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-rw-r--r--lib/rbtree.c656
1 files changed, 350 insertions, 306 deletions
diff --git a/lib/rbtree.c b/lib/rbtree.c
index d4175565dc2c..4f56a11d67fa 100644
--- a/lib/rbtree.c
+++ b/lib/rbtree.c
@@ -2,7 +2,8 @@
2 Red Black Trees 2 Red Black Trees
3 (C) 1999 Andrea Arcangeli <andrea@suse.de> 3 (C) 1999 Andrea Arcangeli <andrea@suse.de>
4 (C) 2002 David Woodhouse <dwmw2@infradead.org> 4 (C) 2002 David Woodhouse <dwmw2@infradead.org>
5 5 (C) 2012 Michel Lespinasse <walken@google.com>
6
6 This program is free software; you can redistribute it and/or modify 7 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 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 the Free Software Foundation; either version 2 of the License, or
@@ -20,339 +21,382 @@
20 linux/lib/rbtree.c 21 linux/lib/rbtree.c
21*/ 22*/
22 23
23#include <linux/rbtree.h> 24#include <linux/rbtree_augmented.h>
24#include <linux/export.h> 25#include <linux/export.h>
25 26
26static void __rb_rotate_left(struct rb_node *node, struct rb_root *root) 27/*
27{ 28 * red-black trees properties: http://en.wikipedia.org/wiki/Rbtree
28 struct rb_node *right = node->rb_right; 29 *
29 struct rb_node *parent = rb_parent(node); 30 * 1) A node is either red or black
30 31 * 2) The root is black
31 if ((node->rb_right = right->rb_left)) 32 * 3) All leaves (NULL) are black
32 rb_set_parent(right->rb_left, node); 33 * 4) Both children of every red node are black
33 right->rb_left = node; 34 * 5) Every simple path from root to leaves contains the same number
34 35 * of black nodes.
35 rb_set_parent(right, parent); 36 *
37 * 4 and 5 give the O(log n) guarantee, since 4 implies you cannot have two
38 * consecutive red nodes in a path and every red node is therefore followed by
39 * a black. So if B is the number of black nodes on every simple path (as per
40 * 5), then the longest possible path due to 4 is 2B.
41 *
42 * We shall indicate color with case, where black nodes are uppercase and red
43 * nodes will be lowercase. Unknown color nodes shall be drawn as red within
44 * parentheses and have some accompanying text comment.
45 */
36 46
37 if (parent) 47static inline void rb_set_black(struct rb_node *rb)
38 { 48{
39 if (node == parent->rb_left) 49 rb->__rb_parent_color |= RB_BLACK;
40 parent->rb_left = right;
41 else
42 parent->rb_right = right;
43 }
44 else
45 root->rb_node = right;
46 rb_set_parent(node, right);
47} 50}
48 51
49static void __rb_rotate_right(struct rb_node *node, struct rb_root *root) 52static inline struct rb_node *rb_red_parent(struct rb_node *red)
50{ 53{
51 struct rb_node *left = node->rb_left; 54 return (struct rb_node *)red->__rb_parent_color;
52 struct rb_node *parent = rb_parent(node); 55}
53
54 if ((node->rb_left = left->rb_right))
55 rb_set_parent(left->rb_right, node);
56 left->rb_right = node;
57
58 rb_set_parent(left, parent);
59 56
60 if (parent) 57/*
61 { 58 * Helper function for rotations:
62 if (node == parent->rb_right) 59 * - old's parent and color get assigned to new
63 parent->rb_right = left; 60 * - old gets assigned new as a parent and 'color' as a color.
64 else 61 */
65 parent->rb_left = left; 62static inline void
66 } 63__rb_rotate_set_parents(struct rb_node *old, struct rb_node *new,
67 else 64 struct rb_root *root, int color)
68 root->rb_node = left; 65{
69 rb_set_parent(node, left); 66 struct rb_node *parent = rb_parent(old);
67 new->__rb_parent_color = old->__rb_parent_color;
68 rb_set_parent_color(old, new, color);
69 __rb_change_child(old, new, parent, root);
70} 70}
71 71
72void rb_insert_color(struct rb_node *node, struct rb_root *root) 72static __always_inline void
73__rb_insert(struct rb_node *node, struct rb_root *root,
74 void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
73{ 75{
74 struct rb_node *parent, *gparent; 76 struct rb_node *parent = rb_red_parent(node), *gparent, *tmp;
75 77
76 while ((parent = rb_parent(node)) && rb_is_red(parent)) 78 while (true) {
77 { 79 /*
78 gparent = rb_parent(parent); 80 * Loop invariant: node is red
79 81 *
80 if (parent == gparent->rb_left) 82 * If there is a black parent, we are done.
