[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/core-api/rbtree.rst 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);
}

static __always_inline struct rb_node *
rb_add_augmented_cached(struct rb_node *node, struct rb_root_cached *tree,
			bool (*less)(struct rb_node *, const struct rb_node *),
			const struct rb_augment_callbacks *augment)
{
	struct rb_node **link = &tree->rb_root.rb_node;
	struct rb_node *parent = NULL;
	bool leftmost = true;

	while (*link) {
		parent = *link;
		if (less(node, parent)) {
			link = &parent->rb_left;
		} else {
			link = &parent->rb_right;
			leftmost = false;
		}
	}

	rb_link_node(node, parent, link);
	augment->propagate(parent, NULL); /* suboptimal */
	rb_insert_augmented_cached(node, tree, leftmost, augment);

	return leftmost ? node : NULL;
}

/*
 * Template for declaring augmented rbtree callbacks (generic case)
 *
 * 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
 * RBAUGMENTED: name of field within RBSTRUCT holding data for subtree
 * RBCOMPUTE:   name of function that recomputes the RBAUGMENTED data
 */

#define RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME,				\
			     RBSTRUCT, RBFIELD, 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);	\
		if (RBCOMPUTE(node, true))				\
			break;						\
		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;				\
	RBCOMPUTE(old, false);						\
}									\
RBSTATIC const struct rb_augment_callbacks RBNAME = {			\
	.propagate = RBNAME ## _propagate,				\
	.copy = RBNAME ## _copy,					\
	.rotate = RBNAME ## _rotate					\
};

/*
 * Template for declaring augmented rbtree callbacks,
 * computing RBAUGMENTED scalar as max(RBCOMPUTE(node)) for all subtree nodes.
 *
 * 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 returns the per-node RBTYPE scalar
 */

#define RB_DECLARE_CALLBACKS_MAX(RBSTATIC, RBNAME, RBSTRUCT, RBFIELD,	      \
				 RBTYPE, RBAUGMENTED, RBCOMPUTE)	      \
static inline bool RBNAME ## _compute_max(RBSTRUCT *node, bool exit)	      \
{									      \
	RBSTRUCT *child;						      \
	RBTYPE max = RBCOMPUTE(node);					      \
	if (node->RBFIELD.rb_left) {					      \
		child = rb_entry(node->RBFIELD.rb_left, RBSTRUCT, RBFIELD);   \
		if (child->RBAUGMENTED > max)				      \
			max = child->RBAUGMENTED;			      \
	}								      \
	if (node->RBFIELD.rb_right) {					      \
		child = rb_entry(node->RBFIELD.rb_right, RBSTRUCT, RBFIELD);  \
		if (child->RBAUGMENTED > max)				      \
			max = child->RBAUGMENTED;			      \
	}								      \
	if (exit && node->RBAUGMENTED == max)				      \
		return true;						      \
	node->RBAUGMENTED = max;					      \
	return false;							      \
}									      \
RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME,					      \
		     RBSTRUCT, RBFIELD, RBAUGMENTED, RBNAME ## _compute_max)


