[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);

	if (root->augment_cb) {
		root->augment_cb(node);
		root->augment_cb(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);

	if (root->augment_cb) {
		root->augment_cb(node);
		root->augment_cb(left);
	}
}

void rb_insert_color(struct rb_node *node, struct rb_root *root)
{
	struct rb_node *parent, *gparent;

	if (root->augment_cb)
		root->augment_cb(node);

	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;
		int old_parent_cb = 0;
		int successor_parent_cb = 0;

		node = node->rb_right;
		while ((left = node->rb_left) != NULL)
			node = left;

		if (rb_parent(old)) {
			old_parent_cb = 1;
			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 {
			successor_parent_cb = 1;
			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);

		if (root->augment_cb) {
			/*
			 * Here, three different nodes can have new children.
			 * The parent of the successor node that was selected
			 * to replace the node to be erased.
			 * The node that is getting erased and is now replaced
			 * by its successor.
			 * The parent of the node getting erased-replaced.
			 */
			if (successor_parent_cb)
				root->augment_cb(parent);

			root->augment_cb(node);

			if (old_parent_cb)
				root->augment_cb(rb_parent(old));
		}

		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;

		if (root->augment_cb)
			root->augment_cb(parent);

	} else {
		root->rb_node = child;
	}

 color:
	if (color == RB_BLACK)
		__rb_erase_color(child, parent, root);
}
EXPORT_SYMBOL(rb_erase);