81 { 83 * Otherwise, take some corrective action as we don't
82 { 84 * want a red root or two consecutive red nodes.
83 register struct rb_node *uncle = gparent->rb_right; 85 */
84 if (uncle && rb_is_red(uncle)) 86 if (!parent) {
85 { 87 rb_set_parent_color(node, NULL, RB_BLACK);
86 rb_set_black(uncle); 88 break;
87 rb_set_black(parent); 89 } else if (rb_is_black(parent))
88 rb_set_red(gparent); 90 break;
89 node = gparent; 91
90 continue; 92 gparent = rb_red_parent(parent);
91 } 93
94 tmp = gparent->rb_right;
95 if (parent != tmp) { /* parent == gparent->rb_left */
96 if (tmp && rb_is_red(tmp)) {
97 /*
98 * Case 1 - color flips
99 *
100 * G g
101 * / \ / \
102 * p u --> P U
103 * / /
104 * n N
105 *
106 * However, since g's parent might be red, and
107 * 4) does not allow this, we need to recurse
108 * at g.
109 */
110 rb_set_parent_color(tmp, gparent, RB_BLACK);
111 rb_set_parent_color(parent, gparent, RB_BLACK);
112 node = gparent;
113 parent = rb_parent(node);
114 rb_set_parent_color(node, parent, RB_RED);
115 continue;
92 } 116 }
93 117
94 if (parent->rb_right == node) 118 tmp = parent->rb_right;
95 { 119 if (node == tmp) {
96 register struct rb_node *tmp; 120 /*
97 __rb_rotate_left(parent, root); 121 * Case 2 - left rotate at parent
98 tmp = parent; 122 *
123 * G G
124 * / \ / \
125 * p U --> n U
126 * \ /
127 * n p
128 *
129 * This still leaves us in violation of 4), the
130 * continuation into Case 3 will fix that.
131 */
132 parent->rb_right = tmp = node->rb_left;
133 node->rb_left = parent;
134 if (tmp)
135 rb_set_parent_color(tmp, parent,
136 RB_BLACK);
137 rb_set_parent_color(parent, node, RB_RED);
138 augment_rotate(parent, node);
99 parent = node; 139 parent = node;
100 node = tmp; 140 tmp = node->rb_right;
101 } 141 }
102 142
103 rb_set_black(parent); 143 /*
104 rb_set_red(gparent); 144 * Case 3 - right rotate at gparent
105 __rb_rotate_right(gparent, root); 145 *
146 * G P
147 * / \ / \
148 * p U --> n g
149 * / \
150 * n U
151 */
152 gparent->rb_left = tmp; /* == parent->rb_right */
153 parent->rb_right = gparent;
154 if (tmp)
155 rb_set_parent_color(tmp, gparent, RB_BLACK);
156 __rb_rotate_set_parents(gparent, parent, root, RB_RED);
157 augment_rotate(gparent, parent);
158 break;
106 } else { 159 } else {
107 { 160 tmp = gparent->rb_left;
108 register struct rb_node *uncle = gparent->rb_left; 161 if (tmp && rb_is_red(tmp)) {
109 if (uncle && rb_is_red(uncle)) 162 /* Case 1 - color flips */
110 { 163 rb_set_parent_color(tmp, gparent, RB_BLACK);
111 rb_set_black(uncle); 164 rb_set_parent_color(parent, gparent, RB_BLACK);
112 rb_set_black(parent); 165 node = gparent;
113 rb_set_red(gparent); 166 parent = rb_parent(node);
114 node = gparent; 167 rb_set_parent_color(node, parent, RB_RED);
115 continue; 168 continue;
116 }
117 } 169 }
118 170
119 if (parent->rb_left == node) 171 tmp = parent->rb_left;
120 { 172 if (node == tmp) {
121 register struct rb_node *tmp; 173 /* Case 2 - right rotate at parent */
122 __rb_rotate_right(parent, root); 174 parent->rb_left = tmp = node->rb_right;
123 tmp = parent; 175 node->rb_right = parent;
176 if (tmp)
177 rb_set_parent_color(tmp, parent,
178 RB_BLACK);
179 rb_set_parent_color(parent, node, RB_RED);
180 augment_rotate(parent, node);
124 parent = node; 181 parent = node;
125 node = tmp; 182 tmp = node->rb_left;
126 } 183 }
127 184
128 rb_set_black(parent); 185 /* Case 3 - left rotate at gparent */
129 rb_set_red(gparent); 186 gparent->rb_right = tmp; /* == parent->rb_left */
130 __rb_rotate_left(gparent, root); 187 parent->rb_left = gparent;
188 if (tmp)
189 rb_set_parent_color(tmp, gparent, RB_BLACK);
190 __rb_rotate_set_parents(gparent, parent, root, RB_RED);
191 augment_rotate(gparent, parent);
