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00131368 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 | ||
36 | #include <urcu-rbtree.h> | |
37 | #include <urcu-pointer.h> | |
38 | ||
39 | /* | |
40 | * TODO | |
41 | * Deal with memory allocation errors. | |
42 | * Can be ensured by reserving a pool of memory entries before doing the | |
43 | * insertion, which will have to be function of number of | |
44 | * transplantations/rotations required for the operation. | |
45 | */ | |
46 | ||
47 | /* Sentinel (bottom nodes). Don't care about p, left, right and key values */ | |
db5b1669 | 48 | struct rcu_rbtree_node rcu_rbtree_nil = { |
00131368 MD |
49 | .color = COLOR_BLACK, |
50 | }; | |
51 | ||
52 | /* | |
53 | * Iterative rbtree search. | |
54 | */ | |
55 | struct rcu_rbtree_node* rcu_rbtree_search(struct rcu_rbtree_node *x, | |
56 | void *k, rcu_rbtree_comp comp) | |
57 | { | |
58 | x = rcu_dereference(x); | |
59 | ||
a23deda7 | 60 | while (x != &rcu_rbtree_nil && k != x->key) { |
00131368 MD |
61 | if (k < x->key) |
62 | x = rcu_dereference(x->left); | |
63 | else | |
64 | x = rcu_dereference(x->right); | |
65 | } | |
66 | return x; | |
67 | } | |
68 | ||
69 | struct rcu_rbtree_node *rcu_rbtree_min(struct rcu_rbtree_node *x, | |
70 | rcu_rbtree_comp comp) | |
71 | { | |
72 | struct rcu_rbtree_node *xl; | |
73 | ||
74 | x = rcu_dereference(x); | |
75 | ||
a23deda7 | 76 | while ((xl = rcu_dereference(x->left)) != &rcu_rbtree_nil) |
00131368 MD |
77 | x = xl; |
78 | return x; | |
79 | } | |
80 | ||
81 | struct rcu_rbtree_node *rcu_rbtree_max(struct rcu_rbtree_node *x, | |
82 | rcu_rbtree_comp comp) | |
83 | { | |
84 | struct rcu_rbtree_node *xr; | |
85 | ||
86 | x = rcu_dereference(x); | |
87 | ||
a23deda7 | 88 | while ((xr = rcu_dereference(x->right)) != &rcu_rbtree_nil) |
00131368 MD |
89 | x = xr; |
90 | return x; | |
91 | } | |
92 | ||
93 | /* | |
94 | * next and prev need to have mutex held to ensure that parent pointer is | |
95 | * coherent. | |
96 | */ | |
97 | struct rcu_rbtree_node *rcu_rbtree_next(struct rcu_rbtree_node *x, | |
98 | rcu_rbtree_comp comp) | |
99 | { | |
100 | struct rcu_rbtree_node *xr, *y; | |
101 | ||
102 | x = rcu_dereference(x); | |
103 | ||
a23deda7 | 104 | if ((xr = rcu_dereference(x->right)) != &rcu_rbtree_nil) |
00131368 MD |
105 | return rcu_rbtree_min(xr, comp); |
106 | y = rcu_dereference(x->p); | |
a23deda7 | 107 | while (y != &rcu_rbtree_nil && x == rcu_dereference(y->right)) { |
00131368 MD |
108 | x = y; |
109 | y = rcu_dereference(y->p); | |
110 | } | |
111 | return y; | |
112 | } | |
113 | ||
114 | struct rcu_rbtree_node *rcu_rbtree_prev(struct rcu_rbtree_node *x, | |
115 | rcu_rbtree_comp comp) | |
116 | { | |
117 | struct rcu_rbtree_node *xl, *y; | |
118 | ||
119 | x = rcu_dereference(x); | |
120 | ||
a23deda7 | 121 | if ((xl = rcu_dereference(x->left)) != &rcu_rbtree_nil) |
00131368 MD |
122 | return rcu_rbtree_max(xl, comp); |
123 | y = rcu_dereference(x->p); | |
a23deda7 | 124 | while (y != &rcu_rbtree_nil && x == rcu_dereference(y->left)) { |
00131368 MD |
125 | x = y; |
126 | y = rcu_dereference(y->p); | |
127 | } | |
128 | return y; | |
129 | } | |
130 | ||
131 | /* | |
132 | * We have to ensure these assumptions are correct for prev/next | |
133 | * traversal: | |
134 | * | |
