[mirror_ubuntu-artful-kernel.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/export.h>

#define	RB_RED		0
#define	RB_BLACK	1

#define rb_color(r)   ((r)->__rb_parent_color & 1)
#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 &= ~1; } while (0)
#define rb_set_black(r)  do { (r)->__rb_parent_color |= 1; } while (0)

static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
{
	rb->__rb_parent_color = rb_color(rb) | (unsigned long)p;
}
static inline void rb_set_color(struct rb_node *rb, int color)
{
	rb->__rb_parent_color = (rb->__rb_parent_color & ~1) | color;
}

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);
}
EXPORT_SYMBOL(rb_augment_insert);

/*
 * 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;
}
EXPORT_SYMBOL(rb_augment_erase_begin);

/*
 * 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);
}
EXPORT_SYMBOL(rb_augment_erase_end);

/*
 * 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_EMPTY_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_EMPTY_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>
8bc3bcc9	24	#include <linux/export.h>
1da177e4	25
bf7ad8ee ML	26	#define RB_RED 0
	27	#define RB_BLACK 1
	28
	29	#define rb_color(r) ((r)->__rb_parent_color & 1)
	30	#define rb_is_red(r) (!rb_color(r))
	31	#define rb_is_black(r) rb_color(r)
	32	#define rb_set_red(r) do { (r)->__rb_parent_color &= ~1; } while (0)
	33	#define rb_set_black(r) do { (r)->__rb_parent_color \|= 1; } while (0)
	34
	35	static inline void rb_set_parent(struct rb_node rb, struct rb_node p)
	36	{
	37	rb->__rb_parent_color = rb_color(rb) \| (unsigned long)p;
	38	}
	39	static inline void rb_set_color(struct rb_node *rb, int color)
	40	{
	41	rb->__rb_parent_color = (rb->__rb_parent_color & ~1) \| color;
	42	}
	43
1da177e4 LT	44	static void __rb_rotate_left(struct rb_node node, struct rb_root root)
	45	{
	46	struct rb_node *right = node->rb_right;
55a98102	47	struct rb_node *parent = rb_parent(node);
1da177e4 LT	48
1da177e4 LT	49	if ((node->rb_right = right->rb_left))
55a98102	50	rb_set_parent(right->rb_left, node);
1da177e4 LT	51	right->rb_left = node;
1da177e4 LT	52
55a98102 DW	53	rb_set_parent(right, parent);
	54
	55	if (parent)
1da177e4	56	{
55a98102 DW	57	if (node == parent->rb_left)
55a98102 DW	58	parent->rb_left = right;
1da177e4	59	else
55a98102	60	parent->rb_right = right;
1da177e4 LT	61	}
	62	else
	63	root->rb_node = right;
55a98102	64	rb_set_parent(node, right);
1da177e4 LT	65	}
	66
	67	static void __rb_rotate_right(struct rb_node node, struct rb_root root)
	68	{
	69	struct rb_node *left = node->rb_left;
55a98102	70	struct rb_node *parent = rb_parent(node);
1da177e4 LT	71
1da177e4 LT	72	if ((node->rb_left = left->rb_right))
55a98102	73	rb_set_parent(left->rb_right, node);
1da177e4 LT	74	left->rb_right = node;
1da177e4 LT	75
55a98102 DW	76	rb_set_parent(left, parent);
	77
	78	if (parent)
1da177e4	79	{
55a98102 DW	80	if (node == parent->rb_right)
55a98102 DW	81	parent->rb_right = left;
1da177e4	82	else
55a98102	83	parent->rb_left = left;
1da177e4 LT	84	}
	85	else
	86	root->rb_node = left;
55a98102	87	rb_set_parent(node, left);
1da177e4 LT	88	}
	89
	90	void rb_insert_color(struct rb_node node, struct rb_root root)
	91	{
	92	struct rb_node parent, gparent;
	93
55a98102	94	while ((parent = rb_parent(node)) && rb_is_red(parent))
1da177e4	95	{
55a98102	96	gparent = rb_parent(parent);
1da177e4 LT	97
	98	if (parent == gparent->rb_left)
	99	{
	100	{
	101	register struct rb_node *uncle = gparent->rb_right;