192 break;
131 } 193 }
132 } 194 }
133
134 rb_set_black(root->rb_node);
135} 195}
136EXPORT_SYMBOL(rb_insert_color);
137 196
138static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, 197__always_inline void
139 struct rb_root *root) 198__rb_erase_color(struct rb_node *parent, struct rb_root *root,
199 void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
140{ 200{
141 struct rb_node *other; 201 struct rb_node *node = NULL, *sibling, *tmp1, *tmp2;
142 202
143 while ((!node || rb_is_black(node)) && node != root->rb_node) 203 while (true) {
144 { 204 /*
145 if (parent->rb_left == node) 205 * Loop invariants:
146 { 206 * - node is black (or NULL on first iteration)
147 other = parent->rb_right; 207 * - node is not the root (parent is not NULL)
148 if (rb_is_red(other)) 208 * - All leaf paths going through parent and node have a
149 { 209 * black node count that is 1 lower than other leaf paths.
150 rb_set_black(other); 210 */
151 rb_set_red(parent); 211 sibling = parent->rb_right;
152 __rb_rotate_left(parent, root); 212 if (node != sibling) { /* node == parent->rb_left */
153 other = parent->rb_right; 213 if (rb_is_red(sibling)) {
214 /*
215 * Case 1 - left rotate at parent
216 *
217 * P S
218 * / \ / \
219 * N s --> p Sr
220 * / \ / \
221 * Sl Sr N Sl
222 */
223 parent->rb_right = tmp1 = sibling->rb_left;
224 sibling->rb_left = parent;
225 rb_set_parent_color(tmp1, parent, RB_BLACK);
226 __rb_rotate_set_parents(parent, sibling, root,
227 RB_RED);
228 augment_rotate(parent, sibling);
229 sibling = tmp1;
154 } 230 }
155 if ((!other->rb_left || rb_is_black(other->rb_left)) && 231 tmp1 = sibling->rb_right;
156 (!other->rb_right || rb_is_black(other->rb_right))) 232 if (!tmp1 || rb_is_black(tmp1)) {
157 { 233 tmp2 = sibling->rb_left;
158 rb_set_red(other); 234 if (!tmp2 || rb_is_black(tmp2)) {
159 node = parent; 235 /*
160 parent = rb_parent(node); 236 * Case 2 - sibling color flip
161 } 237 * (p could be either color here)
162 else 238 *
163 { 239 * (p) (p)
164 if (!other->rb_right || rb_is_black(other->rb_right)) 240 * / \ / \
165 { 241 * N S --> N s
166 rb_set_black(other->rb_left); 242 * / \ / \
167 rb_set_red(other); 243 * Sl Sr Sl Sr
168 __rb_rotate_right(other, root); 244 *
169 other = parent->rb_right; 245 * This leaves us violating 5) which
246 * can be fixed by flipping p to black
247 * if it was red, or by recursing at p.
248 * p is red when coming from Case 1.
249 */
250 rb_set_parent_color(sibling, parent,
251 RB_RED);
252 if (rb_is_red(parent))
253 rb_set_black(parent);
254 else {
255 node = parent;
256 parent = rb_parent(node);
257 if (parent)
258 continue;
259 }
260 break;
170 } 261 }
171 rb_set_color(other, rb_color(parent)); 262 /*
172 rb_set_black(parent); 263 * Case 3 - right rotate at sibling
173 rb_set_black(other->rb_right); 264 * (p could be either color here)
174 __rb_rotate_left(parent, root); 265 *
175 node = root->rb_node; 266 * (p) (p)
176 break; 267 * / \ / \
177 } 268 * N S --> N Sl
178 } 269 * / \ \
179 else 270 * sl Sr s
180 { 271 * \
181 other = parent->rb_left; 272 * Sr
182 if (rb_is_red(other)) 273 */
183 { 274 sibling->rb_left = tmp1 = tmp2->rb_right;
184 rb_set_black(other); 275 tmp2->rb_right = sibling;
185 rb_set_red(parent); 276 parent->rb_right = tmp2;
186 __rb_rotate_right(parent, root); 277 if (tmp1)
187 other = parent->rb_left; 278 rb_set_parent_color(tmp1, sibling,
279 RB_BLACK);
280 augment_rotate(sibling, tmp2);
281 tmp1 = sibling;
282 sibling = tmp2;
188 } 283 }
189 if ((!other->rb_left || rb_is_black(other->rb_left)) && 284 /*
190 (!other->rb_right || rb_is_black(other->rb_right))) 285 * Case 4 - left rotate at parent + color flips
191 { 286 * (p and sl could be either color here.