135 | * with x being a right child, the assumption that: | |
136 | * x->p->right == x | |
137 | * or if x is a left child, the assumption that: | |
138 | * x->p->left == x | |
139 | * | |
140 | * This explains why we have to allocate a vc copy of the node for left_rotate, | |
141 | * right_rotate and transplant operations. | |
142 | * | |
143 | * We always ensure that the right/left child and correct parent is set in the | |
144 | * node copies *before* we reparent the children and make the upper-level point | |
145 | * to the copy. | |
146 | */ | |
147 | ||
148 | /* RCU: copy x and y, atomically point to new versions. GC old. */ | |
149 | /* Should be eventually followed by a smp_wmc() */ | |
150 | /* Returns the new x. Previous x->right references are changed to yc. */ | |
151 | static struct rcu_rbtree_node *left_rotate(struct rcu_rbtree_node **root, | |
152 | struct rcu_rbtree_node *x, | |
153 | rcu_rbtree_alloc rballoc, | |
154 | rcu_rbtree_free rbfree) | |
155 | { | |
156 | struct rcu_rbtree_node *xc, *y, *yc; | |
157 | ||
158 | y = x->right; | |
159 | ||
21cddea3 MD |
160 | if (x != &rcu_rbtree_nil) { |
161 | xc = rballoc(); | |
162 | *xc = *x; | |
a23deda7 MD |
163 | } |
164 | ||
165 | if (y != &rcu_rbtree_nil) { | |
166 | yc = rballoc(); | |
167 | *yc = *y; | |
168 | } | |
169 | ||
170 | /* Modify children and parents in the node copies */ | |
171 | if (x != &rcu_rbtree_nil) { | |
21cddea3 MD |
172 | xc->right = y->left; |
173 | xc->p = yc; | |
174 | } else | |
175 | xc = &rcu_rbtree_nil; | |
176 | ||
177 | if (y != &rcu_rbtree_nil) { | |
21cddea3 MD |
178 | yc->left = xc; |
179 | yc->p = x->p; | |
180 | } else | |
181 | yc = &rcu_rbtree_nil; | |
00131368 MD |
182 | |
183 | /* | |
184 | * Order stores to node copies (children/parents) before stores that | |
185 | * will make the copies visible to the rest of the tree. | |
186 | */ | |
187 | smp_wmb(); | |
188 | ||
189 | /* Make parents point to the copies */ | |
db5b1669 | 190 | if (x->p == &rcu_rbtree_nil) |
00131368 MD |
191 | _STORE_SHARED(*root, yc); |
192 | else if (x == x->p->left) | |
193 | _STORE_SHARED(x->p->left, yc); | |
194 | else | |
195 | _STORE_SHARED(x->p->right, yc); | |
196 | ||
197 | /* Assign children parents to copies */ | |
21cddea3 MD |
198 | if (x != &rcu_rbtree_nil) { |
199 | _STORE_SHARED(xc->right->p, xc); | |
200 | _STORE_SHARED(xc->left->p, xc); | |
201 | defer_rcu(rbfree, x); | |
202 | } | |
203 | if (y != &rcu_rbtree_nil) { | |
204 | _STORE_SHARED(yc->right->p, yc); | |
205 | defer_rcu(rbfree, y); | |
206 | /* yc->left is xc, its parent is already set in node copy */ | |
207 | } | |
00131368 MD |
208 | return xc; |
209 | } | |
210 | ||
211 | #if 0 /* orig */ | |
212 | static void left_rotate(struct rcu_rbtree_node **root, | |
213 | struct rcu_rbtree_node *x, | |
214 | rcu_rbtree_alloc rballoc) | |
215 | { | |
216 | struct rcu_rbtree_node *y; | |
217 | ||
218 | y = x->right; | |
219 | x->right = y->left; | |
db5b1669 | 220 | if (y->left != &rcu_rbtree_nil) |
00131368 MD |
221 | y->left->p = x; |
222 | y->p = x->p; | |
db5b1669 | 223 | if (x->p == &rcu_rbtree_nil) |
00131368 MD |
224 | *root = y; |
225 | else if (x == x->p->left) | |
226 | x->p->left = y; | |
227 | else | |
228 | x->p->right = y; | |
229 | y->left = x; | |
230 | x->p = y; | |
231 | } | |