55a98102	102	if (uncle && rb_is_red(uncle))
1da177e4	103	{
55a98102 DW	104	rb_set_black(uncle);
	105	rb_set_black(parent);
	106	rb_set_red(gparent);
1da177e4 LT	107	node = gparent;
	108	continue;
	109	}
	110	}
	111
	112	if (parent->rb_right == node)
	113	{
	114	register struct rb_node *tmp;
	115	__rb_rotate_left(parent, root);
	116	tmp = parent;
	117	parent = node;
	118	node = tmp;
	119	}
	120
55a98102 DW	121	rb_set_black(parent);
55a98102 DW	122	rb_set_red(gparent);
1da177e4 LT	123	__rb_rotate_right(gparent, root);
	124	} else {
	125	{
	126	register struct rb_node *uncle = gparent->rb_left;
55a98102	127	if (uncle && rb_is_red(uncle))
1da177e4	128	{
55a98102 DW	129	rb_set_black(uncle);
	130	rb_set_black(parent);
	131	rb_set_red(gparent);
1da177e4 LT	132	node = gparent;
	133	continue;
	134	}
	135	}
	136
	137	if (parent->rb_left == node)
	138	{
	139	register struct rb_node *tmp;
	140	__rb_rotate_right(parent, root);
	141	tmp = parent;
	142	parent = node;
	143	node = tmp;
	144	}
	145
55a98102 DW	146	rb_set_black(parent);
55a98102 DW	147	rb_set_red(gparent);
1da177e4 LT	148	__rb_rotate_left(gparent, root);
	149	}
	150	}
	151
55a98102	152	rb_set_black(root->rb_node);
1da177e4 LT	153	}
	154	EXPORT_SYMBOL(rb_insert_color);
	155
	156	static void __rb_erase_color(struct rb_node node, struct rb_node parent,
	157	struct rb_root *root)
	158	{
	159	struct rb_node *other;
	160
55a98102	161	while ((!node \|\| rb_is_black(node)) && node != root->rb_node)
1da177e4 LT	162	{
	163	if (parent->rb_left == node)
	164	{
	165	other = parent->rb_right;
55a98102	166	if (rb_is_red(other))
1da177e4	167	{
55a98102 DW	168	rb_set_black(other);
55a98102 DW	169	rb_set_red(parent);
1da177e4 LT	170	__rb_rotate_left(parent, root);
	171	other = parent->rb_right;
	172	}
55a98102 DW	173	if ((!other->rb_left \|\| rb_is_black(other->rb_left)) &&
55a98102 DW	174	(!other->rb_right \|\| rb_is_black(other->rb_right)))
1da177e4	175	{
55a98102	176	rb_set_red(other);
1da177e4	177	node = parent;
55a98102	178	parent = rb_parent(node);
1da177e4 LT	179	}
	180	else
	181	{
55a98102	182	if (!other->rb_right \|\| rb_is_black(other->rb_right))
1da177e4	183	{
55a63998	184	rb_set_black(other->rb_left);
55a98102	185	rb_set_red(other);
1da177e4 LT	186	__rb_rotate_right(other, root);
	187	other = parent->rb_right;
	188	}
2f3243ae	189	rb_set_color(other, rb_color(parent));
55a98102	190	rb_set_black(parent);
55a63998	191	rb_set_black(other->rb_right);
1da177e4 LT	192	__rb_rotate_left(parent, root);
	193	node = root->rb_node;
	194	break;
	195	}
	196	}
	197	else
	198	{
	199	other = parent->rb_left;
55a98102	200	if (rb_is_red(other))
1da177e4	201	{
55a98102 DW	202	rb_set_black(other);
55a98102 DW	203	rb_set_red(parent);
1da177e4 LT	204	__rb_rotate_right(parent, root);
	205	other = parent->rb_left;
	206	}
55a98102 DW	207	if ((!other->rb_left \|\| rb_is_black(other->rb_left)) &&
55a98102 DW	208	(!other->rb_right \|\| rb_is_black(other->rb_right)))
1da177e4	209	{
55a98102	210	rb_set_red(other);
1da177e4	211	node = parent;
55a98102	212	parent = rb_parent(node);
1da177e4 LT	213	}
	214	else
	215	{
55a98102	216	if (!other->rb_left \|\| rb_is_black(other->rb_left))
1da177e4	217	{
55a63998	218	rb_set_black(other->rb_right);
55a98102	219	rb_set_red(other);
1da177e4 LT	220	__rb_rotate_left(other, root);
	221	other = parent->rb_left;
	222	}
2f3243ae	223	rb_set_color(other, rb_color(parent));
55a98102	224	rb_set_black(parent);
55a63998	225	rb_set_black(other->rb_left);
