1 // SPDX-License-Identifier: GPL-2.0-or-later <<
2 /* 1 /*
3 Red Black Trees 2 Red Black Trees
4 (C) 1999 Andrea Arcangeli <andrea@suse.de> 3 (C) 1999 Andrea Arcangeli <andrea@suse.de>
5 (C) 2002 David Woodhouse <dwmw2@infradead.o 4 (C) 2002 David Woodhouse <dwmw2@infradead.org>
6 (C) 2012 Michel Lespinasse <walken@google.c 5 (C) 2012 Michel Lespinasse <walken@google.com>
7 6
>> 7 This program is free software; you can redistribute it and/or modify
>> 8 it under the terms of the GNU General Public License as published by
>> 9 the Free Software Foundation; either version 2 of the License, or
>> 10 (at your option) any later version.
>> 11
>> 12 This program is distributed in the hope that it will be useful,
>> 13 but WITHOUT ANY WARRANTY; without even the implied warranty of
>> 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> 15 GNU General Public License for more details.
>> 16
>> 17 You should have received a copy of the GNU General Public License
>> 18 along with this program; if not, write to the Free Software
>> 19 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
8 20
9 linux/lib/rbtree.c 21 linux/lib/rbtree.c
10 */ 22 */
11 23
12 #include <linux/rbtree_augmented.h> 24 #include <linux/rbtree_augmented.h>
13 #include <linux/export.h> 25 #include <linux/export.h>
14 26
15 /* 27 /*
16 * red-black trees properties: https://en.wik !! 28 * red-black trees properties: http://en.wikipedia.org/wiki/Rbtree
17 * 29 *
18 * 1) A node is either red or black 30 * 1) A node is either red or black
19 * 2) The root is black 31 * 2) The root is black
20 * 3) All leaves (NULL) are black 32 * 3) All leaves (NULL) are black
21 * 4) Both children of every red node are bla 33 * 4) Both children of every red node are black
22 * 5) Every simple path from root to leaves c 34 * 5) Every simple path from root to leaves contains the same number
23 * of black nodes. 35 * of black nodes.
24 * 36 *
25 * 4 and 5 give the O(log n) guarantee, since 37 * 4 and 5 give the O(log n) guarantee, since 4 implies you cannot have two
26 * consecutive red nodes in a path and every 38 * consecutive red nodes in a path and every red node is therefore followed by
27 * a black. So if B is the number of black no 39 * a black. So if B is the number of black nodes on every simple path (as per
28 * 5), then the longest possible path due to 40 * 5), then the longest possible path due to 4 is 2B.
29 * 41 *
30 * We shall indicate color with case, where b 42 * We shall indicate color with case, where black nodes are uppercase and red
31 * nodes will be lowercase. Unknown color nod 43 * nodes will be lowercase. Unknown color nodes shall be drawn as red within
32 * parentheses and have some accompanying tex 44 * parentheses and have some accompanying text comment.
33 */ 45 */
34 46
35 /* 47 /*
36 * Notes on lockless lookups: 48 * Notes on lockless lookups:
37 * 49 *
38 * All stores to the tree structure (rb_left a 50 * All stores to the tree structure (rb_left and rb_right) must be done using
39 * WRITE_ONCE(). And we must not inadvertently 51 * WRITE_ONCE(). And we must not inadvertently cause (temporary) loops in the
40 * tree structure as seen in program order. 52 * tree structure as seen in program order.
41 * 53 *
42 * These two requirements will allow lockless 54 * These two requirements will allow lockless iteration of the tree -- not
43 * correct iteration mind you, tree rotations 55 * correct iteration mind you, tree rotations are not atomic so a lookup might
44 * miss entire subtrees. 56 * miss entire subtrees.
45 * 57 *
46 * But they do guarantee that any such travers 58 * But they do guarantee that any such traversal will only see valid elements
47 * and that it will indeed complete -- does no 59 * and that it will indeed complete -- does not get stuck in a loop.
