[mirror_ubuntu-zesty-kernel.git] / include / linux / rbtree_augmented.h

/*
  Red Black Trees
  (C) 1999  Andrea Arcangeli <andrea@suse.de>
  (C) 2002  David Woodhouse <dwmw2@infradead.org>
  (C) 2012  Michel Lespinasse <walken@google.com>

  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/include/linux/rbtree_augmented.h
*/

#ifndef _LINUX_RBTREE_AUGMENTED_H
#define _LINUX_RBTREE_AUGMENTED_H

#include <linux/compiler.h>
#include <linux/rbtree.h>

/*
 * Please note - only struct rb_augment_callbacks and the prototypes for
 * rb_insert_augmented() and rb_erase_augmented() are intended to be public.
 * The rest are implementation details you are not expected to depend on.
 *
 * See Documentation/rbtree.txt for documentation and samples.
 */

struct rb_augment_callbacks {
	void (*propagate)(struct rb_node *node, struct rb_node *stop);
	void (*copy)(struct rb_node *old, struct rb_node *new);
	void (*rotate)(struct rb_node *old, struct rb_node *new);
};

extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
	void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
/*
 * Fixup the rbtree and update the augmented information when rebalancing.
 *
 * On insertion, the user must update the augmented information on the path
 * leading to the inserted node, then call rb_link_node() as usual and
 * rb_augment_inserted() instead of the usual rb_insert_color() call.
 * If rb_augment_inserted() rebalances the rbtree, it will callback into
 * a user provided function to update the augmented information on the
 * affected subtrees.
 */
static inline void
rb_insert_augmented(struct rb_node *node, struct rb_root *root,
		    const struct rb_augment_callbacks *augment)
{
	__rb_insert_augmented(node, root, augment->rotate);
}

#define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield,	\
			     rbtype, rbaugmented, rbcompute)		\
static inline void							\
rbname ## _propagate(struct rb_node *rb, struct rb_node *stop)		\
{									\
	while (rb != stop) {						\
		rbstruct *node = rb_entry(rb, rbstruct, rbfield);	\
		rbtype augmented = rbcompute(node);			\
		if (node->rbaugmented == augmented)			\
			break;						\
		node->rbaugmented = augmented;				\
		rb = rb_parent(&node->rbfield);				\
	}								\
}									\
static inline void							\
rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new)		\
{									\
	rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);		\
	rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);		\
	new->rbaugmented = old->rbaugmented;				\
}									\
static void								\
rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new)	\
{									\
	rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);		\
	rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);		\
	new->rbaugmented = old->rbaugmented;				\
	old->rbaugmented = rbcompute(old);				\
}									\
rbstatic const struct rb_augment_callbacks rbname = {			\
	rbname ## _propagate, rbname ## _copy, rbname ## _rotate	\
};


#define	RB_RED		0
#define	RB_BLACK	1

#define __rb_parent(pc)    ((struct rb_node *)(pc & ~3))

#define __rb_color(pc)     ((pc) & 1)
#define __rb_is_black(pc)  __rb_color(pc)
#define __rb_is_red(pc)    (!__rb_color(pc))
#define rb_color(rb)       __rb_color((rb)->__rb_parent_color)
#define rb_is_red(rb)      __rb_is_red((rb)->__rb_parent_color)
#define rb_is_black(rb)    __rb_is_black((rb)->__rb_parent_color)

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_parent_color(struct rb_node *rb,
				       struct rb_node *p, int color)
{
	rb->__rb_parent_color = (unsigned long)p | color;
}

static inline void
__rb_change_child(struct rb_node *old, struct rb_node *new,
		  struct rb_node *parent, struct rb_root *root)
{
	if (parent) {
		if (parent->rb_left == old)
			WRITE_ONCE(parent->rb_left, new);
		else
			WRITE_ONCE(parent->rb_right, new);
	} else
		WRITE_ONCE(root->rb_node, new);
}

static inline void
__rb_change_child_rcu(struct rb_node *old, struct rb_node *new,
		      struct rb_node *parent, struct rb_root *root)
{
	if (parent) {
		if (parent->rb_left == old)
			rcu_assign_pointer(parent->rb_left, new);
		else
			rcu_assign_pointer(parent->rb_right, new);
	} else
		rcu_assign_pointer(root->rb_node, new);
}

extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
	void (*augment_rotate)(struct rb_node *old, struct rb_node *new));

