[net-next-2.6.git] / lib / rbtree.c

/*
  Red Black Trees
  (C) 1999  Andrea Arcangeli <andrea@suse.de>
  (C) 2002  David Woodhouse <dwmw2@infradead.org>
  
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

  linux/lib/rbtree.c
*/

#include <linux/rbtree.h>
#include <linux/module.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);

	if ((node->rb_right = right->rb_left))
		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);

	if ((node->rb_left = left->rb_right))
		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);
}
EXPORT_SYMBOL(rb_insert_color);

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) != NULL)
			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);
}
EXPORT_SYMBOL(rb_erase);

static void rb_augment_path(struct rb_node *node, rb_augment_f func, void *data)
{
	struct rb_node *parent;

up:
	func(node, data);
	parent = rb_parent(node);
	if (!parent)
		return;

	if (node == parent->rb_left && parent->rb_right)
		func(parent->rb_right, data);
	else if (parent->rb_left)
		func(parent->rb_left, data);

	node = parent;
	goto up;
}

/*
 * after inserting @node into the tree, update the tree to account for
 * both the new entry and any damage done by rebalance
 */
void rb_augment_insert(struct rb_node *node, rb_augment_f func, void *data)
{
	if (node->rb_left)
		node = node->rb_left;
	else if (node->rb_right)
		node = node->rb_right;

	rb_augment_path(node, func, data);
}

/*
 * before removing the node, find the deepest node on the rebalance path
 * that will still be there after @node gets removed
 */
struct rb_node *rb_augment_erase_begin(struct rb_node *node)
{
	struct rb_node *deepest;

	if (!node->rb_right && !node->rb_left)
		deepest = rb_parent(node);
	else if (!node->rb_right)
		deepest = node->rb_left;
	else if (!node->rb_left)
		deepest = node->rb_right;
	else {
		deepest = rb_next(node);
		if (deepest->rb_right)
			deepest = deepest->rb_right;
		else if (rb_parent(deepest) != node)
			deepest = rb_parent(deepest);
	}

	return deepest;
}

/*
 * after removal, update the tree to account for the removed entry
 * and any rebalance damage.
 */
void rb_augment_erase_end(struct rb_node *node, rb_augment_f func, void *data)
{
	if (node)
		rb_augment_path(node, func, data);
}

/*
 * 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;
}
EXPORT_SYMBOL(rb_first);

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;
}
EXPORT_SYMBOL(rb_last);

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;
}
EXPORT_SYMBOL(rb_next);

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;
}
EXPORT_SYMBOL(rb_prev);

