1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3 Red Black Trees
4 (C) 1999 Andrea Arcangeli <andrea@suse.de>
5 (C) 2002 David Woodhouse <dwmw2@infradead.org>
6 (C) 2012 Michel Lespinasse <walken@google.com>
7
8
9 linux/include/linux/rbtree_augmented.h
10 */
11
12 #ifndef _LINUX_RBTREE_AUGMENTED_H
13 #define _LINUX_RBTREE_AUGMENTED_H
14
15 #include <linux/compiler.h>
16 #include <linux/rbtree.h>
17 #include <linux/rcupdate.h>
18 #include <linux/args.h>
19 #include <linux/minmax.h>
20
21 /*
22 * Please note - only struct rb_augment_callbacks and the prototypes for
23 * rb_insert_augmented() and rb_erase_augmented() are intended to be public.
24 * The rest are implementation details you are not expected to depend on.
25 *
26 * See Documentation/core-api/rbtree.rst for documentation and samples.
27 */
28
29 struct rb_augment_callbacks {
30 void (*propagate)(struct rb_node *node, struct rb_node *stop);
31 void (*copy)(struct rb_node *old, struct rb_node *new);
32 void (*rotate)(struct rb_node *old, struct rb_node *new);
33 void (*merge)(struct rb_node *node, struct rb_node *new);
34 };
35
36 extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
37 void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
38
39 /*
40 * Fixup the rbtree and update the augmented information when rebalancing.
41 *
42 * On insertion, the user must update the augmented information on the path
43 * leading to the inserted node, then call rb_link_node() as usual and
44 * rb_insert_augmented() instead of the usual rb_insert_color() call.
45 * If rb_insert_augmented() rebalances the rbtree, it will callback into
46 * a user provided function to update the augmented information on the
47 * affected subtrees.
48 */
49 static inline void
rb_insert_augmented(struct rb_node * node,struct rb_root * root,const struct rb_augment_callbacks * augment)50 rb_insert_augmented(struct rb_node *node, struct rb_root *root,
51 const struct rb_augment_callbacks *augment)
52 {
53 __rb_insert_augmented(node, root, augment->rotate);
54 }
55
56 static inline void
rb_insert_augmented_cached(struct rb_node * node,struct rb_root_cached * root,bool newleft,const struct rb_augment_callbacks * augment)57 rb_insert_augmented_cached(struct rb_node *node,
58 struct rb_root_cached *root, bool newleft,
59 const struct rb_augment_callbacks *augment)
60 {
61 if (newleft)
62 root->rb_leftmost = node;
63 rb_insert_augmented(node, &root->rb_root, augment);
64 }
65
66 /*
67 * Insert @node into the leftmost cached augmented tree @tree.
68 *
69 * The augmented data of @node must already describe @node alone; it is
70 * merged into every ancestor on the way down through augment->merge().
71 */
72 static __always_inline struct rb_node *
rb_add_augmented_cached(struct rb_node * node,struct rb_root_cached * tree,bool (* less)(struct rb_node *,const struct rb_node *),const struct rb_augment_callbacks * augment)73 rb_add_augmented_cached(struct rb_node *node, struct rb_root_cached *tree,
74 bool (*less)(struct rb_node *, const struct rb_node *),
75 const struct rb_augment_callbacks *augment)
76 {
77 struct rb_node **link = &tree->rb_root.rb_node;
78 struct rb_node *parent = NULL;
79 bool leftmost = true;
80
81 while (*link) {
82 parent = *link;
83 augment->merge(parent, node);
84 if (less(node, parent)) {
