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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | Red Black Trees | |
3 | (C) 1999 Andrea Arcangeli <andrea@suse.de> | |
4 | (C) 2002 David Woodhouse <dwmw2@infradead.org> | |
5 | ||
6 | This program is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 2 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | This program is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with this program; if not, write to the Free Software | |
18 | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
19 | ||
20 | linux/lib/rbtree.c | |
21 | */ | |
22 | ||
23 | #include <linux/rbtree.h> | |
8bc3bcc9 | 24 | #include <linux/export.h> |
1da177e4 | 25 | |
5bc9188a ML |
26 | /* |
27 | * red-black trees properties: http://en.wikipedia.org/wiki/Rbtree | |
28 | * | |
29 | * 1) A node is either red or black | |
30 | * 2) The root is black | |
31 | * 3) All leaves (NULL) are black | |
32 | * 4) Both children of every red node are black | |
33 | * 5) Every simple path from root to leaves contains the same number | |
34 | * of black nodes. | |
35 | * | |
36 | * 4 and 5 give the O(log n) guarantee, since 4 implies you cannot have two | |
37 | * consecutive red nodes in a path and every red node is therefore followed by | |
38 | * a black. So if B is the number of black nodes on every simple path (as per | |
39 | * 5), then the longest possible path due to 4 is 2B. | |
40 | * | |
41 | * We shall indicate color with case, where black nodes are uppercase and red | |
6280d235 ML |
42 | * nodes will be lowercase. Unknown color nodes shall be drawn as red within |
43 | * parentheses and have some accompanying text comment. | |
5bc9188a ML |
44 | */ |
45 | ||
bf7ad8ee ML |
46 | #define RB_RED 0 |
47 | #define RB_BLACK 1 | |
48 | ||
49 | #define rb_color(r) ((r)->__rb_parent_color & 1) | |
50 | #define rb_is_red(r) (!rb_color(r)) | |
51 | #define rb_is_black(r) rb_color(r) | |
bf7ad8ee ML |
52 | |
53 | static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p) | |
54 | { | |
55 | rb->__rb_parent_color = rb_color(rb) | (unsigned long)p; | |
56 | } | |
bf7ad8ee | 57 | |
5bc9188a ML |
58 | static inline void rb_set_parent_color(struct rb_node *rb, |
59 | struct rb_node *p, int color) | |
60 | { | |
61 | rb->__rb_parent_color = (unsigned long)p | color; | |
62 | } | |
63 | ||
64 | static inline struct rb_node *rb_red_parent(struct rb_node *red) | |
65 | { | |
66 | return (struct rb_node *)red->__rb_parent_color; | |
67 | } | |
68 | ||
5bc9188a ML |
69 | /* |
70 | * Helper function for rotations: | |
71 | * - old's parent and color get assigned to new | |
72 | * - old gets assigned new as a parent and 'color' as a color. | |
73 | */ | |
74 | static inline void | |
75 | __rb_rotate_set_parents(struct rb_node *old, struct rb_node *new, | |
76 | struct rb_root *root, int color) | |
77 | { | |
78 | struct rb_node *parent = rb_parent(old); | |
79 | new->__rb_parent_color = old->__rb_parent_color; | |
80 | rb_set_parent_color(old, new, color); | |
81 | if (parent) { | |
82 | if (parent->rb_left == old) | |
83 | parent->rb_left = new; | |
84 | else | |
85 | parent->rb_right = new; | |
86 | } else | |
87 | root->rb_node = new; | |
88 | } | |
89 | ||
1da177e4 LT |
90 | void rb_insert_color(struct rb_node *node, struct rb_root *root) |
91 | { | |
5bc9188a | 92 | struct rb_node *parent = rb_red_parent(node), *gparent, *tmp; |
