Commit | Line | Data |
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dff86257 MD |
1 | /* |
2 | * urcu-rbtree.c | |
3 | * | |
4 | * Userspace RCU library - Red-Black Tree | |
5 | * | |
6 | * Copyright (c) 2010 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
7 | * | |
8 | * This library is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU Lesser General Public | |
10 | * License as published by the Free Software Foundation; either | |
11 | * version 2.1 of the License, or (at your option) any later version. | |
12 | * | |
13 | * This library is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | * Lesser General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU Lesser General Public | |
19 | * License along with this library; if not, write to the Free Software | |
20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
21 | * | |
22 | * Implementation of RCU-adapted data structures and operations based on the RB | |
23 | * tree algorithms found in chapter 12 of: | |
24 | * | |
25 | * Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest, and | |
26 | * Clifford Stein. Introduction to Algorithms, Third Edition. The MIT | |
27 | * Press, September 2009. | |
28 | */ | |
29 | ||
30 | #define _BSD_SOURCE | |
31 | #define _LGPL_SOURCE | |
32 | ||
33 | #include <stdio.h> | |
34 | #include <pthread.h> | |
35 | #include <assert.h> | |
269a9ef6 | 36 | #include <string.h> |
230dd288 | 37 | #include <unistd.h> |
8f354bc4 | 38 | #include <errno.h> |
dff86257 MD |
39 | |
40 | #include <urcu/rcurbtree.h> | |
41 | #include <urcu-pointer.h> | |
c479601c | 42 | #include <urcu-call-rcu.h> |
dca45c9f | 43 | #include <urcu/compiler.h> |
dff86257 | 44 | |
ae46d4ae MD |
45 | /* |
46 | * Explanation of next/prev walk coherency and search coherency when | |
47 | * performed concurrently with updates. | |
48 | * | |
49 | * next/prev walk coherency with respect to concurrent updates: | |
50 | * | |
51 | * There are 3 scenarios for which we need to model and validate this: | |
52 | * rotation, transplant and "teleportation" (the latter being a remote | |
53 | * transplant in a remove non-nil case). | |
54 | * | |
55 | * - rotation left (right is symmetric) | |
56 | * xl and yr point to the same parent nodes before/after left | |
57 | * rotation. yll and ylr also point to the same parent node | |
58 | * before/after left rotation. | |
59 | * As we are copying x, y and yl (the 3 nodes which parent/child | |
60 | * relationship are changed) to "new" version of this node cluster, | |
61 | * all external references to the cluster either point to the old | |
62 | * cluster or the new one. If we take this cluster as a "black box" | |
63 | * from the point of view of next/prev traversal, all we have to | |
64 | * ensure is that the old and the new cluster behave in the exact same | |
65 | * way with respect to traversal order. | |
66 | * | |
67 | * - transplant | |
68 | * In this operation, we transplant a copy of "v" into its parent | |
69 | * location (u), thus replacing it. The children of "v", vl and vr, | |
70 | * still point to v (new version) after the transplant, so it does not | |
71 | * change the behavior when considering the next/prev traversal. "v" | |
72 | * being copied to a new version ensures that the parent pointers of v | |
73 | * are pointing to its new parent (parent of u) before it is published | |
74 | * to readers (by setting the child pointer of u's parent to the new | |
75 | * copy of v). | |
76 | * | |
77 | * - teleportation | |
78 | * This one is probably the most tricky and will require some ascii | |
79 | * art to explain. | |
80 | * | |
81 | * We want to remove z from this tree: | |
82 | * | |
83 | * zp | |
84 | * \ | |
85 | * z | |
86 | * / \ | |
87 | * zl zr | |
88 | * / | |
89 | * a | |
90 | * / \ | |
91 | * b ar | |
92 | * / \ | |
93 | * y br | |
94 | * \ | |
95 | * yr | |
96 | * / \ | |
97 | * yrl yrr | |
98 | * | |
99 | * What we are going to do is to "teleport" y into z's location, | |
100 | * reparenting yr to b. We are taking care to create a new cluster | |
101 | * copy that is isolated from any reader. We will represent the new | |
102 | * members of the cluster with capital letters. | |
103 | * | |
104 | * zp | |
105 | * \ | |
106 | * Y | |
107 | * / \ | |
108 | * zl ZR | |
109 | * / | |
110 | * A | |
111 | * / \ | |
112 | * B ar | |
113 | * / \ | |
114 | * YR br | |
115 | * / \ | |
116 | * yrl yrr | |
117 | * | |
118 | * In this transient state, we notice that the pointers within the | |
119 | * cluster all point to the new cluster nodes, and they point to the | |
120 | * correct external nodes. However, no external pointer point to the | |
121 | * cluster (yet). The first pointer to point to this cluster will be | |
122 | * "zp->right". It will therefore make the cluster visible for search. | |
123 | * | |
124 | * In this intermediate state, we can walk through the new cluster | |
125 | * when coming from the top (in a next/prev traversal), but can come | |
126 | * back to the old cluster when going back up from the children nodes. | |
127 | * All we have to ensure is that the two clusters, taken as a black | |
128 | * box from a next/prev traversal perspective, yield to the exact same | |
129 | * result. | |
130 | * | |
131 | * Search coherency with concurrent updates: | |
132 | * | |
133 | * Simple "search" (only going down the tree) is also handled by this | |
134 | * cluster scheme. The explanation is a subset of the prev/next | |
135 | * explanation, where we don't have to care about the intermediate | |
136 | * stages where the children point to the old cluster, because we only | |
137 | * ever use the top level pointers to go down into the children nodes, | |
138 | * we never go back up. So by simply making sure that all the cluster | |
139 | * internal nodes pointers are setup correctly before making the | |
140 | * cluster visible to the readers (by setting the parent pointer to | |
141 | * the topmost new node in the cluster), we are sure that readers will | |
142 | * see a coherent view of the cluster at all times. | |
143 | */ | |
144 | ||
dff86257 MD |
145 | #ifdef DEBUG |
146 | #define dbg_printf(args...) printf(args) | |
9c161ee1 | 147 | #define dbg_usleep(usecs) usleep(usecs) |
dff86257 MD |
148 | #else |
149 | #define dbg_printf(args...) | |
9c161ee1 | 150 | #define dbg_usleep(usecs) |
dff86257 MD |
151 | #endif |
152 | ||
6daf6090 MD |
