[mirror_ubuntu-bionic-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,
				  bool newleft, struct rb_node **leftmost,
	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, false, NULL, augment->rotate);
}

static inline void
rb_insert_augmented_cached(struct rb_node *node,
			   struct rb_root_cached *root, bool newleft,
			   const struct rb_augment_callbacks *augment)
{
	__rb_insert_augmented(node, &root->rb_root,
			      newleft, &root->rb_leftmost, 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 = {			\
	.propagate = rbname ## _propagate,				\
	.copy = rbname ## _copy,					\
	.rotate = 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,
		     struct rb_node **leftmost,
		     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 (leftmost && node == *leftmost)
		*leftmost = rb_next(node);

	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,
							 NULL, augment);
	if (rebalance)
		__rb_erase_color(rebalance, root, augment->rotate);
}

static __always_inline void
rb_erase_augmented_cached(struct rb_node *node, struct rb_root_cached *root,
			  const struct rb_augment_callbacks *augment)
{
	struct rb_node *rebalance = __rb_erase_augmented(node, &root->rb_root,
							 &root->rb_leftmost,
							 augment);
	if (rebalance)
		__rb_erase_color(rebalance, &root->rb_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
cd9e61ed DB	44	extern void __rb_insert_augmented(struct rb_node *node,
	45	struct rb_root *root,
	46	bool newleft, struct rb_node **leftmost,
9c079add	47	void (augment_rotate)(struct rb_node old, struct rb_node *new));
a841b659 LJ	48	/*
	49	* Fixup the rbtree and update the augmented information when rebalancing.
	50	*
	51	* On insertion, the user must update the augmented information on the path
	52	* leading to the inserted node, then call rb_link_node() as usual and
	53	* rb_augment_inserted() instead of the usual rb_insert_color() call.
	54	* If rb_augment_inserted() rebalances the rbtree, it will callback into
	55	* a user provided function to update the augmented information on the
	56	* affected subtrees.
	57	*/
9c079add ML	58	static inline void
	59	rb_insert_augmented(struct rb_node node, struct rb_root root,
	60	const struct rb_augment_callbacks *augment)
	61	{
cd9e61ed DB	62	__rb_insert_augmented(node, root, false, NULL, augment->rotate);
	63	}
	64
	65	static inline void
	66	rb_insert_augmented_cached(struct rb_node *node,
	67	struct rb_root_cached *root, bool newleft,
	68	const struct rb_augment_callbacks *augment)
	69	{
	70	__rb_insert_augmented(node, &root->rb_root,
	71	newleft, &root->rb_leftmost, augment->rotate);
9c079add ML	72	}
	73
	74	#define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield, \
	75	rbtype, rbaugmented, rbcompute) \
	76	static inline void \
	77	rbname ## _propagate(struct rb_node rb, struct rb_node stop) \
	78	{ \
	79	while (rb != stop) { \
	80	rbstruct *node = rb_entry(rb, rbstruct, rbfield); \
	81	rbtype augmented = rbcompute(node); \
	82	if (node->rbaugmented == augmented) \
	83	break; \
	84	node->rbaugmented = augmented; \
	85	rb = rb_parent(&node->rbfield); \
	86	} \
	87	} \
	88	static inline void \
	89	rbname ## _copy(struct rb_node rb_old, struct rb_node rb_new) \
	90	{ \
	91	rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \
	92	rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \
	93	new->rbaugmented = old->rbaugmented; \
	94	} \
	95	static void \
	96	rbname ## _rotate(struct rb_node rb_old, struct rb_node rb_new) \
	97	{ \
	98	rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \
	99	rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \
	100	new->rbaugmented = old->rbaugmented; \
	101	old->rbaugmented = rbcompute(old); \
	102	} \
	103	rbstatic const struct rb_augment_callbacks rbname = { \
f231aebf KC	104	.propagate = rbname ## _propagate, \
	105	.copy = rbname ## _copy, \
	106	.rotate = rbname ## _rotate \
9c079add ML	107	};
	108
	109
	110	#define RB_RED 0
	111	#define RB_BLACK 1
	112
	113	#define __rb_parent(pc) ((struct rb_node *)(pc & ~3))
	114
	115	#define __rb_color(pc) ((pc) & 1)
	116	#define __rb_is_black(pc) __rb_color(pc)
	117	#define __rb_is_red(pc) (!__rb_color(pc))
	118	#define rb_color(rb) __rb_color((rb)->__rb_parent_color)
	119	#define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color)
	120	#define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color)
	121
	122	static inline void rb_set_parent(struct rb_node rb, struct rb_node p)
	123	{
	124	rb->__rb_parent_color = rb_color(rb) \| (unsigned long)p;
	125	}
	126
	127	static inline void rb_set_parent_color(struct rb_node *rb,
	128	struct rb_node *p, int color)
	129	{
	130	rb->__rb_parent_color = (unsigned long)p \| color;
	131	}
	132
	133	static inline void