232 | #endif //0 | |
233 | ||
234 | /* RCU: copy x and y, atomically point to new versions. GC old. */ | |
235 | /* Should be eventually followed by a smp_wmc() */ | |
236 | /* Returns the new x. Previous x->left references are changed to yc. */ | |
237 | static struct rcu_rbtree_node *right_rotate(struct rcu_rbtree_node **root, | |
238 | struct rcu_rbtree_node *x, | |
239 | rcu_rbtree_alloc rballoc, | |
240 | rcu_rbtree_free rbfree) | |
241 | { | |
242 | struct rcu_rbtree_node *xc, *y, *yc; | |
243 | ||
244 | y = x->left; | |
245 | ||
21cddea3 MD |
246 | if (x != &rcu_rbtree_nil) { |
247 | xc = rballoc(); | |
248 | *xc = *x; | |
a23deda7 MD |
249 | } |
250 | ||
251 | if (y != &rcu_rbtree_nil) { | |
252 | yc = rballoc(); | |
253 | *yc = *y; | |
254 | } | |
255 | ||
256 | /* Modify children and parents in the node copies */ | |
257 | if (x != &rcu_rbtree_nil) { | |
21cddea3 MD |
258 | xc->left = y->right; |
259 | xc->p = yc; | |
260 | } else | |
261 | xc = &rcu_rbtree_nil; | |
262 | ||
263 | if (y != &rcu_rbtree_nil) { | |
21cddea3 MD |
264 | yc->right = xc; |
265 | yc->p = x->p; | |
266 | } else | |
267 | yc = &rcu_rbtree_nil; | |
00131368 MD |
268 | |
269 | /* | |
270 | * Order stores to node copies (children/parents) before stores that | |
271 | * will make the copies visible to the rest of the tree. | |
272 | */ | |
273 | smp_wmb(); | |
274 | ||
275 | /* Make parents point to the copies */ | |
db5b1669 | 276 | if (x->p == &rcu_rbtree_nil) |
00131368 MD |
277 | _STORE_SHARED(*root, yc); |
278 | else if (x == x->p->right) | |
279 | _STORE_SHARED(x->p->right, yc); | |
280 | else | |
281 | _STORE_SHARED(x->p->left, yc); | |
282 | ||
283 | /* Assign children parents to copies */ | |
21cddea3 MD |
284 | if (x != &rcu_rbtree_nil) { |
285 | _STORE_SHARED(xc->left->p, xc); | |
286 | _STORE_SHARED(xc->right->p, xc); | |
287 | defer_rcu(rbfree, x); | |
288 | } | |
289 | if (y != &rcu_rbtree_nil) { | |
290 | _STORE_SHARED(yc->left->p, yc); | |
291 | defer_rcu(rbfree, y); | |
292 | /* yc->right is xc, its parent is already set in node copy */ | |
293 | } | |
00131368 MD |
294 | return xc; |
295 | } | |
296 | ||
297 | #if 0 //orig | |
298 | static void right_rotate(struct rcu_rbtree_node **root, | |
299 | struct rcu_rbtree_node *x, | |
300 | rcu_rbtree_alloc rballoc) | |
301 | { | |
302 | struct rcu_rbtree_node *y; | |
303 | ||
304 | y = x->left; | |
305 | x->left = y->right; | |
db5b1669 | 306 | if (y->right != &rcu_rbtree_nil) |
00131368 MD |
307 | y->right->p = x; |
308 | y->p = x->p; | |
db5b1669 | 309 | if (x->p == &rcu_rbtree_nil) |
00131368 MD |
310 | *root = y; |
311 | else if (x == x->p->right) | |
312 | x->p->right = y; | |
313 | else | |
314 | x->p->left = y; | |
315 | y->right = x; | |
316 | x->p = y; | |
317 | } | |
318 | #endif //0 | |
319 | ||
320 | static void rcu_rbtree_insert_fixup(struct rcu_rbtree_node **root, | |
321 | struct rcu_rbtree_node *z, | |
322 | rcu_rbtree_alloc rballoc, | |
323 | rcu_rbtree_free rbfree) | |
324 | { | |
325 | struct rcu_rbtree_node *y; | |
326 | ||
327 | while (z->p->color == COLOR_RED) { | |
328 | if (z->p == z->p->p->left) { | |
329 | y = z->p->p->right; | |
330 | if (y->color == COLOR_RED) { | |
331 | z->p->color = COLOR_BLACK; | |
332 | y->color = COLOR_BLACK; | |
333 | z->p->p->color = COLOR_RED; | |