48 * 60 *
49 * It also guarantees that if the lookup retur 61 * It also guarantees that if the lookup returns an element it is the 'correct'
50 * one. But not returning an element does _NOT 62 * one. But not returning an element does _NOT_ mean it's not present.
51 * 63 *
52 * NOTE: 64 * NOTE:
53 * 65 *
54 * Stores to __rb_parent_color are not importa 66 * Stores to __rb_parent_color are not important for simple lookups so those
55 * are left undone as of now. Nor did I check 67 * are left undone as of now. Nor did I check for loops involving parent
56 * pointers. 68 * pointers.
57 */ 69 */
58 70
59 static inline void rb_set_black(struct rb_node 71 static inline void rb_set_black(struct rb_node *rb)
60 { 72 {
61 rb->__rb_parent_color += RB_BLACK; !! 73 rb->__rb_parent_color |= RB_BLACK;
62 } 74 }
63 75
64 static inline struct rb_node *rb_red_parent(st 76 static inline struct rb_node *rb_red_parent(struct rb_node *red)
65 { 77 {
66 return (struct rb_node *)red->__rb_par 78 return (struct rb_node *)red->__rb_parent_color;
67 } 79 }
68 80
69 /* 81 /*
70 * Helper function for rotations: 82 * Helper function for rotations:
71 * - old's parent and color get assigned to ne 83 * - old's parent and color get assigned to new
72 * - old gets assigned new as a parent and 'co 84 * - old gets assigned new as a parent and 'color' as a color.
73 */ 85 */
74 static inline void 86 static inline void
75 __rb_rotate_set_parents(struct rb_node *old, s 87 __rb_rotate_set_parents(struct rb_node *old, struct rb_node *new,
76 struct rb_root *root, 88 struct rb_root *root, int color)
77 { 89 {
78 struct rb_node *parent = rb_parent(old 90 struct rb_node *parent = rb_parent(old);
79 new->__rb_parent_color = old->__rb_par 91 new->__rb_parent_color = old->__rb_parent_color;
80 rb_set_parent_color(old, new, color); 92 rb_set_parent_color(old, new, color);
81 __rb_change_child(old, new, parent, ro 93 __rb_change_child(old, new, parent, root);
82 } 94 }
83 95
84 static __always_inline void 96 static __always_inline void
85 __rb_insert(struct rb_node *node, struct rb_ro 97 __rb_insert(struct rb_node *node, struct rb_root *root,
>> 98 bool newleft, struct rb_node **leftmost,
86 void (*augment_rotate)(struct rb_n 99 void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
87 { 100 {
88 struct rb_node *parent = rb_red_parent 101 struct rb_node *parent = rb_red_parent(node), *gparent, *tmp;
89 102
>> 103 if (newleft)
>> 104 *leftmost = node;
>> 105
90 while (true) { 106 while (true) {
91 /* 107 /*
92 * Loop invariant: node is red 108 * Loop invariant: node is red.
93 */ 109 */
94 if (unlikely(!parent)) { 110 if (unlikely(!parent)) {
95 /* 111 /*
96 * The inserted node i 112 * The inserted node is root. Either this is the
97 * first node, or we r 113 * first node, or we recursed at Case 1 below and
98 * are no longer viola 114 * are no longer violating 4).
99 */ 115 */
100 rb_set_parent_color(no 116 rb_set_parent_color(node, NULL, RB_BLACK);
101 break; 117 break;
102 } 118 }
103 119
104 /* 120 /*
105 * If there is a black parent, 121 * If there is a black parent, we are done.
106 * Otherwise, take some correc 122 * Otherwise, take some corrective action as,
107 * per 4), we don't want a red 123 * per 4), we don't want a red root or two
108 * consecutive red nodes. 124 * consecutive red nodes.
