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
36 struct 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
43 struct rb_root {
44 struct rb_node *rb_node;
45 };
46
47
48 #define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3))
49
50 #define RB_ROOT (struct rb_root) { NULL, }
51 #define rb_entry(ptr, type, member) container_of(ptr, type, member)
52
53 #define RB_EMPTY_ROOT(root) (READ_ONCE((root)->rb_node) == NULL)
54
55 /* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
56 #define RB_EMPTY_NODE(node) \
57 ((node)->__rb_parent_color == (unsigned long)(node))
58 #define RB_CLEAR_NODE(node) \
59 ((node)->__rb_parent_color = (unsigned long)(node))
60
61
62 extern void rb_insert_color(struct rb_node *, struct rb_root *);
63 extern void rb_erase(struct rb_node *, struct rb_root *);
64
65
66 /* Find logical next and previous nodes in a tree */
67 extern struct rb_node *rb_next(const struct rb_node *);
68 extern struct rb_node *rb_prev(const struct rb_node *);
69 extern struct rb_node *rb_first(const struct rb_root *);
70 extern struct rb_node *rb_last(const struct rb_root *);
71
72 /* Postorder iteration - always visit the parent after its children */
73 extern struct rb_node *rb_first_postorder(const struct rb_root *);
74 extern struct rb_node *rb_next_postorder(const struct rb_node *);
75
76 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
77 extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
78 struct rb_root *root);
79 extern void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new,
80 struct rb_root *root);
81
rb_link_node(struct rb_node * node,struct rb_node * parent,struct rb_node ** rb_link)82 static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
83 struct rb_node **rb_link)
84 {
85 node->__rb_parent_color = (unsigned long)parent;
86 node->rb_left = node->rb_right = NULL;
87
88 *rb_link = node;
89 }
90
rb_link_node_rcu(struct rb_node * node,struct rb_node * parent,struct rb_node ** rb_link)91 static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent,
92 struct rb_node **rb_link)
93 {
94 node->__rb_parent_color = (unsigned long)parent;
95 node->rb_left = node->rb_right = NULL;
96
97 rcu_assign_pointer(*rb_link, node);
98 }
99
100 #define rb_entry_safe(ptr, type, member) \
101 ({ typeof(ptr) ____ptr = (ptr); \
102 ____ptr ? rb_entry(____ptr, type, member) : NULL; \
103 })
104
105 /**
106 * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
107 * given type allowing the backing memory of @pos to be invalidated
108 *
109 * @pos: the 'type *' to use as a loop cursor.
110 * @n: another 'type *' to use as temporary storage
111 * @root: 'rb_root *' of the rbtree.
112 * @field: the name of the rb_node field within 'type'.
113 *
114 * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
115 * list_for_each_entry_safe() and allows the iteration to continue independent
116 * of changes to @pos by the body of the loop.
117 *
118 * Note, however, that it cannot handle other modifications that re-order the
119 * rbtree it is iterating over. This includes calling rb_erase() on @pos, as
120 * rb_erase() may rebalance the tree, causing us to miss some nodes.
121 */
122 #define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
123 for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
124 pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
125 typeof(*pos), field); 1; }); \
126 pos = n)
127
128 #endif /* _LINUX_RBTREE_H */
129