192 rb_set_red(other); 287 * After rotation, p becomes black, s acquires
193 node = parent; 288 * p's color, and sl keeps its color)
194 parent = rb_parent(node); 289 *
290 * (p) (s)
291 * / \ / \
292 * N S --> P Sr
293 * / \ / \
294 * (sl) sr N (sl)
295 */
296 parent->rb_right = tmp2 = sibling->rb_left;
297 sibling->rb_left = parent;
298 rb_set_parent_color(tmp1, sibling, RB_BLACK);
299 if (tmp2)
300 rb_set_parent(tmp2, parent);
301 __rb_rotate_set_parents(parent, sibling, root,
302 RB_BLACK);
303 augment_rotate(parent, sibling);
304 break;
305 } else {
306 sibling = parent->rb_left;
307 if (rb_is_red(sibling)) {
308 /* Case 1 - right rotate at parent */
309 parent->rb_left = tmp1 = sibling->rb_right;
310 sibling->rb_right = parent;
311 rb_set_parent_color(tmp1, parent, RB_BLACK);
312 __rb_rotate_set_parents(parent, sibling, root,
313 RB_RED);
314 augment_rotate(parent, sibling);
315 sibling = tmp1;
195 } 316 }
196 else 317 tmp1 = sibling->rb_left;
197 { 318 if (!tmp1 || rb_is_black(tmp1)) {
198 if (!other->rb_left || rb_is_black(other->rb_left)) 319 tmp2 = sibling->rb_right;
199 { 320 if (!tmp2 || rb_is_black(tmp2)) {
200 rb_set_black(other->rb_right); 321 /* Case 2 - sibling color flip */
201 rb_set_red(other); 322 rb_set_parent_color(sibling, parent,
202 __rb_rotate_left(other, root); 323 RB_RED);
203 other = parent->rb_left; 324 if (rb_is_red(parent))
325 rb_set_black(parent);
326 else {
327 node = parent;
328 parent = rb_parent(node);
329 if (parent)
330 continue;
331 }
332 break;
204 } 333 }
205 rb_set_color(other, rb_color(parent)); 334 /* Case 3 - right rotate at sibling */
206 rb_set_black(parent); 335 sibling->rb_right = tmp1 = tmp2->rb_left;
207 rb_set_black(other->rb_left); 336 tmp2->rb_left = sibling;
208 __rb_rotate_right(parent, root); 337 parent->rb_left = tmp2;
209 node = root->rb_node; 338 if (tmp1)
210 break; 339 rb_set_parent_color(tmp1, sibling,
340 RB_BLACK);
341 augment_rotate(sibling, tmp2);
342 tmp1 = sibling;
343 sibling = tmp2;
211 } 344 }
345 /* Case 4 - left rotate at parent + color flips */
346 parent->rb_left = tmp2 = sibling->rb_right;
347 sibling->rb_right = parent;
348 rb_set_parent_color(tmp1, sibling, RB_BLACK);
349 if (tmp2)
350 rb_set_parent(tmp2, parent);
351 __rb_rotate_set_parents(parent, sibling, root,
352 RB_BLACK);
353 augment_rotate(parent, sibling);
354 break;
212 } 355 }
213 } 356 }
214 if (node)
215 rb_set_black(node);
216} 357}
358EXPORT_SYMBOL(__rb_erase_color);
217 359
218void rb_erase(struct rb_node *node, struct rb_root *root) 360/*
219{ 361 * Non-augmented rbtree manipulation functions.
220 struct rb_node *child, *parent; 362 *
221 int color; 363 * We use dummy augmented callbacks here, and have the compiler optimize them
222 364 * out of the rb_insert_color() and rb_erase() function definitions.