153 | /* |
154 | * Undefine this to enable the non-RCU rotate and transplant functions | |
2abaffb0 MD |
155 | * (for debugging). Note that these versions don't support the tree |
156 | * max_end updates, so lookups must be performed with | |
157 | * rcu_rbtree_search_begin_key when using this debug facility. | |
6daf6090 | 158 | */ |
dbe4ae98 MD |
159 | #define RBTREE_RCU_SUPPORT_ROTATE_LEFT |
160 | #define RBTREE_RCU_SUPPORT_ROTATE_RIGHT | |
6daf6090 | 161 | #define RBTREE_RCU_SUPPORT_TRANSPLANT |
c2ceb27c | 162 | #define RBTREE_RCU_SUPPORT |
6daf6090 | 163 | |
230dd288 MD |
164 | #ifdef EXTRA_DEBUG |
165 | static pthread_mutex_t test_mutex = PTHREAD_MUTEX_INITIALIZER; | |
166 | static pthread_mutex_t outer_mutex = PTHREAD_MUTEX_INITIALIZER; | |
167 | ||
168 | static | |
169 | void lock_outer_mutex(void) | |
170 | { | |
171 | pthread_mutex_lock(&outer_mutex); | |
172 | } | |
173 | ||
174 | static | |
175 | void unlock_outer_mutex(void) | |
176 | { | |
177 | pthread_mutex_unlock(&outer_mutex); | |
178 | } | |
179 | ||
180 | static | |
181 | void lock_test_mutex(void) | |
182 | { | |
183 | pthread_mutex_lock(&test_mutex); | |
184 | } | |
185 | ||
186 | static | |
187 | void unlock_test_mutex(void) | |
188 | { | |
189 | pthread_mutex_unlock(&test_mutex); | |
190 | } | |
191 | #endif | |
192 | ||
7ba89e62 MD |
193 | static |
194 | void set_parent(struct rcu_rbtree_node *node, | |
195 | struct rcu_rbtree_node *parent, | |
196 | unsigned int pos) | |
197 | { | |
9606ca85 | 198 | _CMM_STORE_SHARED(node->parent, ((unsigned long) parent) | pos); |
7ba89e62 MD |
199 | } |
200 | ||
201 | static | |
202 | struct rcu_rbtree_node *get_parent(struct rcu_rbtree_node *node) | |
203 | { | |
204 | return (struct rcu_rbtree_node *) (node->parent & ~1UL); | |
205 | } | |
206 | ||
207 | static | |
208 | unsigned int get_pos(struct rcu_rbtree_node *node) | |
209 | { | |
210 | return (unsigned int) (node->parent & 1UL); | |
211 | } | |
212 | ||
213 | static | |
214 | struct rcu_rbtree_node *get_parent_and_pos(struct rcu_rbtree_node *node, | |
215 | unsigned int *pos) | |
216 | { | |
217 | unsigned long parent_pos = rcu_dereference(node->parent); | |
218 | ||
219 | *pos = (unsigned int) (parent_pos & 1UL); | |
220 | return (struct rcu_rbtree_node *) (parent_pos & ~1UL); | |
221 | } | |
222 | ||
269a9ef6 MD |
223 | static |
224 | void set_decay(struct rcu_rbtree_node *x, struct rcu_rbtree_node *xc) | |
225 | { | |
226 | x->decay_next = xc; | |
227 | } | |
228 | ||
229 | static | |
230 | struct rcu_rbtree_node *get_decay(struct rcu_rbtree_node *x) | |
231 | { | |
dbe4ae98 MD |
232 | if (!x) |
233 | return NULL; | |
269a9ef6 MD |
234 | while (x->decay_next) |
235 | x = x->decay_next; | |
236 | return x; | |
237 | } | |
238 | ||
239 | static | |
240 | struct rcu_rbtree_node *is_decay(struct rcu_rbtree_node *x) | |
241 | { | |
242 | return x->decay_next; | |
243 | } | |
244 | ||
3c672595 | 245 | static |
8f354bc4 MD |
246 | struct rcu_rbtree_node *_rcu_rbtree_alloc_node(struct rcu_rbtree *rbtree) |
247 | { | |
248 | return rbtree->rballoc(sizeof(struct rcu_rbtree_node)); | |
249 | } | |
250 | ||
251 | static | |
252 | void _rcu_rbtree_free_node(struct rcu_head *head) | |
3c672595 MD |
253 | { |
254 | struct rcu_rbtree_node *node = | |
255 | caa_container_of(head, struct rcu_rbtree_node, head); | |
256 | node->rbtree->rbfree(node); | |
257 | } | |
258 | ||
c2ceb27c MD |
259 | #ifdef RBTREE_RCU_SUPPORT |
260 | ||
269a9ef6 MD |
261 | static |
262 | struct rcu_rbtree_node *dup_decay_node(struct rcu_rbtree *rbtree, | |
263 | struct rcu_rbtree_node *x) | |
264 | { | |
265 | struct rcu_rbtree_node *xc; | |
266 | ||
8ded5fe9 | 267 | if (rcu_rbtree_is_nil(rbtree, x)) |
269a9ef6 MD |
268 | return x; |
269 | ||
8f354bc4 | 270 | xc = _rcu_rbtree_alloc_node(rbtree); |
3c672595 | 271 | memcpy(xc, x, sizeof(*xc)); |
269a9ef6 MD |
272 | xc->decay_next = NULL; |
273 | set_decay(x, xc); | |
1cdd423d | 274 | rbtree->call_rcu(&x->head, _rcu_rbtree_free_node); |
269a9ef6 MD |
275 | return xc; |
276 | } | |
277 | ||
c2ceb27c MD |
278 | #else /* RBTREE_RCU_SUPPORT */ |
279 | ||
280 | static | |
281 | struct rcu_rbtree_node *dup_decay_node(struct rcu_rbtree *rbtree, | |
282 | struct rcu_rbtree_node *x) | |
283 | { | |
284 | return x; | |
285 | } | |
286 | ||
287 | #endif | |
288 | ||
dca45c9f MD |
289 | /* |
290 | * Info for range lookups: | |
291 | * Range lookup information is only valid when used when searching for | |
292 | * ranges. It should never be used in next/prev traversal because the | |
293 | * pointers to parents are not in sync with the parent vision of the | |
294 | * children range. | |
295 | */ | |
296 | static | |
a84e8c8e MD |
297 | void set_left(struct rcu_rbtree *rbtree, struct rcu_rbtree_node *node, |
298 | struct rcu_rbtree_node *left) | |
dca45c9f | 299 | { |
dca45c9f | 300 | node->_left = left; |
dca45c9f MD |
301 | } |
302 | ||
303 | static | |
a84e8c8e MD |
304 | void set_right(struct rcu_rbtree *rbtree, struct rcu_rbtree_node *node, |
305 | struct rcu_rbtree_node *right) | |
dca45c9f | 306 | { |
dca45c9f | 307 | node->_right = right; |
dca45c9f MD |
308 | } |
309 | ||
66b64c35 MD |
310 | static |
311 | void *calculate_node_max_end(struct rcu_rbtree *rbtree, struct rcu_rbtree_node *node) | |
312 | { | |
313 | void *max_end; | |
314 | ||
315 | max_end = node->end; | |
316 | if (!rcu_rbtree_is_nil(rbtree, node->_right)) { | |
317 | if (rbtree->comp(max_end, node->_right->max_end) < 0) | |
318 | max_end = node->_right->max_end; | |
319 | } | |
320 | if (!rcu_rbtree_is_nil(rbtree, node->_left)) { | |
321 | if (rbtree->comp(max_end, node->_left->max_end) < 0) | |
322 | max_end = node->_left->max_end; | |
323 | } | |
324 | return max_end; | |
325 | } | |
326 | ||
dff86257 MD |
327 | /* |
328 | * TODO | |
329 | * Deal with memory allocation errors. | |
330 | * Can be ensured by reserving a pool of memory entries before doing the | |
331 | * insertion, which will have to be function of number of | |
e20fb727 MD |
332 | * transplantations/rotations required for the operation (which is a |
333 | * multiple of the tree height). | |
dff86257 MD |
334 | */ |
335 | ||
5d2c985d | 336 | #ifdef DEBUG |
dff86257 MD |
337 | static |
338 | void show_tree(struct rcu_rbtree *rbtree) | |
339 | { | |
340 | struct rcu_rbtree_node *node; | |
341 | ||
342 | node = rcu_rbtree_min(rbtree, rbtree->root); | |