/*
 * 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);
17d9ddc7 PV	47
	48	if (root->augment_cb) {
	49	root->augment_cb(node);
	50	root->augment_cb(right);
	51	}
1da177e4 LT	52	}
	53
	54	static void __rb_rotate_right(struct rb_node node, struct rb_root root)
	55	{
	56	struct rb_node *left = node->rb_left;
55a98102	57	struct rb_node *parent = rb_parent(node);
1da177e4 LT	58
1da177e4 LT	59	if ((node->rb_left = left->rb_right))
55a98102	60	rb_set_parent(left->rb_right, node);
1da177e4 LT	61	left->rb_right = node;
1da177e4 LT	62
55a98102 DW	63	rb_set_parent(left, parent);
	64
	65	if (parent)
1da177e4	66	{
55a98102 DW	67	if (node == parent->rb_right)
55a98102 DW	68	parent->rb_right = left;
1da177e4	69	else
55a98102	70	parent->rb_left = left;
1da177e4 LT	71	}
	72	else
	73	root->rb_node = left;
55a98102	74	rb_set_parent(node, left);
17d9ddc7 PV	75
	76	if (root->augment_cb) {
	77	root->augment_cb(node);
	78	root->augment_cb(left);
	79	}
1da177e4 LT	80	}
	81
	82	void rb_insert_color(struct rb_node node, struct rb_root root)
	83	{
	84	struct rb_node parent, gparent;
	85
17d9ddc7 PV	86	if (root->augment_cb)
	87	root->augment_cb(node);
	88
55a98102	89	while ((parent = rb_parent(node)) && rb_is_red(parent))
1da177e4	90	{
55a98102	91	gparent = rb_parent(parent);
1da177e4 LT	92
	93	if (parent == gparent->rb_left)
	94	{
	95	{
	96	register struct rb_node *uncle = gparent->rb_right;
55a98102	97	if (uncle && rb_is_red(uncle))
1da177e4	98	{
55a98102 DW	99	rb_set_black(uncle);
	100	rb_set_black(parent);
	101	rb_set_red(gparent);
1da177e4 LT	102	node = gparent;
	103	continue;
	104	}
	105	}
	106
	107	if (parent->rb_right == node)
	108	{
	109	register struct rb_node *tmp;
	110	__rb_rotate_left(parent, root);
	111	tmp = parent;
	112	parent = node;
	113	node = tmp;
	114	}
	115
55a98102 DW	116	rb_set_black(parent);
55a98102 DW	117	rb_set_red(gparent);
1da177e4 LT	118	__rb_rotate_right(gparent, root);
	119	} else {
	120	{
	121	register struct rb_node *uncle = gparent->rb_left;
55a98102	122	if (uncle && rb_is_red(uncle))
1da177e4	123	{
55a98102 DW	124	rb_set_black(uncle);
	125	rb_set_black(parent);
	126	rb_set_red(gparent);
1da177e4 LT	127	node = gparent;
	128	continue;
	129	}
	130	}
	131
	132	if (parent->rb_left == node)
	133	{
	134	register struct rb_node *tmp;
	135	__rb_rotate_right(parent, root);
	136	tmp = parent;
	137	parent = node;
	138	node = tmp;
	139	}
	140
55a98102 DW	141	rb_set_black(parent);
55a98102 DW	142	rb_set_red(gparent);
1da177e4 LT	143	__rb_rotate_left(gparent, root);
	144	}
	145	}
	146
55a98102	147	rb_set_black(root->rb_node);
1da177e4 LT	148	}
	149	EXPORT_SYMBOL(rb_insert_color);
	150
	151	static void __rb_erase_color(struct rb_node node, struct rb_node parent,
	152	struct rb_root *root)
	153	{
	154	struct rb_node *other;
	155
55a98102	156	while ((!node \|\| rb_is_black(node)) && node != root->rb_node)
1da177e4 LT	157	{
	158	if (parent->rb_left == node)
	159	{
	160	other = parent->rb_right;
55a98102	161	if (rb_is_red(other))
1da177e4	162	{
55a98102 DW	163	rb_set_black(other);
55a98102 DW	164	rb_set_red(parent);
1da177e4 LT	165	__rb_rotate_left(parent, root);
	166	other = parent->rb_right;
	167	}
55a98102 DW	168	if ((!other->rb_left \|\| rb_is_black(other->rb_left)) &&
55a98102 DW	169	(!other->rb_right \|\| rb_is_black(other->rb_right)))
1da177e4	170	{
55a98102	171	rb_set_red(other);
1da177e4	172	node = parent;
55a98102	173	parent = rb_parent(node);
1da177e4 LT	174	}
	175	else
	176	{
55a98102	177	if (!other->rb_right \|\| rb_is_black(other->rb_right))
1da177e4	178	{
55a63998	179	rb_set_black(other->rb_left);
