Commit | Line | Data |
---|---|---|
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 | ||
7abc704a ML |
69 | static inline void |
70 | __rb_change_child(struct rb_node *old, struct rb_node *new, | |
71 | struct rb_node *parent, struct rb_root *root) | |
72 | { | |
73 | if (parent) { | |
74 | if (parent->rb_left == old) | |
75 | parent->rb_left = new; | |
76 | else | |
77 | parent->rb_right = new; | |
78 | } else | |
79 | root->rb_node = new; | |
80 | } | |
81 | ||
5bc9188a ML |
82 | /* |
83 | * Helper function for rotations: | |
84 | * - old's parent and color get assigned to new | |
85 | * - old gets assigned new as a parent and 'color' as a color. | |
86 | */ | |
87 | static inline void | |
88 | __rb_rotate_set_parents(struct rb_node *old, struct rb_node *new, | |
89 | struct rb_root *root, int color) | |
90 | { | |
91 | struct rb_node *parent = rb_parent(old); | |
92 | new->__rb_parent_color = old->__rb_parent_color; | |
93 | rb_set_parent_color(old, new, color); | |
7abc704a | 94 | __rb_change_child(old, new, parent, root); |
5bc9188a ML |
95 | } |
96 | ||
1da177e4 LT |
97 | void rb_insert_color(struct rb_node *node, struct rb_root *root) |
98 | { | |
5bc9188a | 99 | struct rb_node *parent = rb_red_parent(node), *gparent, *tmp; |
1da177e4 | 100 | |
6d58452d ML |
101 | while (true) { |
102 | /* | |
103 | * Loop invariant: node is red | |
104 | * | |
105 | * If there is a black parent, we are done. | |
106 | * Otherwise, take some corrective action as we don't | |
107 | * want a red root or two consecutive red nodes. | |
108 | */ | |
6d58452d | 109 | if (!parent) { |
5bc9188a | 110 | rb_set_parent_color(node, NULL, RB_BLACK); |
6d58452d ML |
111 | break; |
112 | } else if (rb_is_black(parent)) | |
113 | break; | |
114 | ||
5bc9188a ML |
115 | gparent = rb_red_parent(parent); |
116 | ||
59633abf ML |
117 | tmp = gparent->rb_right; |
118 | if (parent != tmp) { /* parent == gparent->rb_left */ | |
5bc9188a ML |
119 | if (tmp && rb_is_red(tmp)) { |
120 | /* | |
121 | * Case 1 - color flips | |
122 | * | |
123 | * G g | |
124 | * / \ / \ | |
125 | * p u --> P U | |
126 | * / / | |
127 | * n N | |
128 | * | |
129 | * However, since g's parent might be red, and | |
130 | * 4) does not allow this, we need to recurse | |
131 | * at g. | |
132 | */ | |
133 | rb_set_parent_color(tmp, gparent, RB_BLACK); | |
134 | rb_set_parent_color(parent, gparent, RB_BLACK); | |
135 | node = gparent; | |
136 | parent = rb_parent(node); | |
137 | rb_set_parent_color(node, parent, RB_RED); | |
138 | continue; | |
1da177e4 LT |
139 | } |
140 | ||
59633abf ML |
141 | tmp = parent->rb_right; |
142 | if (node == tmp) { | |
5bc9188a ML |
143 | /* |
144 | * Case 2 - left rotate at parent | |
145 | * | |
146 | * G G | |
147 | * / \ / \ | |
148 | * p U --> n U | |
149 | * \ / | |
150 | * n p | |
151 | * | |
152 | * This still leaves us in violation of 4), the | |
153 | * continuation into Case 3 will fix that. | |
154 | */ | |
155 | parent->rb_right = tmp = node->rb_left; | |
156 | node->rb_left = parent; | |