	134	__rb_change_child(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)
d72da4a4	139	WRITE_ONCE(parent->rb_left, new);
9c079add	140	else
d72da4a4	141	WRITE_ONCE(parent->rb_right, new);
9c079add	142	} else
d72da4a4	143	WRITE_ONCE(root->rb_node, new);
9c079add ML	144	}
9c079add ML	145
c1adf200 DH	146	static inline void
	147	__rb_change_child_rcu(struct rb_node old, struct rb_node new,
	148	struct rb_node parent, struct rb_root root)
	149	{
	150	if (parent) {
	151	if (parent->rb_left == old)
	152	rcu_assign_pointer(parent->rb_left, new);
	153	else
	154	rcu_assign_pointer(parent->rb_right, new);
	155	} else
	156	rcu_assign_pointer(root->rb_node, new);
	157	}
	158
9c079add ML	159	extern void __rb_erase_color(struct rb_node parent, struct rb_root root,
	160	void (augment_rotate)(struct rb_node old, struct rb_node *new));
	161
3cb7a563 ML	162	static __always_inline struct rb_node *
3cb7a563 ML	163	__rb_erase_augmented(struct rb_node node, struct rb_root root,
cd9e61ed	164	struct rb_node **leftmost,
3cb7a563	165	const struct rb_augment_callbacks *augment)
9c079add	166	{
d72da4a4 PZ	167	struct rb_node *child = node->rb_right;
d72da4a4 PZ	168	struct rb_node *tmp = node->rb_left;
9c079add ML	169	struct rb_node parent, rebalance;
	170	unsigned long pc;
	171
cd9e61ed DB	172	if (leftmost && node == *leftmost)
	173	*leftmost = rb_next(node);
	174
9c079add ML	175	if (!tmp) {
	176	/*
	177	* Case 1: node to erase has no more than 1 child (easy!)
	178	*
	179	* Note that if there is one child it must be red due to 5)
	180	* and node must be black due to 4). We adjust colors locally
	181	* so as to bypass __rb_erase_color() later on.
	182	*/
	183	pc = node->__rb_parent_color;
	184	parent = __rb_parent(pc);
	185	__rb_change_child(node, child, parent, root);
	186	if (child) {
	187	child->__rb_parent_color = pc;
	188	rebalance = NULL;
	189	} else
	190	rebalance = __rb_is_black(pc) ? parent : NULL;
	191	tmp = parent;
	192	} else if (!child) {
	193	/* Still case 1, but this time the child is node->rb_left */
	194	tmp->__rb_parent_color = pc = node->__rb_parent_color;
	195	parent = __rb_parent(pc);
	196	__rb_change_child(node, tmp, parent, root);
	197	rebalance = NULL;
	198	tmp = parent;
	199	} else {
	200	struct rb_node successor = child, child2;
d72da4a4	201
9c079add ML	202	tmp = child->rb_left;
	203	if (!tmp) {
	204	/*
	205	* Case 2: node's successor is its right child
	206	*
	207	* (n) (s)
	208	* / \ / \
	209	* (x) (s) -> (x) (c)
	210	* \
	211	* (c)
	212	*/
	213	parent = successor;
	214	child2 = successor->rb_right;
d72da4a4	215
9c079add ML	216	augment->copy(node, successor);
	217	} else {
	218	/*
	219	* Case 3: node's successor is leftmost under
	220	* node's right child subtree
	221	*
	222	* (n) (s)
	223	* / \ / \
	224	* (x) (y) -> (x) (y)
	225	* / /
	226	* (p) (p)
	227	* / /
	228	* (s) (c)
	229	* \
	230	* (c)
	231	*/
	232	do {
	233	parent = successor;
	234	successor = tmp;
	235	tmp = tmp->rb_left;
	236	} while (tmp);
d72da4a4 PZ	237	child2 = successor->rb_right;
	238	WRITE_ONCE(parent->rb_left, child2);
	239	WRITE_ONCE(successor->rb_right, child);
9c079add	240	rb_set_parent(child, successor);
d72da4a4	241
9c079add ML	242	augment->copy(node, successor);
	243	augment->propagate(parent, successor);
	244	}
	245
d72da4a4 PZ	246	tmp = node->rb_left;
d72da4a4 PZ	247	WRITE_ONCE(successor->rb_left, tmp);
9c079add ML	248	rb_set_parent(tmp, successor);
	249
	250	pc = node->__rb_parent_color;
	251	tmp = __rb_parent(pc);
	252	__rb_change_child(node, successor, tmp, root);
d72da4a4	253
9c079add ML	254	if (child2) {
	255	successor->__rb_parent_color = pc;
	256	rb_set_parent_color(child2, parent, RB_BLACK);
	257	rebalance = NULL;
	258	} else {
	259	unsigned long pc2 = successor->__rb_parent_color;
	260	successor->__rb_parent_color = pc;
	261	rebalance = __rb_is_black(pc2) ? parent : NULL;
	262	}
	263	tmp = successor;
	264	}
	265
	266	augment->propagate(tmp, NULL);
3cb7a563 ML	267	return rebalance;
	268	}
	269
	270	static __always_inline void
	271	rb_erase_augmented(struct rb_node node, struct rb_root root,
	272	const struct rb_augment_callbacks *augment)
	273	{
cd9e61ed DB	274	struct rb_node *rebalance = __rb_erase_augmented(node, root,
cd9e61ed DB	275	NULL, augment);
9c079add ML	276	if (rebalance)
	277	__rb_erase_color(rebalance, root, augment->rotate);
	278	}
	279
cd9e61ed DB	280	static __always_inline void
	281	rb_erase_augmented_cached(struct rb_node node, struct rb_root_cached root,
	282	const struct rb_augment_callbacks *augment)
	283	{
	284	struct rb_node *rebalance = __rb_erase_augmented(node, &root->rb_root,
	285	&root->rb_leftmost,
	286	augment);
	287	if (rebalance)
	288	__rb_erase_color(rebalance, &root->rb_root, augment->rotate);
	289	}
	290
9c079add	291	#endif /* _LINUX_RBTREE_AUGMENTED_H */