8ded5fe9 | 343 | while (!rcu_rbtree_is_nil(rbtree, node)) { |
269a9ef6 | 344 | assert(!is_decay(node)); |
fcb4eea8 | 345 | printf("{ b:%lX e:%lX pb: %lX r:%lX l:%lX %s %s %s} ", |
3366b9c0 MD |
346 | (unsigned long) node->begin, |
347 | (unsigned long) node->end, | |
348 | (unsigned long) get_parent(node)->begin, | |
fcb4eea8 MD |
349 | (unsigned long) node->_right->begin, |
350 | (unsigned long) node->_left->begin, | |
dff86257 | 351 | node->color ? "red" : "black", |
7ba89e62 | 352 | get_pos(node) ? "right" : "left", |
a84e8c8e | 353 | rcu_rbtree_is_nil(rbtree, node) ? "nil" : ""); |
dff86257 MD |
354 | node = rcu_rbtree_next(rbtree, node); |
355 | } | |
356 | printf("\n"); | |
357 | } | |
66b64c35 MD |
358 | |
359 | #define check_max_end(rbtree, x) \ | |
360 | do { \ | |
361 | if (rcu_rbtree_is_nil(rbtree, x)) \ | |
362 | break; \ | |
363 | assert(rbtree->comp(x->max_end, \ | |
364 | calculate_node_max_end(rbtree, x)) == 0); \ | |
365 | } while (0) | |
366 | ||
5d2c985d MD |
367 | #else /* DEBUG */ |
368 | static | |
369 | void show_tree(struct rcu_rbtree *rbtree) | |
370 | { | |
371 | } | |
66b64c35 MD |
372 | |
373 | static | |
374 | void check_max_end(struct rcu_rbtree *rbtree, struct rcu_rbtree_node *x) | |
375 | { | |
376 | } | |
5d2c985d | 377 | #endif /* DEBUG */ |
dff86257 MD |
378 | |
379 | static | |
380 | struct rcu_rbtree_node *make_nil(struct rcu_rbtree *rbtree) | |
381 | { | |
382 | return &rbtree->nil_node; | |
383 | } | |
384 | ||
385 | /* | |
386 | * Iterative rbtree search. | |
387 | */ | |
00539351 | 388 | struct rcu_rbtree_node *rcu_rbtree_search(struct rcu_rbtree *rbtree, |
66b64c35 MD |
389 | struct rcu_rbtree_node *x, |
390 | void *point) | |
391 | { | |
392 | struct rcu_rbtree_node *xl; | |
393 | ||
394 | dbg_printf("searching point 0x%lx\n", (unsigned long) point); | |
395 | x = rcu_dereference(x); | |
396 | ||
397 | while (!rcu_rbtree_is_nil(rbtree, x)) { | |
398 | dbg_usleep(10); | |
399 | xl = rcu_dereference(x->_left); | |
400 | dbg_printf("search x %lx x_end %lx x_max_end %lx\n", (unsigned long) x->begin, | |
401 | (unsigned long) x->end, (unsigned long) x->max_end); | |
402 | dbg_printf("search xl %lx xl_end %lx xl_max_end %lx\n", (unsigned long) xl->begin, | |
403 | (unsigned long) xl->end, (unsigned long) xl->max_end); | |
404 | if (!rcu_rbtree_is_nil(rbtree, xl) | |
405 | && (rbtree->comp(xl->max_end, point) > 0)) { | |
406 | dbg_printf("go left\n"); | |
407 | x = xl; | |
3d8a234b | 408 | } else if (rbtree->comp(x->begin, point) <= 0 |
66b64c35 MD |
409 | && rbtree->comp(point, x->end) < 0) { |
410 | dbg_printf("got it!\n"); | |
411 | break; | |
412 | } else if (rbtree->comp(point, x->begin) > 0) { | |
413 | dbg_printf("go right\n"); | |
414 | x = rcu_dereference(x->_right); | |
415 | } else { | |
416 | dbg_printf("not found!\n"); | |
417 | x = make_nil(rbtree); | |
418 | } | |
419 | } | |
420 | if (rcu_rbtree_is_nil(rbtree, x)) | |
421 | dbg_printf("Reached bottom of tree.\n"); | |
422 | ||
423 | return x; | |
424 | } | |
425 | ||
426 | struct rcu_rbtree_node *rcu_rbtree_search_range(struct rcu_rbtree *rbtree, | |
427 | struct rcu_rbtree_node *x, | |
428 | void *begin, void *end) | |
429 | { | |
430 | struct rcu_rbtree_node *node; | |
431 | ||
432 | node = rcu_rbtree_search(rbtree, x, begin); | |
433 | if (rcu_rbtree_is_nil(rbtree, node)) | |
434 | return node; | |
435 | if (rbtree->comp(node->end, end) < 0) | |
436 | return NULL; /* High is outside lookup range */ | |
437 | return node; | |
438 | } | |
439 | ||
440 | /* | |
441 | * Search by exact range start value. | |
442 | */ | |
443 | struct rcu_rbtree_node *rcu_rbtree_search_begin_key(struct rcu_rbtree *rbtree, | |
dff86257 MD |
444 | struct rcu_rbtree_node *x, |
445 | void *k) | |
446 | { | |
447 | x = rcu_dereference(x); | |
ac5f3963 | 448 | int comp; |
dff86257 | 449 | |
3366b9c0 | 450 | while (!rcu_rbtree_is_nil(rbtree, x) && (comp = rbtree->comp(k, x->begin)) != 0) { |
9c161ee1 | 451 | dbg_usleep(10); |
ac5f3963 | 452 | if (comp < 0) |
dca45c9f | 453 | x = rcu_dereference(x->_left); |
dff86257 | 454 | else |
dca45c9f | 455 | x = rcu_dereference(x->_right); |
dff86257 MD |
456 | } |
457 | return x; | |
458 | } | |
459 | ||
230dd288 MD |
460 | static |
461 | struct rcu_rbtree_node *rcu_rbtree_min_dup_decay(struct rcu_rbtree *rbtree, | |
462 | struct rcu_rbtree_node *x, | |
463 | struct rcu_rbtree_node **zr) | |
464 | { | |
465 | struct rcu_rbtree_node *xl; | |
466 | ||
467 | x = rcu_dereference(x); | |
468 | ||
8ded5fe9 | 469 | if (rcu_rbtree_is_nil(rbtree, x)) { |
230dd288 MD |
470 | *zr = x; |
471 | return x; | |
472 | } else | |
473 | *zr = x = dup_decay_node(rbtree, x); | |
474 | ||
8ded5fe9 | 475 | while (!rcu_rbtree_is_nil(rbtree, xl = rcu_dereference(x->_left))) { |
230dd288 | 476 | x = dup_decay_node(rbtree, xl); |
7ba89e62 | 477 | set_parent(x, get_decay(get_parent(x)), get_pos(x)); |
dca45c9f | 478 | get_parent(x)->_left = get_decay(get_parent(x)->_left); |
230dd288 MD |
479 | } |
480 | return x; | |
481 | } | |
482 | ||
483 | static | |
484 | struct rcu_rbtree_node *rcu_rbtree_min_update_decay(struct rcu_rbtree *rbtree, | |
485 | struct rcu_rbtree_node *x) | |
486 | { | |
487 | struct rcu_rbtree_node *xl; | |
488 | ||
489 | x = rcu_dereference(x); | |
490 | ||
8ded5fe9 | 491 | if (rcu_rbtree_is_nil(rbtree, x)) |
230dd288 MD |
492 | return x; |
493 | else { | |
dca45c9f MD |
494 | set_parent(x->_right, get_decay(get_parent(x->_right)), |
495 | get_pos(x->_right)); | |
496 | set_parent(x->_left, get_decay(get_parent(x->_left)), | |
497 | get_pos(x->_left)); | |
230dd288 MD |
498 | } |
499 | ||
8ded5fe9 | 500 | while (!rcu_rbtree_is_nil(rbtree, xl = rcu_dereference(x->_left))) { |
230dd288 | 501 | x = xl; |
dca45c9f MD |
502 | set_parent(x->_right, get_decay(get_parent(x->_right)), |
503 | get_pos(x->_right)); | |
504 | set_parent(x->_left, get_decay(get_parent(x->_left)), | |
505 | get_pos(x->_left)); | |
230dd288 MD |
506 | } |
507 | return x; | |
508 | } | |
509 | ||
dff86257 MD |
510 | struct rcu_rbtree_node *rcu_rbtree_min(struct rcu_rbtree *rbtree, |
511 | struct rcu_rbtree_node *x) | |
512 | { | |
513 | struct rcu_rbtree_node *xl; | |
514 | ||
515 | x = rcu_dereference(x); | |
516 | ||
8ded5fe9 | 517 | if (rcu_rbtree_is_nil(rbtree, x)) |
dff86257 MD |
518 | return x; |
519 | ||
8ded5fe9 | 520 | while (!rcu_rbtree_is_nil(rbtree, xl = rcu_dereference(x->_left))) |
dff86257 MD |
521 | x = xl; |