157 | if (tmp) | |
158 | rb_set_parent_color(tmp, parent, | |
159 | RB_BLACK); | |
160 | rb_set_parent_color(parent, node, RB_RED); | |
1da177e4 | 161 | parent = node; |
59633abf | 162 | tmp = node->rb_right; |
1da177e4 LT |
163 | } |
164 | ||
5bc9188a ML |
165 | /* |
166 | * Case 3 - right rotate at gparent | |
167 | * | |
168 | * G P | |
169 | * / \ / \ | |
170 | * p U --> n g | |
171 | * / \ | |
172 | * n U | |
173 | */ | |
59633abf | 174 | gparent->rb_left = tmp; /* == parent->rb_right */ |
5bc9188a ML |
175 | parent->rb_right = gparent; |
176 | if (tmp) | |
177 | rb_set_parent_color(tmp, gparent, RB_BLACK); | |
178 | __rb_rotate_set_parents(gparent, parent, root, RB_RED); | |
1f052865 | 179 | break; |
1da177e4 | 180 | } else { |
5bc9188a ML |
181 | tmp = gparent->rb_left; |
182 | if (tmp && rb_is_red(tmp)) { | |
183 | /* Case 1 - color flips */ | |
184 | rb_set_parent_color(tmp, gparent, RB_BLACK); | |
185 | rb_set_parent_color(parent, gparent, RB_BLACK); | |
186 | node = gparent; | |
187 | parent = rb_parent(node); | |
188 | rb_set_parent_color(node, parent, RB_RED); | |
189 | continue; | |
1da177e4 LT |
190 | } |
191 | ||
59633abf ML |
192 | tmp = parent->rb_left; |
193 | if (node == tmp) { | |
5bc9188a ML |
194 | /* Case 2 - right rotate at parent */ |
195 | parent->rb_left = tmp = node->rb_right; | |
196 | node->rb_right = parent; | |
197 | if (tmp) | |
198 | rb_set_parent_color(tmp, parent, | |
199 | RB_BLACK); | |
200 | rb_set_parent_color(parent, node, RB_RED); | |
1da177e4 | 201 | parent = node; |
59633abf | 202 | tmp = node->rb_left; |
1da177e4 LT |
203 | } |
204 | ||
5bc9188a | 205 | /* Case 3 - left rotate at gparent */ |
59633abf | 206 | gparent->rb_right = tmp; /* == parent->rb_left */ |
5bc9188a ML |
207 | parent->rb_left = gparent; |
208 | if (tmp) | |
209 | rb_set_parent_color(tmp, gparent, RB_BLACK); | |
210 | __rb_rotate_set_parents(gparent, parent, root, RB_RED); | |
1f052865 | 211 | break; |
1da177e4 LT |
212 | } |
213 | } | |
1da177e4 LT |
214 | } |
215 | EXPORT_SYMBOL(rb_insert_color); | |
216 | ||
217 | static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, | |
218 | struct rb_root *root) | |
219 | { | |
6280d235 | 220 | struct rb_node *sibling, *tmp1, *tmp2; |
1da177e4 | 221 | |
d6ff1273 ML |
222 | while (true) { |
223 | /* | |
224 | * Loop invariant: all leaf paths going through node have a | |
225 | * black node count that is 1 lower than other leaf paths. | |
226 | * | |
227 | * If node is red, we can flip it to black to adjust. | |
228 | * If node is the root, all leaf paths go through it. | |
229 | * Otherwise, we need to adjust the tree through color flips | |
230 | * and tree rotations as per one of the 4 cases below. | |
231 | */ | |
232 | if (node && rb_is_red(node)) { | |
6280d235 | 233 | rb_set_parent_color(node, parent, RB_BLACK); |
d6ff1273 ML |
234 | break; |
235 | } else if (!parent) { | |
236 | break; | |
59633abf ML |
237 | } |
238 | sibling = parent->rb_right; | |
239 | if (node != sibling) { /* node == parent->rb_left */ | |
