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

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
  Red Black Trees
  (C) 1999  Andrea Arcangeli <andrea@suse.de>
  

  linux/include/linux/rbtree.h

  To use rbtrees you'll have to implement your own insert and search cores.
  This will avoid us to use callbacks and to drop drammatically performances.
  I know it's not the cleaner way,  but in C (not in C++) to get
  performances and genericity...

  See Documentation/rbtree.txt for documentation and samples.
*/

#ifndef	_LINUX_RBTREE_H
#define	_LINUX_RBTREE_H

#include <linux/kernel.h>
#include <linux/stddef.h>
#include <linux/rcupdate.h>

struct rb_node {
	unsigned long  __rb_parent_color;
	struct rb_node *rb_right;
	struct rb_node *rb_left;
} __attribute__((aligned(sizeof(long))));
    /* The alignment might seem pointless, but allegedly CRIS needs it */

struct rb_root {
	struct rb_node *rb_node;
};

#define rb_parent(r)   ((struct rb_node *)((r)->__rb_parent_color & ~3))

#define RB_ROOT	(struct rb_root) { NULL, }
#define	rb_entry(ptr, type, member) container_of(ptr, type, member)

#define RB_EMPTY_ROOT(root)  (READ_ONCE((root)->rb_node) == NULL)

/* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
#define RB_EMPTY_NODE(node)  \
	((node)->__rb_parent_color == (unsigned long)(node))
#define RB_CLEAR_NODE(node)  \
	((node)->__rb_parent_color = (unsigned long)(node))


extern void rb_insert_color(struct rb_node *, struct rb_root *);
extern void rb_erase(struct rb_node *, struct rb_root *);


/* Find logical next and previous nodes in a tree */
extern struct rb_node *rb_next(const struct rb_node *);
extern struct rb_node *rb_prev(const struct rb_node *);
extern struct rb_node *rb_first(const struct rb_root *);
extern struct rb_node *rb_last(const struct rb_root *);

/* Postorder iteration - always visit the parent after its children */
extern struct rb_node *rb_first_postorder(const struct rb_root *);
extern struct rb_node *rb_next_postorder(const struct rb_node *);

/* Fast replacement of a single node without remove/rebalance/add/rebalance */
extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
			    struct rb_root *root);
extern void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new,
				struct rb_root *root);

static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
				struct rb_node **rb_link)
{
	node->__rb_parent_color = (unsigned long)parent;
	node->rb_left = node->rb_right = NULL;

	*rb_link = node;
}

static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent,
				    struct rb_node **rb_link)
{
	node->__rb_parent_color = (unsigned long)parent;
	node->rb_left = node->rb_right = NULL;

	rcu_assign_pointer(*rb_link, node);
}

#define rb_entry_safe(ptr, type, member) \
	({ typeof(ptr) ____ptr = (ptr); \
	   ____ptr ? rb_entry(____ptr, type, member) : NULL; \
	})

/**
 * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
 * given type allowing the backing memory of @pos to be invalidated
 *
 * @pos:	the 'type *' to use as a loop cursor.
 * @n:		another 'type *' to use as temporary storage
 * @root:	'rb_root *' of the rbtree.
 * @field:	the name of the rb_node field within 'type'.
 *
 * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
 * list_for_each_entry_safe() and allows the iteration to continue independent
 * of changes to @pos by the body of the loop.
 *
 * Note, however, that it cannot handle other modifications that re-order the
 * rbtree it is iterating over. This includes calling rb_erase() on @pos, as
 * rb_erase() may rebalance the tree, causing us to miss some nodes.
 */
#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
	for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
	     pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
			typeof(*pos), field); 1; }); \
	     pos = n)

/*
 * Leftmost-cached rbtrees.
 *
 * We do not cache the rightmost node based on footprint
 * size vs number of potential users that could benefit
 * from O(1) rb_last(). Just not worth it, users that want
 * this feature can always implement the logic explicitly.
 * Furthermore, users that want to cache both pointers may
 * find it a bit asymmetric, but that's ok.
 */
struct rb_root_cached {
	struct rb_root rb_root;
	struct rb_node *rb_leftmost;
};