109 */ 125 */
110 if(rb_is_black(parent)) 126 if(rb_is_black(parent))
111 break; 127 break;
112 128
113 gparent = rb_red_parent(parent 129 gparent = rb_red_parent(parent);
114 130
115 tmp = gparent->rb_right; 131 tmp = gparent->rb_right;
116 if (parent != tmp) { /* par 132 if (parent != tmp) { /* parent == gparent->rb_left */
117 if (tmp && rb_is_red(t 133 if (tmp && rb_is_red(tmp)) {
118 /* 134 /*
119 * Case 1 - no 135 * Case 1 - node's uncle is red (color flips).
120 * 136 *
121 * G 137 * G g
122 * / \ 138 * / \ / \
123 * p u 139 * p u --> P U
124 * / 140 * / /
125 * n 141 * n n
126 * 142 *
127 * However, si 143 * However, since g's parent might be red, and
128 * 4) does not 144 * 4) does not allow this, we need to recurse
129 * at g. 145 * at g.
130 */ 146 */
131 rb_set_parent_ 147 rb_set_parent_color(tmp, gparent, RB_BLACK);
132 rb_set_parent_ 148 rb_set_parent_color(parent, gparent, RB_BLACK);
133 node = gparent 149 node = gparent;
134 parent = rb_pa 150 parent = rb_parent(node);
135 rb_set_parent_ 151 rb_set_parent_color(node, parent, RB_RED);
136 continue; 152 continue;
137 } 153 }
138 154
139 tmp = parent->rb_right 155 tmp = parent->rb_right;
140 if (node == tmp) { 156 if (node == tmp) {
141 /* 157 /*
142 * Case 2 - no 158 * Case 2 - node's uncle is black and node is
143 * the parent' 159 * the parent's right child (left rotate at parent).
144 * 160 *
145 * G 161 * G G
146 * / \ 162 * / \ / \
147 * p U - 163 * p U --> n U
148 * \ 164 * \ /
149 * n 165 * n p
150 * 166 *
151 * This still 167 * This still leaves us in violation of 4), the
152 * continuatio 168 * continuation into Case 3 will fix that.
153 */ 169 */
154 tmp = node->rb 170 tmp = node->rb_left;
155 WRITE_ONCE(par 171 WRITE_ONCE(parent->rb_right, tmp);
156 WRITE_ONCE(nod 172 WRITE_ONCE(node->rb_left, parent);
157 if (tmp) 173 if (tmp)
158 rb_set 174 rb_set_parent_color(tmp, parent,
159 175 RB_BLACK);
160 rb_set_parent_ 176 rb_set_parent_color(parent, node, RB_RED);
161 augment_rotate 177 augment_rotate(parent, node);
162 parent = node; 178 parent = node;
163 tmp = node->rb 179 tmp = node->rb_right;
164 } 180 }
165 181
166 /* 182 /*
167 * Case 3 - node's unc 183 * Case 3 - node's uncle is black and node is
168 * the parent's left c 184 * the parent's left child (right rotate at gparent).