522 | return x; | |
523 | } | |
524 | ||
525 | struct rcu_rbtree_node *rcu_rbtree_max(struct rcu_rbtree *rbtree, | |
526 | struct rcu_rbtree_node *x) | |
527 | { | |
528 | struct rcu_rbtree_node *xr; | |
529 | ||
530 | x = rcu_dereference(x); | |
531 | ||
8ded5fe9 | 532 | if (rcu_rbtree_is_nil(rbtree, x)) |
dff86257 MD |
533 | return x; |
534 | ||
8ded5fe9 | 535 | while (!rcu_rbtree_is_nil(rbtree, xr = rcu_dereference(x->_right))) |
dff86257 MD |
536 | x = xr; |
537 | return x; | |
538 | } | |
539 | ||
dff86257 | 540 | /* |
7ba89e62 MD |
541 | * RCU read lock must be held across the next/prev calls to ensure validity of |
542 | * the returned node. | |
dff86257 MD |
543 | */ |
544 | struct rcu_rbtree_node *rcu_rbtree_next(struct rcu_rbtree *rbtree, | |
545 | struct rcu_rbtree_node *x) | |
546 | { | |
269a9ef6 | 547 | struct rcu_rbtree_node *xr, *y; |
7ba89e62 | 548 | unsigned int x_pos; |
dff86257 MD |
549 | |
550 | x = rcu_dereference(x); | |
551 | ||
8ded5fe9 | 552 | if (!rcu_rbtree_is_nil(rbtree, xr = rcu_dereference(x->_right))) |
dff86257 | 553 | return rcu_rbtree_min(rbtree, xr); |
7ba89e62 | 554 | y = get_parent_and_pos(x, &x_pos); |
8ded5fe9 | 555 | while (!rcu_rbtree_is_nil(rbtree, y) && x_pos == IS_RIGHT) { |
dff86257 | 556 | x = y; |
7ba89e62 | 557 | y = get_parent_and_pos(y, &x_pos); |
dff86257 MD |
558 | } |
559 | return y; | |
560 | } | |
561 | ||
562 | struct rcu_rbtree_node *rcu_rbtree_prev(struct rcu_rbtree *rbtree, | |
563 | struct rcu_rbtree_node *x) | |
564 | { | |
269a9ef6 | 565 | struct rcu_rbtree_node *xl, *y; |
7ba89e62 | 566 | unsigned int x_pos; |
dff86257 MD |
567 | |
568 | x = rcu_dereference(x); | |
569 | ||
8ded5fe9 | 570 | if (!rcu_rbtree_is_nil(rbtree, xl = rcu_dereference(x->_left))) |
4aa30442 | 571 | return rcu_rbtree_max(rbtree, xl); |
7ba89e62 | 572 | y = get_parent_and_pos(x, &x_pos); |
8ded5fe9 | 573 | while (!rcu_rbtree_is_nil(rbtree, y) && x_pos == IS_LEFT) { |
dff86257 | 574 | x = y; |
7ba89e62 | 575 | y = get_parent_and_pos(y, &x_pos); |
dff86257 MD |
576 | } |
577 | return y; | |
578 | } | |
579 | ||
7bc64d1d MD |
580 | /* |
581 | * "node" needs to be non-visible by readers. | |
582 | */ | |
583 | static | |
584 | void populate_node_end(struct rcu_rbtree *rbtree, struct rcu_rbtree_node *node, | |
fcb4eea8 | 585 | unsigned int copy_parents, struct rcu_rbtree_node *stop) |
7bc64d1d MD |
586 | { |
587 | struct rcu_rbtree_node *prev = NULL, *orig_node = node, *top; | |
588 | ||
589 | do { | |
590 | void *max_end; | |
591 | ||
fcb4eea8 | 592 | assert(node); |
7bc64d1d | 593 | assert(!rcu_rbtree_is_nil(rbtree, node)); |
4459c487 | 594 | |
66b64c35 MD |
595 | if (prev && copy_parents) { |
596 | node = dup_decay_node(rbtree, node); | |
597 | if (get_pos(prev) == IS_RIGHT) | |
598 | node->_right = prev; | |
599 | else | |
600 | node->_left = prev; | |
601 | set_parent(prev, node, get_pos(prev)); | |
602 | } | |
603 | ||
fda7316a | 604 | max_end = calculate_node_max_end(rbtree, node); |
66b64c35 MD |
605 | /* |
606 | * Compare the node max_end keys to make sure we replace | |
607 | * references to a key belonging to a node we remove | |
608 | * from the tree. Otherwise we would still be using this | |
609 | * pointer as an invalid reference after garbage | |
610 | * collection of the node and of its associated | |
611 | * begin/end pointers. | |
612 | */ | |
613 | if (max_end != node->max_end) { | |
7bc64d1d MD |
614 | node->max_end = max_end; |
615 | } else { | |
7bc64d1d MD |
616 | top = get_parent(node); |
617 | cmm_smp_wmb(); /* write into node before publish */ | |
618 | /* make new branch visible to readers */ | |
619 | if (rcu_rbtree_is_nil(rbtree, top)) | |
620 | _CMM_STORE_SHARED(rbtree->root, node); | |
621 | if (get_pos(node) == IS_LEFT) | |
622 | _CMM_STORE_SHARED(top->_left, node); | |
623 | else | |
624 | _CMM_STORE_SHARED(top->_right, node); | |
625 | goto end; | |
626 | } | |
fcb4eea8 MD |
627 | |
628 | /* Check for propagation stop */ | |
629 | if (node == stop) | |
630 | return; | |
631 | ||
7bc64d1d | 632 | prev = node; |
fcb4eea8 MD |
633 | node = get_parent(node); |
634 | } while (!rcu_rbtree_is_nil(rbtree, node)); | |
7bc64d1d MD |
635 | |
636 | top = node; /* nil */ | |
637 | cmm_smp_wmb(); /* write into node before publish */ | |
638 | /* make new branch visible to readers */ | |
639 | _CMM_STORE_SHARED(rbtree->root, prev); | |
640 | ||
641 | end: | |
fcb4eea8 MD |
642 | if (!copy_parents) |
643 | return; | |
7bc64d1d MD |
644 | /* update children */ |
645 | node = orig_node; | |
646 | do { | |
647 | assert(!rcu_rbtree_is_nil(rbtree, node)); | |
648 | set_parent(node->_left, get_decay(get_parent(node->_left)), IS_LEFT); | |
649 | set_parent(node->_right, get_decay(get_parent(node->_right)), IS_RIGHT); | |
650 | } while ((node = get_parent(node)) != top); | |
651 | } | |
652 | ||
dff86257 MD |
653 | /* |
654 | * We have to ensure these assumptions are correct for prev/next | |
655 | * traversal: | |
656 | * | |
657 | * with x being a right child, the assumption that: | |
dca45c9f | 658 | * get_parent(x)->_right == x |
dff86257 | 659 | * or if x is a left child, the assumption that: |
dca45c9f | 660 | * get_parent(x)->_left == x |
dff86257 MD |
661 | * |
662 | * This explains why we have to allocate a vc copy of the node for left_rotate, | |
663 | * right_rotate and transplant operations. | |
664 | * | |
665 | * We always ensure that the right/left child and correct parent is set in the | |
666 | * node copies *before* we reparent the children and make the upper-level point | |
667 | * to the copy. | |
668 | */ | |
669 | ||
670 | /* RCU: copy x and y, atomically point to new versions. GC old. */ | |
671 | /* Should be eventually followed by a cmm_smp_wmc() */ | |
dff86257 | 672 | |
dbe4ae98 MD |
673 | #ifdef RBTREE_RCU_SUPPORT_ROTATE_LEFT |
674 | ||
dff86257 | 675 | static |
269a9ef6 MD |
676 | void left_rotate(struct rcu_rbtree *rbtree, |
677 | struct rcu_rbtree_node *x) | |
dff86257 | 678 | { |
a84e8c8e | 679 | struct rcu_rbtree_node *y, *y_left; |
dff86257 | 680 | |
66b64c35 MD |
681 | dbg_printf("left rotate %lx\n", (unsigned long) x->begin); |
682 | ||
dca45c9f MD |
683 | y = x->_right; |
684 | y_left = y->_left; | |
269a9ef6 MD |
685 | |
686 | /* Now operate on new copy, decay old versions */ | |
dbe4ae98 MD |
687 | x = dup_decay_node(rbtree, x); |
688 | y = dup_decay_node(rbtree, y); | |
689 | y_left = dup_decay_node(rbtree, y_left); | |
