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/kernel.h>
21 : #include <linux/stddef.h>
22 : #include <linux/rcupdate.h>
23 :
24 : struct rb_node {
25 : unsigned long __rb_parent_color;
26 : struct rb_node *rb_right;
27 : struct rb_node *rb_left;
28 : } __attribute__((aligned(sizeof(long))));
29 : /* The alignment might seem pointless, but allegedly CRIS needs it */
30 :
31 : struct rb_root {
32 : struct rb_node *rb_node;
33 : };
34 :
35 : #define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3))
36 :
37 : #define RB_ROOT (struct rb_root) { NULL, }
38 : #define rb_entry(ptr, type, member) container_of(ptr, type, member)
39 :
40 : #define RB_EMPTY_ROOT(root) (READ_ONCE((root)->rb_node) == NULL)
41 :
42 : /* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
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))
47 :
48 :
49 : extern void rb_insert_color(struct rb_node *, struct rb_root *);
50 : extern void rb_erase(struct rb_node *, struct rb_root *);
51 :
52 :
53 : /* Find logical next and previous nodes in a tree */
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 *);
58 :
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 :
63 : /* Fast replacement of a single node without remove/rebalance/add/rebalance */
64 : extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
65 : struct rb_root *root);
66 : extern void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new,
67 : struct rb_root *root);
68 :
69 1106338 : static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
70 : struct rb_node **rb_link)
71 : {
72 1106338 : node->__rb_parent_color = (unsigned long)parent;
73 1106338 : node->rb_left = node->rb_right = NULL;
74 :
75 1106338 : *rb_link = node;
76 0 : }
77 :
78 0 : static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent,
79 : struct rb_node **rb_link)
80 : {
81 0 : node->__rb_parent_color = (unsigned long)parent;
82 0 : node->rb_left = node->rb_right = NULL;
83 :
84 0 : rcu_assign_pointer(*rb_link, node);
85 : }
86 :
87 : #define rb_entry_safe(ptr, type, member) \
88 : ({ typeof(ptr) ____ptr = (ptr); \
89 : ____ptr ? rb_entry(____ptr, type, member) : NULL; \
90 : })
91 :
92 : /**
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
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'.
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.
108 : */
109 : #define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
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)
114 :
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 22941 : static inline void rb_insert_color_cached(struct rb_node *node,
136 : struct rb_root_cached *root,
137 : bool leftmost)
138 : {
139 22941 : if (leftmost)
140 16642 : root->rb_leftmost = node;
141 22941 : rb_insert_color(node, &root->rb_root);
142 21979 : }
143 :
144 :
145 : static inline struct rb_node *
146 22836 : rb_erase_cached(struct rb_node *node, struct rb_root_cached *root)
147 : {
148 22836 : struct rb_node *leftmost = NULL;
149 :
150 22836 : if (root->rb_leftmost == node)
151 22118 : leftmost = root->rb_leftmost = rb_next(node);
152 :
153 22835 : rb_erase(node, &root->rb_root);
154 :
155 22832 : return leftmost;
156 : }
157 :
158 : static inline void rb_replace_node_cached(struct rb_node *victim,
159 : struct rb_node *new,
160 : struct rb_root_cached *root)
161 : {
162 : if (root->rb_leftmost == victim)
163 : root->rb_leftmost = new;
164 : rb_replace_node(victim, new, &root->rb_root);
165 : }
166 :
167 : /*
168 : * The below helper functions use 2 operators with 3 different
169 : * calling conventions. The operators are related like:
170 : *
171 : * comp(a->key,b) < 0 := less(a,b)
172 : * comp(a->key,b) > 0 := less(b,a)
173 : * comp(a->key,b) == 0 := !less(a,b) && !less(b,a)
174 : *
175 : * If these operators define a partial order on the elements we make no
176 : * guarantee on which of the elements matching the key is found. See
177 : * rb_find().
178 : *
179 : * The reason for this is to allow the find() interface without requiring an
180 : * on-stack dummy object, which might not be feasible due to object size.
181 : */
182 :
183 : /**
184 : * rb_add_cached() - insert @node into the leftmost cached tree @tree
185 : * @node: node to insert
186 : * @tree: leftmost cached tree to insert @node into
187 : * @less: operator defining the (partial) node order
188 : *
189 : * Returns @node when it is the new leftmost, or NULL.