169 * 185 *
170 * G 186 * G P
171 * / \ / 187 * / \ / \
172 * p U --> n 188 * p U --> n g
173 * / 189 * / \
174 * n 190 * n U
175 */ 191 */
176 WRITE_ONCE(gparent->rb 192 WRITE_ONCE(gparent->rb_left, tmp); /* == parent->rb_right */
177 WRITE_ONCE(parent->rb_ 193 WRITE_ONCE(parent->rb_right, gparent);
178 if (tmp) 194 if (tmp)
179 rb_set_parent_ 195 rb_set_parent_color(tmp, gparent, RB_BLACK);
180 __rb_rotate_set_parent 196 __rb_rotate_set_parents(gparent, parent, root, RB_RED);
181 augment_rotate(gparent 197 augment_rotate(gparent, parent);
182 break; 198 break;
183 } else { 199 } else {
184 tmp = gparent->rb_left 200 tmp = gparent->rb_left;
185 if (tmp && rb_is_red(t 201 if (tmp && rb_is_red(tmp)) {
186 /* Case 1 - co 202 /* Case 1 - color flips */
187 rb_set_parent_ 203 rb_set_parent_color(tmp, gparent, RB_BLACK);
188 rb_set_parent_ 204 rb_set_parent_color(parent, gparent, RB_BLACK);
189 node = gparent 205 node = gparent;
190 parent = rb_pa 206 parent = rb_parent(node);
191 rb_set_parent_ 207 rb_set_parent_color(node, parent, RB_RED);
192 continue; 208 continue;
193 } 209 }
194 210
195 tmp = parent->rb_left; 211 tmp = parent->rb_left;
196 if (node == tmp) { 212 if (node == tmp) {
197 /* Case 2 - ri 213 /* Case 2 - right rotate at parent */
198 tmp = node->rb 214 tmp = node->rb_right;
199 WRITE_ONCE(par 215 WRITE_ONCE(parent->rb_left, tmp);
200 WRITE_ONCE(nod 216 WRITE_ONCE(node->rb_right, parent);
201 if (tmp) 217 if (tmp)
202 rb_set 218 rb_set_parent_color(tmp, parent,
203 219 RB_BLACK);
204 rb_set_parent_ 220 rb_set_parent_color(parent, node, RB_RED);
205 augment_rotate 221 augment_rotate(parent, node);
206 parent = node; 222 parent = node;
207 tmp = node->rb 223 tmp = node->rb_left;
208 } 224 }
209 225
210 /* Case 3 - left rotat 226 /* Case 3 - left rotate at gparent */
211 WRITE_ONCE(gparent->rb 227 WRITE_ONCE(gparent->rb_right, tmp); /* == parent->rb_left */
212 WRITE_ONCE(parent->rb_ 228 WRITE_ONCE(parent->rb_left, gparent);
213 if (tmp) 229 if (tmp)
214 rb_set_parent_ 230 rb_set_parent_color(tmp, gparent, RB_BLACK);
215 __rb_rotate_set_parent 231 __rb_rotate_set_parents(gparent, parent, root, RB_RED);
216 augment_rotate(gparent 232 augment_rotate(gparent, parent);
217 break; 233 break;
218 } 234 }
219 } 235 }
220 } 236 }
221 237
222 /* 238 /*
223 * Inline version for rb_erase() use - we want 239 * Inline version for rb_erase() use - we want to be able to inline
224 * and eliminate the dummy_rotate callback the 240 * and eliminate the dummy_rotate callback there
225 */ 241 */
226 static __always_inline void 242 static __always_inline void
227 ____rb_erase_color(struct rb_node *parent, str 243 ____rb_erase_color(struct rb_node *parent, struct rb_root *root,
228 void (*augment_rotate)(struct rb_node 244 void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
229 { 245 {
230 struct rb_node *node = NULL, *sibling, 246 struct rb_node *node = NULL, *sibling, *tmp1, *tmp2;
231 247
232 while (true) { 248 while (true) {
233 /* 249 /*
234 * Loop invariants: 250 * Loop invariants:
235 * - node is black (or NULL on 251 * - node is black (or NULL on first iteration)
236 * - node is not the root (par 252 * - node is not the root (parent is not NULL)
237 * - All leaf paths going thro 253 * - All leaf paths going through parent and node have a
238 * black node count that is 254 * black node count that is 1 lower than other leaf paths.