269a9ef6 | 690 | |
66b64c35 MD |
691 | check_max_end(rbtree, get_parent(x)); |
692 | check_max_end(rbtree, x); | |
693 | check_max_end(rbtree, y); | |
694 | ||
676dd8b6 | 695 | /* Internal node modifications */ |
7ba89e62 MD |
696 | set_parent(y, get_parent(x), get_pos(x)); |
697 | set_parent(x, y, IS_LEFT); | |
a84e8c8e MD |
698 | set_left(rbtree, y, x); |
699 | set_right(rbtree, x, y_left); | |
dca45c9f | 700 | |
8ded5fe9 | 701 | if (!rcu_rbtree_is_nil(rbtree, y_left)) |
7ba89e62 | 702 | set_parent(y_left, x, IS_RIGHT); |
676dd8b6 | 703 | |
fda7316a MD |
704 | /* |
705 | * We only changed the relative position of x and y wrt their | |
706 | * children, and reparented y (but are keeping the same nodes in | |
707 | * place, so its parent does not need to have end value | |
708 | * recalculated). | |
709 | */ | |
710 | x->max_end = calculate_node_max_end(rbtree, x); | |
711 | y->max_end = calculate_node_max_end(rbtree, y); | |
712 | ||
676dd8b6 MD |
713 | cmm_smp_wmb(); /* write into node before publish */ |
714 | ||
715 | /* External references update (visible by readers) */ | |
a84e8c8e MD |
716 | if (rcu_rbtree_is_nil(rbtree, get_parent(y))) |
717 | _CMM_STORE_SHARED(rbtree->root, y); | |
718 | else if (get_pos(y) == IS_LEFT) | |
719 | _CMM_STORE_SHARED(get_parent(y)->_left, y); | |
676dd8b6 | 720 | else |
a84e8c8e | 721 | _CMM_STORE_SHARED(get_parent(y)->_right, y); |
676dd8b6 | 722 | |
dbe4ae98 | 723 | /* Point children to new copy (parent only used by updates/next/prev) */ |
dca45c9f MD |
724 | set_parent(x->_left, get_decay(get_parent(x->_left)), |
725 | get_pos(x->_left)); | |
726 | set_parent(y->_right, get_decay(get_parent(y->_right)), | |
727 | get_pos(y->_right)); | |
8ded5fe9 | 728 | if (!rcu_rbtree_is_nil(rbtree, y_left)) { |
dca45c9f MD |
729 | set_parent(y_left->_right, |
730 | get_decay(get_parent(y_left->_right)), | |
731 | get_pos(y_left->_right)); | |
732 | set_parent(y_left->_left, | |
733 | get_decay(get_parent(y_left->_left)), | |
734 | get_pos(y_left->_left)); | |
dbe4ae98 | 735 | } |
269a9ef6 MD |
736 | |
737 | /* Sanity checks */ | |
dca45c9f MD |
738 | assert(y == rbtree->root || get_parent(y)->_left == y |
739 | || get_parent(y)->_right == y); | |
740 | assert(x == rbtree->root || get_parent(x)->_left == x | |
741 | || get_parent(x)->_right == x); | |
8ded5fe9 MD |
742 | assert(rcu_rbtree_is_nil(rbtree, x->_right) || get_parent(x->_right) == x); |
743 | assert(rcu_rbtree_is_nil(rbtree, x->_left) || get_parent(x->_left) == x); | |
744 | assert(rcu_rbtree_is_nil(rbtree, y->_right) || get_parent(y->_right) == y); | |
745 | assert(rcu_rbtree_is_nil(rbtree, y->_left) || get_parent(y->_left) == y); | |
269a9ef6 MD |
746 | assert(!is_decay(rbtree->root)); |
747 | assert(!is_decay(x)); | |
748 | assert(!is_decay(y)); | |
dca45c9f MD |
749 | assert(!is_decay(x->_right)); |
750 | assert(!is_decay(x->_left)); | |
751 | assert(!is_decay(y->_right)); | |
752 | assert(!is_decay(y->_left)); | |
66b64c35 MD |
753 | check_max_end(rbtree, get_parent(y)); |
754 | check_max_end(rbtree, x); | |
755 | check_max_end(rbtree, y); | |
dff86257 MD |
756 | } |
757 | ||
dbe4ae98 MD |
758 | #else |
759 | ||
760 | /* non-rcu version */ | |
761 | static | |
762 | void left_rotate(struct rcu_rbtree *rbtree, | |
763 | struct rcu_rbtree_node *x) | |
764 | { | |
765 | struct rcu_rbtree_node *y; | |
766 | ||
230dd288 | 767 | lock_test_mutex(); |
dca45c9f MD |
768 | y = x->_right; |
769 | x->_right = y->_left; | |
8ded5fe9 | 770 | if (!rcu_rbtree_is_nil(rbtree, y->_left)) |
dca45c9f | 771 | set_parent(y->_left, x, IS_RIGHT); |
7ba89e62 | 772 | set_parent(y, get_parent(x), get_pos(x)); |
8ded5fe9 | 773 | if (rcu_rbtree_is_nil(rbtree, get_parent(x))) |
dbe4ae98 | 774 | rbtree->root = y; |
dca45c9f MD |
775 | else if (x == get_parent(x)->_left) { |
776 | get_parent(x)->_left = y; | |
dbe4ae98 | 777 | } else { |
dca45c9f | 778 | get_parent(x)->_right = y; |
dbe4ae98 | 779 | } |
dca45c9f | 780 | y->_left = x; |
7ba89e62 | 781 | set_parent(x, y, IS_LEFT); |
230dd288 | 782 | unlock_test_mutex(); |
dbe4ae98 MD |
783 | } |
784 | ||
785 | #endif | |
786 | ||
787 | #ifdef RBTREE_RCU_SUPPORT_ROTATE_RIGHT | |
dff86257 | 788 | static |
269a9ef6 MD |
789 | void right_rotate(struct rcu_rbtree *rbtree, |
790 | struct rcu_rbtree_node *x) | |
dff86257 | 791 | { |
a84e8c8e | 792 | struct rcu_rbtree_node *y, *y_right; |
dff86257 | 793 | |
66b64c35 MD |
794 | dbg_printf("right rotate %lx\n", (unsigned long) x->begin); |
795 | ||
dca45c9f MD |
796 | y = x->_left; |
797 | y_right = y->_right; | |
269a9ef6 MD |
798 | |
799 | /* Now operate on new copy, decay old versions */ | |
dbe4ae98 MD |
800 | x = dup_decay_node(rbtree, x); |
801 | y = dup_decay_node(rbtree, y); | |
802 | y_right = dup_decay_node(rbtree, y_right); | |
269a9ef6 | 803 | |
66b64c35 MD |
804 | check_max_end(rbtree, get_parent(x)); |
805 | check_max_end(rbtree, x); | |
806 | check_max_end(rbtree, y); | |
807 | ||
676dd8b6 | 808 | /* Internal node modifications */ |
7ba89e62 MD |
809 | set_parent(y, get_parent(x), get_pos(x)); |
810 | set_parent(x, y, IS_RIGHT); | |
a84e8c8e MD |
811 | set_right(rbtree, y, x); |
812 | set_left(rbtree, x, y_right); | |
dca45c9f | 813 | |
8ded5fe9 | 814 | if (!rcu_rbtree_is_nil(rbtree, y_right)) |
7ba89e62 | 815 | set_parent(y_right, x, IS_LEFT); |
676dd8b6 | 816 | |
fda7316a MD |
817 | /* |
818 | * We only changed the relative position of x and y wrt their | |
819 | * children, and reparented y (but are keeping the same nodes in | |
820 | * place, so its parent does not need to have end value | |
821 | * recalculated). | |
822 | */ | |
823 | x->max_end = calculate_node_max_end(rbtree, x); | |
824 | y->max_end = calculate_node_max_end(rbtree, y); | |
825 | ||
676dd8b6 MD |
826 | cmm_smp_wmb(); /* write into node before publish */ |
827 | ||
828 | /* External references update (visible by readers) */ | |
a84e8c8e MD |
829 | if (rcu_rbtree_is_nil(rbtree, get_parent(y))) |
830 | _CMM_STORE_SHARED(rbtree->root, y); | |
831 | else if (get_pos(y) == IS_RIGHT) | |
832 | _CMM_STORE_SHARED(get_parent(y)->_right, y); | |
676dd8b6 | 833 | else |
a84e8c8e | 834 | _CMM_STORE_SHARED(get_parent(y)->_left, y); |
676dd8b6 | 835 | |
dbe4ae98 | 836 | /* Point children to new copy (parent only used by updates/next/prev) */ |
dca45c9f MD |
837 | set_parent(x->_right, get_decay(get_parent(x->_right)), |
838 | get_pos(x->_right)); | |