55a98102	180	rb_set_red(other);
1da177e4 LT	181	__rb_rotate_right(other, root);
	182	other = parent->rb_right;
	183	}
2f3243ae	184	rb_set_color(other, rb_color(parent));
55a98102	185	rb_set_black(parent);
55a63998	186	rb_set_black(other->rb_right);
1da177e4 LT	187	__rb_rotate_left(parent, root);
	188	node = root->rb_node;
	189	break;
	190	}
	191	}
	192	else
	193	{
	194	other = parent->rb_left;
55a98102	195	if (rb_is_red(other))
1da177e4	196	{
55a98102 DW	197	rb_set_black(other);
55a98102 DW	198	rb_set_red(parent);
1da177e4 LT	199	__rb_rotate_right(parent, root);
	200	other = parent->rb_left;
	201	}
55a98102 DW	202	if ((!other->rb_left \|\| rb_is_black(other->rb_left)) &&
55a98102 DW	203	(!other->rb_right \|\| rb_is_black(other->rb_right)))
1da177e4	204	{
55a98102	205	rb_set_red(other);
1da177e4	206	node = parent;
55a98102	207	parent = rb_parent(node);
1da177e4 LT	208	}
	209	else
	210	{
55a98102	211	if (!other->rb_left \|\| rb_is_black(other->rb_left))
1da177e4	212	{
55a63998	213	rb_set_black(other->rb_right);
55a98102	214	rb_set_red(other);
1da177e4 LT	215	__rb_rotate_left(other, root);
	216	other = parent->rb_left;
	217	}
2f3243ae	218	rb_set_color(other, rb_color(parent));
55a98102	219	rb_set_black(parent);
55a63998	220	rb_set_black(other->rb_left);
1da177e4 LT	221	__rb_rotate_right(parent, root);
	222	node = root->rb_node;
	223	break;
	224	}
	225	}
	226	}
	227	if (node)
55a98102	228	rb_set_black(node);
1da177e4 LT	229	}
	230
	231	void rb_erase(struct rb_node node, struct rb_root root)
	232	{
	233	struct rb_node child, parent;
	234	int color;
	235
	236	if (!node->rb_left)
	237	child = node->rb_right;
	238	else if (!node->rb_right)
	239	child = node->rb_left;
	240	else
	241	{
	242	struct rb_node old = node, left;
17d9ddc7 PV	243	int old_parent_cb = 0;
17d9ddc7 PV	244	int successor_parent_cb = 0;
1da177e4 LT	245
	246	node = node->rb_right;
	247	while ((left = node->rb_left) != NULL)
	248	node = left;
16c047ad WS	249
16c047ad WS	250	if (rb_parent(old)) {
17d9ddc7	251	old_parent_cb = 1;
16c047ad WS	252	if (rb_parent(old)->rb_left == old)
	253	rb_parent(old)->rb_left = node;
	254	else
	255	rb_parent(old)->rb_right = node;
	256	} else
	257	root->rb_node = node;
	258
1da177e4	259	child = node->rb_right;
55a98102	260	parent = rb_parent(node);
2f3243ae	261	color = rb_color(node);
1da177e4	262
55a98102	263	if (parent == old) {
1da177e4	264	parent = node;
4c601178	265	} else {
17d9ddc7	266	successor_parent_cb = 1;
4c601178 WS	267	if (child)
4c601178 WS	268	rb_set_parent(child, parent);
17d9ddc7	269
1975e593	270	parent->rb_left = child;
4b324126 WS	271
	272	node->rb_right = old->rb_right;
	273	rb_set_parent(old->rb_right, node);
4c601178	274	}
1975e593	275
2f3243ae	276	node->rb_parent_color = old->rb_parent_color;
1da177e4	277	node->rb_left = old->rb_left;
55a98102	278	rb_set_parent(old->rb_left, node);
4b324126	279
17d9ddc7 PV	280	if (root->augment_cb) {
	281	/*
	282	* Here, three different nodes can have new children.
	283	* The parent of the successor node that was selected
	284	* to replace the node to be erased.
	285	* The node that is getting erased and is now replaced
	286	* by its successor.
	287	* The parent of the node getting erased-replaced.
	288	*/
	289	if (successor_parent_cb)
	290	root->augment_cb(parent);
	291
	292	root->augment_cb(node);
	293
	294	if (old_parent_cb)
	295	root->augment_cb(rb_parent(old));
	296	}
	297
1da177e4 LT	298	goto color;
	299	}
	300
55a98102	301	parent = rb_parent(node);
2f3243ae	302	color = rb_color(node);
1da177e4 LT	303
1da177e4 LT	304	if (child)
55a98102	305	rb_set_parent(child, parent);
17d9ddc7 PV	306