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;
}
EXPORT_SYMBOL(rb_replace_node);
Commit	Line	Data
1da177e4 LT	1	/*
	2	Red Black Trees
	3	(C) 1999 Andrea Arcangeli <andrea@suse.de>
	4	(C) 2002 David Woodhouse <dwmw2@infradead.org>
	5
	6	This program is free software; you can redistribute it and/or modify
	7	it under the terms of the GNU General Public License as published by
	8	the Free Software Foundation; either version 2 of the License, or
	9	(at your option) any later version.
	10
	11	This program is distributed in the hope that it will be useful,
	12	but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	GNU General Public License for more details.
	15
	16	You should have received a copy of the GNU General Public License
	17	along with this program; if not, write to the Free Software
	18	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	19
	20	linux/lib/rbtree.c
	21	*/
	22
	23	#include <linux/rbtree.h>
	24	#include <linux/module.h>
	25
	26	static void __rb_rotate_left(struct rb_node node, struct rb_root root)
	27	{
	28	struct rb_node *right = node->rb_right;
55a98102	29	struct rb_node *parent = rb_parent(node);
1da177e4 LT	30
1da177e4 LT	31	if ((node->rb_right = right->rb_left))
55a98102	32	rb_set_parent(right->rb_left, node);
1da177e4 LT	33	right->rb_left = node;
1da177e4 LT	34
55a98102 DW	35	rb_set_parent(right, parent);
	36
	37	if (parent)
1da177e4	38	{
55a98102 DW	39	if (node == parent->rb_left)
55a98102 DW	40	parent->rb_left = right;
1da177e4	41	else
55a98102	42	parent->rb_right = right;
1da177e4 LT	43	}
	44	else
	45	root->rb_node = right;
55a98102	46	rb_set_parent(node, right);
1da177e4 LT	47	}
	48
	49	static void __rb_rotate_right(struct rb_node node, struct rb_root root)
	50	{
	51	struct rb_node *left = node->rb_left;
55a98102	52	struct rb_node *parent = rb_parent(node);
1da177e4 LT	53
1da177e4 LT	54	if ((node->rb_left = left->rb_right))
55a98102	55	rb_set_parent(left->rb_right, node);
1da177e4 LT	56	left->rb_right = node;
1da177e4 LT	57
55a98102 DW	58	rb_set_parent(left, parent);
	59
	60	if (parent)
1da177e4	61	{
55a98102 DW	62	if (node == parent->rb_right)
55a98102 DW	63	parent->rb_right = left;
1da177e4	64	else
55a98102	65	parent->rb_left = left;
1da177e4 LT	66	}
	67	else
	68	root->rb_node = left;
55a98102	69	rb_set_parent(node, left);
1da177e4 LT	70	}
	71
	72	void rb_insert_color(struct rb_node node, struct rb_root root)
	73	{
	74	struct rb_node parent, gparent;
	75
55a98102	76	while ((parent = rb_parent(node)) && rb_is_red(parent))
1da177e4	77	{
55a98102	78	gparent = rb_parent(parent);
1da177e4 LT	79
	80	if (parent == gparent->rb_left)
	81	{
	82	{
	83	register struct rb_node *uncle = gparent->rb_right;
55a98102	84	if (uncle && rb_is_red(uncle))
1da177e4	85	{
55a98102 DW	86	rb_set_black(uncle);
	87	rb_set_black(parent);
	88	rb_set_red(gparent);
1da177e4 LT	89	node = gparent;
	90	continue;
	91	}
	92	}
	93
	94	if (parent->rb_right == node)
	95	{
	96	register struct rb_node *tmp;
	97	__rb_rotate_left(parent, root);
	98	tmp = parent;
	99	parent = node;
	100	node = tmp;
	101	}
	102
55a98102 DW	103	rb_set_black(parent);
55a98102 DW	104	rb_set_red(gparent);
1da177e4 LT	105	__rb_rotate_right(gparent, root);
	106	} else {
	107	{
	108	register struct rb_node *uncle = gparent->rb_left;
55a98102	109	if (uncle && rb_is_red(uncle))
1da177e4	110	{
55a98102 DW	111	rb_set_black(uncle);
	112	rb_set_black(parent);
	113	rb_set_red(gparent);
1da177e4 LT	114	node = gparent;
	115	continue;
	116	}
	117	}
	118
	119	if (parent->rb_left == node)
	120	{
	121	register struct rb_node *tmp;
	122	__rb_rotate_right(parent, root);
	123	tmp = parent;
	124	parent = node;
	125	node = tmp;
	126	}
	127
55a98102 DW	128	rb_set_black(parent);
55a98102 DW	129	rb_set_red(gparent);
1da177e4 LT	130	__rb_rotate_left(gparent, root);
	131	}
	132	}
	133
55a98102	134	rb_set_black(root->rb_node);
1da177e4 LT	135	}
	136	EXPORT_SYMBOL(rb_insert_color);
	137
	138	static void __rb_erase_color(struct rb_node node, struct rb_node parent,
	139	struct rb_root *root)
	140	{
	141	struct rb_node *other;
	142
55a98102	143	while ((!node \|\| rb_is_black(node)) && node != root->rb_node)
1da177e4 LT	144	{
	145	if (parent->rb_left == node)
	146	{
	147	other = parent->rb_right;
55a98102	148	if (rb_is_red(other))
1da177e4	149	{
55a98102 DW	150	rb_set_black(other);
55a98102 DW	151	rb_set_red(parent);