85 link = &parent->rb_left;
86 } else {
87 link = &parent->rb_right;
88 leftmost = false;
89 }
90 }
91
92 rb_link_node(node, parent, link);
93 rb_insert_augmented_cached(node, tree, leftmost, augment);
94
95 return leftmost ? node : NULL;
96 }
97
98 #define RB_FOR_EACH_1(what, RBNAME, RBSTRUCT, RBFIELD, x) \
99 what(1, RBNAME, RBSTRUCT, RBFIELD, x)
100
101 #define RB_FOR_EACH_2(what, RBNAME, RBSTRUCT, RBFIELD, x, ...) \
102 what(2, RBNAME, RBSTRUCT, RBFIELD, x) \
103 RB_FOR_EACH_1(what, RBNAME, RBSTRUCT, RBFIELD, __VA_ARGS__)
104
105 #define RB_FOR_EACH_3(what, RBNAME, RBSTRUCT, RBFIELD, x, ...) \
106 what(3, RBNAME, RBSTRUCT, RBFIELD, x) \
107 RB_FOR_EACH_2(what, RBNAME, RBSTRUCT, RBFIELD, __VA_ARGS__)
108
109 #define RB_FOR_EACH_4(what, RBNAME, RBSTRUCT, RBFIELD, x, ...) \
110 what(4, RBNAME, RBSTRUCT, RBFIELD, x) \
111 RB_FOR_EACH_3(what, RBNAME, RBSTRUCT, RBFIELD, __VA_ARGS__)
112
113 #define RB_FOR_EACH_5(what, RBNAME, RBSTRUCT, RBFIELD, x, ...) \
114 what(5, RBNAME, RBSTRUCT, RBFIELD, x) \
115 RB_FOR_EACH_4(what, RBNAME, RBSTRUCT, RBFIELD, __VA_ARGS__)
116
117 #define RB_FOR_EACH_6(what, RBNAME, RBSTRUCT, RBFIELD, x, ...) \
118 what(6, RBNAME, RBSTRUCT, RBFIELD, x) \
119 RB_FOR_EACH_5(what, RBNAME, RBSTRUCT, RBFIELD, __VA_ARGS__)
120
121 #define RB_FOR_EACH_7(what, RBNAME, RBSTRUCT, RBFIELD, x, ...) \
122 what(7, RBNAME, RBSTRUCT, RBFIELD, x) \
123 RB_FOR_EACH_6(what, RBNAME, RBSTRUCT, RBFIELD, __VA_ARGS__)
124
125 #define RB_FOR_EACH_8(what, RBNAME, RBSTRUCT, RBFIELD, x, ...) \
126 what(8, RBNAME, RBSTRUCT, RBFIELD, x) \
127 RB_FOR_EACH_7(what, RBNAME, RBSTRUCT, RBFIELD, __VA_ARGS__)
128
129 #define RB_FOR_EACH(action, RBNAME, RBSTRUCT, RBFIELD, ...) \
130 CONCATENATE(RB_FOR_EACH_, COUNT_ARGS(__VA_ARGS__)) \
131 (action, RBNAME, RBSTRUCT, RBFIELD, __VA_ARGS__)
132
133 /*
134 * One augmented field: @val is the node's own contribution (a member for
135 * RB_AUG(), a function of the node for RB_AUG_FUNC()), @aug the member
136 * holding the aggregate over the subtree, and @fold(a, b) combines two
137 * aggregates: min, max, a sum, ... It must be commutative and associative.
138 */
139 #define RB_AUG_FUNC(val, aug, fold) (val(s), aug, fold)
140 #define RB_AUG(val, aug, fold) (s->val, aug, fold)
141 #define RB_UNPACK(...) __VA_ARGS__
142
143 #define __RB_INST(n, RBNAME, RBSTRUCT, RBFIELD, val, aug, fold) \
144 static inline void \
145 RBNAME ## _copy_ ## n(RBSTRUCT *old, RBSTRUCT *new) \
146 { \
147 new->aug = old->aug; \
148 } \
149 static inline bool \
150 RBNAME ## _compute_ ## n(RBSTRUCT *s, bool exit) \
151 { \
152 TYPEOF_UNQUAL(s->aug) _old_aug = s->aug; \
153 TYPEOF_UNQUAL(s->aug) _val = val; \
154 struct rb_node *_node = &s->RBFIELD; \
155 if (_node->rb_right) { \
156 RBSTRUCT *_c = container_of(_node->rb_right, typeof(*s), RBFIELD); \
157 _val = fold(_val, _c->aug); \
158 } \
159 if (_node->rb_left) { \
160 RBSTRUCT *_c = container_of(_node->rb_left, typeof(*s), RBFIELD); \
161 _val = fold(_val, _c->aug); \
162 } \
163 if (exit && _old_aug == _val) \
164 return true; \
165 s->aug = _val; \
166 return false; \
167 }
168 #define _RB_INST(n, RBNAME, RBSTRUCT, RBFIELD, args) \
169 __RB_INST(n, RBNAME, RBSTRUCT, RBFIELD, args)
170 #define RB_INST(n, RBNAME, RBSTRUCT, RBFIELD, x) \
171 _RB_INST(n, RBNAME, RBSTRUCT, RBFIELD, RB_UNPACK x)
172