223 if (!node->rb_left) 365 */
224 child = node->rb_right;
225 else if (!node->rb_right)
226 child = node->rb_left;
227 else
228 {
229 struct rb_node *old = node, *left;
230
231 node = node->rb_right;
232 while ((left = node->rb_left) != NULL)
233 node = left;
234
235 if (rb_parent(old)) {
236 if (rb_parent(old)->rb_left == old)
237 rb_parent(old)->rb_left = node;
238 else
239 rb_parent(old)->rb_right = node;
240 } else
241 root->rb_node = node;
242
243 child = node->rb_right;
244 parent = rb_parent(node);
245 color = rb_color(node);
246
247 if (parent == old) {
248 parent = node;
249 } else {
250 if (child)
251 rb_set_parent(child, parent);
252 parent->rb_left = child;
253
254 node->rb_right = old->rb_right;
255 rb_set_parent(old->rb_right, node);
256 }
257
258 node->rb_parent_color = old->rb_parent_color;
259 node->rb_left = old->rb_left;
260 rb_set_parent(old->rb_left, node);
261 366
262 goto color; 367static inline void dummy_propagate(struct rb_node *node, struct rb_node *stop) {}
263 } 368static inline void dummy_copy(struct rb_node *old, struct rb_node *new) {}
369static inline void dummy_rotate(struct rb_node *old, struct rb_node *new) {}
264 370
265 parent = rb_parent(node); 371static const struct rb_augment_callbacks dummy_callbacks = {
266 color = rb_color(node); 372 dummy_propagate, dummy_copy, dummy_rotate
267 373};
268 if (child)
269 rb_set_parent(child, parent);
270 if (parent)
271 {
272 if (parent->rb_left == node)
273 parent->rb_left = child;
274 else
275 parent->rb_right = child;
276 }
277 else
278 root->rb_node = child;
279 374
280 color: 375void rb_insert_color(struct rb_node *node, struct rb_root *root)
281 if (color == RB_BLACK)
282 __rb_erase_color(child, parent, root);
283}
284EXPORT_SYMBOL(rb_erase);
285
286static void rb_augment_path(struct rb_node *node, rb_augment_f func, void *data)
287{ 376{
288 struct rb_node *parent; 377 __rb_insert(node, root, dummy_rotate);
289
290up:
291 func(node, data);
292 parent = rb_parent(node);
293 if (!parent)
294 return;
295
296 if (node == parent->rb_left && parent->rb_right)
297 func(parent->rb_right, data);
298 else if (parent->rb_left)
299 func(parent->rb_left, data);
300
301 node = parent;
302 goto up;
303} 378}
379EXPORT_SYMBOL(rb_insert_color);
304 380
305/* 381void rb_erase(struct rb_node *node, struct rb_root *root)
306 * after inserting @node into the tree, update the tree to account for
307 * both the new entry and any damage done by rebalance
308 */
309void rb_augment_insert(struct rb_node *node, rb_augment_f func, void *data)
310{ 382{
311 if (node->rb_left) 383 rb_erase_augmented(node, root, &dummy_callbacks);
312 node = node->rb_left;
313 else if (node->rb_right)
314 node = node->rb_right;
315
316 rb_augment_path(node, func, data);
317} 384}
318EXPORT_SYMBOL(rb_augment_insert); 385EXPORT_SYMBOL(rb_erase);
319 386
320/* 387/*
321 * before removing the node, find the deepest node on the rebalance path 388 * Augmented rbtree manipulation functions.
322 * that will still be there after @node gets removed 389 *
390 * This instantiates the same __always_inline functions as in the non-augmented
391 * case, but this time with user-defined callbacks.
323 */ 392 */
324struct rb_node *rb_augment_erase_begin(struct rb_node *node)
325{
326 struct rb_node *deepest;
327
328 if (!node->rb_right && !node->rb_left)
329 deepest = rb_parent(node);
330 else if (!node->rb_right)
331 deepest = node->rb_left;
332 else if (!node->rb_left)
333 deepest = node->rb_right;
334 else {
335 deepest = rb_next(node);
336 if (deepest->rb_right)
337 deepest = deepest->rb_right;
338 else if (rb_parent(deepest) != node)
339 deepest = rb_parent(deepest);
340 }
341
342 return deepest;
343}
344EXPORT_SYMBOL(rb_augment_erase_begin);
345 393
346/* 394void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
347 * after removal, update the tree to account for the removed entry 395 void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
348 * and any rebalance damage.
