Add rbtree helpers

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>

Makefile

@@ -36,6 +36,7 @@ OBJS		+= util.o
 OBJS		+= util-net.o
 OBJS		+= sysctl.o
 OBJS		+= ptrace.o
+OBJS		+= rbtree.o
 OBJS		+= log.o
 OBJS		+= libnetlink.o
 OBJS		+= sockets.o

include/rbtree.h

+/*
+ * RBtree implementation adopted from the Linux kernel sources.
+ */
+
+#ifndef RBTREE_H__
+#define RBTREE_H__
+
+#include <stddef.h>
+
+#include "compiler.h"
+#include "types.h"
+
+#define	RB_RED		0
+#define	RB_BLACK	1
+#define RB_MASK		3
+
+struct rb_node {
+	unsigned long	rb_parent_color; /* Keeps both parent anc color */
+	struct rb_node	*rb_right;
+	struct rb_node	*rb_left;
+} __aligned(sizeof(long));
+
+struct rb_root {
+	struct rb_node	*rb_node;
+};
+
+#define rb_parent(r)	((struct rb_node *)((r)->rb_parent_color & ~RB_MASK))
+#define rb_color(r)	((r)->rb_parent_color & RB_BLACK)
+#define rb_is_red(r)	(!rb_color(r))
+#define rb_is_black(r)	(rb_color(r))
+#define rb_set_red(r)	do { (r)->rb_parent_color &= ~RB_BLACK; } while (0)
+#define rb_set_black(r)	do { (r)->rb_parent_color |= RB_BLACK; } while (0)
+
+static void rb_set_parent(struct rb_node *rb, struct rb_node *p)
+{
+	rb->rb_parent_color = (rb->rb_parent_color & RB_MASK) | (unsigned long)p;
+}
+
+static void rb_set_color(struct rb_node *rb, int color)
+{
+	rb->rb_parent_color = (rb->rb_parent_color & ~RB_BLACK) | color;
+}
+
+#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))
+
+static void rb_init_node(struct rb_node *node)
+{
+	*node = (struct rb_node){ };
+
+	RB_CLEAR_NODE(node);
+}
+
+static void rb_attach_node(struct rb_root *root, struct rb_node *node)
+{
+	root->rb_node = node;
+}
+
+extern void rb_insert_color(struct rb_node *node, struct rb_root *root);
+extern void rb_erase(struct rb_node *node, struct rb_root *root);
+
+/* Find logical next and previous nodes in a tree */
+extern struct rb_node *rb_first(const struct rb_root *root);
+extern struct rb_node *rb_last(const struct rb_root *root);
+extern struct rb_node *rb_next(const struct rb_node *node);
+extern struct rb_node *rb_prev(const struct rb_node *node);
+
+/* Fast replacement of a single node without remove/rebalance/add/rebalance */
+extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
+			    struct rb_root *root);
+
+static void rb_link_node(struct rb_node *node, struct rb_node *parent,
+			 struct rb_node **rb_link)
+{
+	node->rb_parent_color = (unsigned long)parent;
+	node->rb_left = node->rb_right = NULL;
+
+	*rb_link = node;
+}
+
+#endif /* RBTREE_H__ */