#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) {
			rb_set_parent_color(child2, parent, RB_BLACK);
			rebalance = NULL;
		} else {
			rebalance = rb_is_black(successor) ? parent : NULL;
		}
		successor->__rb_parent_color = pc;
		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	*
14bbe3e3	24	* See Documentation/core-api/rbtree.rst for documentation and samples.
9c079add ML	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
99d4d265 PZ	63	static __always_inline struct rb_node *
	64	rb_add_augmented_cached(struct rb_node node, struct rb_root_cached tree,
	65	bool (less)(struct rb_node , const struct rb_node *),
	66	const struct rb_augment_callbacks *augment)
	67	{
	68	struct rb_node **link = &tree->rb_root.rb_node;
	69	struct rb_node *parent = NULL;
	70	bool leftmost = true;
	71
	72	while (*link) {
	73	parent = *link;
	74	if (less(node, parent)) {
	75	link = &parent->rb_left;
	76	} else {
	77	link = &parent->rb_right;
	78	leftmost = false;
	79	}
	80	}
	81
	82	rb_link_node(node, parent, link);
	83	augment->propagate(parent, NULL); /* suboptimal */
	84	rb_insert_augmented_cached(node, tree, leftmost, augment);
	85
	86	return leftmost ? node : NULL;
	87	}
	88
444b8a83	89	/*
315cc066	90	* Template for declaring augmented rbtree callbacks (generic case)
444b8a83 ML	91	*
	92	* RBSTATIC: 'static' or empty
	93	* RBNAME: name of the rb_augment_callbacks structure
	94	* RBSTRUCT: struct type of the tree nodes
	95	* RBFIELD: name of struct rb_node field within RBSTRUCT
6d2052d1	96	* RBAUGMENTED: name of field within RBSTRUCT holding data for subtree
444b8a83 ML	97	* RBCOMPUTE: name of function that recomputes the RBAUGMENTED data
	98	*/
	99
6d2052d1 ML	100	#define RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME, \
6d2052d1 ML	101	RBSTRUCT, RBFIELD, RBAUGMENTED, RBCOMPUTE) \
9c079add	102	static inline void \
444b8a83	103	RBNAME ## _propagate(struct rb_node rb, struct rb_node stop) \
9c079add ML	104	{ \
9c079add ML	105	while (rb != stop) { \
444b8a83	106	RBSTRUCT *node = rb_entry(rb, RBSTRUCT, RBFIELD); \
6d2052d1	107	if (RBCOMPUTE(node, true)) \
9c079add	108	break; \
444b8a83	109	rb = rb_parent(&node->RBFIELD); \
9c079add ML	110	} \
	111	} \
	112	static inline void \
444b8a83	113	RBNAME ## _copy(struct rb_node rb_old, struct rb_node rb_new) \
9c079add	114	{ \
444b8a83 ML	115	RBSTRUCT *old = rb_entry(rb_old, RBSTRUCT, RBFIELD); \
	116	RBSTRUCT *new = rb_entry(rb_new, RBSTRUCT, RBFIELD); \
	117	new->RBAUGMENTED = old->RBAUGMENTED; \
9c079add ML	118	} \
9c079add ML	119	static void \
444b8a83	120	RBNAME ## _rotate(struct rb_node rb_old, struct rb_node rb_new) \
9c079add	121	{ \
444b8a83 ML	122	RBSTRUCT *old = rb_entry(rb_old, RBSTRUCT, RBFIELD); \
	123	RBSTRUCT *new = rb_entry(rb_new, RBSTRUCT, RBFIELD); \
	124	new->RBAUGMENTED = old->RBAUGMENTED; \
6d2052d1	125	RBCOMPUTE(old, false); \
9c079add	126	} \
444b8a83 ML	127	RBSTATIC const struct rb_augment_callbacks RBNAME = { \
	128	.propagate = RBNAME ## _propagate, \
	129	.copy = RBNAME ## _copy, \
	130	.rotate = RBNAME ## _rotate \
9c079add ML	131	};
9c079add ML	132
315cc066 ML	133	/*
	134	* Template for declaring augmented rbtree callbacks,
	135	* computing RBAUGMENTED scalar as max(RBCOMPUTE(node)) for all subtree nodes.
	136	*
	137	* RBSTATIC: 'static' or empty
	138	* RBNAME: name of the rb_augment_callbacks structure