334 | z = z->p->p; | |
335 | } else { | |
336 | if (z == z->p->right) { | |
337 | z = z->p; | |
338 | z = left_rotate(root, z, | |
339 | rballoc, rbfree); | |
340 | } | |
341 | z->p->color = COLOR_BLACK; | |
342 | z->p->p->color = COLOR_RED; | |
a23deda7 | 343 | right_rotate(root, z->p->p, rballoc, rbfree); |
00131368 MD |
344 | } |
345 | } else { | |
346 | y = z->p->p->left; | |
347 | if (y->color == COLOR_RED) { | |
348 | z->p->color = COLOR_BLACK; | |
349 | y->color = COLOR_BLACK; | |
350 | z->p->p->color = COLOR_RED; | |
351 | z = z->p->p; | |
352 | } else { | |
353 | if (z == z->p->left) { | |
354 | z = z->p; | |
355 | z = right_rotate(root, z, | |
356 | rballoc, rbfree); | |
357 | } | |
358 | z->p->color = COLOR_BLACK; | |
359 | z->p->p->color = COLOR_RED; | |
a23deda7 | 360 | left_rotate(root, z->p->p, rballoc, rbfree); |
00131368 MD |
361 | } |
362 | } | |
363 | } | |
364 | (*root)->color = COLOR_BLACK; | |
365 | } | |
366 | ||
367 | /* | |
368 | * rcu_rbtree_insert - Insert a node in the RCU rbtree | |
369 | * | |
370 | * Returns 0 on success, or < 0 on error. | |
371 | */ | |
372 | int rcu_rbtree_insert(struct rcu_rbtree_node **root, | |
373 | struct rcu_rbtree_node *z, | |
374 | rcu_rbtree_comp comp, | |
375 | rcu_rbtree_alloc rballoc, | |
376 | rcu_rbtree_free rbfree) | |
377 | { | |
378 | struct rcu_rbtree_node *x, *y; | |
379 | ||
db5b1669 | 380 | y = &rcu_rbtree_nil; |
00131368 MD |
381 | x = *root; |
382 | ||
db5b1669 | 383 | while (x != &rcu_rbtree_nil) { |
00131368 MD |
384 | y = x; |
385 | if (comp(z->key, x->key) < 0) | |
386 | x = x->left; | |
387 | else | |
388 | x = x->right; | |
389 | } | |
390 | ||
391 | z->p = y; | |
db5b1669 MD |
392 | z->left = &rcu_rbtree_nil; |
393 | z->right = &rcu_rbtree_nil; | |
00131368 MD |
394 | z->color = COLOR_RED; |
395 | ||
396 | /* | |
397 | * Order stores to z (children/parents) before stores that will make it | |
398 | * visible to the rest of the tree. | |
399 | */ | |
400 | smp_wmb(); | |
401 | ||
db5b1669 | 402 | if (y == &rcu_rbtree_nil) |
00131368 MD |
403 | _STORE_SHARED(*root, z); |
404 | else if (comp(z->key, y->key) < 0) | |
405 | _STORE_SHARED(y->left, z); | |
406 | else | |
407 | _STORE_SHARED(y->right, z); | |
408 | rcu_rbtree_insert_fixup(root, z, rballoc, rbfree); | |
409 | /* | |
410 | * Make sure to commit all _STORE_SHARED() for non-coherent caches. | |
411 | */ | |
412 | smp_wmc(); | |
413 | ||
414 | return 0; | |
415 | } | |
416 | ||
417 | /* | |
418 | * Transplant v into u position. | |
419 | * Returns new copy of v. | |
420 | */ | |
421 | static struct rcu_rbtree_node * | |
422 | rcu_rbtree_transplant(struct rcu_rbtree_node **root, | |
423 | struct rcu_rbtree_node *u, | |
424 | struct rcu_rbtree_node *v, | |
425 | rcu_rbtree_alloc rballoc, | |
426 | rcu_rbtree_free rbfree) | |
427 | { | |
428 | struct rcu_rbtree_node *vc; | |
429 | ||
21cddea3 MD |
430 | if (v != &rcu_rbtree_nil) { |
431 | vc = rballoc(); | |
432 | *vc = *v; | |
00131368 | 433 | |
21cddea3 MD |
434 | /* Change vc parent pointer */ |
435 | vc->p = u->p; | |
00131368 | 436 | |
21cddea3 MD |
437 | /* |
438 | * Order stores to node copies (children/parents) before stores | |
439 | * that will make the copies visible to the rest of the tree. | |
440 | */ | |
441 | smp_wmb(); | |
442 | } else { | |
