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