239 */ 255 */
240 sibling = parent->rb_right; 256 sibling = parent->rb_right;
241 if (node != sibling) { /* nod 257 if (node != sibling) { /* node == parent->rb_left */
242 if (rb_is_red(sibling) 258 if (rb_is_red(sibling)) {
243 /* 259 /*
244 * Case 1 - le 260 * Case 1 - left rotate at parent
245 * 261 *
246 * P 262 * P S
247 * / \ 263 * / \ / \
248 * N s 264 * N s --> p Sr
249 * / \ 265 * / \ / \
250 * Sl Sr 266 * Sl Sr N Sl
251 */ 267 */
252 tmp1 = sibling 268 tmp1 = sibling->rb_left;
253 WRITE_ONCE(par 269 WRITE_ONCE(parent->rb_right, tmp1);
254 WRITE_ONCE(sib 270 WRITE_ONCE(sibling->rb_left, parent);
255 rb_set_parent_ 271 rb_set_parent_color(tmp1, parent, RB_BLACK);
256 __rb_rotate_se 272 __rb_rotate_set_parents(parent, sibling, root,
257 273 RB_RED);
258 augment_rotate 274 augment_rotate(parent, sibling);
259 sibling = tmp1 275 sibling = tmp1;
260 } 276 }
261 tmp1 = sibling->rb_rig 277 tmp1 = sibling->rb_right;
262 if (!tmp1 || rb_is_bla 278 if (!tmp1 || rb_is_black(tmp1)) {
263 tmp2 = sibling 279 tmp2 = sibling->rb_left;
264 if (!tmp2 || r 280 if (!tmp2 || rb_is_black(tmp2)) {
265 /* 281 /*
266 * Cas 282 * Case 2 - sibling color flip
267 * (p 283 * (p could be either color here)
268 * 284 *
269 * 285 * (p) (p)
270 * 286 * / \ / \
271 * N 287 * N S --> N s
272 * 288 * / \ / \
273 * 289 * Sl Sr Sl Sr
274 * 290 *
275 * Thi 291 * This leaves us violating 5) which
276 * can 292 * can be fixed by flipping p to black
277 * if 293 * if it was red, or by recursing at p.
278 * p i 294 * p is red when coming from Case 1.
279 */ 295 */
280 rb_set 296 rb_set_parent_color(sibling, parent,
281 297 RB_RED);
282 if (rb 298 if (rb_is_red(parent))
283 299 rb_set_black(parent);
284 else { 300 else {
285 301 node = parent;
286 302 parent = rb_parent(node);
287 303 if (parent)
288 304 continue;
289 } 305 }
290 break; 306 break;
291 } 307 }
292 /* 308 /*
293 * Case 3 - ri 309 * Case 3 - right rotate at sibling
294 * (p could be 310 * (p could be either color here)
295 * 311 *
296 * (p) 312 * (p) (p)
297 * / \ 313 * / \ / \
298 * N S - 314 * N S --> N sl
299 * / \ 315 * / \ \
300 * sl sr !! 316 * sl Sr S
301 * 317 * \
302 * !! 318 * Sr
303 * 319 *
304 * Note: p mig 320 * Note: p might be red, and then both
305 * p and sl ar 321 * p and sl are red after rotation(which
306 * breaks prop 322 * breaks property 4). This is fixed in
307 * Case 4 (in 323 * Case 4 (in __rb_rotate_set_parents()
308 * whi 324 * which set sl the color of p
309 * and 325 * and set p RB_BLACK)
310 * 326 *
311 * (p) 327 * (p) (sl)
312 * / \ 328 * / \ / \
313 * N sl - 329 * N sl --> P S
314 * \ 330 * \ / \
315 * S !! 331 * S N Sr
316 * \ 332 * \
317 * sr !! 333 * Sr
318 */ 334 */
319 tmp1 = tmp2->r 335 tmp1 = tmp2->rb_right;
320 WRITE_ONCE(sib 336 WRITE_ONCE(sibling->rb_left, tmp1);
321 WRITE_ONCE(tmp 337 WRITE_ONCE(tmp2->rb_right, sibling);
322 WRITE_ONCE(par 338 WRITE_ONCE(parent->rb_right, tmp2);
323 if (tmp1) 339 if (tmp1)
324 rb_set 340 rb_set_parent_color(tmp1, sibling,
325 341 RB_BLACK);
326 augment_rotate 342 augment_rotate(sibling, tmp2);
327 tmp1 = sibling 343 tmp1 = sibling;
328 sibling = tmp2 344 sibling = tmp2;
329 } 345 }
330 /* 346 /*
331 * Case 4 - left rotat 347 * Case 4 - left rotate at parent + color flips
332 * (p and sl could be 348 * (p and sl could be either color here.