#define RB_ROOT_CACHED (struct rb_root_cached) { {NULL, }, NULL }

/* Same as rb_first(), but O(1) */
#define rb_first_cached(root) (root)->rb_leftmost

static inline void rb_insert_color_cached(struct rb_node *node,
					  struct rb_root_cached *root,
					  bool leftmost)
{
	if (leftmost)
		root->rb_leftmost = node;
	rb_insert_color(node, &root->rb_root);
}

static inline void rb_erase_cached(struct rb_node *node,
				   struct rb_root_cached *root)
{
	if (root->rb_leftmost == node)
		root->rb_leftmost = rb_next(node);
	rb_erase(node, &root->rb_root);
}

static inline void rb_replace_node_cached(struct rb_node *victim,
					  struct rb_node *new,
					  struct rb_root_cached *root)
{
	if (root->rb_leftmost == victim)
		root->rb_leftmost = new;
	rb_replace_node(victim, new, &root->rb_root);
}

#endif	/* _LINUX_RBTREE_H */
Commit	Line	Data
1a59d1b8	1	/* SPDX-License-Identifier: GPL-2.0-or-later */
1da177e4 LT	2	/*
	3	Red Black Trees
	4	(C) 1999 Andrea Arcangeli <andrea@suse.de>
	5
1da177e4 LT	6
	7	linux/include/linux/rbtree.h
	8
	9	To use rbtrees you'll have to implement your own insert and search cores.
	10	This will avoid us to use callbacks and to drop drammatically performances.
	11	I know it's not the cleaner way, but in C (not in C++) to get
	12	performances and genericity...
	13
1457d287	14	See Documentation/rbtree.txt for documentation and samples.
1da177e4 LT	15	*/
	16
	17	#ifndef _LINUX_RBTREE_H
	18	#define _LINUX_RBTREE_H
	19
	20	#include <linux/kernel.h>
	21	#include <linux/stddef.h>
d72da4a4	22	#include <linux/rcupdate.h>
1da177e4	23
bf7ad8ee ML	24	struct rb_node {
bf7ad8ee ML	25	unsigned long __rb_parent_color;
1da177e4 LT	26	struct rb_node *rb_right;
1da177e4 LT	27	struct rb_node *rb_left;
e977145a DW	28	} __attribute__((aligned(sizeof(long))));
e977145a DW	29	/* The alignment might seem pointless, but allegedly CRIS needs it */
1da177e4	30
bf7ad8ee	31	struct rb_root {
1da177e4 LT	32	struct rb_node *rb_node;
	33	};
	34
bf7ad8ee	35	#define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3))
55a98102	36
b945d6b2	37	#define RB_ROOT (struct rb_root) { NULL, }
1da177e4 LT	38	#define rb_entry(ptr, type, member) container_of(ptr, type, member)
1da177e4 LT	39
a460bece	40	#define RB_EMPTY_ROOT(root) (READ_ONCE((root)->rb_node) == NULL)
4c199a93	41
7647f14f	42	/* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
bf7ad8ee ML	43	#define RB_EMPTY_NODE(node) \
	44	((node)->__rb_parent_color == (unsigned long)(node))
	45	#define RB_CLEAR_NODE(node) \
	46	((node)->__rb_parent_color = (unsigned long)(node))
dd67d051	47
88d19cf3	48
1da177e4 LT	49	extern void rb_insert_color(struct rb_node , struct rb_root );
	50	extern void rb_erase(struct rb_node , struct rb_root );
	51
14b94af0	52
1da177e4	53	/* Find logical next and previous nodes in a tree */
f4b477c4 AB	54	extern struct rb_node rb_next(const struct rb_node );
	55	extern struct rb_node rb_prev(const struct rb_node );
	56	extern struct rb_node rb_first(const struct rb_root );
	57	extern struct rb_node rb_last(const struct rb_root );
1da177e4	58
9dee5c51 CS	59	/* Postorder iteration - always visit the parent after its children */
	60	extern struct rb_node rb_first_postorder(const struct rb_root );
	61	extern struct rb_node rb_next_postorder(const struct rb_node );
	62
1da177e4	63	/* Fast replacement of a single node without remove/rebalance/add/rebalance */
d72da4a4	64	extern void rb_replace_node(struct rb_node victim, struct rb_node new,
1da177e4	65	struct rb_root *root);