static __always_inline struct rb_node *
__rb_erase_augmented(struct rb_node *node, struct rb_root *root,
		     const struct rb_augment_callbacks *augment)
{
	struct rb_node *child = node->rb_right;
	struct rb_node *tmp = node->rb_left;
	struct rb_node *parent, *rebalance;
	unsigned long pc;

	if (!tmp) {
		/*
		 * Case 1: node to erase has no more than 1 child (easy!)
		 *
		 * Note that if there is one child it must be red due to 5)
		 * and node must be black due to 4). We adjust colors locally
		 * so as to bypass __rb_erase_color() later on.
		 */
		pc = node->__rb_parent_color;
		parent = __rb_parent(pc);
		__rb_change_child(node, child, parent, root);
		if (child) {
			child->__rb_parent_color = pc;
			rebalance = NULL;
		} else
			rebalance = __rb_is_black(pc) ? parent : NULL;
		tmp = parent;
	} else if (!child) {
		/* Still case 1, but this time the child is node->rb_left */
		tmp->__rb_parent_color = pc = node->__rb_parent_color;
		parent = __rb_parent(pc);
		__rb_change_child(node, tmp, parent, root);
		rebalance = NULL;
		tmp = parent;
	} else {
		struct rb_node *successor = child, *child2;

		tmp = child->rb_left;
		if (!tmp) {
			/*
			 * Case 2: node's successor is its right child
			 *
			 *    (n)          (s)
			 *    / \          / \
			 *  (x) (s)  ->  (x) (c)
			 *        \
			 *        (c)
			 */
			parent = successor;
			child2 = successor->rb_right;

			augment->copy(node, successor);
		} else {
			/*
			 * Case 3: node's successor is leftmost under
			 * node's right child subtree
			 *
			 *    (n)          (s)
			 *    / \          / \
			 *  (x) (y)  ->  (x) (y)
			 *      /            /
			 *    (p)          (p)
			 *    /            /
			 *  (s)          (c)
			 *    \
			 *    (c)
			 */
			do {
				parent = successor;
				successor = tmp;
				tmp = tmp->rb_left;
			} while (tmp);
			child2 = successor->rb_right;
			WRITE_ONCE(parent->rb_left, child2);
			WRITE_ONCE(successor->rb_right, child);
			rb_set_parent(child, successor);

			augment->copy(node, successor);
			augment->propagate(parent, successor);
		}

		tmp = node->rb_left;
		WRITE_ONCE(successor->rb_left, tmp);
		rb_set_parent(tmp, successor);

		pc = node->__rb_parent_color;
		tmp = __rb_parent(pc);
		__rb_change_child(node, successor, tmp, root);

		if (child2) {
			successor->__rb_parent_color = pc;
			rb_set_parent_color(child2, parent, RB_BLACK);
			rebalance = NULL;
		} else {
			unsigned long pc2 = successor->__rb_parent_color;
			successor->__rb_parent_color = pc;
			rebalance = __rb_is_black(pc2) ? parent : NULL;
		}
		tmp = successor;
	}

	augment->propagate(tmp, NULL);
	return rebalance;
}

static __always_inline void
rb_erase_augmented(struct rb_node *node, struct rb_root *root,
		   const struct rb_augment_callbacks *augment)
{
	struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);
	if (rebalance)
		__rb_erase_color(rebalance, root, augment->rotate);
}