	139	* RBSTRUCT: struct type of the tree nodes
	140	* RBFIELD: name of struct rb_node field within RBSTRUCT
	141	* RBTYPE: type of the RBAUGMENTED field
	142	* RBAUGMENTED: name of RBTYPE field within RBSTRUCT holding data for subtree
	143	* RBCOMPUTE: name of function that returns the per-node RBTYPE scalar
	144	*/
	145
	146	#define RB_DECLARE_CALLBACKS_MAX(RBSTATIC, RBNAME, RBSTRUCT, RBFIELD, \
	147	RBTYPE, RBAUGMENTED, RBCOMPUTE) \
6d2052d1	148	static inline bool RBNAME ## _compute_max(RBSTRUCT *node, bool exit) \
315cc066 ML	149	{ \
	150	RBSTRUCT *child; \
	151	RBTYPE max = RBCOMPUTE(node); \
	152	if (node->RBFIELD.rb_left) { \
	153	child = rb_entry(node->RBFIELD.rb_left, RBSTRUCT, RBFIELD); \
	154	if (child->RBAUGMENTED > max) \
	155	max = child->RBAUGMENTED; \
	156	} \
	157	if (node->RBFIELD.rb_right) { \
	158	child = rb_entry(node->RBFIELD.rb_right, RBSTRUCT, RBFIELD); \
	159	if (child->RBAUGMENTED > max) \
	160	max = child->RBAUGMENTED; \
	161	} \
6d2052d1 ML	162	if (exit && node->RBAUGMENTED == max) \
	163	return true; \
	164	node->RBAUGMENTED = max; \
	165	return false; \
315cc066	166	} \
6d2052d1 ML	167	RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME, \
6d2052d1 ML	168	RBSTRUCT, RBFIELD, RBAUGMENTED, RBNAME ## _compute_max)
315cc066	169
9c079add ML	170
	171	#define RB_RED 0
	172	#define RB_BLACK 1
	173
	174	#define __rb_parent(pc) ((struct rb_node *)(pc & ~3))
	175
	176	#define __rb_color(pc) ((pc) & 1)
	177	#define __rb_is_black(pc) __rb_color(pc)
	178	#define __rb_is_red(pc) (!__rb_color(pc))
	179	#define rb_color(rb) __rb_color((rb)->__rb_parent_color)
	180	#define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color)
	181	#define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color)
	182
	183	static inline void rb_set_parent(struct rb_node rb, struct rb_node p)
	184	{
b0687c11	185	rb->__rb_parent_color = rb_color(rb) + (unsigned long)p;
9c079add ML	186	}
	187
	188	static inline void rb_set_parent_color(struct rb_node *rb,
	189	struct rb_node *p, int color)
	190	{
b0687c11	191	rb->__rb_parent_color = (unsigned long)p + color;
9c079add ML	192	}
	193
	194	static inline void
	195	__rb_change_child(struct rb_node old, struct rb_node new,
	196	struct rb_node parent, struct rb_root root)
	197	{
	198	if (parent) {
	199	if (parent->rb_left == old)
d72da4a4	200	WRITE_ONCE(parent->rb_left, new);
9c079add	201	else
d72da4a4	202	WRITE_ONCE(parent->rb_right, new);
9c079add	203	} else
d72da4a4	204	WRITE_ONCE(root->rb_node, new);
9c079add ML	205	}
9c079add ML	206
c1adf200 DH	207	static inline void
	208	__rb_change_child_rcu(struct rb_node old, struct rb_node new,
	209	struct rb_node parent, struct rb_root root)
	210	{
	211	if (parent) {
	212	if (parent->rb_left == old)
	213	rcu_assign_pointer(parent->rb_left, new);
	214	else
	215	rcu_assign_pointer(parent->rb_right, new);
	216	} else
	217	rcu_assign_pointer(root->rb_node, new);
	218	}
	219
9c079add ML	220	extern void __rb_erase_color(struct rb_node parent, struct rb_root root,
	221	void (augment_rotate)(struct rb_node old, struct rb_node *new));
	222
3cb7a563 ML	223	static __always_inline struct rb_node *
	224	__rb_erase_augmented(struct rb_node node, struct rb_root root,
	225	const struct rb_augment_callbacks *augment)
9c079add	226	{
d72da4a4 PZ	227	struct rb_node *child = node->rb_right;
d72da4a4 PZ	228	struct rb_node *tmp = node->rb_left;
