Move reverse list traverse macros from glamor to list.hglamor-pixmaps

Glamor added some macros to traverse lists backwards as a part of its
cache management code. Move these to list.h so that they become part
of the standard API.

Signed-off-by: Keith Packard <keithp@keithp.com>

2 files changed, 37 insertions, 12 deletions

diff --git a/glamor/glamor_fbo.c b/glamor/glamor_fbo.c
index 0ba732c25..a2625c9de 100644
--- a/glamor/glamor_fbo.c
+++ b/glamor/glamor_fbo.c
@@ -38,18 +38,6 @@
 //#define NO_FBO_CACHE 1
 #define FBO_CACHE_THRESHOLD  (256*1024*1024)
 
-/* Loop from the tail to the head. */
-#define xorg_list_for_each_entry_reverse(pos, head, member)             \
-    for (pos = __container_of((head)->prev, pos, member);               \
-         &pos->member != (head);                                        \
-         pos = __container_of(pos->member.prev, pos, member))
-
-#define xorg_list_for_each_entry_safe_reverse(pos, tmp, head, member)   \
-    for (pos = __container_of((head)->prev, pos, member),               \
-         tmp = __container_of(pos->member.prev, pos, member);           \
-         &pos->member != (head);                                        \
-         pos = tmp, tmp = __container_of(pos->member.prev, tmp, member))
-
 inline static int
 cache_wbucket(int size)
 {
diff --git a/include/list.h b/include/list.h
index 39f198590..e79378b1a 100644
--- a/include/list.h
+++ b/include/list.h
@@ -322,6 +322,43 @@ xorg_list_is_empty(struct xorg_list *head)
 	 &pos->member != (head);					\
 	 pos = tmp, tmp = __container_of(pos->member.next, tmp, member))
 
+/**
+ * Loop backwards through the list given by head and set pos to struct
+ * in the list.
+ *
+ * Example:
+ * struct foo *iterator;
+ * xorg_list_for_each_entry_reverse(iterator, &bar->list_of_foos, entry) {
+ *      [modify iterator]
+ * }
+ *
+ * This macro is not safe for node deletion. Use
+ * xorg_list_for_each_entry_safe_reverse instead.
+ *
+ * @param pos Iterator variable of the type of the list elements.
+ * @param head List head
+ * @param member Member name of the struct xorg_list in the list elements.
+ *
+ */
+
+#define xorg_list_for_each_entry_reverse(pos, head, member)             \
+    for (pos = __container_of((head)->prev, pos, member);               \
+         &pos->member != (head);                                        \
+         pos = __container_of(pos->member.prev, pos, member))
+
+/**
+ * Loop backwards through the list, keeping a backup pointer to the
+ * element. This macro allows for the deletion of a list element while
+ * looping through the list.
+ *
+ * See xorg_list_for_each_entry_reverse for more details.
+ */
+#define xorg_list_for_each_entry_safe_reverse(pos, tmp, head, member)   \
+    for (pos = __container_of((head)->prev, pos, member),               \
+         tmp = __container_of(pos->member.prev, pos, member);           \
+         &pos->member != (head);                                        \
+         pos = tmp, tmp = __container_of(pos->member.prev, tmp, member))
+
 /* NULL-Terminated List Interface
  *
  * The interface below does _not_ use the struct xorg_list as described above.