#endif	/* _LINUX_RBTREE_AUGMENTED_H */
Commit	Line	Data
9c079add ML	1	/*
	2	Red Black Trees
	3	(C) 1999 Andrea Arcangeli <andrea@suse.de>
	4	(C) 2002 David Woodhouse <dwmw2@infradead.org>
	5	(C) 2012 Michel Lespinasse <walken@google.com>
	6
	7	This program is free software; you can redistribute it and/or modify
	8	it under the terms of the GNU General Public License as published by
	9	the Free Software Foundation; either version 2 of the License, or
	10	(at your option) any later version.
	11
	12	This program is distributed in the hope that it will be useful,
	13	but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	GNU General Public License for more details.
	16
	17	You should have received a copy of the GNU General Public License
	18	along with this program; if not, write to the Free Software
	19	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	20
	21	linux/include/linux/rbtree_augmented.h
	22	*/
	23
	24	#ifndef _LINUX_RBTREE_AUGMENTED_H
	25	#define _LINUX_RBTREE_AUGMENTED_H
	26
29fc7c5a	27	#include <linux/compiler.h>
9c079add ML	28	#include <linux/rbtree.h>
	29
	30	/*
	31	* Please note - only struct rb_augment_callbacks and the prototypes for
	32	* rb_insert_augmented() and rb_erase_augmented() are intended to be public.
	33	* The rest are implementation details you are not expected to depend on.
	34	*
	35	* See Documentation/rbtree.txt for documentation and samples.
	36	*/
	37
	38	struct rb_augment_callbacks {
	39	void (propagate)(struct rb_node node, struct rb_node *stop);
	40	void (copy)(struct rb_node old, struct rb_node *new);
	41	void (rotate)(struct rb_node old, struct rb_node *new);
	42	};
	43
	44	extern void __rb_insert_augmented(struct rb_node node, struct rb_root root,
	45	void (augment_rotate)(struct rb_node old, struct rb_node *new));
a841b659 LJ	46	/*
	47	* Fixup the rbtree and update the augmented information when rebalancing.
	48	*
	49	* On insertion, the user must update the augmented information on the path
	50	* leading to the inserted node, then call rb_link_node() as usual and
	51	* rb_augment_inserted() instead of the usual rb_insert_color() call.
	52	* If rb_augment_inserted() rebalances the rbtree, it will callback into
	53	* a user provided function to update the augmented information on the
	54	* affected subtrees.
	55	*/
9c079add ML	56	static inline void
	57	rb_insert_augmented(struct rb_node node, struct rb_root root,
	58	const struct rb_augment_callbacks *augment)
	59	{
	60	__rb_insert_augmented(node, root, augment->rotate);
	61	}
	62
	63	#define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield, \
	64	rbtype, rbaugmented, rbcompute) \
	65	static inline void \
	66	rbname ## _propagate(struct rb_node rb, struct rb_node stop) \
	67	{ \
	68	while (rb != stop) { \
	69	rbstruct *node = rb_entry(rb, rbstruct, rbfield); \
	70	rbtype augmented = rbcompute(node); \
	71	if (node->rbaugmented == augmented) \
	72	break; \
	73	node->rbaugmented = augmented; \
	74	rb = rb_parent(&node->rbfield); \
	75	} \
	76	} \
	77	static inline void \
	78	rbname ## _copy(struct rb_node rb_old, struct rb_node rb_new) \
	79	{ \
	80	rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \
	81	rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \
	82	new->rbaugmented = old->rbaugmented; \
	83	} \
	84	static void \
	85	rbname ## _rotate(struct rb_node rb_old, struct rb_node rb_new) \
	86	{ \
	87	rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \
	88	rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \
	89	new->rbaugmented = old->rbaugmented; \
	90	old->rbaugmented = rbcompute(old); \
	91	} \
	92	rbstatic const struct rb_augment_callbacks rbname = { \
	93	rbname ## _propagate, rbname ## _copy, rbname ## _rotate \
	94	};
	95
	96
	97	#define RB_RED 0
	98	#define RB_BLACK 1
	99
	100	#define __rb_parent(pc) ((struct rb_node *)(pc & ~3))
	101
	102	#define __rb_color(pc) ((pc) & 1)
	103	#define __rb_is_black(pc) __rb_color(pc)
	104	#define __rb_is_red(pc) (!__rb_color(pc))
	105	#define rb_color(rb) __rb_color((rb)->__rb_parent_color)
	106	#define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color)
	107	#define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color)
	108
	109	static inline void rb_set_parent(struct rb_node rb, struct rb_node p)
	110	{
	111	rb->__rb_parent_color = rb_color(rb) \| (unsigned long)p;
	112	}
	113
	114	static inline void rb_set_parent_color(struct rb_node *rb,