1da177e4 | 93 | |
6d58452d ML |
94 | while (true) { |
95 | /* | |
96 | * Loop invariant: node is red | |
97 | * | |
98 | * If there is a black parent, we are done. | |
99 | * Otherwise, take some corrective action as we don't | |
100 | * want a red root or two consecutive red nodes. | |
101 | */ | |
6d58452d | 102 | if (!parent) { |
5bc9188a | 103 | rb_set_parent_color(node, NULL, RB_BLACK); |
6d58452d ML |
104 | break; |
105 | } else if (rb_is_black(parent)) | |
106 | break; | |
107 | ||
5bc9188a ML |
108 | gparent = rb_red_parent(parent); |
109 | ||
110 | if (parent == gparent->rb_left) { | |
111 | tmp = gparent->rb_right; | |
112 | if (tmp && rb_is_red(tmp)) { | |
113 | /* | |
114 | * Case 1 - color flips | |
115 | * | |
116 | * G g | |
117 | * / \ / \ | |
118 | * p u --> P U | |
119 | * / / | |
120 | * n N | |
121 | * | |
122 | * However, since g's parent might be red, and | |
123 | * 4) does not allow this, we need to recurse | |
124 | * at g. | |
125 | */ | |
126 | rb_set_parent_color(tmp, gparent, RB_BLACK); | |
127 | rb_set_parent_color(parent, gparent, RB_BLACK); | |
128 | node = gparent; | |
129 | parent = rb_parent(node); | |
130 | rb_set_parent_color(node, parent, RB_RED); | |
131 | continue; | |
1da177e4 LT |
132 | } |
133 | ||
1f052865 | 134 | if (parent->rb_right == node) { |
5bc9188a ML |
135 | /* |
136 | * Case 2 - left rotate at parent | |
137 | * | |
138 | * G G | |
139 | * / \ / \ | |
140 | * p U --> n U | |
141 | * \ / | |
142 | * n p | |
143 | * | |
144 | * This still leaves us in violation of 4), the | |
145 | * continuation into Case 3 will fix that. | |
146 | */ | |
147 | parent->rb_right = tmp = node->rb_left; | |
148 | node->rb_left = parent; | |
149 | if (tmp) | |
150 | rb_set_parent_color(tmp, parent, | |
151 | RB_BLACK); | |
152 | rb_set_parent_color(parent, node, RB_RED); | |
1da177e4 | 153 | parent = node; |
1da177e4 LT |
154 | } |
155 | ||
5bc9188a ML |
156 | /* |
157 | * Case 3 - right rotate at gparent | |
158 | * | |
159 | * G P | |
160 | * / \ / \ | |
161 | * p U --> n g | |
162 | * / \ | |
163 | * n U | |
164 | */ | |
165 | gparent->rb_left = tmp = parent->rb_right; | |
166 | parent->rb_right = gparent; | |
167 | if (tmp) | |
168 | rb_set_parent_color(tmp, gparent, RB_BLACK); | |
169 | __rb_rotate_set_parents(gparent, parent, root, RB_RED); | |
1f052865 | 170 | break; |
1da177e4 | 171 | } else { |
5bc9188a ML |
172 | tmp = gparent->rb_left; |
173 | if (tmp && rb_is_red(tmp)) { | |
174 | /* Case 1 - color flips */ | |
175 | rb_set_parent_color(tmp, gparent, RB_BLACK); | |
176 | rb_set_parent_color(parent, gparent, RB_BLACK); | |
177 | node = gparent; | |
178 | parent = rb_parent(node); | |
179 | rb_set_parent_color(node, parent, RB_RED); | |
180 | continue; | |
1da177e4 LT |
181 | } |
182 | ||
1f052865 | 183 | if (parent->rb_left == node) { |
5bc9188a ML |
184 | /* Case 2 - right rotate at parent */ |
185 | parent->rb_left = tmp = node->rb_right; | |
186 | node->rb_right = parent; | |
187 | if (tmp) | |
188 | rb_set_parent_color(tmp, parent, | |
189 | RB_BLACK); | |
190 | rb_set_parent_color(parent, node, RB_RED); | |
1da177e4 | 191 | parent = node; |
1da177e4 LT |
192 | } |
193 | ||
5bc9188a ML |
194 | /* Case 3 - left rotate at gparent */ |
195 | gparent->rb_right = tmp = parent->rb_left; | |
196 | parent->rb_left = gparent; | |
197 | if (tmp) | |
198 | rb_set_parent_color(tmp, gparent, RB_BLACK); | |