443 | vc = &rcu_rbtree_nil; | |
444 | } | |
00131368 MD |
445 | |
446 | /* Assign upper-level pointer to vc, replacing u. */ | |
db5b1669 | 447 | if (u->p == &rcu_rbtree_nil) |
00131368 MD |
448 | _STORE_SHARED(*root, vc); |
449 | else if (u == u->p->left) | |
450 | _STORE_SHARED(u->p->left, vc); | |
451 | else | |
452 | _STORE_SHARED(u->p->right, vc); | |
453 | ||
21cddea3 MD |
454 | if (v != &rcu_rbtree_nil) { |
455 | /* | |
456 | * The children pointers in vc are the same as v. We can | |
457 | * therefore reparent v's children to vc safely. | |
458 | */ | |
459 | _STORE_SHARED(vc->right->p, vc); | |
460 | _STORE_SHARED(vc->left->p, vc); | |
00131368 | 461 | |
21cddea3 MD |
462 | defer_rcu(rbfree, v); |
463 | } | |
00131368 MD |
464 | return vc; |
465 | } | |
466 | ||
467 | static void rcu_rbtree_remove_fixup(struct rcu_rbtree_node **root, | |
468 | struct rcu_rbtree_node *x, | |
469 | rcu_rbtree_alloc rballoc, | |
470 | rcu_rbtree_free rbfree) | |
471 | { | |
472 | while (x != *root && x->color == COLOR_BLACK) { | |
473 | if (x == x->p->left) { | |
474 | struct rcu_rbtree_node *w; | |
475 | ||
476 | w = x->p->right; | |
477 | if (w->color == COLOR_RED) { | |
478 | w->color == COLOR_BLACK; | |
479 | x->p->color = COLOR_RED; | |
480 | left_rotate(root, x->p, rballoc, rbfree); | |
481 | /* x is a left node, not copied by rotation */ | |
482 | w = x->p->right; | |
483 | } | |
484 | if (w->left->color == COLOR_BLACK | |
485 | && w->right->color == COLOR_BLACK) { | |
486 | w->color = COLOR_RED; | |
487 | x = x->p; | |
488 | } else { | |
489 | if (w->right->color == COLOR_BLACK) { | |
490 | w->left->color = COLOR_BLACK; | |
491 | w->color = COLOR_RED; | |
492 | right_rotate(root, w, rballoc, rbfree); | |
493 | w = x->p->right; | |
494 | } | |
495 | w->color = x->p->color; | |
496 | x->p->color = COLOR_BLACK; | |
497 | w->right->color = COLOR_BLACK; | |
498 | left_rotate(root, x->p, rballoc, rbfree); | |
499 | x = *root; | |
500 | } | |
501 | } else { | |
502 | struct rcu_rbtree_node *w; | |
503 | ||
504 | w = x->p->left; | |
505 | if (w->color == COLOR_RED) { | |
506 | w->color == COLOR_BLACK; | |
507 | x->p->color = COLOR_RED; | |
508 | right_rotate(root, x->p, rballoc, rbfree); | |
509 | /* x is a right node, not copied by rotation */ | |
510 | w = x->p->left; | |
511 | } | |
512 | if (w->right->color == COLOR_BLACK | |
513 | && w->left->color == COLOR_BLACK) { | |
514 | w->color = COLOR_RED; | |
515 | x = x->p; | |
516 | } else { | |
517 | if (w->left->color == COLOR_BLACK) { | |
518 | w->right->color = COLOR_BLACK; | |
519 | w->color = COLOR_RED; | |
520 | left_rotate(root, w, rballoc, rbfree); | |
521 | w = x->p->left; | |
522 | } | |
523 | w->color = x->p->color; | |
524 | x->p->color = COLOR_BLACK; | |
525 | w->left->color = COLOR_BLACK; | |
526 | right_rotate(root, x->p, rballoc, rbfree); | |
527 | x = *root; | |
528 | } | |
529 | } | |
530 | } | |
531 | x->color = COLOR_BLACK; | |
532 | } | |
533 | ||
534 | /* Returns the new copy of y->right */ | |
535 | static struct rcu_rbtree_node * | |
536 | rcu_rbtree_remove_nonil(struct rcu_rbtree_node **root, | |
537 | struct rcu_rbtree_node *z, | |
538 | struct rcu_rbtree_node *y, | |
539 | rcu_rbtree_comp comp, | |
540 | rcu_rbtree_alloc rballoc, | |
541 | rcu_rbtree_free rbfree) | |
542 | { | |
