
117 119 struct media_entity_graph {
118 120 struct {
119 121 struct media_entity *entity;
120 122 int link;
121 123 } stack[MEDIA_ENTITY_ENUM_MAX_DEPTH];
  124 +
  125 + DECLARE_BITMAP(entities, MEDIA_ENTITY_ENUM_MAX_ID);
122 126 int top;
123 127 };
124 128