[linux-2.6-block.git] / include / linux / rbtree_augmented.h

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
  Red Black Trees
  (C) 1999  Andrea Arcangeli <andrea@suse.de>
  (C) 2002  David Woodhouse <dwmw2@infradead.org>
  (C) 2012  Michel Lespinasse <walken@google.com>


  linux/include/linux/rbtree_augmented.h
*/

#ifndef _LINUX_RBTREE_AUGMENTED_H
#define _LINUX_RBTREE_AUGMENTED_H

#include <linux/compiler.h>
#include <linux/rbtree.h>
#include <linux/rcupdate.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_insert_augmented() instead of the usual rb_insert_color() call.
 * If rb_insert_augmented() 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);
}

static inline void
rb_insert_augmented_cached(struct rb_node *node,
			   struct rb_root_cached *root, bool newleft,
			   const struct rb_augment_callbacks *augment)
{
	if (newleft)
		root->rb_leftmost = node;
	rb_insert_augmented(node, &root->rb_root, augment);
}

/*
 * Template for declaring augmented rbtree callbacks
 *
 * RBSTATIC:    'static' or empty
 * RBNAME:      name of the rb_augment_callbacks structure
 * RBSTRUCT:    struct type of the tree nodes
 * RBFIELD:     name of struct rb_node field within RBSTRUCT
 * RBTYPE:      type of the RBAUGMENTED field
 * RBAUGMENTED: name of RBTYPE field within RBSTRUCT holding data for subtree
 * RBCOMPUTE:   name of function that recomputes the RBAUGMENTED data
 */

#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,
		     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);
}

static __always_inline void
rb_erase_augmented_cached(struct rb_node *node, struct rb_root_cached *root,
			  const struct rb_augment_callbacks *augment)
{
	if (root->rb_leftmost == node)
		root->rb_leftmost = rb_next(node);
	rb_erase_augmented(node, &root->rb_root, augment);
}