rbtree.c

+/*
+ * RBtree implementation adopted from the Linux kernel sources.
+ */
+
+#include "rbtree.h"
+
+static void __rb_rotate_left(struct rb_node *node, struct rb_root *root)
+{
+	struct rb_node *right = node->rb_right;
+	struct rb_node *parent = rb_parent(node);
+
+	node->rb_right = right->rb_left;
+	if (node->rb_right)
+		rb_set_parent(right->rb_left, node);
+	right->rb_left = node;
+
+	rb_set_parent(right, parent);
+
+	if (parent) {
+		if (node == parent->rb_left)
+			parent->rb_left = right;
+		else
+			parent->rb_right = right;
+	} else
+		root->rb_node = right;
+	rb_set_parent(node, right);
+}
+
+static void __rb_rotate_right(struct rb_node *node, struct rb_root *root)
+{
+	struct rb_node *left = node->rb_left;
+	struct rb_node *parent = rb_parent(node);
+
+	node->rb_left = left->rb_right;
+	if (node->rb_left)
+		rb_set_parent(left->rb_right, node);
+	left->rb_right = node;
+
+	rb_set_parent(left, parent);
+
+	if (parent) {
+		if (node == parent->rb_right)
+			parent->rb_right = left;
+		else
+			parent->rb_left = left;
+	} else
+		root->rb_node = left;
+	rb_set_parent(node, left);
+}
+
+void rb_insert_color(struct rb_node *node, struct rb_root *root)
+{
+	struct rb_node *parent, *gparent;
+
+	while ((parent = rb_parent(node)) && rb_is_red(parent)) {
+		gparent = rb_parent(parent);
+
+		if (parent == gparent->rb_left) {
+			{
+				register struct rb_node *uncle = gparent->rb_right;
+				if (uncle && rb_is_red(uncle)) {
+					rb_set_black(uncle);
+					rb_set_black(parent);
+					rb_set_red(gparent);
+					node = gparent;
+					continue;
+				}
+			}
+
+			if (parent->rb_right == node) {
+				register struct rb_node *tmp;
+				__rb_rotate_left(parent, root);
+				tmp = parent;
+				parent = node;
+				node = tmp;
+			}
+
+			rb_set_black(parent);
+			rb_set_red(gparent);
+			__rb_rotate_right(gparent, root);
+		} else {
+			{
+				register struct rb_node *uncle = gparent->rb_left;
+				if (uncle && rb_is_red(uncle)) {
+					rb_set_black(uncle);
+					rb_set_black(parent);
+					rb_set_red(gparent);
+					node = gparent;
+					continue;
+				}
+			}
+
+			if (parent->rb_left == node) {
+				register struct rb_node *tmp;
+				__rb_rotate_right(parent, root);
+				tmp = parent;
+				parent = node;
+				node = tmp;
+			}
+
+			rb_set_black(parent);
+			rb_set_red(gparent);
+			__rb_rotate_left(gparent, root);
+		}
+	}
+
+	rb_set_black(root->rb_node);
+}
+
+static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
+			     struct rb_root *root)
+{
+	struct rb_node *other;
+
+	while ((!node || rb_is_black(node)) && node != root->rb_node) {
+		if (parent->rb_left == node) {
+			other = parent->rb_right;
+			if (rb_is_red(other)) {
+				rb_set_black(other);
+				rb_set_red(parent);
+				__rb_rotate_left(parent, root);
+				other = parent->rb_right;
+			}
+			if ((!other->rb_left  || rb_is_black(other->rb_left)) &&
+			    (!other->rb_right || rb_is_black(other->rb_right))) {
+				rb_set_red(other);
+				node = parent;
+				parent = rb_parent(node);
+			} else {
+				if (!other->rb_right || rb_is_black(other->rb_right)) {
+					rb_set_black(other->rb_left);
+					rb_set_red(other);
+					__rb_rotate_right(other, root);
+					other = parent->rb_right;
+				}
+				rb_set_color(other, rb_color(parent));
+				rb_set_black(parent);
+				rb_set_black(other->rb_right);
+				__rb_rotate_left(parent, root);
+				node = root->rb_node;
+				break;
+			}
+		} else {
+			other = parent->rb_left;
+			if (rb_is_red(other)) {
+				rb_set_black(other);
+				rb_set_red(parent);
+				__rb_rotate_right(parent, root);
+				other = parent->rb_left;
+			}
+			if ((!other->rb_left  || rb_is_black(other->rb_left)) &&
+			    (!other->rb_right || rb_is_black(other->rb_right))) {
+				rb_set_red(other);
+				node = parent;
+				parent = rb_parent(node);
+			} else {
+				if (!other->rb_left || rb_is_black(other->rb_left)) {
+					rb_set_black(other->rb_right);
+					rb_set_red(other);
+					__rb_rotate_left(other, root);
+					other = parent->rb_left;