199 | __rb_rotate_set_parents(gparent, parent, root, RB_RED); | |
1f052865 | 200 | break; |
1da177e4 LT |
201 | } |
202 | } | |
1da177e4 LT |
203 | } |
204 | EXPORT_SYMBOL(rb_insert_color); | |
205 | ||
206 | static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, | |
207 | struct rb_root *root) | |
208 | { | |
6280d235 | 209 | struct rb_node *sibling, *tmp1, *tmp2; |
1da177e4 | 210 | |
d6ff1273 ML |
211 | while (true) { |
212 | /* | |
213 | * Loop invariant: all leaf paths going through node have a | |
214 | * black node count that is 1 lower than other leaf paths. | |
215 | * | |
216 | * If node is red, we can flip it to black to adjust. | |
217 | * If node is the root, all leaf paths go through it. | |
218 | * Otherwise, we need to adjust the tree through color flips | |
219 | * and tree rotations as per one of the 4 cases below. | |
220 | */ | |
221 | if (node && rb_is_red(node)) { | |
6280d235 | 222 | rb_set_parent_color(node, parent, RB_BLACK); |
d6ff1273 ML |
223 | break; |
224 | } else if (!parent) { | |
225 | break; | |
226 | } else if (parent->rb_left == node) { | |
6280d235 ML |
227 | sibling = parent->rb_right; |
228 | if (rb_is_red(sibling)) { | |
229 | /* | |
230 | * Case 1 - left rotate at parent | |
231 | * | |
232 | * P S | |
233 | * / \ / \ | |
234 | * N s --> p Sr | |
235 | * / \ / \ | |
236 | * Sl Sr N Sl | |
237 | */ | |
238 | parent->rb_right = tmp1 = sibling->rb_left; | |
239 | sibling->rb_left = parent; | |
240 | rb_set_parent_color(tmp1, parent, RB_BLACK); | |
241 | __rb_rotate_set_parents(parent, sibling, root, | |
242 | RB_RED); | |
243 | sibling = tmp1; | |
1da177e4 | 244 | } |
6280d235 ML |
245 | tmp1 = sibling->rb_right; |
246 | if (!tmp1 || rb_is_black(tmp1)) { | |
247 | tmp2 = sibling->rb_left; | |
248 | if (!tmp2 || rb_is_black(tmp2)) { | |
249 | /* | |
250 | * Case 2 - sibling color flip | |
251 | * (p could be either color here) | |
252 | * | |
253 | * (p) (p) | |
254 | * / \ / \ | |
255 | * N S --> N s | |
256 | * / \ / \ | |
257 | * Sl Sr Sl Sr | |
258 | * | |
259 | * This leaves us violating 5), so | |
260 | * recurse at p. If p is red, the | |
261 | * recursion will just flip it to black | |
262 | * and exit. If coming from Case 1, | |
263 | * p is known to be red. | |
264 | */ | |
265 | rb_set_parent_color(sibling, parent, | |
266 | RB_RED); | |
e125d147 ML |
267 | node = parent; |
268 | parent = rb_parent(node); | |
269 | continue; | |
1da177e4 | 270 | } |
6280d235 ML |
271 | /* |
272 | * Case 3 - right rotate at sibling | |
273 | * (p could be either color here) | |
274 | * | |
275 | * (p) (p) | |
276 | * / \ / \ | |
277 | * N S --> N Sl | |
278 | * / \ \ | |
279 | * sl Sr s | |
280 | * \ | |
281 | * Sr | |
282 | */ | |
283 | sibling->rb_left = tmp1 = tmp2->rb_right; | |
284 | tmp2->rb_right = sibling; | |
285 | parent->rb_right = tmp2; | |
286 | if (tmp1) | |
287 | rb_set_parent_color(tmp1, sibling, | |
288 | RB_BLACK); | |
289 | tmp1 = sibling; | |
290 | sibling = tmp2; | |
1da177e4 | 291 | } |
6280d235 ML |
292 | /* |
293 | * Case 4 - left rotate at parent + color flips | |
294 | * (p and sl could be either color here. | |
295 | * After rotation, p becomes black, s acquires | |
296 | * p's color, and sl keeps its color) | |
297 | * | |
298 | * (p) (s) | |
299 | * / \ / \ | |
300 | * N S --> P Sr | |
301 | * / \ / \ | |
302 | * (sl) sr N (sl) | |
303 | */ | |