6280d235 ML |
240 | if (rb_is_red(sibling)) { |
241 | /* | |
242 | * Case 1 - left rotate at parent | |
243 | * | |
244 | * P S | |
245 | * / \ / \ | |
246 | * N s --> p Sr | |
247 | * / \ / \ | |
248 | * Sl Sr N Sl | |
249 | */ | |
250 | parent->rb_right = tmp1 = sibling->rb_left; | |
251 | sibling->rb_left = parent; | |
252 | rb_set_parent_color(tmp1, parent, RB_BLACK); | |
253 | __rb_rotate_set_parents(parent, sibling, root, | |
254 | RB_RED); | |
255 | sibling = tmp1; | |
1da177e4 | 256 | } |
6280d235 ML |
257 | tmp1 = sibling->rb_right; |
258 | if (!tmp1 || rb_is_black(tmp1)) { | |
259 | tmp2 = sibling->rb_left; | |
260 | if (!tmp2 || rb_is_black(tmp2)) { | |
261 | /* | |
262 | * Case 2 - sibling color flip | |
263 | * (p could be either color here) | |
264 | * | |
265 | * (p) (p) | |
266 | * / \ / \ | |
267 | * N S --> N s | |
268 | * / \ / \ | |
269 | * Sl Sr Sl Sr | |
270 | * | |
271 | * This leaves us violating 5), so | |
272 | * recurse at p. If p is red, the | |
273 | * recursion will just flip it to black | |
274 | * and exit. If coming from Case 1, | |
275 | * p is known to be red. | |
276 | */ | |
277 | rb_set_parent_color(sibling, parent, | |
278 | RB_RED); | |
e125d147 ML |
279 | node = parent; |
280 | parent = rb_parent(node); | |
281 | continue; | |
1da177e4 | 282 | } |
6280d235 ML |
283 | /* |
284 | * Case 3 - right rotate at sibling | |
285 | * (p could be either color here) | |
286 | * | |
287 | * (p) (p) | |
288 | * / \ / \ | |
289 | * N S --> N Sl | |
290 | * / \ \ | |
291 | * sl Sr s | |
292 | * \ | |
293 | * Sr | |
294 | */ | |
295 | sibling->rb_left = tmp1 = tmp2->rb_right; | |
296 | tmp2->rb_right = sibling; | |
297 | parent->rb_right = tmp2; | |
298 | if (tmp1) | |
299 | rb_set_parent_color(tmp1, sibling, | |
300 | RB_BLACK); | |
301 | tmp1 = sibling; | |
302 | sibling = tmp2; | |
1da177e4 | 303 | } |
6280d235 ML |
304 | /* |
305 | * Case 4 - left rotate at parent + color flips | |
306 | * (p and sl could be either color here. | |
307 | * After rotation, p becomes black, s acquires | |
308 | * p's color, and sl keeps its color) | |
309 | * | |
310 | * (p) (s) | |
311 | * / \ / \ | |
312 | * N S --> P Sr | |
313 | * / \ / \ | |
314 | * (sl) sr N (sl) | |
315 | */ | |
316 | parent->rb_right = tmp2 = sibling->rb_left; | |
317 | sibling->rb_left = parent; | |
318 | rb_set_parent_color(tmp1, sibling, RB_BLACK); | |
319 | if (tmp2) | |
320 | rb_set_parent(tmp2, parent); | |
321 | __rb_rotate_set_parents(parent, sibling, root, | |
322 | RB_BLACK); | |
e125d147 | 323 | break; |
d6ff1273 | 324 | } else { |
6280d235 ML |
325 | sibling = parent->rb_left; |
326 | if (rb_is_red(sibling)) { | |
327 | /* Case 1 - right rotate at parent */ | |
328 | parent->rb_left = tmp1 = sibling->rb_right; | |
329 | sibling->rb_right = parent; | |
330 | rb_set_parent_color(tmp1, parent, RB_BLACK); | |
331 | __rb_rotate_set_parents(parent, sibling, root, | |
332 | RB_RED); | |
333 | sibling = tmp1; | |
1da177e4 | 334 | } |
6280d235 ML |
335 | tmp1 = sibling->rb_left; |
