[mirror_ubuntu-eoan-kernel.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,
				  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_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, 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
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
cd9e61ed DB	33	extern void __rb_insert_augmented(struct rb_node *node,
	34	struct rb_root *root,
	35	bool newleft, struct rb_node **leftmost,
9c079add	36	void (augment_rotate)(struct rb_node old, struct rb_node *new));
a841b659 LJ	37	/*
	38	* Fixup the rbtree and update the augmented information when rebalancing.
	39	*
	40	* On insertion, the user must update the augmented information on the path
	41	* leading to the inserted node, then call rb_link_node() as usual and
7e5ca363 WY	42	* rb_insert_augmented() instead of the usual rb_insert_color() call.
7e5ca363 WY	43	* If rb_insert_augmented() rebalances the rbtree, it will callback into
a841b659 LJ	44	* a user provided function to update the augmented information on the
	45	* affected subtrees.
	46	*/
9c079add ML	47	static inline void
	48	rb_insert_augmented(struct rb_node node, struct rb_root root,
	49	const struct rb_augment_callbacks *augment)
	50	{
cd9e61ed DB	51	__rb_insert_augmented(node, root, false, NULL, augment->rotate);
	52	}
	53
	54	static inline void
	55	rb_insert_augmented_cached(struct rb_node *node,
	56	struct rb_root_cached *root, bool newleft,
	57	const struct rb_augment_callbacks *augment)
	58	{
	59	__rb_insert_augmented(node, &root->rb_root,
	60	newleft, &root->rb_leftmost, augment->rotate);
9c079add ML	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 = { \
f231aebf KC	93	.propagate = rbname ## _propagate, \
	94	.copy = rbname ## _copy, \
	95	.rotate = rbname ## _rotate \
9c079add ML	96	};
	97
	98
	99	#define RB_RED 0
	100	#define RB_BLACK 1
	101
	102	#define __rb_parent(pc) ((struct rb_node *)(pc & ~3))
	103
	104	#define __rb_color(pc) ((pc) & 1)
	105	#define __rb_is_black(pc) __rb_color(pc)
	106	#define __rb_is_red(pc) (!__rb_color(pc))
	107	#define rb_color(rb) __rb_color((rb)->__rb_parent_color)
	108	#define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color)
	109	#define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color)
	110
	111	static inline void rb_set_parent(struct rb_node rb, struct rb_node p)
	112	{
	113	rb->__rb_parent_color = rb_color(rb) \| (unsigned long)p;
	114	}
	115
	116	static inline void rb_set_parent_color(struct rb_node *rb,
	117	struct rb_node *p, int color)
	118	{
	119	rb->__rb_parent_color = (unsigned long)p \| color;
	120	}
	121
	122	static inline void
	123	__rb_change_child(struct rb_node old, struct rb_node new,
	124	struct rb_node parent, struct rb_root root)
	125	{
	126	if (parent) {
	127	if (parent->rb_left == old)
d72da4a4	128	WRITE_ONCE(parent->rb_left, new);
9c079add	129	else
d72da4a4	130	WRITE_ONCE(parent->rb_right, new);
9c079add	131	} else
d72da4a4	132	WRITE_ONCE(root->rb_node, new);
9c079add ML	133	}
9c079add ML	134
c1adf200 DH	135	static inline void
	136	__rb_change_child_rcu(struct rb_node old, struct rb_node new,
	137	struct rb_node parent, struct rb_root root)
	138	{
	139	if (parent) {
	140	if (parent->rb_left == old)
	141	rcu_assign_pointer(parent->rb_left, new);
	142	else
	143	rcu_assign_pointer(parent->rb_right, new);
	144	} else
	145	rcu_assign_pointer(root->rb_node, new);
	146	}
	147
9c079add ML	148	extern void __rb_erase_color(struct rb_node parent, struct rb_root root,
	149	void (augment_rotate)(struct rb_node old, struct rb_node *new));
	150
3cb7a563 ML	151	static __always_inline struct rb_node *
3cb7a563 ML	152	__rb_erase_augmented(struct rb_node node, struct rb_root root,
cd9e61ed	153	struct rb_node **leftmost,
3cb7a563	154	const struct rb_augment_callbacks *augment)
9c079add	155	{
d72da4a4 PZ	156	struct rb_node *child = node->rb_right;
d72da4a4 PZ	157	struct rb_node *tmp = node->rb_left;
9c079add ML	158	struct rb_node parent, rebalance;
	159	unsigned long pc;
	160
cd9e61ed DB	161	if (leftmost && node == *leftmost)
	162	*leftmost = rb_next(node);
	163
9c079add ML	164	if (!tmp) {
	165	/*
	166	* Case 1: node to erase has no more than 1 child (easy!)