839 | set_parent(y->_left, get_decay(get_parent(y->_left)), | |
840 | get_pos(y->_left)); | |
8ded5fe9 | 841 | if (!rcu_rbtree_is_nil(rbtree, y_right)) { |
dca45c9f MD |
842 | set_parent(y_right->_left, |
843 | get_decay(get_parent(y_right->_left)), | |
844 | get_pos(y_right->_left)); | |
845 | set_parent(y_right->_right, | |
846 | get_decay(get_parent(y_right->_right)), | |
847 | get_pos(y_right->_right)); | |
dbe4ae98 | 848 | } |
269a9ef6 MD |
849 | |
850 | /* Sanity checks */ | |
dca45c9f MD |
851 | assert(y == rbtree->root || get_parent(y)->_right == y |
852 | || get_parent(y)->_left == y); | |
853 | assert(x == rbtree->root || get_parent(x)->_right == x | |
854 | || get_parent(x)->_left == x); | |
8ded5fe9 MD |
855 | assert(rcu_rbtree_is_nil(rbtree, x->_left) || get_parent(x->_left) == x); |
856 | assert(rcu_rbtree_is_nil(rbtree, x->_right) || get_parent(x->_right) == x); | |
857 | assert(rcu_rbtree_is_nil(rbtree, y->_left) || get_parent(y->_left) == y); | |
858 | assert(rcu_rbtree_is_nil(rbtree, y->_right) || get_parent(y->_right) == y); | |
269a9ef6 MD |
859 | assert(!is_decay(rbtree->root)); |
860 | assert(!is_decay(x)); | |
861 | assert(!is_decay(y)); | |
dca45c9f MD |
862 | assert(!is_decay(x->_left)); |
863 | assert(!is_decay(x->_right)); | |
864 | assert(!is_decay(y->_left)); | |
865 | assert(!is_decay(y->_right)); | |
66b64c35 MD |
866 | check_max_end(rbtree, x); |
867 | check_max_end(rbtree, y); | |
868 | check_max_end(rbtree, get_parent(y)); | |
dff86257 MD |
869 | } |
870 | ||
6daf6090 MD |
871 | #else |
872 | ||
dbe4ae98 | 873 | /* non-rcu version */ |
6daf6090 MD |
874 | static |
875 | void right_rotate(struct rcu_rbtree *rbtree, | |
876 | struct rcu_rbtree_node *x) | |
877 | { | |
878 | struct rcu_rbtree_node *y; | |
879 | ||
230dd288 | 880 | lock_test_mutex(); |
dca45c9f MD |
881 | y = x->_left; |
882 | x->_left = y->_right; | |
8ded5fe9 | 883 | if (!rcu_rbtree_is_nil(rbtree, y->_right)) |
dca45c9f | 884 | set_parent(y->_right, x, IS_LEFT); |
7ba89e62 | 885 | set_parent(y, get_parent(x), get_pos(x)); |
8ded5fe9 | 886 | if (rcu_rbtree_is_nil(rbtree, get_parent(x))) |
6daf6090 | 887 | rbtree->root = y; |
dca45c9f MD |
888 | else if (x == get_parent(x)->_right) { |
889 | get_parent(x)->_right = y; | |
6daf6090 | 890 | } else { |
dca45c9f | 891 | get_parent(x)->_left = y; |
6daf6090 | 892 | } |
dca45c9f | 893 | y->_right = x; |
7ba89e62 | 894 | set_parent(x, y, IS_RIGHT); |
230dd288 | 895 | unlock_test_mutex(); |
6daf6090 MD |
896 | } |
897 | ||
898 | #endif | |
899 | ||
dff86257 MD |
900 | static void rcu_rbtree_insert_fixup(struct rcu_rbtree *rbtree, |
901 | struct rcu_rbtree_node *z) | |
902 | { | |
903 | struct rcu_rbtree_node *y; | |
904 | ||
3366b9c0 | 905 | dbg_printf("insert fixup %p\n", z->begin); |
269a9ef6 | 906 | assert(!is_decay(rbtree->root)); |
dff86257 | 907 | |
7ba89e62 | 908 | while (get_parent(z)->color == COLOR_RED) { |
dca45c9f MD |
909 | if (get_parent(z) == get_parent(get_parent(z))->_left) { |
910 | y = get_parent(get_parent(z))->_right; | |
dff86257 | 911 | if (y->color == COLOR_RED) { |
7ba89e62 | 912 | get_parent(z)->color = COLOR_BLACK; |
dff86257 | 913 | y->color = COLOR_BLACK; |
7ba89e62 MD |
914 | get_parent(get_parent(z))->color = COLOR_RED; |
915 | z = get_parent(get_parent(z)); | |
dff86257 | 916 | } else { |
dca45c9f | 917 | if (z == get_parent(z)->_right) { |
7ba89e62 | 918 | z = get_parent(z); |
dff86257 | 919 | left_rotate(rbtree, z); |
269a9ef6 MD |
920 | z = get_decay(z); |
921 | assert(!is_decay(rbtree->root)); | |
dff86257 | 922 | } |
7ba89e62 MD |
923 | get_parent(z)->color = COLOR_BLACK; |
924 | get_parent(get_parent(z))->color = COLOR_RED; | |
269a9ef6 | 925 | assert(!is_decay(z)); |
7ba89e62 MD |
926 | assert(!is_decay(get_parent(z))); |
927 | assert(!is_decay(get_parent(get_parent(z)))); | |
928 | right_rotate(rbtree, get_parent(get_parent(z))); | |
269a9ef6 MD |
929 | assert(!is_decay(z)); |
930 | assert(!is_decay(rbtree->root)); | |
dff86257 MD |
931 | } |
932 | } else { | |
dca45c9f | 933 | y = get_parent(get_parent(z))->_left; |
dff86257 | 934 | if (y->color == COLOR_RED) { |
7ba89e62 | 935 | get_parent(z)->color = COLOR_BLACK; |
dff86257 | 936 | y->color = COLOR_BLACK; |
7ba89e62 MD |
937 | get_parent(get_parent(z))->color = COLOR_RED; |
938 | z = get_parent(get_parent(z)); | |
dff86257 | 939 | } else { |
dca45c9f | 940 | if (z == get_parent(z)->_left) { |
7ba89e62 | 941 | z = get_parent(z); |
dff86257 | 942 | right_rotate(rbtree, z); |
269a9ef6 MD |
943 | z = get_decay(z); |
944 | assert(!is_decay(rbtree->root)); | |
dff86257 | 945 | } |
7ba89e62 MD |
946 | get_parent(z)->color = COLOR_BLACK; |
947 | get_parent(get_parent(z))->color = COLOR_RED; | |
948 | left_rotate(rbtree, get_parent(get_parent(z))); | |
269a9ef6 MD |
949 | assert(!is_decay(z)); |
950 | assert(!is_decay(rbtree->root)); | |
dff86257 MD |
951 | } |
952 | } | |
953 | } | |
954 | rbtree->root->color = COLOR_BLACK; | |
955 | } | |
956 | ||
957 | /* | |
958 | * rcu_rbtree_insert - Insert a node in the RCU rbtree | |
959 | * | |
960 | * Returns 0 on success, or < 0 on error. | |
961 | */ | |
962 | int rcu_rbtree_insert(struct rcu_rbtree *rbtree, | |
3c672595 | 963 | void *begin, void *end) |
dff86257 | 964 | { |
3c672595 MD |
965 | struct rcu_rbtree_node *x, *y, *z; |
966 | ||
8f354bc4 MD |
967 | z = _rcu_rbtree_alloc_node(rbtree); |
968 | if (!z) | |
969 | return -ENOMEM; | |
3c672595 MD |
970 | z->begin = begin; |
971 | z->end = end; | |
dff86257 | 972 | |
3366b9c0 | 973 | dbg_printf("insert %p\n", z->begin); |
269a9ef6 | 974 | assert(!is_decay(rbtree->root)); |
dff86257 MD |
975 | |
976 | y = make_nil(rbtree); | |
dff86257 | 977 | x = rbtree->root; |
8ded5fe9 | 978 | while (!rcu_rbtree_is_nil(rbtree, x)) { |
dff86257 | 979 | y = x; |
3366b9c0 | 980 | if (rbtree->comp(z->begin, x->begin) < 0) |
dca45c9f | 981 | x = x->_left; |
dff86257 | 982 | else |
dca45c9f | 983 | x = x->_right; |
dff86257 MD |
984 | } |
985 | ||
dca45c9f MD |
986 | z->_left = make_nil(rbtree); |
987 | z->_right = make_nil(rbtree); | |
dff86257 | 988 | z->color = COLOR_RED; |
269a9ef6 | 989 | z->decay_next = NULL; |
55b5e812 | 990 | z->max_end = z->end; |
3c672595 | 991 | z->rbtree = rbtree; |
dff86257 | 992 | |
8ded5fe9 | 993 | if (rcu_rbtree_is_nil(rbtree, y)) { |
7bc64d1d | 994 | set_parent(z, y, IS_RIGHT); /* pos arbitrary for root node */ |
0bd215cc MD |
995 | /* |