173 #define __RB_COPY(n, RBNAME, RBSTRUCT, RBFIELD, val, aug, fold) \
174 RBNAME ## _copy_ ## n(old, new);
175 #define _RB_COPY(n, RBNAME, RBSTRUCT, RBFIELD, args) \
176 __RB_COPY(n, RBNAME, RBSTRUCT, RBFIELD, args)
177 #define RB_COPY(n, RBNAME, RBSTRUCT, RBFIELD, x) \
178 _RB_COPY(n, RBNAME, RBSTRUCT, RBFIELD, RB_UNPACK x)
179
180 #define __RB_COMPUTE(n, RBNAME, RBSTRUCT, RBFIELD, val, aug, fold) \
181 ret &= RBNAME ## _compute_ ## n(node, exit);
182 #define _RB_COMPUTE(n, RBNAME, RBSTRUCT, RBFIELD, args) \
183 __RB_COMPUTE(n, RBNAME, RBSTRUCT, RBFIELD, args)
184 #define RB_COMPUTE(n, RBNAME, RBSTRUCT, RBFIELD, x) \
185 _RB_COMPUTE(n, RBNAME, RBSTRUCT, RBFIELD, RB_UNPACK x)
186
187 /* fold @new, about to become a descendant of @node, into @node */
188 #define __RB_MERGE(n, RBNAME, RBSTRUCT, RBFIELD, val, aug, fold) \
189 node->aug = fold(node->aug, new->aug);
190 #define _RB_MERGE(n, RBNAME, RBSTRUCT, RBFIELD, args) \
191 __RB_MERGE(n, RBNAME, RBSTRUCT, RBFIELD, args)
192 #define RB_MERGE(n, RBNAME, RBSTRUCT, RBFIELD, x) \
193 _RB_MERGE(n, RBNAME, RBSTRUCT, RBFIELD, RB_UNPACK x)
194
195 /*
196 * Template for declaring augmented rbtree callbacks (generic multi fields)
197 *
198 * RBSTATIC: 'static' or empty
199 * RBNAME: name of the rb_augment_callbacks structure
200 * RBSTRUCT: struct type of the tree nodes
201 * RBFIELD: name of struct rb_node field within RBSTRUCT
202 * RBAUG...: list of RB_AUG() describing the augmented data
203 */
204 #define RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME, \
205 RBSTRUCT, RBFIELD, RBAUG...) \
206 RB_FOR_EACH(RB_INST, RBNAME, RBSTRUCT, RBFIELD, RBAUG) \
207 static inline void \
208 RBNAME ## __copy(RBSTRUCT *old, RBSTRUCT *new) \
209 { \
210 RB_FOR_EACH(RB_COPY, RBNAME, RBSTRUCT, RBFIELD, RBAUG); \
211 } \
212 static inline bool \
213 RBNAME ## __compute(RBSTRUCT *node, bool exit) \
214 { \
215 bool ret = true; \
216 RB_FOR_EACH(RB_COMPUTE, RBNAME, RBSTRUCT, RBFIELD, RBAUG); \
217 return ret; \
218 } \
219 static inline void \
220 RBNAME ## _propagate(struct rb_node *rb, struct rb_node *stop) \
221 { \
222 while (rb != stop) { \
223 RBSTRUCT *node = rb_entry(rb, RBSTRUCT, RBFIELD); \
224 if (RBNAME ## __compute(node, true)) \
225 break; \
226 rb = rb_parent(&node->RBFIELD); \
227 } \
228 } \
229 static inline void \
230 RBNAME ## _copy(struct rb_node *rb_old, struct rb_node *rb_new) \
231 { \
232 RBSTRUCT *old = rb_entry(rb_old, RBSTRUCT, RBFIELD); \
233 RBSTRUCT *new = rb_entry(rb_new, RBSTRUCT, RBFIELD); \
234 RBNAME ## __copy(old, new); \
235 } \
236 static void \
237 RBNAME ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new) \
238 { \
239 RBSTRUCT *old = rb_entry(rb_old, RBSTRUCT, RBFIELD); \
240 RBSTRUCT *new = rb_entry(rb_new, RBSTRUCT, RBFIELD); \
241 RBNAME ## __copy(old, new); \
242 RBNAME ## __compute(old, false); \
243 } \
244 static inline void \
245 RBNAME ## _merge(struct rb_node *rb, struct rb_node *rb_new) \
246 { \
247 RBSTRUCT *node = rb_entry(rb, RBSTRUCT, RBFIELD); \
248 RBSTRUCT *new = rb_entry(rb_new, RBSTRUCT, RBFIELD); \
249 RB_FOR_EACH(RB_MERGE, RBNAME, RBSTRUCT, RBFIELD, RBAUG); \
250 } \
251 RBSTATIC const struct rb_augment_callbacks RBNAME = { \
252 .propagate = RBNAME ## _propagate, \
253 .copy = RBNAME ## _copy, \
254 .rotate = RBNAME ## _rotate, \