349 */
350void rb_augment_erase_end(struct rb_node *node, rb_augment_f func, void *data)
351{ 396{
352 if (node) 397 __rb_insert(node, root, augment_rotate);
353 rb_augment_path(node, func, data);
354} 398}
355EXPORT_SYMBOL(rb_augment_erase_end); 399EXPORT_SYMBOL(__rb_insert_augmented);
356 400
357/* 401/*
358 * This function returns the first node (in sort order) of the tree. 402 * This function returns the first node (in sort order) of the tree.
@@ -387,11 +431,13 @@ struct rb_node *rb_next(const struct rb_node *node)
387{ 431{
388 struct rb_node *parent; 432 struct rb_node *parent;
389 433
390 if (rb_parent(node) == node) 434 if (RB_EMPTY_NODE(node))
391 return NULL; 435 return NULL;
392 436
393 /* If we have a right-hand child, go down and then left as far 437 /*
394 as we can. */ 438 * If we have a right-hand child, go down and then left as far
439 * as we can.
440 */
395 if (node->rb_right) { 441 if (node->rb_right) {
396 node = node->rb_right; 442 node = node->rb_right;
397 while (node->rb_left) 443 while (node->rb_left)
@@ -399,12 +445,13 @@ struct rb_node *rb_next(const struct rb_node *node)
399 return (struct rb_node *)node; 445 return (struct rb_node *)node;
400 } 446 }
401 447
402 /* No right-hand children. Everything down and left is 448 /*
403 smaller than us, so any 'next' node must be in the general 449 * No right-hand children. Everything down and left is smaller than us,
404 direction of our parent. Go up the tree; any time the 450 * so any 'next' node must be in the general direction of our parent.
405 ancestor is a right-hand child of its parent, keep going 451 * Go up the tree; any time the ancestor is a right-hand child of its
406 up. First time it's a left-hand child of its parent, said 452 * parent, keep going up. First time it's a left-hand child of its
407 parent is our 'next' node. */ 453 * parent, said parent is our 'next' node.
454 */
408 while ((parent = rb_parent(node)) && node == parent->rb_right) 455 while ((parent = rb_parent(node)) && node == parent->rb_right)
409 node = parent; 456 node = parent;
410 457
@@ -416,11 +463,13 @@ struct rb_node *rb_prev(const struct rb_node *node)
416{ 463{
417 struct rb_node *parent; 464 struct rb_node *parent;
418 465
419 if (rb_parent(node) == node) 466 if (RB_EMPTY_NODE(node))
420 return NULL; 467 return NULL;
421 468
422 /* If we have a left-hand child, go down and then right as far 469 /*
423 as we can. */ 470 * If we have a left-hand child, go down and then right as far
471 * as we can.
472 */
424 if (node->rb_left) { 473 if (node->rb_left) {
425 node = node->rb_left; 474 node = node->rb_left;
426 while (node->rb_right) 475 while (node->rb_right)
@@ -428,8 +477,10 @@ struct rb_node *rb_prev(const struct rb_node *node)
428 return (struct rb_node *)node; 477 return (struct rb_node *)node;
429 } 478 }
430 479
431 /* No left-hand children. Go up till we find an ancestor which 480 /*
432 is a right-hand child of its parent */ 481 * No left-hand children. Go up till we find an ancestor which
482 * is a right-hand child of its parent.
483 */
433 while ((parent = rb_parent(node)) && node == parent->rb_left) 484 while ((parent = rb_parent(node)) && node == parent->rb_left)
434 node = parent; 485 node = parent;
435 486
@@ -443,14 +494,7 @@ void rb_replace_node(struct rb_node *victim, struct rb_node *new,
443 struct rb_node *parent = rb_parent(victim); 494 struct rb_node *parent = rb_parent(victim);
444 495
445 /* Set the surrounding nodes to point to the replacement */ 496 /* Set the surrounding nodes to point to the replacement */
446 if (parent) { 497 __rb_change_child(victim, new, parent, root);
447 if (victim == parent->rb_left)
448 parent->rb_left = new;
449 else
450 parent->rb_right = new;
451 } else {
452 root->rb_node = new;
453 }
454 if (victim->rb_left) 498 if (victim->rb_left)
455 rb_set_parent(victim->rb_left, new); 499 rb_set_parent(victim->rb_left, new);
456 if (victim->rb_right) 500 if (victim->rb_right)
generated by cgit v1.2.2 (git 2.25.0) at 2025-01-12 15:54:52 -0500