304 | parent->rb_right = tmp2 = sibling->rb_left; | |
305 | sibling->rb_left = parent; | |
306 | rb_set_parent_color(tmp1, sibling, RB_BLACK); | |
307 | if (tmp2) | |
308 | rb_set_parent(tmp2, parent); | |
309 | __rb_rotate_set_parents(parent, sibling, root, | |
310 | RB_BLACK); | |
e125d147 | 311 | break; |
d6ff1273 | 312 | } else { |
6280d235 ML |
313 | sibling = parent->rb_left; |
314 | if (rb_is_red(sibling)) { | |
315 | /* Case 1 - right rotate at parent */ | |
316 | parent->rb_left = tmp1 = sibling->rb_right; | |
317 | sibling->rb_right = parent; | |
318 | rb_set_parent_color(tmp1, parent, RB_BLACK); | |
319 | __rb_rotate_set_parents(parent, sibling, root, | |
320 | RB_RED); | |
321 | sibling = tmp1; | |
1da177e4 | 322 | } |
6280d235 ML |
323 | tmp1 = sibling->rb_left; |
324 | if (!tmp1 || rb_is_black(tmp1)) { | |
325 | tmp2 = sibling->rb_right; | |
326 | if (!tmp2 || rb_is_black(tmp2)) { | |
327 | /* Case 2 - sibling color flip */ | |
328 | rb_set_parent_color(sibling, parent, | |
329 | RB_RED); | |
e125d147 ML |
330 | node = parent; |
331 | parent = rb_parent(node); | |
332 | continue; | |
1da177e4 | 333 | } |
6280d235 ML |
334 | /* Case 3 - right rotate at sibling */ |
335 | sibling->rb_right = tmp1 = tmp2->rb_left; | |
336 | tmp2->rb_left = sibling; | |
337 | parent->rb_left = tmp2; | |
338 | if (tmp1) | |
339 | rb_set_parent_color(tmp1, sibling, | |
340 | RB_BLACK); | |
341 | tmp1 = sibling; | |
342 | sibling = tmp2; | |
1da177e4 | 343 | } |
6280d235 ML |
344 | /* Case 4 - left rotate at parent + color flips */ |
345 | parent->rb_left = tmp2 = sibling->rb_right; | |
346 | sibling->rb_right = parent; | |
347 | rb_set_parent_color(tmp1, sibling, RB_BLACK); | |
348 | if (tmp2) | |
349 | rb_set_parent(tmp2, parent); | |
350 | __rb_rotate_set_parents(parent, sibling, root, | |
351 | RB_BLACK); | |
e125d147 | 352 | break; |
1da177e4 LT |
353 | } |
354 | } | |
1da177e4 LT |
355 | } |
356 | ||
357 | void rb_erase(struct rb_node *node, struct rb_root *root) | |
358 | { | |
359 | struct rb_node *child, *parent; | |
360 | int color; | |
361 | ||
362 | if (!node->rb_left) | |
363 | child = node->rb_right; | |
364 | else if (!node->rb_right) | |
365 | child = node->rb_left; | |
7ce6ff9e | 366 | else { |
1da177e4 LT |
367 | struct rb_node *old = node, *left; |
368 | ||
369 | node = node->rb_right; | |
370 | while ((left = node->rb_left) != NULL) | |
371 | node = left; | |
16c047ad WS |
372 | |
373 | if (rb_parent(old)) { | |
374 | if (rb_parent(old)->rb_left == old) | |
375 | rb_parent(old)->rb_left = node; | |
376 | else | |
377 | rb_parent(old)->rb_right = node; | |
378 | } else | |
379 | root->rb_node = node; | |
380 | ||
1da177e4 | 381 | child = node->rb_right; |
55a98102 | 382 | parent = rb_parent(node); |
2f3243ae | 383 | color = rb_color(node); |
1da177e4 | 384 | |
55a98102 | 385 | if (parent == old) { |
1da177e4 | 386 | parent = node; |
4c601178 WS |
387 | } else { |
388 | if (child) | |
389 | rb_set_parent(child, parent); | |
1975e593 | 390 | parent->rb_left = child; |
4b324126 WS |
391 | |
392 | node->rb_right = old->rb_right; | |
393 | rb_set_parent(old->rb_right, node); | |
4c601178 | 394 | } |
1975e593 | 395 | |
bf7ad8ee | 396 | node->__rb_parent_color = old->__rb_parent_color; |
1da177e4 | 397 | node->rb_left = old->rb_left; |
55a98102 | 398 | rb_set_parent(old->rb_left, node); |
4b324126 | 399 | |
1da177e4 LT |
400 | goto color; |
401 | } | |