	115	struct rb_node *p, int color)
	116	{
	117	rb->__rb_parent_color = (unsigned long)p \| color;
	118	}
	119
120	static inline void
121	__rb_change_child(struct rb_node old, struct rb_node new,
122	struct rb_node parent, struct rb_root root)
123	{
124	if (parent) {
125	if (parent->rb_left == old)
d72da4a4	126	WRITE_ONCE(parent->rb_left, new);
9c079add	127	else
d72da4a4	128	WRITE_ONCE(parent->rb_right, new);
9c079add	129	} else
d72da4a4	130	WRITE_ONCE(root->rb_node, new);
9c079add ML	131	}
9c079add ML	132
c1adf200 DH	133	static inline void
	134	__rb_change_child_rcu(struct rb_node old, struct rb_node new,
	135	struct rb_node parent, struct rb_root root)
	136	{
	137	if (parent) {
	138	if (parent->rb_left == old)
	139	rcu_assign_pointer(parent->rb_left, new);
	140	else
	141	rcu_assign_pointer(parent->rb_right, new);
	142	} else
	143	rcu_assign_pointer(root->rb_node, new);
	144	}
	145
9c079add ML	146	extern void __rb_erase_color(struct rb_node parent, struct rb_root root,
	147	void (augment_rotate)(struct rb_node old, struct rb_node *new));
	148
3cb7a563 ML	149	static __always_inline struct rb_node *
	150	__rb_erase_augmented(struct rb_node node, struct rb_root root,
	151	const struct rb_augment_callbacks *augment)
9c079add	152	{
d72da4a4 PZ	153	struct rb_node *child = node->rb_right;
d72da4a4 PZ	154	struct rb_node *tmp = node->rb_left;
9c079add ML	155	struct rb_node parent, rebalance;
	156	unsigned long pc;
	157
	158	if (!tmp) {
	159	/*
	160	* Case 1: node to erase has no more than 1 child (easy!)
	161	*
	162	* Note that if there is one child it must be red due to 5)
	163	* and node must be black due to 4). We adjust colors locally
	164	* so as to bypass __rb_erase_color() later on.
	165	*/
	166	pc = node->__rb_parent_color;
	167	parent = __rb_parent(pc);
	168	__rb_change_child(node, child, parent, root);
	169	if (child) {
	170	child->__rb_parent_color = pc;
	171	rebalance = NULL;
	172	} else
	173	rebalance = __rb_is_black(pc) ? parent : NULL;
	174	tmp = parent;
	175	} else if (!child) {
	176	/* Still case 1, but this time the child is node->rb_left */
	177	tmp->__rb_parent_color = pc = node->__rb_parent_color;
	178	parent = __rb_parent(pc);
	179	__rb_change_child(node, tmp, parent, root);
	180	rebalance = NULL;
	181	tmp = parent;
	182	} else {
	183	struct rb_node successor = child, child2;
d72da4a4	184
9c079add ML	185	tmp = child->rb_left;
	186	if (!tmp) {
	187	/*
	188	* Case 2: node's successor is its right child
	189	*
	190	* (n) (s)
	191	* / \ / \
	192	* (x) (s) -> (x) (c)
	193	* \
	194	* (c)
	195	*/
	196	parent = successor;
	197	child2 = successor->rb_right;
d72da4a4	198
9c079add ML	199	augment->copy(node, successor);
	200	} else {
	201	/*
	202	* Case 3: node's successor is leftmost under
	203	* node's right child subtree
	204	*
	205	* (n) (s)
	206	* / \ / \
	207	* (x) (y) -> (x) (y)
	208	* / /
	209	* (p) (p)
	210	* / /
	211	* (s) (c)
	212	* \
	213	* (c)
	214	*/
	215	do {
	216	parent = successor;
	217	successor = tmp;
	218	tmp = tmp->rb_left;
	219	} while (tmp);
d72da4a4 PZ	220	child2 = successor->rb_right;
	221	WRITE_ONCE(parent->rb_left, child2);
	222	WRITE_ONCE(successor->rb_right, child);
9c079add	223	rb_set_parent(child, successor);
d72da4a4	224
9c079add ML	225	augment->copy(node, successor);
	226	augment->propagate(parent, successor);
	227	}
	228
d72da4a4 PZ	229	tmp = node->rb_left;
d72da4a4 PZ	230	WRITE_ONCE(successor->rb_left, tmp);
9c079add ML	231	rb_set_parent(tmp, successor);
	232
	233	pc = node->__rb_parent_color;
	234	tmp = __rb_parent(pc);
	235	__rb_change_child(node, successor, tmp, root);
d72da4a4	236
9c079add ML	237	if (child2) {
	238	successor->__rb_parent_color = pc;
	239	rb_set_parent_color(child2, parent, RB_BLACK);
	240	rebalance = NULL;
	241	} else {
	242	unsigned long pc2 = successor->__rb_parent_color;
	243	successor->__rb_parent_color = pc;
	244	rebalance = __rb_is_black(pc2) ? parent : NULL;
	245	}
	246	tmp = successor;
	247	}
	248
	249	augment->propagate(tmp, NULL);
3cb7a563 ML	250	return rebalance;
	251	}
	252
	253	static __always_inline void
	254	rb_erase_augmented(struct rb_node node, struct rb_root root,
	255	const struct rb_augment_callbacks *augment)
	256	{
	257	struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);
9c079add ML	258	if (rebalance)
	259	__rb_erase_color(rebalance, root, augment->rotate);
	260	}
	261
	262	#endif /* _LINUX_RBTREE_AUGMENTED_H */