c1adf200 DH	66	extern void rb_replace_node_rcu(struct rb_node victim, struct rb_node new,
c1adf200 DH	67	struct rb_root *root);
1da177e4	68
d72da4a4 PZ	69	static inline void rb_link_node(struct rb_node node, struct rb_node parent,
d72da4a4 PZ	70	struct rb_node **rb_link)
1da177e4	71	{
bf7ad8ee	72	node->__rb_parent_color = (unsigned long)parent;
1da177e4 LT	73	node->rb_left = node->rb_right = NULL;
	74
	75	*rb_link = node;
	76	}
	77
d72da4a4 PZ	78	static inline void rb_link_node_rcu(struct rb_node node, struct rb_node parent,
	79	struct rb_node **rb_link)
	80	{
	81	node->__rb_parent_color = (unsigned long)parent;
	82	node->rb_left = node->rb_right = NULL;
	83
	84	rcu_assign_pointer(*rb_link, node);
	85	}
	86
1310a5a9 JK	87	#define rb_entry_safe(ptr, type, member) \
	88	({ typeof(ptr) ____ptr = (ptr); \
	89	____ptr ? rb_entry(____ptr, type, member) : NULL; \
	90	})
	91
2b529089	92	/**
8de1ee7e CS	93	* rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
8de1ee7e CS	94	* given type allowing the backing memory of @pos to be invalidated
2b529089 CS	95	*
	96	* @pos: the 'type *' to use as a loop cursor.
	97	* @n: another 'type *' to use as temporary storage
	98	* @root: 'rb_root *' of the rbtree.
	99	* @field: the name of the rb_node field within 'type'.
8de1ee7e CS	100	*
	101	* rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
	102	* list_for_each_entry_safe() and allows the iteration to continue independent
	103	* of changes to @pos by the body of the loop.
	104	*
	105	* Note, however, that it cannot handle other modifications that re-order the
	106	* rbtree it is iterating over. This includes calling rb_erase() on @pos, as
	107	* rb_erase() may rebalance the tree, causing us to miss some nodes.
2b529089 CS	108	*/
2b529089 CS	109	#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
1310a5a9 JK	110	for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
	111	pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
	112	typeof(*pos), field); 1; }); \
	113	pos = n)
2b529089	114
9f973cb3 ML	115	/*
	116	* Leftmost-cached rbtrees.
	117	*
	118	* We do not cache the rightmost node based on footprint
	119	* size vs number of potential users that could benefit
	120	* from O(1) rb_last(). Just not worth it, users that want
	121	* this feature can always implement the logic explicitly.
	122	* Furthermore, users that want to cache both pointers may
	123	* find it a bit asymmetric, but that's ok.
	124	*/
	125	struct rb_root_cached {
	126	struct rb_root rb_root;
	127	struct rb_node *rb_leftmost;
	128	};
	129
	130	#define RB_ROOT_CACHED (struct rb_root_cached) { {NULL, }, NULL }
	131
	132	/* Same as rb_first(), but O(1) */
	133	#define rb_first_cached(root) (root)->rb_leftmost
	134
	135	static inline void rb_insert_color_cached(struct rb_node *node,
	136	struct rb_root_cached *root,
	137	bool leftmost)
	138	{
	139	if (leftmost)
	140	root->rb_leftmost = node;
	141	rb_insert_color(node, &root->rb_root);
	142	}
	143
	144	static inline void rb_erase_cached(struct rb_node *node,
	145	struct rb_root_cached *root)
	146	{
	147	if (root->rb_leftmost == node)
	148	root->rb_leftmost = rb_next(node);
	149	rb_erase(node, &root->rb_root);
	150	}
	151
	152	static inline void rb_replace_node_cached(struct rb_node *victim,
	153	struct rb_node *new,
	154	struct rb_root_cached *root)
	155	{
	156	if (root->rb_leftmost == victim)
	157	root->rb_leftmost = new;
	158	rb_replace_node(victim, new, &root->rb_root);
	159	}
	160
1da177e4	161	#endif /* _LINUX_RBTREE_H */