402 | ||
55a98102 | 403 | parent = rb_parent(node); |
2f3243ae | 404 | color = rb_color(node); |
1da177e4 LT |
405 | |
406 | if (child) | |
55a98102 | 407 | rb_set_parent(child, parent); |
7ce6ff9e | 408 | if (parent) { |
1da177e4 LT |
409 | if (parent->rb_left == node) |
410 | parent->rb_left = child; | |
411 | else | |
412 | parent->rb_right = child; | |
7ce6ff9e | 413 | } else |
b945d6b2 | 414 | root->rb_node = child; |
1da177e4 | 415 | |
7ce6ff9e | 416 | color: |
1da177e4 LT |
417 | if (color == RB_BLACK) |
418 | __rb_erase_color(child, parent, root); | |
419 | } | |
420 | EXPORT_SYMBOL(rb_erase); | |
421 | ||
b945d6b2 PZ |
422 | static void rb_augment_path(struct rb_node *node, rb_augment_f func, void *data) |
423 | { | |
424 | struct rb_node *parent; | |
425 | ||
426 | up: | |
427 | func(node, data); | |
428 | parent = rb_parent(node); | |
429 | if (!parent) | |
430 | return; | |
431 | ||
432 | if (node == parent->rb_left && parent->rb_right) | |
433 | func(parent->rb_right, data); | |
434 | else if (parent->rb_left) | |
435 | func(parent->rb_left, data); | |
436 | ||
437 | node = parent; | |
438 | goto up; | |
439 | } | |
440 | ||
441 | /* | |
442 | * after inserting @node into the tree, update the tree to account for | |
443 | * both the new entry and any damage done by rebalance | |
444 | */ | |
445 | void rb_augment_insert(struct rb_node *node, rb_augment_f func, void *data) | |
446 | { | |
447 | if (node->rb_left) | |
448 | node = node->rb_left; | |
449 | else if (node->rb_right) | |
450 | node = node->rb_right; | |
451 | ||
452 | rb_augment_path(node, func, data); | |
453 | } | |
0b6bb66d | 454 | EXPORT_SYMBOL(rb_augment_insert); |
b945d6b2 PZ |
455 | |
456 | /* | |
457 | * before removing the node, find the deepest node on the rebalance path | |
458 | * that will still be there after @node gets removed | |
459 | */ | |
460 | struct rb_node *rb_augment_erase_begin(struct rb_node *node) | |
461 | { | |
462 | struct rb_node *deepest; | |
463 | ||
464 | if (!node->rb_right && !node->rb_left) | |
465 | deepest = rb_parent(node); | |
466 | else if (!node->rb_right) | |
467 | deepest = node->rb_left; | |
468 | else if (!node->rb_left) | |
469 | deepest = node->rb_right; | |
470 | else { | |
471 | deepest = rb_next(node); | |
472 | if (deepest->rb_right) | |
473 | deepest = deepest->rb_right; | |
474 | else if (rb_parent(deepest) != node) | |
475 | deepest = rb_parent(deepest); | |
476 | } | |
477 | ||
478 | return deepest; | |
479 | } | |
0b6bb66d | 480 | EXPORT_SYMBOL(rb_augment_erase_begin); |
b945d6b2 PZ |
481 | |
482 | /* | |
483 | * after removal, update the tree to account for the removed entry | |
484 | * and any rebalance damage. | |
485 | */ | |
486 | void rb_augment_erase_end(struct rb_node *node, rb_augment_f func, void *data) | |
487 | { | |
488 | if (node) | |
489 | rb_augment_path(node, func, data); | |
490 | } | |
0b6bb66d | 491 | EXPORT_SYMBOL(rb_augment_erase_end); |
b945d6b2 | 492 | |
1da177e4 LT |
493 | /* |
494 | * This function returns the first node (in sort order) of the tree. | |
495 | */ | |
f4b477c4 | 496 | struct rb_node *rb_first(const struct rb_root *root) |
1da177e4 LT |
497 | { |
498 | struct rb_node *n; | |
499 | ||
500 | n = root->rb_node; | |
501 | if (!n) | |
502 | return NULL; | |
503 | while (n->rb_left) | |
504 | n = n->rb_left; | |
505 | return n; | |
506 | } | |
507 | EXPORT_SYMBOL(rb_first); | |