	167	*
	168	* Note that if there is one child it must be red due to 5)
	169	* and node must be black due to 4). We adjust colors locally
	170	* so as to bypass __rb_erase_color() later on.
	171	*/
	172	pc = node->__rb_parent_color;
	173	parent = __rb_parent(pc);
	174	__rb_change_child(node, child, parent, root);
	175	if (child) {
	176	child->__rb_parent_color = pc;
	177	rebalance = NULL;
	178	} else
	179	rebalance = __rb_is_black(pc) ? parent : NULL;
	180	tmp = parent;
	181	} else if (!child) {
	182	/* Still case 1, but this time the child is node->rb_left */
	183	tmp->__rb_parent_color = pc = node->__rb_parent_color;
	184	parent = __rb_parent(pc);
	185	__rb_change_child(node, tmp, parent, root);
	186	rebalance = NULL;
	187	tmp = parent;
	188	} else {
	189	struct rb_node successor = child, child2;
d72da4a4	190
9c079add ML	191	tmp = child->rb_left;
	192	if (!tmp) {
	193	/*
	194	* Case 2: node's successor is its right child
	195	*
	196	* (n) (s)
	197	* / \ / \
	198	* (x) (s) -> (x) (c)
	199	* \
	200	* (c)
	201	*/
	202	parent = successor;
	203	child2 = successor->rb_right;
d72da4a4	204
9c079add ML	205	augment->copy(node, successor);
	206	} else {
	207	/*
	208	* Case 3: node's successor is leftmost under
	209	* node's right child subtree
	210	*
	211	* (n) (s)
	212	* / \ / \
	213	* (x) (y) -> (x) (y)
	214	* / /
	215	* (p) (p)
	216	* / /
	217	* (s) (c)
	218	* \
	219	* (c)
	220	*/
	221	do {
	222	parent = successor;
	223	successor = tmp;
	224	tmp = tmp->rb_left;
	225	} while (tmp);
d72da4a4 PZ	226	child2 = successor->rb_right;
	227	WRITE_ONCE(parent->rb_left, child2);
	228	WRITE_ONCE(successor->rb_right, child);
9c079add	229	rb_set_parent(child, successor);
d72da4a4	230
9c079add ML	231	augment->copy(node, successor);
	232	augment->propagate(parent, successor);
	233	}
	234
d72da4a4 PZ	235	tmp = node->rb_left;
d72da4a4 PZ	236	WRITE_ONCE(successor->rb_left, tmp);
9c079add ML	237	rb_set_parent(tmp, successor);
	238
	239	pc = node->__rb_parent_color;
	240	tmp = __rb_parent(pc);
	241	__rb_change_child(node, successor, tmp, root);
d72da4a4	242
9c079add ML	243	if (child2) {
	244	successor->__rb_parent_color = pc;
	245	rb_set_parent_color(child2, parent, RB_BLACK);
	246	rebalance = NULL;
	247	} else {
	248	unsigned long pc2 = successor->__rb_parent_color;
	249	successor->__rb_parent_color = pc;
	250	rebalance = __rb_is_black(pc2) ? parent : NULL;
	251	}
	252	tmp = successor;
	253	}
	254
	255	augment->propagate(tmp, NULL);
3cb7a563 ML	256	return rebalance;
	257	}
	258
	259	static __always_inline void
	260	rb_erase_augmented(struct rb_node node, struct rb_root root,
	261	const struct rb_augment_callbacks *augment)
	262	{
cd9e61ed DB	263	struct rb_node *rebalance = __rb_erase_augmented(node, root,
cd9e61ed DB	264	NULL, augment);
9c079add ML	265	if (rebalance)
	266	__rb_erase_color(rebalance, root, augment->rotate);
	267	}
	268
cd9e61ed DB	269	static __always_inline void
	270	rb_erase_augmented_cached(struct rb_node node, struct rb_root_cached root,
	271	const struct rb_augment_callbacks *augment)
	272	{
	273	struct rb_node *rebalance = __rb_erase_augmented(node, &root->rb_root,
	274	&root->rb_leftmost,
	275	augment);
	276	if (rebalance)
	277	__rb_erase_color(rebalance, &root->rb_root, augment->rotate);
	278	}
	279
9c079add	280	#endif /* _LINUX_RBTREE_AUGMENTED_H */