543 | struct rcu_rbtree_node *x, *xc, *yc; | |
544 | ||
545 | x = y->right; | |
546 | ||
a23deda7 MD |
547 | if (x != &rcu_rbtree_nil) { |
548 | xc = rballoc(); | |
549 | *xc = *x; | |
550 | } else | |
551 | xc = &rcu_rbtree_nil; | |
552 | ||
00131368 | 553 | yc = rballoc(); |
00131368 MD |
554 | *yc = *y; |
555 | ||
556 | /* Update parent and children pointers within copies */ | |
557 | if (y->p == z) | |
558 | xc->p = yc; | |
559 | else { | |
560 | /* Transplant y->right (xc) into y, within copy */ | |
561 | xc->p = y->p; | |
562 | /* But also change the right pointer of yc */ | |
563 | yc->right = z->right; | |
564 | } | |
565 | /* Transplant y into z, within copy */ | |
566 | yc->p = z->p; | |
567 | ||
568 | yc->left = z->left; | |
569 | yc->color = z->color; | |
570 | ||
571 | /* | |
572 | * Order stores to node copies (children/parents) before stores that | |
573 | * will make the copies visible to the rest of the tree. | |
574 | */ | |
575 | smp_wmb(); | |
576 | ||
577 | /* Update external pointers */ | |
578 | ||
579 | if (y->p != z) { | |
580 | /* Transplant y->right into y, external parent links */ | |
581 | ||
582 | /* Assign upper-level pointer to xc, replacing y. */ | |
db5b1669 | 583 | if (y->p == &rcu_rbtree_nil) |
00131368 MD |
584 | _STORE_SHARED(*root, xc); |
585 | else if (y == y->p->left) | |
586 | _STORE_SHARED(y->p->left, xc); | |
587 | else | |
588 | _STORE_SHARED(y->p->right, xc); | |
589 | } | |
590 | ||
591 | /* Transplant y into z, update external parent links */ | |
db5b1669 | 592 | if (z->p == &rcu_rbtree_nil) |
00131368 MD |
593 | _STORE_SHARED(*root, yc); |
594 | else if (z == z->p->left) | |
595 | _STORE_SHARED(z->p->left, yc); | |
596 | else | |
597 | _STORE_SHARED(z->p->right, yc); | |
598 | ||
a23deda7 MD |
599 | if (x != &rcu_rbtree_nil) { |
600 | /* Reparent xc's children to xc. */ | |
601 | _STORE_SHARED(xc->right->p, xc); | |
602 | _STORE_SHARED(xc->left->p, xc); | |
603 | defer_rcu(rbfree, x); | |
604 | } | |
605 | ||
00131368 MD |
606 | /* Reparent yc's children to yc */ |
607 | _STORE_SHARED(yc->right->p, yc); | |
608 | _STORE_SHARED(yc->left->p, yc); | |
00131368 MD |
609 | defer_rcu(rbfree, y); |
610 | ||
611 | return xc; | |
612 | } | |
613 | ||
614 | int rcu_rbtree_remove(struct rcu_rbtree_node **root, | |
615 | struct rcu_rbtree_node *z, | |
616 | rcu_rbtree_comp comp, | |
617 | rcu_rbtree_alloc rballoc, | |
618 | rcu_rbtree_free rbfree) | |
619 | { | |
620 | struct rcu_rbtree_node *x, *y; | |
621 | unsigned int y_original_color; | |
622 | ||
623 | y = z; | |
624 | y_original_color = y->color; | |
625 | ||
db5b1669 | 626 | if (z->left == &rcu_rbtree_nil) { |
00131368 | 627 | x = rcu_rbtree_transplant(root, z, z->right, rballoc, rbfree); |
db5b1669 | 628 | } else if (z->right == &rcu_rbtree_nil) { |
00131368 MD |
629 | x = rcu_rbtree_transplant(root, z, z->left, rballoc, rbfree); |
630 | } else { | |
631 | y = rcu_rbtree_min(z->right, comp); | |
632 | y_original_color = y->color; | |
633 | x = rcu_rbtree_remove_nonil(root, z, y, comp, rballoc, rbfree); | |
634 | } | |
635 | if (y_original_color == COLOR_BLACK) | |
636 | rcu_rbtree_remove_fixup(root, x, rballoc, rbfree); | |
637 | /* | |
638 | * Commit all _STORE_SHARED(). | |
639 | */ | |
640 | smp_wmc(); | |
641 | ||
642 | return 0; | |
643 | } |