+				}
+				rb_set_color(other, rb_color(parent));
+				rb_set_black(parent);
+				rb_set_black(other->rb_left);
+				__rb_rotate_right(parent, root);
+				node = root->rb_node;
+				break;
+			}
+		}
+	}
+
+	if (node)
+		rb_set_black(node);
+}
+
+void rb_erase(struct rb_node *node, struct rb_root *root)
+{
+	struct rb_node *child, *parent;
+	int color;
+
+	if (!node->rb_left)
+		child = node->rb_right;
+	else if (!node->rb_right)
+		child = node->rb_left;
+	else {
+		struct rb_node *old = node, *left;
+
+		node = node->rb_right;
+		while ((left = node->rb_left))
+			node = left;
+
+		if (rb_parent(old)) {
+			if (rb_parent(old)->rb_left == old)
+				rb_parent(old)->rb_left = node;
+			else
+				rb_parent(old)->rb_right = node;
+		} else
+			root->rb_node = node;
+
+		child = node->rb_right;
+		parent = rb_parent(node);
+		color = rb_color(node);
+
+		if (parent == old) {
+			parent = node;
+		} else {
+			if (child)
+				rb_set_parent(child, parent);
+			parent->rb_left = child;
+
+			node->rb_right = old->rb_right;
+			rb_set_parent(old->rb_right, node);
+		}
+
+		node->rb_parent_color = old->rb_parent_color;
+		node->rb_left = old->rb_left;
+		rb_set_parent(old->rb_left, node);
+
+		goto color;
+	}
+
+	parent = rb_parent(node);
+	color = rb_color(node);
+
+	if (child)
+		rb_set_parent(child, parent);
+
+	if (parent) {
+		if (parent->rb_left == node)
+			parent->rb_left = child;
+		else
+			parent->rb_right = child;
+	} else
+		root->rb_node = child;
+
+ color:
+	if (color == RB_BLACK)
+		__rb_erase_color(child, parent, root);
+}
+
+/*
+ * This function returns the first node (in sort order) of the tree.
+ */
+struct rb_node *rb_first(const struct rb_root *root)
+{
+	struct rb_node	*n;
+
+	n = root->rb_node;
+	if (!n)
+		return NULL;
+
+	while (n->rb_left)
+		n = n->rb_left;
+
+	return n;
+}
+
+struct rb_node *rb_last(const struct rb_root *root)
+{
+	struct rb_node	*n;
+
+	n = root->rb_node;
+	if (!n)
+		return NULL;
+
+	while (n->rb_right)
+		n = n->rb_right;
+
+	return n;
+}
+
+struct rb_node *rb_next(const struct rb_node *node)
+{
+	struct rb_node *parent;
+
+	if (rb_parent(node) == node)
+		return NULL;
+
+	/*
+	 * If we have a right-hand child, go down and
+	 * then left as far as we can.
+	 */
+	if (node->rb_right) {
+		node = node->rb_right;
+		while (node->rb_left)
+			node=node->rb_left;
+		return (struct rb_node *)node;
+	}
+
+	/*
+	 * No right-hand children.  Everything down and left is
+	 * smaller than us, so any 'next' node must be in the general
+	 * direction of our parent. Go up the tree; any time the
+	 * ancestor is a right-hand child of its parent, keep going
+	 * up. First time it's a left-hand child of its parent, said
+	 * parent is our 'next' node.
+	 */
+	while ((parent = rb_parent(node)) && node == parent->rb_right)
+		node = parent;
+
+	return parent;
+}
+
+struct rb_node *rb_prev(const struct rb_node *node)
+{
+	struct rb_node *parent;
+
+	if (rb_parent(node) == node)
+		return NULL;
+
+	/*
+	 * If we have a left-hand child, go down and
+	 * then right as far as we can.
+	 */
+	if (node->rb_left) {
+		node = node->rb_left;
+		while (node->rb_right)
+			node = node->rb_right;
+		return (struct rb_node *)node;
+	}
+
+	/*
+	 * No left-hand children. Go up till we find
+	 * an ancestor which is a right-hand child of its parent.
+	 */
+	while ((parent = rb_parent(node)) && node == parent->rb_left)
+		node = parent;
+
+	return parent;
+}
+
+void rb_replace_node(struct rb_node *victim,
+		     struct rb_node *new,
+		     struct rb_root *root)
+{
+	struct rb_node *parent = rb_parent(victim);
+
+	/* Set the surrounding nodes to point to the replacement */
+	if (parent) {
+		if (victim == parent->rb_left)
+			parent->rb_left = new;
+		else
+			parent->rb_right = new;
+	} else
+		root->rb_node = new;
+
+	if (victim->rb_left)
+		rb_set_parent(victim->rb_left, new);
+
+	if (victim->rb_right)
+		rb_set_parent(victim->rb_right, new);
+
+	/* Copy the pointers/colour from the victim to the replacement */
+	*new = *victim;
+}