9c079add ML	229	struct rb_node parent, rebalance;
	230	unsigned long pc;
	231
	232	if (!tmp) {
	233	/*
	234	* Case 1: node to erase has no more than 1 child (easy!)
	235	*
	236	* Note that if there is one child it must be red due to 5)
	237	* and node must be black due to 4). We adjust colors locally
	238	* so as to bypass __rb_erase_color() later on.
	239	*/
	240	pc = node->__rb_parent_color;
	241	parent = __rb_parent(pc);
	242	__rb_change_child(node, child, parent, root);
	243	if (child) {
	244	child->__rb_parent_color = pc;
	245	rebalance = NULL;
	246	} else
	247	rebalance = __rb_is_black(pc) ? parent : NULL;
	248	tmp = parent;
	249	} else if (!child) {
	250	/* Still case 1, but this time the child is node->rb_left */
	251	tmp->__rb_parent_color = pc = node->__rb_parent_color;
	252	parent = __rb_parent(pc);
	253	__rb_change_child(node, tmp, parent, root);
	254	rebalance = NULL;
	255	tmp = parent;
	256	} else {
	257	struct rb_node successor = child, child2;
d72da4a4	258
9c079add ML	259	tmp = child->rb_left;
	260	if (!tmp) {
	261	/*
	262	* Case 2: node's successor is its right child
	263	*
	264	* (n) (s)
	265	* / \ / \
	266	* (x) (s) -> (x) (c)
	267	* \
	268	* (c)
	269	*/
	270	parent = successor;
	271	child2 = successor->rb_right;
d72da4a4	272
9c079add ML	273	augment->copy(node, successor);
	274	} else {
	275	/*
	276	* Case 3: node's successor is leftmost under
	277	* node's right child subtree
	278	*
	279	* (n) (s)
	280	* / \ / \
	281	* (x) (y) -> (x) (y)
	282	* / /
	283	* (p) (p)
	284	* / /
	285	* (s) (c)
	286	* \
	287	* (c)
	288	*/
	289	do {
	290	parent = successor;
	291	successor = tmp;
	292	tmp = tmp->rb_left;
	293	} while (tmp);
d72da4a4 PZ	294	child2 = successor->rb_right;
	295	WRITE_ONCE(parent->rb_left, child2);
	296	WRITE_ONCE(successor->rb_right, child);
9c079add	297	rb_set_parent(child, successor);
d72da4a4	298
9c079add ML	299	augment->copy(node, successor);
	300	augment->propagate(parent, successor);
	301	}
	302
d72da4a4 PZ	303	tmp = node->rb_left;
d72da4a4 PZ	304	WRITE_ONCE(successor->rb_left, tmp);
9c079add ML	305	rb_set_parent(tmp, successor);
	306
	307	pc = node->__rb_parent_color;
	308	tmp = __rb_parent(pc);
	309	__rb_change_child(node, successor, tmp, root);
d72da4a4	310
9c079add	311	if (child2) {
9c079add ML	312	rb_set_parent_color(child2, parent, RB_BLACK);
	313	rebalance = NULL;
	314	} else {
8b7569a2	315	rebalance = rb_is_black(successor) ? parent : NULL;
9c079add	316	}
11d43e62	317	successor->__rb_parent_color = pc;
9c079add ML	318	tmp = successor;
	319	}
	320
	321	augment->propagate(tmp, NULL);
3cb7a563 ML	322	return rebalance;
	323	}
	324
	325	static __always_inline void
	326	rb_erase_augmented(struct rb_node node, struct rb_root root,
	327	const struct rb_augment_callbacks *augment)
	328	{
9f973cb3	329	struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);
9c079add ML	330	if (rebalance)
	331	__rb_erase_color(rebalance, root, augment->rotate);
	332	}
	333
cd9e61ed DB	334	static __always_inline void
	335	rb_erase_augmented_cached(struct rb_node node, struct rb_root_cached root,
	336	const struct rb_augment_callbacks *augment)
	337	{
9f973cb3 ML	338	if (root->rb_leftmost == node)
	339	root->rb_leftmost = rb_next(node);
	340	rb_erase_augmented(node, &root->rb_root, augment);
cd9e61ed DB	341	}
cd9e61ed DB	342
9c079add	343	#endif /* _LINUX_RBTREE_AUGMENTED_H */