Line data Source code
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/core-api/rbtree.rst for documentation and samples.
15 : */
16 :
17 : #ifndef _LINUX_RBTREE_H
18 : #define _LINUX_RBTREE_H
19 :
20 : #include <linux/container_of.h>
21 : #include <linux/rbtree_types.h>
22 :
23 : #include <linux/stddef.h>
24 : #include <linux/rcupdate.h>
25 :
26 : #define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3))
27 :
28 : #define rb_entry(ptr, type, member) container_of(ptr, type, member)
29 :
30 : #define RB_EMPTY_ROOT(root) (READ_ONCE((root)->rb_node) == NULL)
31 :
32 : /* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
33 : #define RB_EMPTY_NODE(node) \
34 : ((node)->__rb_parent_color == (unsigned long)(node))
35 : #define RB_CLEAR_NODE(node) \
36 : ((node)->__rb_parent_color = (unsigned long)(node))
37 :
38 :
39 : extern void rb_insert_color(struct rb_node *, struct rb_root *);
40 : extern void rb_erase(struct rb_node *, struct rb_root *);
41 :
42 :
43 : /* Find logical next and previous nodes in a tree */
44 : extern struct rb_node *rb_next(const struct rb_node *);
45 : extern struct rb_node *rb_prev(const struct rb_node *);
46 : extern struct rb_node *rb_first(const struct rb_root *);
47 : extern struct rb_node *rb_last(const struct rb_root *);
48 :
49 : /* Postorder iteration - always visit the parent after its children */
50 : extern struct rb_node *rb_first_postorder(const struct rb_root *);
51 : extern struct rb_node *rb_next_postorder(const struct rb_node *);
52 :
53 : /* Fast replacement of a single node without remove/rebalance/add/rebalance */
54 : extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
55 : struct rb_root *root);
56 : extern void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new,
57 : struct rb_root *root);
58 :
59 : static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
60 : struct rb_node **rb_link)
61 : {
62 29663489 : node->__rb_parent_color = (unsigned long)parent;
63 29663489 : node->rb_left = node->rb_right = NULL;
64 :
65 29663489 : *rb_link = node;
66 : }
67 :
68 : static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent,
69 : struct rb_node **rb_link)
70 : {
71 : node->__rb_parent_color = (unsigned long)parent;
72 : node->rb_left = node->rb_right = NULL;
73 :
74 : rcu_assign_pointer(*rb_link, node);
75 : }
76 :
77 : #define rb_entry_safe(ptr, type, member) \
78 : ({ typeof(ptr) ____ptr = (ptr); \
79 : ____ptr ? rb_entry(____ptr, type, member) : NULL; \
80 : })
81 :
82 : /**
83 : * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
84 : * given type allowing the backing memory of @pos to be invalidated
85 : *
86 : * @pos: the 'type *' to use as a loop cursor.
87 : * @n: another 'type *' to use as temporary storage
88 : * @root: 'rb_root *' of the rbtree.
89 : * @field: the name of the rb_node field within 'type'.
90 : *
91 : * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
92 : * list_for_each_entry_safe() and allows the iteration to continue independent
93 : * of changes to @pos by the body of the loop.
94 : *
95 : * Note, however, that it cannot handle other modifications that re-order the
96 : * rbtree it is iterating over. This includes calling rb_erase() on @pos, as
97 : * rb_erase() may rebalance the tree, causing us to miss some nodes.
98 : */
99 : #define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
100 : for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
101 : pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
102 : typeof(*pos), field); 1; }); \
103 : pos = n)
104 :
105 : /* Same as rb_first(), but O(1) */
106 : #define rb_first_cached(root) (root)->rb_leftmost
107 :
108 2268 : static inline void rb_insert_color_cached(struct rb_node *node,
109 : struct rb_root_cached *root,
110 : bool leftmost)
111 : {
112 11269804 : if (leftmost)
113 6266745 : root->rb_leftmost = node;
114 11269804 : rb_insert_color(node, &root->rb_root);
115 2268 : }
116 :
117 :
118 : static inline struct rb_node *
119 11269524 : rb_erase_cached(struct rb_node *node, struct rb_root_cached *root)
120 : {
121 11269524 : struct rb_node *leftmost = NULL;
122 :
123 11269524 : if (root->rb_leftmost == node)
124 6321379 : leftmost = root->rb_leftmost = rb_next(node);
125 :
126 11269524 : rb_erase(node, &root->rb_root);
127 :
128 11269524 : return leftmost;
129 : }
130 :
131 : static inline void rb_replace_node_cached(struct rb_node *victim,
132 : struct rb_node *new,
133 : struct rb_root_cached *root)
134 : {
135 365415 : if (root->rb_leftmost == victim)
136 208896 : root->rb_leftmost = new;
137 365415 : rb_replace_node(victim, new, &root->rb_root);
138 : }
139 :
140 : /*
141 : * The below helper functions use 2 operators with 3 different
142 : * calling conventions. The operators are related like:
143 : *
144 : * comp(a->key,b) < 0 := less(a,b)
145 : * comp(a->key,b) > 0 := less(b,a)
146 : * comp(a->key,b) == 0 := !less(a,b) && !less(b,a)
147 : *
148 : * If these operators define a partial order on the elements we make no
149 : * guarantee on which of the elements matching the key is found. See
150 : * rb_find().
151 : *
152 : * The reason for this is to allow the find() interface without requiring an
153 : * on-stack dummy object, which might not be feasible due to object size.
154 : */
155 :
156 : /**
157 : * rb_add_cached() - insert @node into the leftmost cached tree @tree
158 : * @node: node to insert
159 : * @tree: leftmost cached tree to insert @node into
160 : * @less: operator defining the (partial) node order
161 : *
162 : * Returns @node when it is the new leftmost, or NULL.