#endif	/* _LINUX_RBTREE_AUGMENTED_H */
Commit	Line	Data
1a59d1b8	1	/* SPDX-License-Identifier: GPL-2.0-or-later */
9c079add ML	2	/*
	3	Red Black Trees
	4	(C) 1999 Andrea Arcangeli <andrea@suse.de>
	5	(C) 2002 David Woodhouse <dwmw2@infradead.org>
	6	(C) 2012 Michel Lespinasse <walken@google.com>
	7
9c079add ML	8
	9	linux/include/linux/rbtree_augmented.h
	10	*/
	11
	12	#ifndef _LINUX_RBTREE_AUGMENTED_H
	13	#define _LINUX_RBTREE_AUGMENTED_H
	14
29fc7c5a	15	#include <linux/compiler.h>
9c079add	16	#include <linux/rbtree.h>
2075b16e	17	#include <linux/rcupdate.h>
9c079add ML	18
	19	/*
	20	* Please note - only struct rb_augment_callbacks and the prototypes for
	21	* rb_insert_augmented() and rb_erase_augmented() are intended to be public.
	22	* The rest are implementation details you are not expected to depend on.
	23	*
	24	* See Documentation/rbtree.txt for documentation and samples.
	25	*/
	26
	27	struct rb_augment_callbacks {
	28	void (propagate)(struct rb_node node, struct rb_node *stop);
	29	void (copy)(struct rb_node old, struct rb_node *new);
	30	void (rotate)(struct rb_node old, struct rb_node *new);
	31	};
	32
9f973cb3	33	extern void __rb_insert_augmented(struct rb_node node, struct rb_root root,
9c079add	34	void (augment_rotate)(struct rb_node old, struct rb_node *new));
9f973cb3	35
a841b659 LJ	36	/*
	37	* Fixup the rbtree and update the augmented information when rebalancing.
	38	*
	39	* On insertion, the user must update the augmented information on the path
	40	* leading to the inserted node, then call rb_link_node() as usual and
7e5ca363 WY	41	* rb_insert_augmented() instead of the usual rb_insert_color() call.
7e5ca363 WY	42	* If rb_insert_augmented() rebalances the rbtree, it will callback into
a841b659 LJ	43	* a user provided function to update the augmented information on the
	44	* affected subtrees.
	45	*/
9c079add ML	46	static inline void
	47	rb_insert_augmented(struct rb_node node, struct rb_root root,
	48	const struct rb_augment_callbacks *augment)
	49	{
9f973cb3	50	__rb_insert_augmented(node, root, augment->rotate);
cd9e61ed DB	51	}
	52
	53	static inline void
	54	rb_insert_augmented_cached(struct rb_node *node,
	55	struct rb_root_cached *root, bool newleft,
	56	const struct rb_augment_callbacks *augment)
	57	{
9f973cb3 ML	58	if (newleft)
	59	root->rb_leftmost = node;
	60	rb_insert_augmented(node, &root->rb_root, augment);
9c079add ML	61	}
9c079add ML	62
444b8a83 ML	63	/*
	64	* Template for declaring augmented rbtree callbacks
	65	*
	66	* RBSTATIC: 'static' or empty
	67	* RBNAME: name of the rb_augment_callbacks structure
	68	* RBSTRUCT: struct type of the tree nodes
	69	* RBFIELD: name of struct rb_node field within RBSTRUCT
	70	* RBTYPE: type of the RBAUGMENTED field
	71	* RBAUGMENTED: name of RBTYPE field within RBSTRUCT holding data for subtree
	72	* RBCOMPUTE: name of function that recomputes the RBAUGMENTED data
	73	*/
	74
	75	#define RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME, RBSTRUCT, RBFIELD, \
	76	RBTYPE, RBAUGMENTED, RBCOMPUTE) \
9c079add	77	static inline void \
444b8a83	78	RBNAME ## _propagate(struct rb_node rb, struct rb_node stop) \
9c079add ML	79	{ \
9c079add ML	80	while (rb != stop) { \
444b8a83 ML	81	RBSTRUCT *node = rb_entry(rb, RBSTRUCT, RBFIELD); \
	82	RBTYPE augmented = RBCOMPUTE(node); \
	83	if (node->RBAUGMENTED == augmented) \
9c079add	84	break; \
444b8a83 ML	85	node->RBAUGMENTED = augmented; \
444b8a83 ML	86	rb = rb_parent(&node->RBFIELD); \
9c079add ML	87	} \
	88	} \
	89	static inline void \
444b8a83	90	RBNAME ## _copy(struct rb_node rb_old, struct rb_node rb_new) \
9c079add	91	{ \
444b8a83 ML	92	RBSTRUCT *old = rb_entry(rb_old, RBSTRUCT, RBFIELD); \
	93	RBSTRUCT *new = rb_entry(rb_new, RBSTRUCT, RBFIELD); \
	94	new->RBAUGMENTED = old->RBAUGMENTED; \
9c079add ML	95	} \
9c079add ML	96	static void \
444b8a83	97	RBNAME ## _rotate(struct rb_node rb_old, struct rb_node rb_new) \
9c079add	98	{ \
444b8a83 ML	99	RBSTRUCT *old = rb_entry(rb_old, RBSTRUCT, RBFIELD); \
	100	RBSTRUCT *new = rb_entry(rb_new, RBSTRUCT, RBFIELD); \
	101	new->RBAUGMENTED = old->RBAUGMENTED; \
	102	old->RBAUGMENTED = RBCOMPUTE(old); \
9c079add	103	} \
444b8a83 ML	104	RBSTATIC const struct rb_augment_callbacks RBNAME = { \
	105	.propagate = RBNAME ## _propagate, \
	106	.copy = RBNAME ## _copy, \
	107	.rotate = RBNAME ## _rotate \
9c079add ML	108	};
	109
	110
	111	#define RB_RED 0
	112	#define RB_BLACK 1
	113
	114	#define __rb_parent(pc) ((struct rb_node *)(pc & ~3))
	115
	116	#define __rb_color(pc) ((pc) & 1)
	117	#define __rb_is_black(pc) __rb_color(pc)
	118	#define __rb_is_red(pc) (!__rb_color(pc))
	119	#define rb_color(rb) __rb_color((rb)->__rb_parent_color)
	120	#define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color)
	121	#define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color)