508 | ||
f4b477c4 | 509 | struct rb_node *rb_last(const struct rb_root *root) |
1da177e4 LT |
510 | { |
511 | struct rb_node *n; | |
512 | ||
513 | n = root->rb_node; | |
514 | if (!n) | |
515 | return NULL; | |
516 | while (n->rb_right) | |
517 | n = n->rb_right; | |
518 | return n; | |
519 | } | |
520 | EXPORT_SYMBOL(rb_last); | |
521 | ||
f4b477c4 | 522 | struct rb_node *rb_next(const struct rb_node *node) |
1da177e4 | 523 | { |
55a98102 DW |
524 | struct rb_node *parent; |
525 | ||
4c199a93 | 526 | if (RB_EMPTY_NODE(node)) |
10fd48f2 JA |
527 | return NULL; |
528 | ||
7ce6ff9e ML |
529 | /* |
530 | * If we have a right-hand child, go down and then left as far | |
531 | * as we can. | |
532 | */ | |
1da177e4 LT |
533 | if (node->rb_right) { |
534 | node = node->rb_right; | |
535 | while (node->rb_left) | |
536 | node=node->rb_left; | |
f4b477c4 | 537 | return (struct rb_node *)node; |
1da177e4 LT |
538 | } |
539 | ||
7ce6ff9e ML |
540 | /* |
541 | * No right-hand children. Everything down and left is smaller than us, | |
542 | * so any 'next' node must be in the general direction of our parent. | |
543 | * Go up the tree; any time the ancestor is a right-hand child of its | |
544 | * parent, keep going up. First time it's a left-hand child of its | |
545 | * parent, said parent is our 'next' node. | |
546 | */ | |
55a98102 DW |
547 | while ((parent = rb_parent(node)) && node == parent->rb_right) |
548 | node = parent; | |
1da177e4 | 549 | |
55a98102 | 550 | return parent; |
1da177e4 LT |
551 | } |
552 | EXPORT_SYMBOL(rb_next); | |
553 | ||
f4b477c4 | 554 | struct rb_node *rb_prev(const struct rb_node *node) |
1da177e4 | 555 | { |
55a98102 DW |
556 | struct rb_node *parent; |
557 | ||
4c199a93 | 558 | if (RB_EMPTY_NODE(node)) |
10fd48f2 JA |
559 | return NULL; |
560 | ||
7ce6ff9e ML |
561 | /* |
562 | * If we have a left-hand child, go down and then right as far | |
563 | * as we can. | |
564 | */ | |
1da177e4 LT |
565 | if (node->rb_left) { |
566 | node = node->rb_left; | |
567 | while (node->rb_right) | |
568 | node=node->rb_right; | |
f4b477c4 | 569 | return (struct rb_node *)node; |
1da177e4 LT |
570 | } |
571 | ||
7ce6ff9e ML |
572 | /* |
573 | * No left-hand children. Go up till we find an ancestor which | |
574 | * is a right-hand child of its parent. | |
575 | */ | |
55a98102 DW |
576 | while ((parent = rb_parent(node)) && node == parent->rb_left) |
577 | node = parent; | |
1da177e4 | 578 | |
55a98102 | 579 | return parent; |
1da177e4 LT |
580 | } |
581 | EXPORT_SYMBOL(rb_prev); | |
582 | ||
583 | void rb_replace_node(struct rb_node *victim, struct rb_node *new, | |
584 | struct rb_root *root) | |
585 | { | |
55a98102 | 586 | struct rb_node *parent = rb_parent(victim); |
1da177e4 LT |
587 | |
588 | /* Set the surrounding nodes to point to the replacement */ | |
589 | if (parent) { | |
590 | if (victim == parent->rb_left) | |
591 | parent->rb_left = new; | |
592 | else | |
593 | parent->rb_right = new; | |
594 | } else { | |
595 | root->rb_node = new; | |
596 | } | |
597 | if (victim->rb_left) | |
55a98102 | 598 | rb_set_parent(victim->rb_left, new); |
1da177e4 | 599 | if (victim->rb_right) |
55a98102 | 600 | rb_set_parent(victim->rb_right, new); |
1da177e4 LT |
601 | |
602 | /* Copy the pointers/colour from the victim to the replacement */ | |
603 | *new = *victim; | |
604 | } | |
605 | EXPORT_SYMBOL(rb_replace_node); |