255 .merge = RBNAME ## _merge \
256 };
257
258 /*
259 * Template for declaring augmented rbtree callbacks,
260 * computing RBAUGMENTED scalar as max(RBCOMPUTE(node)) for all subtree nodes.
261 *
262 * RBSTATIC: 'static' or empty
263 * RBNAME: name of the rb_augment_callbacks structure
264 * RBSTRUCT: struct type of the tree nodes
265 * RBFIELD: name of struct rb_node field within RBSTRUCT
266 * RBTYPE: type of the RBAUGMENTED field -- unused, assumed typeof(RBAUGMENTED)
267 * RBAUGMENTED: name of field within RBSTRUCT holding data for subtree
268 * RBVALUE: name of function that returns the per-node RBTYPE scalar
269 */
270
271 #define RB_DECLARE_CALLBACKS_MAX(RBSTATIC, RBNAME, RBSTRUCT, RBFIELD, \
272 RBTYPE, RBAUGMENTED, RBVALUE) \
273 RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME, RBSTRUCT, RBFIELD, \
274 RB_AUG_FUNC(RBVALUE, RBAUGMENTED, max))
275
276
277 #define RB_RED 0
278 #define RB_BLACK 1
279
280 #define __rb_parent(pc) ((struct rb_node *)(pc & ~3))
281
282 #define __rb_color(pc) ((pc) & 1)
283 #define __rb_is_black(pc) __rb_color(pc)
284 #define __rb_is_red(pc) (!__rb_color(pc))
285 #define rb_color(rb) __rb_color((rb)->__rb_parent_color)
286 #define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color)
287 #define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color)
288
rb_set_parent(struct rb_node * rb,struct rb_node * p)289 static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
290 {
291 rb->__rb_parent_color = rb_color(rb) + (unsigned long)p;
292 }
293
rb_set_parent_color(struct rb_node * rb,struct rb_node * p,int color)294 static inline void rb_set_parent_color(struct rb_node *rb,
295 struct rb_node *p, int color)
296 {
297 rb->__rb_parent_color = (unsigned long)p + color;
298 }
299
300 static inline void
__rb_change_child(struct rb_node * old,struct rb_node * new,struct rb_node * parent,struct rb_root * root)301 __rb_change_child(struct rb_node *old, struct rb_node *new,
302 struct rb_node *parent, struct rb_root *root)
303 {
304 if (parent) {
305 if (parent->rb_left == old)
306 WRITE_ONCE(parent->rb_left, new);
307 else
308 WRITE_ONCE(parent->rb_right, new);
309 } else
310 WRITE_ONCE(root->rb_node, new);
311 }
312
313 static inline void
__rb_change_child_rcu(struct rb_node * old,struct rb_node * new,struct rb_node * parent,struct rb_root * root)314 __rb_change_child_rcu(struct rb_node *old, struct rb_node *new,
315 struct rb_node *parent, struct rb_root *root)
316 {
317 if (parent) {
318 if (parent->rb_left == old)
319 rcu_assign_pointer(parent->rb_left, new);
320 else
321 rcu_assign_pointer(parent->rb_right, new);
322 } else
323 rcu_assign_pointer(root->rb_node, new);
324 }
325
326 extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
327 void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
328
329 static __always_inline struct rb_node *
__rb_erase_augmented(struct rb_node * node,struct rb_root * root,const struct rb_augment_callbacks * augment)330 __rb_erase_augmented(struct rb_node *node, struct rb_root *root,
331 const struct rb_augment_callbacks *augment)
332 {
333 struct rb_node *child = node->rb_right;
334 struct rb_node *tmp = node->rb_left;
335 struct rb_node *parent, *rebalance;
336 unsigned long pc;
337
338 if (!tmp) {
339 /*
340 * Case 1: node to erase has no more than 1 child (easy!)