163 : */
164 : static __always_inline struct rb_node *
165 : rb_add_cached(struct rb_node *node, struct rb_root_cached *tree,
166 : bool (*less)(struct rb_node *, const struct rb_node *))
167 : {
168 2268 : struct rb_node **link = &tree->rb_root.rb_node;
169 2268 : struct rb_node *parent = NULL;
170 2268 : bool leftmost = true;
171 :
172 3152 : while (*link) {
173 884 : parent = *link;
174 884 : if (less(node, parent)) {
175 47 : link = &parent->rb_left;
176 : } else {
177 837 : link = &parent->rb_right;
178 837 : leftmost = false;
179 : }
180 : }
181 :
182 2268 : rb_link_node(node, parent, link);
183 2268 : rb_insert_color_cached(node, tree, leftmost);
184 :
185 0 : return leftmost ? node : NULL;
186 : }
187 :
188 : /**
189 : * rb_add() - insert @node into @tree
190 : * @node: node to insert
191 : * @tree: tree to insert @node into
192 : * @less: operator defining the (partial) node order
193 : */
194 : static __always_inline void
195 : rb_add(struct rb_node *node, struct rb_root *tree,
196 : bool (*less)(struct rb_node *, const struct rb_node *))
197 : {
198 0 : struct rb_node **link = &tree->rb_node;
199 0 : struct rb_node *parent = NULL;
200 :
201 0 : while (*link) {
202 0 : parent = *link;
203 0 : if (less(node, parent))
204 0 : link = &parent->rb_left;
205 : else
206 0 : link = &parent->rb_right;
207 : }
208 :
209 0 : rb_link_node(node, parent, link);
210 0 : rb_insert_color(node, tree);
211 : }
212 :
213 : /**
214 : * rb_find_add() - find equivalent @node in @tree, or add @node
215 : * @node: node to look-for / insert
216 : * @tree: tree to search / modify
217 : * @cmp: operator defining the node order
218 : *
219 : * Returns the rb_node matching @node, or NULL when no match is found and @node
220 : * is inserted.
221 : */
222 : static __always_inline struct rb_node *
223 : rb_find_add(struct rb_node *node, struct rb_root *tree,
224 : int (*cmp)(struct rb_node *, const struct rb_node *))
225 : {
226 : struct rb_node **link = &tree->rb_node;
227 : struct rb_node *parent = NULL;
228 : int c;
229 :
230 : while (*link) {
231 : parent = *link;
232 : c = cmp(node, parent);
233 :
234 : if (c < 0)
235 : link = &parent->rb_left;
236 : else if (c > 0)
237 : link = &parent->rb_right;
238 : else
239 : return parent;
240 : }
241 :
242 : rb_link_node(node, parent, link);
243 : rb_insert_color(node, tree);
244 : return NULL;
245 : }
246 :
247 : /**
248 : * rb_find() - find @key in tree @tree
249 : * @key: key to match
250 : * @tree: tree to search
251 : * @cmp: operator defining the node order
252 : *
253 : * Returns the rb_node matching @key or NULL.
254 : */
255 : static __always_inline struct rb_node *
256 : rb_find(const void *key, const struct rb_root *tree,
257 : int (*cmp)(const void *key, const struct rb_node *))
258 : {
259 0 : struct rb_node *node = tree->rb_node;
260 :
261 0 : while (node) {
262 0 : int c = cmp(key, node);
263 :
264 0 : if (c < 0)
265 0 : node = node->rb_left;
266 0 : else if (c > 0)
267 0 : node = node->rb_right;
268 : else
269 : return node;
270 : }
271 :
272 : return NULL;
273 : }
274 :
275 : /**
276 : * rb_find_first() - find the first @key in @tree
277 : * @key: key to match
278 : * @tree: tree to search
279 : * @cmp: operator defining node order
280 : *
281 : * Returns the leftmost node matching @key, or NULL.
282 : */
283 : static __always_inline struct rb_node *
284 : rb_find_first(const void *key, const struct rb_root *tree,
285 : int (*cmp)(const void *key, const struct rb_node *))
286 : {
287 : struct rb_node *node = tree->rb_node;
288 : struct rb_node *match = NULL;
289 :
290 : while (node) {
291 : int c = cmp(key, node);
292 :
293 : if (c <= 0) {
294 : if (!c)
295 : match = node;
296 : node = node->rb_left;
297 : } else if (c > 0) {
298 : node = node->rb_right;
299 : }
300 : }
301 :
302 : return match;
303 : }
304 :
305 : /**
306 : * rb_next_match() - find the next @key in @tree
307 : * @key: key to match
308 : * @tree: tree to search
309 : * @cmp: operator defining node order
310 : *
311 : * Returns the next node matching @key, or NULL.
312 : */
313 : static __always_inline struct rb_node *
314 : rb_next_match(const void *key, struct rb_node *node,
315 : int (*cmp)(const void *key, const struct rb_node *))
316 : {
317 : node = rb_next(node);
318 : if (node && cmp(key, node))
319 : node = NULL;
320 : return node;
321 : }
322 :
323 : /**
324 : * rb_for_each() - iterates a subtree matching @key
325 : * @node: iterator
326 : * @key: key to match
327 : * @tree: tree to search
328 : * @cmp: operator defining node order
329 : */
330 : #define rb_for_each(node, key, tree, cmp) \
331 : for ((node) = rb_find_first((key), (tree), (cmp)); \
332 : (node); (node) = rb_next_match((key), (node), (cmp)))
333 :
334 : #endif /* _LINUX_RBTREE_H */
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