333 * After rotation, p 349 * After rotation, p becomes black, s acquires
334 * p's color, and sl 350 * p's color, and sl keeps its color)
335 * 351 *
336 * (p) 352 * (p) (s)
337 * / \ 353 * / \ / \
338 * N S --> 354 * N S --> P Sr
339 * / \ 355 * / \ / \
340 * (sl) sr N 356 * (sl) sr N (sl)
341 */ 357 */
342 tmp2 = sibling->rb_lef 358 tmp2 = sibling->rb_left;
343 WRITE_ONCE(parent->rb_ 359 WRITE_ONCE(parent->rb_right, tmp2);
344 WRITE_ONCE(sibling->rb 360 WRITE_ONCE(sibling->rb_left, parent);
345 rb_set_parent_color(tm 361 rb_set_parent_color(tmp1, sibling, RB_BLACK);
346 if (tmp2) 362 if (tmp2)
347 rb_set_parent( 363 rb_set_parent(tmp2, parent);
348 __rb_rotate_set_parent 364 __rb_rotate_set_parents(parent, sibling, root,
349 365 RB_BLACK);
350 augment_rotate(parent, 366 augment_rotate(parent, sibling);
351 break; 367 break;
352 } else { 368 } else {
353 sibling = parent->rb_l 369 sibling = parent->rb_left;
354 if (rb_is_red(sibling) 370 if (rb_is_red(sibling)) {
355 /* Case 1 - ri 371 /* Case 1 - right rotate at parent */
356 tmp1 = sibling 372 tmp1 = sibling->rb_right;
357 WRITE_ONCE(par 373 WRITE_ONCE(parent->rb_left, tmp1);
358 WRITE_ONCE(sib 374 WRITE_ONCE(sibling->rb_right, parent);
359 rb_set_parent_ 375 rb_set_parent_color(tmp1, parent, RB_BLACK);
360 __rb_rotate_se 376 __rb_rotate_set_parents(parent, sibling, root,
361 377 RB_RED);
362 augment_rotate 378 augment_rotate(parent, sibling);
363 sibling = tmp1 379 sibling = tmp1;
364 } 380 }
365 tmp1 = sibling->rb_lef 381 tmp1 = sibling->rb_left;
366 if (!tmp1 || rb_is_bla 382 if (!tmp1 || rb_is_black(tmp1)) {
367 tmp2 = sibling 383 tmp2 = sibling->rb_right;
368 if (!tmp2 || r 384 if (!tmp2 || rb_is_black(tmp2)) {
369 /* Cas 385 /* Case 2 - sibling color flip */
370 rb_set 386 rb_set_parent_color(sibling, parent,
371 387 RB_RED);
372 if (rb 388 if (rb_is_red(parent))
373 389 rb_set_black(parent);
374 else { 390 else {
375 391 node = parent;
376 392 parent = rb_parent(node);
377 393 if (parent)
378 394 continue;
379 } 395 }
380 break; 396 break;
381 } 397 }
382 /* Case 3 - le 398 /* Case 3 - left rotate at sibling */
383 tmp1 = tmp2->r 399 tmp1 = tmp2->rb_left;
384 WRITE_ONCE(sib 400 WRITE_ONCE(sibling->rb_right, tmp1);
385 WRITE_ONCE(tmp 401 WRITE_ONCE(tmp2->rb_left, sibling);
386 WRITE_ONCE(par 402 WRITE_ONCE(parent->rb_left, tmp2);
387 if (tmp1) 403 if (tmp1)
388 rb_set 404 rb_set_parent_color(tmp1, sibling,
389 405 RB_BLACK);
390 augment_rotate 406 augment_rotate(sibling, tmp2);
391 tmp1 = sibling 407 tmp1 = sibling;
392 sibling = tmp2 408 sibling = tmp2;
393 } 409 }
394 /* Case 4 - right rota 410 /* Case 4 - right rotate at parent + color flips */
395 tmp2 = sibling->rb_rig 411 tmp2 = sibling->rb_right;
396 WRITE_ONCE(parent->rb_ 412 WRITE_ONCE(parent->rb_left, tmp2);
397 WRITE_ONCE(sibling->rb 413 WRITE_ONCE(sibling->rb_right, parent);
398 rb_set_parent_color(tm 414 rb_set_parent_color(tmp1, sibling, RB_BLACK);
399 if (tmp2) 415 if (tmp2)
400 rb_set_parent( 416 rb_set_parent(tmp2, parent);
401 __rb_rotate_set_parent 417 __rb_rotate_set_parents(parent, sibling, root,
402 418 RB_BLACK);
403 augment_rotate(parent, 419 augment_rotate(parent, sibling);
404 break; 420 break;
405 } 421 }
406 } 422 }
407 } 423 }
408 424