17d9ddc7 PV	307	if (parent) {
1da177e4 LT	308	if (parent->rb_left == node)
	309	parent->rb_left = child;
	310	else
	311	parent->rb_right = child;
17d9ddc7 PV	312
	313	if (root->augment_cb)
	314	root->augment_cb(parent);
	315
	316	} else {
1da177e4	317	root->rb_node = child;
17d9ddc7	318	}
1da177e4 LT	319
	320	color:
	321	if (color == RB_BLACK)
	322	__rb_erase_color(child, parent, root);
	323	}
	324	EXPORT_SYMBOL(rb_erase);
	325
	326	/*
	327	* This function returns the first node (in sort order) of the tree.
	328	*/
f4b477c4	329	struct rb_node rb_first(const struct rb_root root)
1da177e4 LT	330	{
	331	struct rb_node *n;
	332
	333	n = root->rb_node;
	334	if (!n)
	335	return NULL;
	336	while (n->rb_left)
	337	n = n->rb_left;
	338	return n;
	339	}
	340	EXPORT_SYMBOL(rb_first);
	341
f4b477c4	342	struct rb_node rb_last(const struct rb_root root)
1da177e4 LT	343	{
	344	struct rb_node *n;
	345
	346	n = root->rb_node;
	347	if (!n)
	348	return NULL;
	349	while (n->rb_right)
	350	n = n->rb_right;
	351	return n;
	352	}
	353	EXPORT_SYMBOL(rb_last);
	354
f4b477c4	355	struct rb_node rb_next(const struct rb_node node)
1da177e4	356	{
55a98102 DW	357	struct rb_node *parent;
55a98102 DW	358
10fd48f2 JA	359	if (rb_parent(node) == node)
	360	return NULL;
	361
1da177e4 LT	362	/* If we have a right-hand child, go down and then left as far
	363	as we can. */
	364	if (node->rb_right) {
	365	node = node->rb_right;
	366	while (node->rb_left)
	367	node=node->rb_left;
f4b477c4	368	return (struct rb_node *)node;
1da177e4 LT	369	}
	370
	371	/* No right-hand children. Everything down and left is
	372	smaller than us, so any 'next' node must be in the general
	373	direction of our parent. Go up the tree; any time the
	374	ancestor is a right-hand child of its parent, keep going
	375	up. First time it's a left-hand child of its parent, said
	376	parent is our 'next' node. */
55a98102 DW	377	while ((parent = rb_parent(node)) && node == parent->rb_right)
55a98102 DW	378	node = parent;
1da177e4	379
55a98102	380	return parent;
1da177e4 LT	381	}
	382	EXPORT_SYMBOL(rb_next);
	383
f4b477c4	384	struct rb_node rb_prev(const struct rb_node node)
1da177e4	385	{
55a98102 DW	386	struct rb_node *parent;
55a98102 DW	387
10fd48f2 JA	388	if (rb_parent(node) == node)
	389	return NULL;
	390
1da177e4 LT	391	/* If we have a left-hand child, go down and then right as far
	392	as we can. */
	393	if (node->rb_left) {
	394	node = node->rb_left;
	395	while (node->rb_right)
	396	node=node->rb_right;
f4b477c4	397	return (struct rb_node *)node;
1da177e4 LT	398	}
	399
	400	/* No left-hand children. Go up till we find an ancestor which
	401	is a right-hand child of its parent */
55a98102 DW	402	while ((parent = rb_parent(node)) && node == parent->rb_left)
55a98102 DW	403	node = parent;
1da177e4	404
55a98102	405	return parent;
1da177e4 LT	406	}
	407	EXPORT_SYMBOL(rb_prev);
	408
	409	void rb_replace_node(struct rb_node victim, struct rb_node new,
	410	struct rb_root *root)
	411	{
55a98102	412	struct rb_node *parent = rb_parent(victim);
1da177e4 LT	413
	414	/* Set the surrounding nodes to point to the replacement */
	415	if (parent) {
	416	if (victim == parent->rb_left)
	417	parent->rb_left = new;
	418	else
	419	parent->rb_right = new;
	420	} else {
	421	root->rb_node = new;
	422	}
	423	if (victim->rb_left)
55a98102	424	rb_set_parent(victim->rb_left, new);
1da177e4	425	if (victim->rb_right)
55a98102	426	rb_set_parent(victim->rb_right, new);
1da177e4 LT	427
	428	/* Copy the pointers/colour from the victim to the replacement */
	429	new = victim;
	430	}
	431	EXPORT_SYMBOL(rb_replace_node);