996 | * Order stores to z (children/parents) before stores | |
997 | * that will make it visible to the rest of the tree. | |
998 | */ | |
999 | cmm_smp_wmb(); | |
dff86257 | 1000 | _CMM_STORE_SHARED(rbtree->root, z); |
3366b9c0 | 1001 | } else if (rbtree->comp(z->begin, y->begin) < 0) { |
7bc64d1d MD |
1002 | y = dup_decay_node(rbtree, y); |
1003 | set_parent(z, y, IS_LEFT); | |
1004 | if (get_pos(z) == IS_LEFT) | |
a84e8c8e | 1005 | _CMM_STORE_SHARED(y->_left, z); |
dca45c9f | 1006 | else |
a84e8c8e | 1007 | _CMM_STORE_SHARED(y->_right, z); |
fcb4eea8 | 1008 | populate_node_end(rbtree, y, 1, NULL); |
dca45c9f | 1009 | } else { |
7bc64d1d MD |
1010 | y = dup_decay_node(rbtree, y); |
1011 | set_parent(z, y, IS_RIGHT); | |
1012 | if (get_pos(z) == IS_LEFT) | |
a84e8c8e | 1013 | _CMM_STORE_SHARED(y->_left, z); |
dca45c9f | 1014 | else |
a84e8c8e | 1015 | _CMM_STORE_SHARED(y->_right, z); |
fcb4eea8 | 1016 | populate_node_end(rbtree, y, 1, NULL); |
dca45c9f | 1017 | } |
dff86257 MD |
1018 | rcu_rbtree_insert_fixup(rbtree, z); |
1019 | /* | |
1020 | * Make sure to commit all _CMM_STORE_SHARED() for non-coherent caches. | |
1021 | */ | |
1022 | cmm_smp_wmc(); | |
1023 | show_tree(rbtree); | |
66b64c35 MD |
1024 | check_max_end(rbtree, z); |
1025 | check_max_end(rbtree, y); | |
dff86257 MD |
1026 | |
1027 | return 0; | |
1028 | } | |
1029 | ||
1030 | /* | |
1031 | * Transplant v into u position. | |
dff86257 | 1032 | */ |
6daf6090 MD |
1033 | |
1034 | #ifdef RBTREE_RCU_SUPPORT_TRANSPLANT | |
1035 | ||
269a9ef6 MD |
1036 | static |
1037 | void rcu_rbtree_transplant(struct rcu_rbtree *rbtree, | |
1038 | struct rcu_rbtree_node *u, | |
dca45c9f | 1039 | struct rcu_rbtree_node *v, |
fcb4eea8 MD |
1040 | unsigned int copy_parents, |
1041 | struct rcu_rbtree_node *stop) | |
dff86257 | 1042 | { |
3366b9c0 | 1043 | dbg_printf("transplant %p\n", v->begin); |
dff86257 | 1044 | |
8ded5fe9 | 1045 | if (!rcu_rbtree_is_nil(rbtree, v)) |
dbe4ae98 | 1046 | v = dup_decay_node(rbtree, v); |
c479601c | 1047 | |
8ded5fe9 | 1048 | if (rcu_rbtree_is_nil(rbtree, get_parent(u))) { |
7ba89e62 MD |
1049 | /* pos is arbitrary for root node */ |
1050 | set_parent(v, get_parent(u), IS_RIGHT); | |
c479601c MD |
1051 | cmm_smp_wmb(); /* write into node before publish */ |
1052 | _CMM_STORE_SHARED(rbtree->root, v); | |
dff86257 | 1053 | } else { |
fcb4eea8 MD |
1054 | struct rcu_rbtree_node *vp; |
1055 | ||
1056 | vp = get_parent(u); | |
1057 | if (copy_parents) | |
1058 | vp = dup_decay_node(rbtree, vp); | |
1059 | set_parent(v, vp, get_pos(u)); | |
1060 | if (get_pos(v) == IS_LEFT) | |
1061 | _CMM_STORE_SHARED(vp->_left, v); | |
806967f3 | 1062 | else |
fcb4eea8 MD |
1063 | _CMM_STORE_SHARED(vp->_right, v); |
1064 | populate_node_end(rbtree, vp, copy_parents, stop); | |
66b64c35 | 1065 | check_max_end(rbtree, vp); |
c479601c | 1066 | } |
806967f3 | 1067 | |
dbe4ae98 | 1068 | /* Point children to new copy (parent only used by updates/next/prev) */ |
8ded5fe9 | 1069 | if (!rcu_rbtree_is_nil(rbtree, v)) { |
dca45c9f MD |
1070 | set_parent(v->_right, get_decay(get_parent(v->_right)), |
1071 | get_pos(v->_right)); | |
1072 | set_parent(v->_left, get_decay(get_parent(v->_left)), | |
1073 | get_pos(v->_left)); | |
dff86257 | 1074 | } |
269a9ef6 | 1075 | assert(!is_decay(rbtree->root)); |
66b64c35 | 1076 | check_max_end(rbtree, v); |
dff86257 MD |
1077 | } |
1078 | ||
6daf6090 MD |
1079 | #else |
1080 | ||
1081 | /* Non-RCU version */ | |
1082 | static | |
1083 | void rcu_rbtree_transplant(struct rcu_rbtree *rbtree, | |
1084 | struct rcu_rbtree_node *u, | |
dca45c9f | 1085 | struct rcu_rbtree_node *v, |
fcb4eea8 MD |
1086 | unsigned int copy_parents, |
1087 | struct rcu_rbtree_node *stop) | |
6daf6090 | 1088 | { |
3366b9c0 | 1089 | dbg_printf("transplant %p\n", v->begin); |
6daf6090 | 1090 | |
230dd288 | 1091 | lock_test_mutex(); |
8ded5fe9 | 1092 | if (rcu_rbtree_is_nil(rbtree, get_parent(u))) |
6daf6090 | 1093 | rbtree->root = v; |
dca45c9f MD |
1094 | else if (u == get_parent(u)->_left) |
1095 | get_parent(u)->_left = v; | |
7ba89e62 | 1096 | else |
dca45c9f | 1097 | get_parent(u)->_right = v; |
7ba89e62 | 1098 | set_parent(v, get_parent(u), get_pos(u)); |
230dd288 | 1099 | unlock_test_mutex(); |
6daf6090 MD |
1100 | } |
1101 | ||
1102 | #endif | |
1103 | ||
dff86257 MD |
1104 | static void rcu_rbtree_remove_fixup(struct rcu_rbtree *rbtree, |
1105 | struct rcu_rbtree_node *x) | |
1106 | { | |
3366b9c0 | 1107 | dbg_printf("remove fixup %p\n", x->begin); |
dff86257 MD |
1108 | |
1109 | while (x != rbtree->root && x->color == COLOR_BLACK) { | |
7ba89e62 | 1110 | assert(!is_decay(get_parent(x))); |
dca45c9f MD |
1111 | assert(!is_decay(get_parent(x)->_left)); |
1112 | if (x == get_parent(x)->_left) { | |
269a9ef6 | 1113 | struct rcu_rbtree_node *w; |
dff86257 | 1114 | |
dca45c9f | 1115 | w = get_parent(x)->_right; |
dff86257 MD |
1116 | |
1117 | if (w->color == COLOR_RED) { | |
269a9ef6 | 1118 | w->color = COLOR_BLACK; |
7ba89e62 MD |
1119 | get_parent(x)->color = COLOR_RED; |
1120 | left_rotate(rbtree, get_parent(x)); | |
269a9ef6 MD |
1121 | x = get_decay(x); |
1122 | assert(!is_decay(rbtree->root)); | |
dca45c9f | 1123 | w = get_parent(x)->_right; |
dff86257 | 1124 | } |
dca45c9f MD |
1125 | if (w->_left->color == COLOR_BLACK |
1126 | && w->_right->color == COLOR_BLACK) { | |
dff86257 | 1127 | w->color = COLOR_RED; |
7ba89e62 | 1128 | x = get_parent(x); |
c479601c MD |
1129 | assert(!is_decay(rbtree->root)); |
1130 | assert(!is_decay(x)); | |
dff86257 | 1131 | } else { |
dca45c9f MD |
1132 | if (w->_right->color == COLOR_BLACK) { |
1133 | w->_left->color = COLOR_BLACK; | |
dff86257 MD |
1134 | w->color = COLOR_RED; |
1135 | right_rotate(rbtree, w); | |
c479601c | 1136 | assert(!is_decay(rbtree->root)); |
269a9ef6 | 1137 | x = get_decay(x); |
dca45c9f | 1138 | w = get_parent(x)->_right; |
dff86257 | 1139 | } |
7ba89e62 MD |
1140 | w->color = get_parent(x)->color; |
1141 | get_parent(x)->color = COLOR_BLACK; | |
dca45c9f | 1142 | w->_right->color = COLOR_BLACK; |
7ba89e62 | 1143 | left_rotate(rbtree, get_parent(x)); |
269a9ef6 | 1144 | assert(!is_decay(rbtree->root)); |
dff86257 MD |
1145 | x = rbtree->root; |
1146 | } | |
1147 | } else { | |
269a9ef6 | 1148 | struct rcu_rbtree_node *w; |
dff86257 | 1149 | |
dca45c9f | 1150 | w = get_parent(x)->_left; |
dff86257 MD |
1151 | |
1152 | if (w->color == COLOR_RED) { | |
269a9ef6 | 1153 | w->color = COLOR_BLACK; |