409 /* Non-inline version for rb_erase_augmented() 425 /* Non-inline version for rb_erase_augmented() use */
410 void __rb_erase_color(struct rb_node *parent, 426 void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
411 void (*augment_rotate)(struct rb_node 427 void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
412 { 428 {
413 ____rb_erase_color(parent, root, augme 429 ____rb_erase_color(parent, root, augment_rotate);
414 } 430 }
415 EXPORT_SYMBOL(__rb_erase_color); 431 EXPORT_SYMBOL(__rb_erase_color);
416 432
417 /* 433 /*
418 * Non-augmented rbtree manipulation functions 434 * Non-augmented rbtree manipulation functions.
419 * 435 *
420 * We use dummy augmented callbacks here, and 436 * We use dummy augmented callbacks here, and have the compiler optimize them
421 * out of the rb_insert_color() and rb_erase() 437 * out of the rb_insert_color() and rb_erase() function definitions.
422 */ 438 */
423 439
424 static inline void dummy_propagate(struct rb_n 440 static inline void dummy_propagate(struct rb_node *node, struct rb_node *stop) {}
425 static inline void dummy_copy(struct rb_node * 441 static inline void dummy_copy(struct rb_node *old, struct rb_node *new) {}
426 static inline void dummy_rotate(struct rb_node 442 static inline void dummy_rotate(struct rb_node *old, struct rb_node *new) {}
427 443
428 static const struct rb_augment_callbacks dummy 444 static const struct rb_augment_callbacks dummy_callbacks = {
429 .propagate = dummy_propagate, 445 .propagate = dummy_propagate,
430 .copy = dummy_copy, 446 .copy = dummy_copy,
431 .rotate = dummy_rotate 447 .rotate = dummy_rotate
432 }; 448 };
433 449
434 void rb_insert_color(struct rb_node *node, str 450 void rb_insert_color(struct rb_node *node, struct rb_root *root)
435 { 451 {
436 __rb_insert(node, root, dummy_rotate); !! 452 __rb_insert(node, root, false, NULL, dummy_rotate);
437 } 453 }
438 EXPORT_SYMBOL(rb_insert_color); 454 EXPORT_SYMBOL(rb_insert_color);
439 455
440 void rb_erase(struct rb_node *node, struct rb_ 456 void rb_erase(struct rb_node *node, struct rb_root *root)
441 { 457 {
442 struct rb_node *rebalance; 458 struct rb_node *rebalance;
443 rebalance = __rb_erase_augmented(node, !! 459 rebalance = __rb_erase_augmented(node, root,
>> 460 NULL, &dummy_callbacks);
444 if (rebalance) 461 if (rebalance)
445 ____rb_erase_color(rebalance, 462 ____rb_erase_color(rebalance, root, dummy_rotate);
446 } 463 }
447 EXPORT_SYMBOL(rb_erase); 464 EXPORT_SYMBOL(rb_erase);
448 465
>> 466 void rb_insert_color_cached(struct rb_node *node,
>> 467 struct rb_root_cached *root, bool leftmost)
>> 468 {
>> 469 __rb_insert(node, &root->rb_root, leftmost,
>> 470 &root->rb_leftmost, dummy_rotate);
>> 471 }
>> 472 EXPORT_SYMBOL(rb_insert_color_cached);
>> 473
>> 474 void rb_erase_cached(struct rb_node *node, struct rb_root_cached *root)
>> 475 {
>> 476 struct rb_node *rebalance;
>> 477 rebalance = __rb_erase_augmented(node, &root->rb_root,
>> 478 &root->rb_leftmost, &dummy_callbacks);
>> 479 if (rebalance)
>> 480 ____rb_erase_color(rebalance, &root->rb_root, dummy_rotate);
>> 481 }
>> 482 EXPORT_SYMBOL(rb_erase_cached);
>> 483
449 /* 484 /*
450 * Augmented rbtree manipulation functions. 485 * Augmented rbtree manipulation functions.