336 | if (!tmp1 || rb_is_black(tmp1)) { | |
337 | tmp2 = sibling->rb_right; | |
338 | if (!tmp2 || rb_is_black(tmp2)) { | |
339 | /* Case 2 - sibling color flip */ | |
340 | rb_set_parent_color(sibling, parent, | |
341 | RB_RED); | |
e125d147 ML |
342 | node = parent; |
343 | parent = rb_parent(node); | |
344 | continue; | |
1da177e4 | 345 | } |
6280d235 ML |
346 | /* Case 3 - right rotate at sibling */ |
347 | sibling->rb_right = tmp1 = tmp2->rb_left; | |
348 | tmp2->rb_left = sibling; | |
349 | parent->rb_left = tmp2; | |
350 | if (tmp1) | |
351 | rb_set_parent_color(tmp1, sibling, | |
352 | RB_BLACK); | |
353 | tmp1 = sibling; | |
354 | sibling = tmp2; | |
1da177e4 | 355 | } |
6280d235 ML |
356 | /* Case 4 - left rotate at parent + color flips */ |
357 | parent->rb_left = tmp2 = sibling->rb_right; | |
358 | sibling->rb_right = parent; | |
359 | rb_set_parent_color(tmp1, sibling, RB_BLACK); | |
360 | if (tmp2) | |
361 | rb_set_parent(tmp2, parent); | |
362 | __rb_rotate_set_parents(parent, sibling, root, | |
363 | RB_BLACK); | |
e125d147 | 364 | break; |
1da177e4 LT |
365 | } |
366 | } | |
1da177e4 LT |
367 | } |
368 | ||
369 | void rb_erase(struct rb_node *node, struct rb_root *root) | |
370 | { | |
60670b80 ML |
371 | struct rb_node *child = node->rb_right, *tmp = node->rb_left; |
372 | struct rb_node *parent; | |
1da177e4 LT |
373 | int color; |
374 | ||
60670b80 ML |
375 | if (!tmp) { |
376 | case1: | |
377 | /* Case 1: node to erase has no more than 1 child (easy!) */ | |
378 | ||
379 | parent = rb_parent(node); | |
380 | color = rb_color(node); | |
381 | ||
382 | if (child) | |
383 | rb_set_parent(child, parent); | |
384 | __rb_change_child(node, child, parent, root); | |
385 | } else if (!child) { | |
386 | /* Still case 1, but this time the child is node->rb_left */ | |
387 | child = tmp; | |
388 | goto case1; | |
389 | } else { | |
1da177e4 LT |
390 | struct rb_node *old = node, *left; |
391 | ||
60670b80 | 392 | node = child; |
1da177e4 LT |
393 | while ((left = node->rb_left) != NULL) |
394 | node = left; | |
16c047ad | 395 | |
7abc704a | 396 | __rb_change_child(old, node, rb_parent(old), root); |
16c047ad | 397 | |
1da177e4 | 398 | child = node->rb_right; |
55a98102 | 399 | parent = rb_parent(node); |
2f3243ae | 400 | color = rb_color(node); |
1da177e4 | 401 | |
55a98102 | 402 | if (parent == old) { |
1da177e4 | 403 | parent = node; |
4c601178 WS |
404 | } else { |
405 | if (child) | |
406 | rb_set_parent(child, parent); | |
1975e593 | 407 | parent->rb_left = child; |
4b324126 WS |
408 | |
409 | node->rb_right = old->rb_right; | |
410 | rb_set_parent(old->rb_right, node); | |
4c601178 | 411 | } |
1975e593 | 412 | |
bf7ad8ee | 413 | node->__rb_parent_color = old->__rb_parent_color; |
1da177e4 | 414 | node->rb_left = old->rb_left; |
55a98102 | 415 | rb_set_parent(old->rb_left, node); |
1da177e4 LT |
416 | } |
417 | ||
1da177e4 LT |
418 | if (color == RB_BLACK) |
419 | __rb_erase_color(child, parent, root); | |
420 | } | |
421 | EXPORT_SYMBOL(rb_erase); | |