7ba89e62 MD |
1154 | get_parent(x)->color = COLOR_RED; |
1155 | right_rotate(rbtree, get_parent(x)); | |
c479601c | 1156 | assert(!is_decay(rbtree->root)); |
269a9ef6 | 1157 | x = get_decay(x); |
dca45c9f | 1158 | w = get_parent(x)->_left; |
dff86257 | 1159 | } |
dca45c9f MD |
1160 | if (w->_right->color == COLOR_BLACK |
1161 | && w->_left->color == COLOR_BLACK) { | |
dff86257 | 1162 | w->color = COLOR_RED; |
7ba89e62 | 1163 | x = get_parent(x); |
c479601c MD |
1164 | assert(!is_decay(rbtree->root)); |
1165 | assert(!is_decay(x)); | |
dff86257 | 1166 | } else { |
dca45c9f MD |
1167 | if (w->_left->color == COLOR_BLACK) { |
1168 | w->_right->color = COLOR_BLACK; | |
dff86257 MD |
1169 | w->color = COLOR_RED; |
1170 | left_rotate(rbtree, w); | |
269a9ef6 MD |
1171 | assert(!is_decay(rbtree->root)); |
1172 | x = get_decay(x); | |
dca45c9f | 1173 | w = get_parent(x)->_left; |
dff86257 | 1174 | } |
7ba89e62 MD |
1175 | w->color = get_parent(x)->color; |
1176 | get_parent(x)->color = COLOR_BLACK; | |
dca45c9f | 1177 | w->_left->color = COLOR_BLACK; |
7ba89e62 | 1178 | right_rotate(rbtree, get_parent(x)); |
c479601c | 1179 | assert(!is_decay(rbtree->root)); |
dff86257 MD |
1180 | x = rbtree->root; |
1181 | } | |
1182 | } | |
1183 | } | |
1184 | x->color = COLOR_BLACK; | |
1185 | } | |
1186 | ||
1187 | /* | |
269a9ef6 MD |
1188 | * Delete z. All non-copied children left/right positions are unchanged. |
1189 | */ | |
1190 | static | |
1191 | void rcu_rbtree_remove_nonil(struct rcu_rbtree *rbtree, | |
1192 | struct rcu_rbtree_node *z, | |
1193 | struct rcu_rbtree_node *y) | |
dff86257 | 1194 | { |
a84e8c8e | 1195 | struct rcu_rbtree_node *x; |
dff86257 | 1196 | |
3366b9c0 | 1197 | dbg_printf("remove nonil %p\n", z->begin); |
dff86257 MD |
1198 | show_tree(rbtree); |
1199 | ||
c479601c MD |
1200 | assert(!is_decay(z)); |
1201 | assert(!is_decay(y)); | |
dca45c9f | 1202 | assert(!is_decay(y->_right)); |
7ba89e62 | 1203 | assert(!is_decay(get_parent(y))); |
dca45c9f | 1204 | x = y->_right; |
c479601c | 1205 | assert(!is_decay(x)); |
7ba89e62 | 1206 | if (get_parent(y) == z) { |
230dd288 | 1207 | y = dup_decay_node(rbtree, y); |
7ba89e62 | 1208 | set_parent(x, y, get_pos(x)); /* parent for nil */ |
66b64c35 | 1209 | /* y is z's right node */ |
a84e8c8e | 1210 | set_left(rbtree, y, z->_left); |
66b64c35 | 1211 | y->max_end = calculate_node_max_end(rbtree, y); |
fcb4eea8 | 1212 | rcu_rbtree_transplant(rbtree, z, y, 1, NULL); |
230dd288 MD |
1213 | } else { |
1214 | struct rcu_rbtree_node *oy_right, *z_right; | |
1215 | ||
1216 | /* | |
1217 | * Need to make sure y is always visible by readers. | |
1218 | */ | |
dca45c9f | 1219 | y = rcu_rbtree_min_dup_decay(rbtree, z->_right, &z_right); |
269a9ef6 MD |
1220 | assert(!is_decay(y)); |
1221 | assert(!is_decay(z)); | |
dca45c9f MD |
1222 | oy_right = y->_right; |
1223 | ||
1224 | /* | |
3366b9c0 | 1225 | * The max child begin of z_right does not change, because |
dca45c9f MD |
1226 | * we're only changing its left children. |
1227 | */ | |
1228 | y->_right = z_right; | |
1229 | set_parent(y->_right, y, IS_RIGHT); | |
dca45c9f MD |
1230 | assert(!is_decay(z->_left)); |
1231 | y->_left = z->_left; | |
230dd288 | 1232 | assert(!is_decay(oy_right)); |
dca45c9f MD |
1233 | /* |
1234 | * Transplant of oy_right to old y's location will only | |
fcb4eea8 | 1235 | * trigger a "end" value update of the already copied branch |
dca45c9f MD |
1236 | * (which is not visible yet). We are transplanting |
1237 | * oy_right as a left child of old y's parent, so the | |
1238 | * min values update propagated upward necessarily stops | |
1239 | * at z_right. | |
1240 | */ | |
fcb4eea8 | 1241 | rcu_rbtree_transplant(rbtree, y, oy_right, 0, y); |
66b64c35 | 1242 | y->max_end = calculate_node_max_end(rbtree, y); |
fcb4eea8 | 1243 | rcu_rbtree_transplant(rbtree, z, y, 1, NULL); |
230dd288 | 1244 | /* Update children */ |
dca45c9f | 1245 | (void) rcu_rbtree_min_update_decay(rbtree, y->_right); |
dff86257 | 1246 | } |
c479601c | 1247 | y = get_decay(y); |
269a9ef6 | 1248 | assert(!is_decay(z)); |
dca45c9f | 1249 | assert(!is_decay(z->_left)); |
dff86257 | 1250 | y->color = z->color; |
dca45c9f MD |
1251 | set_parent(y->_left, y, IS_LEFT); |
1252 | set_parent(y->_right, get_decay(get_parent(y->_right)), IS_RIGHT); | |
1253 | assert(!is_decay(y->_left)); | |
1254 | assert(!is_decay(y->_right)); | |
dff86257 MD |
1255 | } |
1256 | ||
1257 | int rcu_rbtree_remove(struct rcu_rbtree *rbtree, | |
1258 | struct rcu_rbtree_node *z) | |
1259 | { | |
1260 | struct rcu_rbtree_node *x, *y; | |
1261 | unsigned int y_original_color; | |
1262 | ||
269a9ef6 | 1263 | assert(!is_decay(rbtree->root)); |
3366b9c0 | 1264 | dbg_printf("remove %p\n", z->begin); |
dff86257 MD |
1265 | show_tree(rbtree); |
1266 | ||
c479601c | 1267 | assert(!is_decay(z)); |
dff86257 MD |
1268 | y = z; |
1269 | y_original_color = y->color; | |
1270 | ||
8ded5fe9 | 1271 | if (rcu_rbtree_is_nil(rbtree, z->_left)) { |
fcb4eea8 | 1272 | rcu_rbtree_transplant(rbtree, z, z->_right, 1, NULL); |
269a9ef6 | 1273 | assert(!is_decay(z)); |
dca45c9f | 1274 | x = get_decay(z->_right); |
dff86257 | 1275 | show_tree(rbtree); |
8ded5fe9 | 1276 | } else if (rcu_rbtree_is_nil(rbtree, z->_right)) { |
fcb4eea8 | 1277 | rcu_rbtree_transplant(rbtree, z, z->_left, 1, NULL); |
269a9ef6 | 1278 | assert(!is_decay(z)); |
dca45c9f | 1279 | x = get_decay(z->_left); |
dff86257 MD |
1280 | show_tree(rbtree); |
1281 | } else { | |
dca45c9f | 1282 | y = rcu_rbtree_min(rbtree, z->_right); |
c479601c | 1283 | assert(!is_decay(y)); |
dff86257 | 1284 | y_original_color = y->color; |
dca45c9f | 1285 | x = y->_right; |
269a9ef6 | 1286 | rcu_rbtree_remove_nonil(rbtree, z, y); |
6daf6090 | 1287 | x = get_decay(x); |
dff86257 MD |
1288 | show_tree(rbtree); |
1289 | } | |
1290 | if (y_original_color == COLOR_BLACK) | |
1291 | rcu_rbtree_remove_fixup(rbtree, x); | |
1292 | show_tree(rbtree); | |
66b64c35 MD |
1293 | check_max_end(rbtree, x); |
1294 | check_max_end(rbtree, get_decay(y)); | |
dff86257 MD |
1295 | /* |
1296 | * Commit all _CMM_STORE_SHARED(). | |
1297 | */ | |
1298 | cmm_smp_wmc(); | |
c2ceb27c | 1299 | #ifdef RBTREE_RCU_SUPPORT |
1cdd423d | 1300 | rbtree->call_rcu(&z->head, _rcu_rbtree_free_node); |
c2ceb27c MD |
1301 | #else |
1302 | _rcu_rbtree_free_node(&z->head); | |
1303 | #endif | |
dff86257 MD |
1304 | |
1305 | return 0; | |
1306 | } |