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 __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
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
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
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
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
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 /*
156 * The below helper functions use 2 operators with 3 different
157 * calling conventions. The operators are related like:
158 *
159 * comp(a->key,b) < 0 := less(a,b)
160 * comp(a->key,b) > 0 := less(b,a)
161 * comp(a->key,b) == 0 := !less(a,b) && !less(b,a)
162 *
163 * If these operators define a partial order on the elements we make no
164 * guarantee on which of the elements matching the key is found. See
165 * rb_find().
166 *
167 * The reason for this is to allow the find() interface without requiring an
168 * on-stack dummy object, which might not be feasible due to object size.
169 */
170
171 /**
172 * rb_add_cached() - insert @node into the leftmost cached tree @tree
173 * @node: node to insert
174 * @tree: leftmost cached tree to insert @node into
175 * @less: operator defining the (partial) node order
176 */
177 static __always_inline void
178 rb_add_cached(struct rb_node *node, struct rb_root_cached *tree,
179 bool (*less)(struct rb_node *, const struct rb_node *))
180 {
181 struct rb_node **link = &tree->rb_root.rb_node;
182 struct rb_node *parent = NULL;
183 bool leftmost = true;
184
185 while (*link) {
186 parent = *link;
187 if (less(node, parent)) {
188 link = &parent->rb_left;
189 } else {
190 link = &parent->rb_right;
191 leftmost = false;
192 }
193 }
194
195 rb_link_node(node, parent, link);
196 rb_insert_color_cached(node, tree, leftmost);
197 }
198
199 /**
200 * rb_add() - insert @node into @tree
201 * @node: node to insert
202 * @tree: tree to insert @node into
203 * @less: operator defining the (partial) node order
204 */
205 static __always_inline void
206 rb_add(struct rb_node *node, struct rb_root *tree,
207 bool (*less)(struct rb_node *, const struct rb_node *))
208 {
209 struct rb_node **link = &tree->rb_node;
210 struct rb_node *parent = NULL;
211
212 while (*link) {
213 parent = *link;
214 if (less(node, parent))
215 link = &parent->rb_left;
216 else
217 link = &parent->rb_right;
218 }
219
220 rb_link_node(node, parent, link);
221 rb_insert_color(node, tree);
222 }
223
224 /**
225 * rb_find_add() - find equivalent @node in @tree, or add @node
226 * @node: node to look-for / insert
227 * @tree: tree to search / modify
228 * @cmp: operator defining the node order
229 *
230 * Returns the rb_node matching @node, or NULL when no match is found and @node
231 * is inserted.
232 */
233 static __always_inline struct rb_node *
234 rb_find_add(struct rb_node *node, struct rb_root *tree,
235 int (*cmp)(struct rb_node *, const struct rb_node *))
236 {
237 struct rb_node **link = &tree->rb_node;
238 struct rb_node *parent = NULL;
239 int c;
240
241 while (*link) {
242 parent = *link;
243 c = cmp(node, parent);
244
245 if (c < 0)
246 link = &parent->rb_left;
247 else if (c > 0)
248 link = &parent->rb_right;
249 else
250 return parent;
251 }
252
253 rb_link_node(node, parent, link);
254 rb_insert_color(node, tree);
255 return NULL;
256 }
257
258 /**
259 * rb_find() - find @key in tree @tree
260 * @key: key to match
261 * @tree: tree to search
262 * @cmp: operator defining the node order
263 *
264 * Returns the rb_node matching @key or NULL.
265 */
266 static __always_inline struct rb_node *
267 rb_find(const void *key, const struct rb_root *tree,
268 int (*cmp)(const void *key, const struct rb_node *))
269 {
270 struct rb_node *node = tree->rb_node;
271
272 while (node) {
273 int c = cmp(key, node);
274
275 if (c < 0)
276 node = node->rb_left;
277 else if (c > 0)
278 node = node->rb_right;
279 else
280 return node;
281 }
282
283 return NULL;
284 }
285
286 /**
287 * rb_find_first() - find the first @key in @tree
288 * @key: key to match
289 * @tree: tree to search
290 * @cmp: operator defining node order
291 *
292 * Returns the leftmost node matching @key, or NULL.
293 */
294 static __always_inline struct rb_node *
295 rb_find_first(const void *key, const struct rb_root *tree,
296 int (*cmp)(const void *key, const struct rb_node *))
297 {
298 struct rb_node *node = tree->rb_node;
299 struct rb_node *match = NULL;
300
301 while (node) {
302 int c = cmp(key, node);
303
304 if (c <= 0) {
305 if (!c)
306 match = node;
307 node = node->rb_left;
308 } else if (c > 0) {
309 node = node->rb_right;
310 }
311 }
312
313 return match;
314 }
315
316 /**
317 * rb_next_match() - find the next @key in @tree
318 * @key: key to match
319 * @tree: tree to search
320 * @cmp: operator defining node order
321 *
322 * Returns the next node matching @key, or NULL.
323 */
324 static __always_inline struct rb_node *
325 rb_next_match(const void *key, struct rb_node *node,
326 int (*cmp)(const void *key, const struct rb_node *))
327 {
328 node = rb_next(node);
329 if (node && cmp(key, node))
330 node = NULL;
331 return node;
332 }
333
334 /**
335 * rb_for_each() - iterates a subtree matching @key
336 * @node: iterator
337 * @key: key to match
338 * @tree: tree to search
339 * @cmp: operator defining node order
340 */
341 #define rb_for_each(node, key, tree, cmp) \
342 for ((node) = rb_find_first((key), (tree), (cmp)); \
343 (node); (node) = rb_next_match((key), (node), (cmp)))
344
345 #endif /* __TOOLS_LINUX_PERF_RBTREE_H */
346
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