1/*
2 Red Black Trees
3 (C) 1999 Andrea Arcangeli <andrea@suse.de>
4
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2 of the License, or
8 (at your option) any later version.
9
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software
17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18
19 linux/include/linux/rbtree.h
20
21 To use rbtrees you'll have to implement your own insert and search cores.
22 This will avoid us to use callbacks and to drop drammatically performances.
23 I know it's not the cleaner way, but in C (not in C++) to get
24 performances and genericity...
25
26 See Documentation/rbtree.txt for documentation and samples.
27*/
28
29#ifndef _LINUX_RBTREE_H
30#define _LINUX_RBTREE_H
31
32#include <linux/kernel.h>
33#include <linux/stddef.h>
34#include <linux/rcupdate.h>
35
36struct rb_node {
37 unsigned long __rb_parent_color;
38 struct rb_node *rb_right;
39 struct rb_node *rb_left;
40} __attribute__((aligned(sizeof(long))));
41 /* The alignment might seem pointless, but allegedly CRIS needs it */
42
43struct rb_root {
44 struct rb_node *rb_node;
45};
46
47/*
48 * Leftmost-cached rbtrees.
49 *
50 * We do not cache the rightmost node based on footprint
51 * size vs number of potential users that could benefit
52 * from O(1) rb_last(). Just not worth it, users that want
53 * this feature can always implement the logic explicitly.
54 * Furthermore, users that want to cache both pointers may
55 * find it a bit asymmetric, but that's ok.
56 */
57struct rb_root_cached {
58 struct rb_root rb_root;
59 struct rb_node *rb_leftmost;
60};
61
62#define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3))
63
64#define RB_ROOT (struct rb_root) { NULL, }
65#define RB_ROOT_CACHED (struct rb_root_cached) { {NULL, }, NULL }
66#define rb_entry(ptr, type, member) container_of(ptr, type, member)
67
68#define RB_EMPTY_ROOT(root) (READ_ONCE((root)->rb_node) == NULL)
69
70/* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
71#define RB_EMPTY_NODE(node) \
72 ((node)->__rb_parent_color == (unsigned long)(node))
73#define RB_CLEAR_NODE(node) \
74 ((node)->__rb_parent_color = (unsigned long)(node))
75
76
77extern void rb_insert_color(struct rb_node *, struct rb_root *);
78extern void rb_erase(struct rb_node *, struct rb_root *);
79
80
81/* Find logical next and previous nodes in a tree */
82extern struct rb_node *rb_next(const struct rb_node *);
83extern struct rb_node *rb_prev(const struct rb_node *);
84extern struct rb_node *rb_first(const struct rb_root *);
85extern struct rb_node *rb_last(const struct rb_root *);
86
87extern void rb_insert_color_cached(struct rb_node *,
88 struct rb_root_cached *, bool);
89extern void rb_erase_cached(struct rb_node *node, struct rb_root_cached *);
90/* Same as rb_first(), but O(1) */
91#define rb_first_cached(root) (root)->rb_leftmost
92
93/* Postorder iteration - always visit the parent after its children */
94extern struct rb_node *rb_first_postorder(const struct rb_root *);
95extern struct rb_node *rb_next_postorder(const struct rb_node *);
96
97/* Fast replacement of a single node without remove/rebalance/add/rebalance */
98extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
99 struct rb_root *root);
100extern void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new,
101 struct rb_root *root);
102extern void rb_replace_node_cached(struct rb_node *victim, struct rb_node *new,
103 struct rb_root_cached *root);
104
105static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
106 struct rb_node **rb_link)
107{
108 node->__rb_parent_color = (unsigned long)parent;
109 node->rb_left = node->rb_right = NULL;
110
111 *rb_link = node;
112}
113
114static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent,
115 struct rb_node **rb_link)
116{
117 node->__rb_parent_color = (unsigned long)parent;
118 node->rb_left = node->rb_right = NULL;
119
120 rcu_assign_pointer(*rb_link, node);
121}
122
123#define rb_entry_safe(ptr, type, member) \
124 ({ typeof(ptr) ____ptr = (ptr); \
125 ____ptr ? rb_entry(____ptr, type, member) : NULL; \
126 })
127
128/**
129 * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
130 * given type allowing the backing memory of @pos to be invalidated
131 *
132 * @pos: the 'type *' to use as a loop cursor.
133 * @n: another 'type *' to use as temporary storage
134 * @root: 'rb_root *' of the rbtree.
135 * @field: the name of the rb_node field within 'type'.
136 *
137 * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
138 * list_for_each_entry_safe() and allows the iteration to continue independent
139 * of changes to @pos by the body of the loop.
140 *
141 * Note, however, that it cannot handle other modifications that re-order the
142 * rbtree it is iterating over. This includes calling rb_erase() on @pos, as
143 * rb_erase() may rebalance the tree, causing us to miss some nodes.
144 */
145#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
146 for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
147 pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
148 typeof(*pos), field); 1; }); \
149 pos = n)
150
151#endif /* _LINUX_RBTREE_H */
152