1da177e4 LT	226	__rb_rotate_right(parent, root);
	227	node = root->rb_node;
	228	break;
	229	}
	230	}
	231	}
	232	if (node)
55a98102	233	rb_set_black(node);
1da177e4 LT	234	}
	235
	236	void rb_erase(struct rb_node node, struct rb_root root)
	237	{
	238	struct rb_node child, parent;
	239	int color;
	240
	241	if (!node->rb_left)
	242	child = node->rb_right;
	243	else if (!node->rb_right)
	244	child = node->rb_left;
	245	else
	246	{
	247	struct rb_node old = node, left;
	248
	249	node = node->rb_right;
	250	while ((left = node->rb_left) != NULL)
	251	node = left;
16c047ad WS	252
	253	if (rb_parent(old)) {
	254	if (rb_parent(old)->rb_left == old)
	255	rb_parent(old)->rb_left = node;
	256	else
	257	rb_parent(old)->rb_right = node;
	258	} else
	259	root->rb_node = node;
	260
1da177e4	261	child = node->rb_right;
55a98102	262	parent = rb_parent(node);
2f3243ae	263	color = rb_color(node);
1da177e4	264
55a98102	265	if (parent == old) {
1da177e4	266	parent = node;
4c601178 WS	267	} else {
	268	if (child)
	269	rb_set_parent(child, parent);
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
bf7ad8ee	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
1da177e4 LT	280	goto color;
	281	}
	282
55a98102	283	parent = rb_parent(node);
2f3243ae	284	color = rb_color(node);
1da177e4 LT	285
1da177e4 LT	286	if (child)
55a98102	287	rb_set_parent(child, parent);
b945d6b2 PZ	288	if (parent)
b945d6b2 PZ	289	{
1da177e4 LT	290	if (parent->rb_left == node)
	291	parent->rb_left = child;
	292	else
	293	parent->rb_right = child;
17d9ddc7	294	}
b945d6b2 PZ	295	else
b945d6b2 PZ	296	root->rb_node = child;
1da177e4 LT	297
	298	color:
	299	if (color == RB_BLACK)
	300	__rb_erase_color(child, parent, root);
	301	}
	302	EXPORT_SYMBOL(rb_erase);
	303
b945d6b2 PZ	304	static void rb_augment_path(struct rb_node node, rb_augment_f func, void data)
	305	{
	306	struct rb_node *parent;
	307
	308	up:
	309	func(node, data);
	310	parent = rb_parent(node);
	311	if (!parent)
	312	return;
	313
	314	if (node == parent->rb_left && parent->rb_right)
	315	func(parent->rb_right, data);
	316	else if (parent->rb_left)
	317	func(parent->rb_left, data);
	318
	319	node = parent;
	320	goto up;
	321	}
	322
	323	/*
	324	* after inserting @node into the tree, update the tree to account for
	325	* both the new entry and any damage done by rebalance
	326	*/
	327	void rb_augment_insert(struct rb_node node, rb_augment_f func, void data)
	328	{
	329	if (node->rb_left)
	330	node = node->rb_left;
	331	else if (node->rb_right)
	332	node = node->rb_right;
	333
	334	rb_augment_path(node, func, data);
	335	}
0b6bb66d	336	EXPORT_SYMBOL(rb_augment_insert);
b945d6b2 PZ	337
	338	/*
	339	* before removing the node, find the deepest node on the rebalance path
	340	* that will still be there after @node gets removed
	341	*/
	342	struct rb_node rb_augment_erase_begin(struct rb_node node)
	343	{
	344	struct rb_node *deepest;
	345
	346	if (!node->rb_right && !node->rb_left)
	347	deepest = rb_parent(node);
	348	else if (!node->rb_right)
	349	deepest = node->rb_left;
	350	else if (!node->rb_left)
	351	deepest = node->rb_right;
	352	else {
	353	deepest = rb_next(node);
	354	if (deepest->rb_right)
	355	deepest = deepest->rb_right;
	356	else if (rb_parent(deepest) != node)
	357	deepest = rb_parent(deepest);
	358	}
	359
	360	return deepest;
	361	}
0b6bb66d	362	EXPORT_SYMBOL(rb_augment_erase_begin);
b945d6b2 PZ	363
	364	/*
	365	* after removal, update the tree to account for the removed entry