341 *
342 * Note that if there is one child it must be red due to 5)
343 * and node must be black due to 4). We adjust colors locally
344 * so as to bypass __rb_erase_color() later on.
345 */
346 pc = node->__rb_parent_color;
347 parent = __rb_parent(pc);
348 __rb_change_child(node, child, parent, root);
349 if (child) {
350 child->__rb_parent_color = pc;
351 rebalance = NULL;
352 } else
353 rebalance = __rb_is_black(pc) ? parent : NULL;
354 tmp = parent;
355 } else if (!child) {
356 /* Still case 1, but this time the child is node->rb_left */
357 tmp->__rb_parent_color = pc = node->__rb_parent_color;
358 parent = __rb_parent(pc);
359 __rb_change_child(node, tmp, parent, root);
360 rebalance = NULL;
361 tmp = parent;
362 } else {
363 struct rb_node *successor = child, *child2;
364
365 tmp = child->rb_left;
366 if (!tmp) {
367 /*
368 * Case 2: node's successor is its right child
369 *
370 * (n) (s)
371 * / \ / \
372 * (x) (s) -> (x) (c)
373 * \
374 * (c)
375 */
376 parent = successor;
377 child2 = successor->rb_right;
378
379 augment->copy(node, successor);
380 } else {
381 /*
382 * Case 3: node's successor is leftmost under
383 * node's right child subtree
384 *
385 * (n) (s)
386 * / \ / \
387 * (x) (y) -> (x) (y)
388 * / /
389 * (p) (p)
390 * / /
391 * (s) (c)
392 * \
393 * (c)
394 */
395 do {
396 parent = successor;
397 successor = tmp;
398 tmp = tmp->rb_left;
399 } while (tmp);
400 child2 = successor->rb_right;
401 WRITE_ONCE(parent->rb_left, child2);
402 WRITE_ONCE(successor->rb_right, child);
403 rb_set_parent(child, successor);
404
405 augment->copy(node, successor);
406 augment->propagate(parent, successor);
407 }
408
409 tmp = node->rb_left;
410 WRITE_ONCE(successor->rb_left, tmp);
411 rb_set_parent(tmp, successor);
412
413 pc = node->__rb_parent_color;
414 tmp = __rb_parent(pc);
415 __rb_change_child(node, successor, tmp, root);
416
417 if (child2) {
418 rb_set_parent_color(child2, parent, RB_BLACK);
419 rebalance = NULL;
420 } else {
421 rebalance = rb_is_black(successor) ? parent : NULL;
422 }
423 successor->__rb_parent_color = pc;
424 tmp = successor;
425 }
426
427 augment->propagate(tmp, NULL);
428 return rebalance;
429 }
430
431 static __always_inline void
rb_erase_augmented(struct rb_node * node,struct rb_root * root,const struct rb_augment_callbacks * augment)432 rb_erase_augmented(struct rb_node *node, struct rb_root *root,
433 const struct rb_augment_callbacks *augment)
434 {
435 struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);
436 if (rebalance)
437 __rb_erase_color(rebalance, root, augment->rotate);
438 }
439
440 static __always_inline void
rb_erase_augmented_cached(struct rb_node * node,struct rb_root_cached * root,const struct rb_augment_callbacks * augment)441 rb_erase_augmented_cached(struct rb_node *node, struct rb_root_cached *root,
442 const struct rb_augment_callbacks *augment)
443 {
444 if (root->rb_leftmost == node)
445 root->rb_leftmost = rb_next(node);
446 rb_erase_augmented(node, &root->rb_root, augment);
447 }
448
449 #endif /* _LINUX_RBTREE_AUGMENTED_H */
450