	122
	123	static inline void rb_set_parent(struct rb_node rb, struct rb_node p)
	124	{
	125	rb->__rb_parent_color = rb_color(rb) \| (unsigned long)p;
	126	}
	127
	128	static inline void rb_set_parent_color(struct rb_node *rb,
	129	struct rb_node *p, int color)
	130	{
	131	rb->__rb_parent_color = (unsigned long)p \| color;
	132	}
	133
	134	static inline void
	135	__rb_change_child(struct rb_node old, struct rb_node new,
	136	struct rb_node parent, struct rb_root root)
	137	{
	138	if (parent) {
	139	if (parent->rb_left == old)
d72da4a4	140	WRITE_ONCE(parent->rb_left, new);
9c079add	141	else
d72da4a4	142	WRITE_ONCE(parent->rb_right, new);
9c079add	143	} else
d72da4a4	144	WRITE_ONCE(root->rb_node, new);
9c079add ML	145	}
9c079add ML	146
c1adf200 DH	147	static inline void
	148	__rb_change_child_rcu(struct rb_node old, struct rb_node new,
	149	struct rb_node parent, struct rb_root root)
	150	{
	151	if (parent) {
	152	if (parent->rb_left == old)
	153	rcu_assign_pointer(parent->rb_left, new);
	154	else
	155	rcu_assign_pointer(parent->rb_right, new);
	156	} else
	157	rcu_assign_pointer(root->rb_node, new);
	158	}
	159
9c079add ML	160	extern void __rb_erase_color(struct rb_node parent, struct rb_root root,
	161	void (augment_rotate)(struct rb_node old, struct rb_node *new));
	162
3cb7a563 ML	163	static __always_inline struct rb_node *
	164	__rb_erase_augmented(struct rb_node node, struct rb_root root,
	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
	172	if (!tmp) {
	173	/*
	174	* Case 1: node to erase has no more than 1 child (easy!)
	175	*
	176	* Note that if there is one child it must be red due to 5)
	177	* and node must be black due to 4). We adjust colors locally
	178	* so as to bypass __rb_erase_color() later on.
	179	*/
	180	pc = node->__rb_parent_color;
	181	parent = __rb_parent(pc);
	182	__rb_change_child(node, child, parent, root);
	183	if (child) {
	184	child->__rb_parent_color = pc;
	185	rebalance = NULL;
	186	} else
	187	rebalance = __rb_is_black(pc) ? parent : NULL;
	188	tmp = parent;
	189	} else if (!child) {
	190	/* Still case 1, but this time the child is node->rb_left */
	191	tmp->__rb_parent_color = pc = node->__rb_parent_color;
	192	parent = __rb_parent(pc);
	193	__rb_change_child(node, tmp, parent, root);
	194	rebalance = NULL;
	195	tmp = parent;
	196	} else {
	197	struct rb_node successor = child, child2;
d72da4a4	198
9c079add ML	199	tmp = child->rb_left;
	200	if (!tmp) {
	201	/*
	202	* Case 2: node's successor is its right child
	203	*
	204	* (n) (s)
	205	* / \ / \
	206	* (x) (s) -> (x) (c)
	207	* \
	208	* (c)
	209	*/
	210	parent = successor;
	211	child2 = successor->rb_right;
d72da4a4	212
9c079add ML	213	augment->copy(node, successor);
	214	} else {
	215	/*
	216	* Case 3: node's successor is leftmost under
	217	* node's right child subtree
	218	*
	219	* (n) (s)
	220	* / \ / \
	221	* (x) (y) -> (x) (y)
	222	* / /
	223	* (p) (p)
	224	* / /
	225	* (s) (c)
	226	* \
	227	* (c)
	228	*/
	229	do {
	230	parent = successor;
	231	successor = tmp;
	232	tmp = tmp->rb_left;
	233	} while (tmp);
d72da4a4 PZ	234	child2 = successor->rb_right;
	235	WRITE_ONCE(parent->rb_left, child2);
	236	WRITE_ONCE(successor->rb_right, child);
9c079add	237	rb_set_parent(child, successor);
d72da4a4	238
9c079add ML	239	augment->copy(node, successor);
	240	augment->propagate(parent, successor);
	241	}
	242
d72da4a4 PZ	243	tmp = node->rb_left;
d72da4a4 PZ	244	WRITE_ONCE(successor->rb_left, tmp);
9c079add ML	245	rb_set_parent(tmp, successor);
	246
	247	pc = node->__rb_parent_color;
	248	tmp = __rb_parent(pc);
	249	__rb_change_child(node, successor, tmp, root);
d72da4a4	250
9c079add ML	251	if (child2) {
	252	successor->__rb_parent_color = pc;
	253	rb_set_parent_color(child2, parent, RB_BLACK);
	254	rebalance = NULL;
	255	} else {
	256	unsigned long pc2 = successor->__rb_parent_color;
	257	successor->__rb_parent_color = pc;
	258	rebalance = __rb_is_black(pc2) ? parent : NULL;
	259	}
	260	tmp = successor;
	261	}
	262
	263	augment->propagate(tmp, NULL);
3cb7a563 ML	264	return rebalance;
	265	}
	266
	267	static __always_inline void
	268	rb_erase_augmented(struct rb_node node, struct rb_root root,
	269	const struct rb_augment_callbacks *augment)
	270	{
9f973cb3	271	struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);
9c079add ML	272	if (rebalance)
	273	__rb_erase_color(rebalance, root, augment->rotate);
	274	}
	275
cd9e61ed DB	276	static __always_inline void
	277	rb_erase_augmented_cached(struct rb_node node, struct rb_root_cached root,
	278	const struct rb_augment_callbacks *augment)
	279	{
9f973cb3 ML	280	if (root->rb_leftmost == node)
	281	root->rb_leftmost = rb_next(node);
	282	rb_erase_augmented(node, &root->rb_root, augment);
cd9e61ed DB	283	}
cd9e61ed DB	284
9c079add	285	#endif /* _LINUX_RBTREE_AUGMENTED_H */