[RBTREE] Merge colour and parent fields of struct rb_node.
We only used a single bit for colour information, so having a whole
machine word of space allocated for it was a bit wasteful. Instead,
store it in the lowest bit of the 'parent' pointer, since that was
always going to be aligned anyway.
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h
index ffee81c..748be50 100644
--- a/include/linux/rbtree.h
+++ b/include/linux/rbtree.h
@@ -99,28 +99,35 @@
struct rb_node
{
- struct rb_node *rb_parent;
- int rb_color;
+ unsigned long rb_parent_colour;
#define RB_RED 0
#define RB_BLACK 1
struct rb_node *rb_right;
struct rb_node *rb_left;
};
-#define rb_parent(r) ((r)->rb_parent)
-#define rb_set_parent(r,p) do { (r)->rb_parent = p; } while (0)
-#define rb_colour(r) ((r)->rb_colour)
-#define rb_is_red(r) ((r)->colour == RB_RED)
-#define rb_is_black(r) ((r)->colour == RB_BLACK)
-#define rb_set_red(r) do { (r)->colour = RB_RED; } while (0)
-#define rb_set_black(r) do { (r)->colour = RB_BLACK; } while (0)
-#define rb_set_colour(r,c) do { (r)->colour = (c); } while (0)
-
struct rb_root
{
struct rb_node *rb_node;
};
+
+#define rb_parent(r) ((struct rb_node *)((r)->rb_parent_colour & ~3))
+#define rb_colour(r) ((r)->rb_parent_colour & 1)
+#define rb_is_red(r) (!rb_colour(r))
+#define rb_is_black(r) rb_colour(r)
+#define rb_set_red(r) do { (r)->rb_parent_colour &= ~1; } while (0)
+#define rb_set_black(r) do { (r)->rb_parent_colour |= 1; } while (0)
+
+static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
+{
+ rb->rb_parent_colour = (rb->rb_parent_colour & 3) | (unsigned long)p;
+}
+static inline void rb_set_colour(struct rb_node *rb, int colour)
+{
+ rb->rb_parent_colour = (rb->rb_parent_colour & ~1) | colour;
+}
+
#define RB_ROOT (struct rb_root) { NULL, }
#define rb_entry(ptr, type, member) container_of(ptr, type, member)
@@ -140,8 +147,7 @@
static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
struct rb_node ** rb_link)
{
- node->rb_parent = parent;
- node->rb_color = RB_RED;
+ node->rb_parent_colour = (unsigned long )parent;
node->rb_left = node->rb_right = NULL;
*rb_link = node;