422 | ||
b945d6b2 PZ |
423 | static void rb_augment_path(struct rb_node *node, rb_augment_f func, void *data) |
424 | { | |
425 | struct rb_node *parent; | |
426 | ||
427 | up: | |
428 | func(node, data); | |
429 | parent = rb_parent(node); | |
430 | if (!parent) | |
431 | return; | |
432 | ||
433 | if (node == parent->rb_left && parent->rb_right) | |
434 | func(parent->rb_right, data); | |
435 | else if (parent->rb_left) | |
436 | func(parent->rb_left, data); | |
437 | ||
438 | node = parent; | |
439 | goto up; | |
440 | } | |
441 | ||
442 | /* | |
443 | * after inserting @node into the tree, update the tree to account for | |
444 | * both the new entry and any damage done by rebalance | |
445 | */ | |
446 | void rb_augment_insert(struct rb_node *node, rb_augment_f func, void *data) | |
447 | { | |
448 | if (node->rb_left) | |
449 | node = node->rb_left; | |
450 | else if (node->rb_right) | |
451 | node = node->rb_right; | |
452 | ||
453 | rb_augment_path(node, func, data); | |
454 | } | |
0b6bb66d | 455 | EXPORT_SYMBOL(rb_augment_insert); |
b945d6b2 PZ |
456 | |
457 | /* | |
458 | * before removing the node, find the deepest node on the rebalance path | |
459 | * that will still be there after @node gets removed | |
460 | */ | |
461 | struct rb_node *rb_augment_erase_begin(struct rb_node *node) | |
462 | { | |
463 | struct rb_node *deepest; | |
464 | ||
465 | if (!node->rb_right && !node->rb_left) | |
466 | deepest = rb_parent(node); | |
467 | else if (!node->rb_right) | |
468 | deepest = node->rb_left; | |
469 | else if (!node->rb_left) | |
470 | deepest = node->rb_right; | |
471 | else { | |
472 | deepest = rb_next(node); | |
473 | if (deepest->rb_right) | |
474 | deepest = deepest->rb_right; | |
475 | else if (rb_parent(deepest) != node) | |
476 | deepest = rb_parent(deepest); | |
477 | } | |
478 | ||
479 | return deepest; | |
480 | } | |
0b6bb66d | 481 | EXPORT_SYMBOL(rb_augment_erase_begin); |
b945d6b2 PZ |
482 | |
483 | /* | |
484 | * after removal, update the tree to account for the removed entry | |
485 | * and any rebalance damage. | |
486 | */ | |
487 | void rb_augment_erase_end(struct rb_node *node, rb_augment_f func, void *data) | |
488 | { | |
489 | if (node) | |
490 | rb_augment_path(node, func, data); | |
491 | } | |
0b6bb66d | 492 | EXPORT_SYMBOL(rb_augment_erase_end); |
b945d6b2 | 493 | |
1da177e4 LT |
494 | /* |
495 | * This function returns the first node (in sort order) of the tree. | |
496 | */ | |
f4b477c4 | 497 | struct rb_node *rb_first(const struct rb_root *root) |
1da177e4 LT |
498 | { |
499 | struct rb_node *n; | |
500 | ||
501 | n = root->rb_node; | |
502 | if (!n) | |
503 | return NULL; | |
504 | while (n->rb_left) | |
505 | n = n->rb_left; | |
506 | return n; | |
507 | } | |
508 | EXPORT_SYMBOL(rb_first); | |
509 | ||
f4b477c4 | 510 | struct rb_node *rb_last(const struct rb_root *root) |
1da177e4 LT |
511 | { |
512 | struct rb_node *n; | |
513 | ||
514 | n = root->rb_node; | |
515 | if (!n) | |
516 | return NULL; | |
517 | while (n->rb_right) | |