190 : */
191 : static __always_inline struct rb_node *
192 22636 : rb_add_cached(struct rb_node *node, struct rb_root_cached *tree,
193 : bool (*less)(struct rb_node *, const struct rb_node *))
194 : {
195 22636 : struct rb_node **link = &tree->rb_root.rb_node;
196 22636 : struct rb_node *parent = NULL;
197 22636 : bool leftmost = true;
198 :
199 34154 : while (*link) {
200 11518 : parent = *link;
201 11518 : if (less(node, parent)) {
202 4862 : link = &parent->rb_left;
203 : } else {
204 6656 : link = &parent->rb_right;
205 6656 : leftmost = false;
206 : }
207 : }
208 :
209 22636 : rb_link_node(node, parent, link);
210 22636 : rb_insert_color_cached(node, tree, leftmost);
211 :
212 22634 : return leftmost ? node : NULL;
213 : }
214 :
215 : /**
216 : * rb_add() - insert @node into @tree
217 : * @node: node to insert
218 : * @tree: tree to insert @node into
219 : * @less: operator defining the (partial) node order
220 : */
221 : static __always_inline void
222 0 : rb_add(struct rb_node *node, struct rb_root *tree,
223 : bool (*less)(struct rb_node *, const struct rb_node *))
224 : {
225 0 : struct rb_node **link = &tree->rb_node;
226 0 : struct rb_node *parent = NULL;
227 :
228 0 : while (*link) {
229 0 : parent = *link;
230 0 : if (less(node, parent))
231 0 : link = &parent->rb_left;
232 : else
233 0 : link = &parent->rb_right;
234 : }
235 :
236 0 : rb_link_node(node, parent, link);
237 0 : rb_insert_color(node, tree);
238 : }
239 :
240 : /**
241 : * rb_find_add() - find equivalent @node in @tree, or add @node
242 : * @node: node to look-for / insert
243 : * @tree: tree to search / modify
244 : * @cmp: operator defining the node order
245 : *
246 : * Returns the rb_node matching @node, or NULL when no match is found and @node
247 : * is inserted.
248 : */
249 : static __always_inline struct rb_node *
250 : rb_find_add(struct rb_node *node, struct rb_root *tree,
251 : int (*cmp)(struct rb_node *, const struct rb_node *))
252 : {
253 : struct rb_node **link = &tree->rb_node;
254 : struct rb_node *parent = NULL;
255 : int c;
256 :
257 : while (*link) {
258 : parent = *link;
259 : c = cmp(node, parent);
260 :
261 : if (c < 0)
262 : link = &parent->rb_left;
263 : else if (c > 0)
264 : link = &parent->rb_right;
265 : else
266 : return parent;
267 : }
268 :
269 : rb_link_node(node, parent, link);
270 : rb_insert_color(node, tree);
271 : return NULL;
272 : }
273 :
274 : /**
275 : * rb_find() - find @key in tree @tree
276 : * @key: key to match
277 : * @tree: tree to search
278 : * @cmp: operator defining the node order
279 : *
280 : * Returns the rb_node matching @key or NULL.
281 : */
282 : static __always_inline struct rb_node *
283 : rb_find(const void *key, const struct rb_root *tree,
284 : int (*cmp)(const void *key, const struct rb_node *))
285 : {
286 : struct rb_node *node = tree->rb_node;
287 :
288 : while (node) {
289 : int c = cmp(key, node);
290 :
291 : if (c < 0)
292 : node = node->rb_left;
293 : else if (c > 0)
294 : node = node->rb_right;
295 : else
296 : return node;
297 : }
298 :
299 : return NULL;
300 : }
301 :
302 : /**
303 : * rb_find_first() - find the first @key in @tree
304 : * @key: key to match
305 : * @tree: tree to search
306 : * @cmp: operator defining node order
307 : *
308 : * Returns the leftmost node matching @key, or NULL.
309 : */
310 : static __always_inline struct rb_node *
311 0 : rb_find_first(const void *key, const struct rb_root *tree,
312 : int (*cmp)(const void *key, const struct rb_node *))
313 : {
314 0 : struct rb_node *node = tree->rb_node;
315 0 : struct rb_node *match = NULL;
316 :
317 0 : while (node) {
318 0 : int c = cmp(key, node);
319 :
320 0 : if (c <= 0) {
321 0 : if (!c)
322 0 : match = node;
323 0 : node = node->rb_left;
324 0 : } else if (c > 0) {
325 0 : node = node->rb_right;
326 : }
327 : }
328 :
329 0 : return match;
330 : }
331 :
332 : /**
333 : * rb_next_match() - find the next @key in @tree
334 : * @key: key to match
335 : * @tree: tree to search
336 : * @cmp: operator defining node order
337 : *
338 : * Returns the next node matching @key, or NULL.
339 : */
340 : static __always_inline struct rb_node *
341 0 : rb_next_match(const void *key, struct rb_node *node,
342 : int (*cmp)(const void *key, const struct rb_node *))
343 : {
344 0 : node = rb_next(node);
345 0 : if (node && cmp(key, node))
346 : node = NULL;
347 0 : return node;
348 : }
349 :
350 : /**
351 : * rb_for_each() - iterates a subtree matching @key
352 : * @node: iterator
353 : * @key: key to match
354 : * @tree: tree to search
355 : * @cmp: operator defining node order
356 : */
357 : #define rb_for_each(node, key, tree, cmp) \
358 : for ((node) = rb_find_first((key), (tree), (cmp)); \
359 : (node); (node) = rb_next_match((key), (node), (cmp)))
360 :
361 : #endif /* _LINUX_RBTREE_H */
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