	366	* and any rebalance damage.
	367	*/
	368	void rb_augment_erase_end(struct rb_node node, rb_augment_f func, void data)
	369	{
	370	if (node)
	371	rb_augment_path(node, func, data);
	372	}
0b6bb66d	373	EXPORT_SYMBOL(rb_augment_erase_end);
b945d6b2	374
1da177e4 LT	375	/*
	376	* This function returns the first node (in sort order) of the tree.
	377	*/
f4b477c4	378	struct rb_node rb_first(const struct rb_root root)
1da177e4 LT	379	{
	380	struct rb_node *n;
	381
	382	n = root->rb_node;
	383	if (!n)
	384	return NULL;
	385	while (n->rb_left)
	386	n = n->rb_left;
	387	return n;
	388	}
	389	EXPORT_SYMBOL(rb_first);
	390
f4b477c4	391	struct rb_node rb_last(const struct rb_root root)
1da177e4 LT	392	{
	393	struct rb_node *n;
	394
	395	n = root->rb_node;
	396	if (!n)
	397	return NULL;
	398	while (n->rb_right)
	399	n = n->rb_right;
	400	return n;
	401	}
	402	EXPORT_SYMBOL(rb_last);
	403
f4b477c4	404	struct rb_node rb_next(const struct rb_node node)
1da177e4	405	{
55a98102 DW	406	struct rb_node *parent;
55a98102 DW	407
4c199a93	408	if (RB_EMPTY_NODE(node))
10fd48f2 JA	409	return NULL;
10fd48f2 JA	410
1da177e4 LT	411	/* If we have a right-hand child, go down and then left as far
	412	as we can. */
	413	if (node->rb_right) {
	414	node = node->rb_right;
	415	while (node->rb_left)
	416	node=node->rb_left;
f4b477c4	417	return (struct rb_node *)node;
1da177e4 LT	418	}
	419
	420	/* No right-hand children. Everything down and left is
	421	smaller than us, so any 'next' node must be in the general
	422	direction of our parent. Go up the tree; any time the
	423	ancestor is a right-hand child of its parent, keep going
	424	up. First time it's a left-hand child of its parent, said
	425	parent is our 'next' node. */
55a98102 DW	426	while ((parent = rb_parent(node)) && node == parent->rb_right)
55a98102 DW	427	node = parent;
1da177e4	428
55a98102	429	return parent;
1da177e4 LT	430	}
	431	EXPORT_SYMBOL(rb_next);
	432
f4b477c4	433	struct rb_node rb_prev(const struct rb_node node)
1da177e4	434	{
55a98102 DW	435	struct rb_node *parent;
55a98102 DW	436
4c199a93	437	if (RB_EMPTY_NODE(node))
10fd48f2 JA	438	return NULL;
10fd48f2 JA	439
1da177e4 LT	440	/* If we have a left-hand child, go down and then right as far
	441	as we can. */
	442	if (node->rb_left) {
	443	node = node->rb_left;
	444	while (node->rb_right)
	445	node=node->rb_right;
f4b477c4	446	return (struct rb_node *)node;
1da177e4 LT	447	}
	448
	449	/* No left-hand children. Go up till we find an ancestor which
	450	is a right-hand child of its parent */
55a98102 DW	451	while ((parent = rb_parent(node)) && node == parent->rb_left)
55a98102 DW	452	node = parent;
1da177e4	453
55a98102	454	return parent;
1da177e4 LT	455	}
	456	EXPORT_SYMBOL(rb_prev);
	457
	458	void rb_replace_node(struct rb_node victim, struct rb_node new,
	459	struct rb_root *root)
	460	{
55a98102	461	struct rb_node *parent = rb_parent(victim);
1da177e4 LT	462
	463	/* Set the surrounding nodes to point to the replacement */
	464	if (parent) {
	465	if (victim == parent->rb_left)
	466	parent->rb_left = new;
	467	else
	468	parent->rb_right = new;
	469	} else {
	470	root->rb_node = new;
	471	}
	472	if (victim->rb_left)
55a98102	473	rb_set_parent(victim->rb_left, new);
1da177e4	474	if (victim->rb_right)
55a98102	475	rb_set_parent(victim->rb_right, new);
1da177e4 LT	476
	477	/* Copy the pointers/colour from the victim to the replacement */
	478	new = victim;
	479	}
	480	EXPORT_SYMBOL(rb_replace_node);