518 | n = n->rb_right; | |
519 | return n; | |
520 | } | |
521 | EXPORT_SYMBOL(rb_last); | |
522 | ||
f4b477c4 | 523 | struct rb_node *rb_next(const struct rb_node *node) |
1da177e4 | 524 | { |
55a98102 DW |
525 | struct rb_node *parent; |
526 | ||
4c199a93 | 527 | if (RB_EMPTY_NODE(node)) |
10fd48f2 JA |
528 | return NULL; |
529 | ||
7ce6ff9e ML |
530 | /* |
531 | * If we have a right-hand child, go down and then left as far | |
532 | * as we can. | |
533 | */ | |
1da177e4 LT |
534 | if (node->rb_right) { |
535 | node = node->rb_right; | |
536 | while (node->rb_left) | |
537 | node=node->rb_left; | |
f4b477c4 | 538 | return (struct rb_node *)node; |
1da177e4 LT |
539 | } |
540 | ||
7ce6ff9e ML |
541 | /* |
542 | * No right-hand children. Everything down and left is smaller than us, | |
543 | * so any 'next' node must be in the general direction of our parent. | |
544 | * Go up the tree; any time the ancestor is a right-hand child of its | |
545 | * parent, keep going up. First time it's a left-hand child of its | |
546 | * parent, said parent is our 'next' node. | |
547 | */ | |
55a98102 DW |
548 | while ((parent = rb_parent(node)) && node == parent->rb_right) |
549 | node = parent; | |
1da177e4 | 550 | |
55a98102 | 551 | return parent; |
1da177e4 LT |
552 | } |
553 | EXPORT_SYMBOL(rb_next); | |
554 | ||
f4b477c4 | 555 | struct rb_node *rb_prev(const struct rb_node *node) |
1da177e4 | 556 | { |
55a98102 DW |
557 | struct rb_node *parent; |
558 | ||
4c199a93 | 559 | if (RB_EMPTY_NODE(node)) |
10fd48f2 JA |
560 | return NULL; |
561 | ||
7ce6ff9e ML |
562 | /* |
563 | * If we have a left-hand child, go down and then right as far | |
564 | * as we can. | |
565 | */ | |
1da177e4 LT |
566 | if (node->rb_left) { |
567 | node = node->rb_left; | |
568 | while (node->rb_right) | |
569 | node=node->rb_right; | |
f4b477c4 | 570 | return (struct rb_node *)node; |
1da177e4 LT |
571 | } |
572 | ||
7ce6ff9e ML |
573 | /* |
574 | * No left-hand children. Go up till we find an ancestor which | |
575 | * is a right-hand child of its parent. | |
576 | */ | |
55a98102 DW |
577 | while ((parent = rb_parent(node)) && node == parent->rb_left) |
578 | node = parent; | |
1da177e4 | 579 | |
55a98102 | 580 | return parent; |
1da177e4 LT |
581 | } |
582 | EXPORT_SYMBOL(rb_prev); | |
583 | ||
584 | void rb_replace_node(struct rb_node *victim, struct rb_node *new, | |
585 | struct rb_root *root) | |
586 | { | |
55a98102 | 587 | struct rb_node *parent = rb_parent(victim); |
1da177e4 LT |
588 | |
589 | /* Set the surrounding nodes to point to the replacement */ | |
7abc704a | 590 | __rb_change_child(victim, new, parent, root); |
1da177e4 | 591 | if (victim->rb_left) |
55a98102 | 592 | rb_set_parent(victim->rb_left, new); |
1da177e4 | 593 | if (victim->rb_right) |
55a98102 | 594 | rb_set_parent(victim->rb_right, new); |
1da177e4 LT |
595 | |
596 | /* Copy the pointers/colour from the victim to the replacement */ | |
597 | *new = *victim; | |
598 | } | |
599 | EXPORT_SYMBOL(rb_replace_node); |