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 | ||
14bbe3e3 | 14 | See Documentation/core-api/rbtree.rst 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 { |
25 | unsigned long __rb_parent_color; | |
1da177e4 LT |
26 | struct rb_node *rb_right; |
27 | struct rb_node *rb_left; | |
e977145a DW |
28 | } __attribute__((aligned(sizeof(long)))); |
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) |
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, |
67 | struct rb_root *root); | |
1da177e4 | 68 | |
d72da4a4 PZ |
69 | static inline void rb_link_node(struct rb_node *node, struct rb_node *parent, |
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 |
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 | */ |
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 */ |