1da177e4 LT	152	__rb_rotate_left(parent, root);
	153	other = parent->rb_right;
	154	}
55a98102 DW	155	if ((!other->rb_left \|\| rb_is_black(other->rb_left)) &&
55a98102 DW	156	(!other->rb_right \|\| rb_is_black(other->rb_right)))
1da177e4	157	{
55a98102	158	rb_set_red(other);
1da177e4	159	node = parent;
55a98102	160	parent = rb_parent(node);
1da177e4 LT	161	}
	162	else
	163	{
55a98102	164	if (!other->rb_right \|\| rb_is_black(other->rb_right))
1da177e4	165	{
55a63998	166	rb_set_black(other->rb_left);
55a98102	167	rb_set_red(other);
1da177e4 LT	168	__rb_rotate_right(other, root);
	169	other = parent->rb_right;
	170	}
2f3243ae	171	rb_set_color(other, rb_color(parent));
55a98102	172	rb_set_black(parent);
55a63998	173	rb_set_black(other->rb_right);
1da177e4 LT	174	__rb_rotate_left(parent, root);
	175	node = root->rb_node;
	176	break;
	177	}
	178	}
	179	else
	180	{
	181	other = parent->rb_left;
55a98102	182	if (rb_is_red(other))
1da177e4	183	{
55a98102 DW	184	rb_set_black(other);
55a98102 DW	185	rb_set_red(parent);
1da177e4 LT	186	__rb_rotate_right(parent, root);
	187	other = parent->rb_left;
	188	}
55a98102 DW	189	if ((!other->rb_left \|\| rb_is_black(other->rb_left)) &&
55a98102 DW	190	(!other->rb_right \|\| rb_is_black(other->rb_right)))
1da177e4	191	{
55a98102	192	rb_set_red(other);
1da177e4	193	node = parent;
55a98102	194	parent = rb_parent(node);
1da177e4 LT	195	}
	196	else
	197	{
55a98102	198	if (!other->rb_left \|\| rb_is_black(other->rb_left))
1da177e4	199	{
55a63998	200	rb_set_black(other->rb_right);
55a98102	201	rb_set_red(other);
1da177e4 LT	202	__rb_rotate_left(other, root);
	203	other = parent->rb_left;
	204	}
2f3243ae	205	rb_set_color(other, rb_color(parent));
55a98102	206	rb_set_black(parent);
55a63998	207	rb_set_black(other->rb_left);
1da177e4 LT	208	__rb_rotate_right(parent, root);
	209	node = root->rb_node;
	210	break;
	211	}
	212	}
	213	}
	214	if (node)
55a98102	215	rb_set_black(node);
1da177e4 LT	216	}
	217
	218	void rb_erase(struct rb_node node, struct rb_root root)
	219	{
	220	struct rb_node child, parent;
	221	int color;
	222
	223	if (!node->rb_left)
	224	child = node->rb_right;
	225	else if (!node->rb_right)
	226	child = node->rb_left;
	227	else
	228	{
	229	struct rb_node old = node, left;
	230
	231	node = node->rb_right;
	232	while ((left = node->rb_left) != NULL)
	233	node = left;
16c047ad WS	234
	235	if (rb_parent(old)) {
	236	if (rb_parent(old)->rb_left == old)
	237	rb_parent(old)->rb_left = node;
	238	else
	239	rb_parent(old)->rb_right = node;
	240	} else
	241	root->rb_node = node;
	242
1da177e4	243	child = node->rb_right;
55a98102	244	parent = rb_parent(node);
2f3243ae	245	color = rb_color(node);
1da177e4	246
55a98102	247	if (parent == old) {
1da177e4	248	parent = node;
4c601178 WS	249	} else {
	250	if (child)
	251	rb_set_parent(child, parent);
1975e593	252	parent->rb_left = child;
4b324126 WS	253
	254	node->rb_right = old->rb_right;
	255	rb_set_parent(old->rb_right, node);
4c601178	256	}
1975e593	257
2f3243ae	258	node->rb_parent_color = old->rb_parent_color;
1da177e4	259	node->rb_left = old->rb_left;
55a98102	260	rb_set_parent(old->rb_left, node);
4b324126	261
1da177e4 LT	262	goto color;
	263	}
	264
55a98102	265	parent = rb_parent(node);
2f3243ae	266	color = rb_color(node);
1da177e4 LT	267
1da177e4 LT	268	if (child)
55a98102	269	rb_set_parent(child, parent);
b945d6b2 PZ	270	if (parent)
b945d6b2 PZ	271	{
1da177e4 LT	272	if (parent->rb_left == node)
	273	parent->rb_left = child;
	274	else
	275	parent->rb_right = child;
17d9ddc7	276	}
b945d6b2 PZ	277	else
b945d6b2 PZ	278	root->rb_node = child;
1da177e4 LT	279
	280	color:
	281	if (color == RB_BLACK)
	282	__rb_erase_color(child, parent, root);
	283	}
	284	EXPORT_SYMBOL(rb_erase);
	285
b945d6b2 PZ	286	static void rb_augment_path(struct rb_node node, rb_augment_f func, void data)
	287	{
	288	struct rb_node *parent;
	289
	290	up:
	291	func(node, data);
	292	parent = rb_parent(node);
	293	if (!parent)
	294	return;
	295
	296	if (node == parent->rb_left && parent->rb_right)
	297	func(parent->rb_right, data);
	298	else if (parent->rb_left)
	299	func(parent->rb_left, data);
	300
	301	node = parent;
	302	goto up;
	303	}
	304
	305	/*
	306	* after inserting @node into the tree, update the tree to account for
	307	* both the new entry and any damage done by rebalance
	308	*/
