[PATCH] rbtree: support functions used by the io schedulers
They all duplicate macros to check for empty root and/or node, and
clearing a node. So put those in rbtree.h.
Signed-off-by: Jens Axboe <axboe@suse.de>
diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h
index f37006f..8d5382e 100644
--- a/include/linux/rbtree.h
+++ b/include/linux/rbtree.h
@@ -132,6 +132,10 @@
#define RB_ROOT (struct rb_root) { NULL, }
#define rb_entry(ptr, type, member) container_of(ptr, type, member)
+#define RB_EMPTY_ROOT(root) ((root)->rb_node == NULL)
+#define RB_EMPTY_NODE(node) (rb_parent(node) != node)
+#define RB_CLEAR_NODE(node) (rb_set_parent(node, node))
+
extern void rb_insert_color(struct rb_node *, struct rb_root *);
extern void rb_erase(struct rb_node *, struct rb_root *);