	309	void rb_augment_insert(struct rb_node node, rb_augment_f func, void data)
	310	{
	311	if (node->rb_left)
	312	node = node->rb_left;
	313	else if (node->rb_right)
	314	node = node->rb_right;
	315
	316	rb_augment_path(node, func, data);
	317	}
	318
	319	/*
	320	* before removing the node, find the deepest node on the rebalance path
	321	* that will still be there after @node gets removed
	322	*/
	323	struct rb_node rb_augment_erase_begin(struct rb_node node)
	324	{
	325	struct rb_node *deepest;
	326
	327	if (!node->rb_right && !node->rb_left)
	328	deepest = rb_parent(node);
	329	else if (!node->rb_right)
	330	deepest = node->rb_left;
	331	else if (!node->rb_left)
	332	deepest = node->rb_right;
	333	else {
	334	deepest = rb_next(node);
	335	if (deepest->rb_right)
	336	deepest = deepest->rb_right;
	337	else if (rb_parent(deepest) != node)
	338	deepest = rb_parent(deepest);
	339	}
	340
	341	return deepest;
	342	}
	343
	344	/*
	345	* after removal, update the tree to account for the removed entry
	346	* and any rebalance damage.
	347	*/
	348	void rb_augment_erase_end(struct rb_node node, rb_augment_f func, void data)
	349	{
350	if (node)
351	rb_augment_path(node, func, data);
352	}
353
1da177e4 LT	354	/*
	355	* This function returns the first node (in sort order) of the tree.
	356	*/
f4b477c4	357	struct rb_node rb_first(const struct rb_root root)
1da177e4 LT	358	{
	359	struct rb_node *n;
	360
	361	n = root->rb_node;
	362	if (!n)
	363	return NULL;
	364	while (n->rb_left)
	365	n = n->rb_left;
	366	return n;
	367	}
	368	EXPORT_SYMBOL(rb_first);
	369
f4b477c4	370	struct rb_node rb_last(const struct rb_root root)
1da177e4 LT	371	{
	372	struct rb_node *n;
	373
	374	n = root->rb_node;
	375	if (!n)
	376	return NULL;
	377	while (n->rb_right)
	378	n = n->rb_right;
	379	return n;
	380	}
	381	EXPORT_SYMBOL(rb_last);
	382
f4b477c4	383	struct rb_node rb_next(const struct rb_node node)
1da177e4	384	{
55a98102 DW	385	struct rb_node *parent;
55a98102 DW	386
10fd48f2 JA	387	if (rb_parent(node) == node)
	388	return NULL;
	389
1da177e4 LT	390	/* If we have a right-hand child, go down and then left as far
	391	as we can. */
	392	if (node->rb_right) {
	393	node = node->rb_right;
	394	while (node->rb_left)
	395	node=node->rb_left;
f4b477c4	396	return (struct rb_node *)node;
1da177e4 LT	397	}
	398
	399	/* No right-hand children. Everything down and left is
	400	smaller than us, so any 'next' node must be in the general
	401	direction of our parent. Go up the tree; any time the
	402	ancestor is a right-hand child of its parent, keep going
	403	up. First time it's a left-hand child of its parent, said
	404	parent is our 'next' node. */
55a98102 DW	405	while ((parent = rb_parent(node)) && node == parent->rb_right)
55a98102 DW	406	node = parent;
1da177e4	407
55a98102	408	return parent;
1da177e4 LT	409	}
	410	EXPORT_SYMBOL(rb_next);
	411
f4b477c4	412	struct rb_node rb_prev(const struct rb_node node)
1da177e4	413	{
55a98102 DW	414	struct rb_node *parent;
55a98102 DW	415
10fd48f2 JA	416	if (rb_parent(node) == node)
	417	return NULL;
	418
1da177e4 LT	419	/* If we have a left-hand child, go down and then right as far
	420	as we can. */
	421	if (node->rb_left) {
	422	node = node->rb_left;
	423	while (node->rb_right)
	424	node=node->rb_right;
f4b477c4	425	return (struct rb_node *)node;
1da177e4 LT	426	}
	427
	428	/* No left-hand children. Go up till we find an ancestor which
	429	is a right-hand child of its parent */
55a98102 DW	430	while ((parent = rb_parent(node)) && node == parent->rb_left)
55a98102 DW	431	node = parent;
1da177e4	432
55a98102	433	return parent;
1da177e4 LT	434	}
	435	EXPORT_SYMBOL(rb_prev);
	436
	437	void rb_replace_node(struct rb_node victim, struct rb_node new,
	438	struct rb_root *root)
	439	{
55a98102	440	struct rb_node *parent = rb_parent(victim);
1da177e4 LT	441
	442	/* Set the surrounding nodes to point to the replacement */
	443	if (parent) {
	444	if (victim == parent->rb_left)
	445	parent->rb_left = new;
	446	else
	447	parent->rb_right = new;
	448	} else {
	449	root->rb_node = new;
	450	}
	451	if (victim->rb_left)
55a98102	452	rb_set_parent(victim->rb_left, new);
1da177e4	453	if (victim->rb_right)
55a98102	454	rb_set_parent(victim->rb_right, new);
1da177e4 LT	455
	456	/* Copy the pointers/colour from the victim to the replacement */
	457	new = victim;
	458	}
	459	EXPORT_SYMBOL(rb_replace_node);