451 * 486 *
452 * This instantiates the same __always_inline 487 * This instantiates the same __always_inline functions as in the non-augmented
453 * case, but this time with user-defined callb 488 * case, but this time with user-defined callbacks.
454 */ 489 */
455 490
456 void __rb_insert_augmented(struct rb_node *nod 491 void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
>> 492 bool newleft, struct rb_node **leftmost,
457 void (*augment_rotate)(struct rb_node 493 void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
458 { 494 {
459 __rb_insert(node, root, augment_rotate !! 495 __rb_insert(node, root, newleft, leftmost, augment_rotate);
460 } 496 }
461 EXPORT_SYMBOL(__rb_insert_augmented); 497 EXPORT_SYMBOL(__rb_insert_augmented);
462 498
463 /* 499 /*
464 * This function returns the first node (in so 500 * This function returns the first node (in sort order) of the tree.
465 */ 501 */
466 struct rb_node *rb_first(const struct rb_root 502 struct rb_node *rb_first(const struct rb_root *root)
467 { 503 {
468 struct rb_node *n; 504 struct rb_node *n;
469 505
470 n = root->rb_node; 506 n = root->rb_node;
471 if (!n) 507 if (!n)
472 return NULL; 508 return NULL;
473 while (n->rb_left) 509 while (n->rb_left)
474 n = n->rb_left; 510 n = n->rb_left;
475 return n; 511 return n;
476 } 512 }
477 EXPORT_SYMBOL(rb_first); 513 EXPORT_SYMBOL(rb_first);
478 514
479 struct rb_node *rb_last(const struct rb_root * 515 struct rb_node *rb_last(const struct rb_root *root)
480 { 516 {
481 struct rb_node *n; 517 struct rb_node *n;
482 518
483 n = root->rb_node; 519 n = root->rb_node;
484 if (!n) 520 if (!n)
485 return NULL; 521 return NULL;
486 while (n->rb_right) 522 while (n->rb_right)
487 n = n->rb_right; 523 n = n->rb_right;
488 return n; 524 return n;
489 } 525 }
490 EXPORT_SYMBOL(rb_last); 526 EXPORT_SYMBOL(rb_last);
491 527
492 struct rb_node *rb_next(const struct rb_node * 528 struct rb_node *rb_next(const struct rb_node *node)
493 { 529 {
494 struct rb_node *parent; 530 struct rb_node *parent;
495 531
496 if (RB_EMPTY_NODE(node)) 532 if (RB_EMPTY_NODE(node))
497 return NULL; 533 return NULL;
498 534
499 /* 535 /*
500 * If we have a right-hand child, go d 536 * If we have a right-hand child, go down and then left as far
501 * as we can. 537 * as we can.
502 */ 538 */
503 if (node->rb_right) { 539 if (node->rb_right) {
504 node = node->rb_right; 540 node = node->rb_right;
505 while (node->rb_left) 541 while (node->rb_left)
506 node = node->rb_left; !! 542 node=node->rb_left;
507 return (struct rb_node *)node; 543 return (struct rb_node *)node;
508 } 544 }
509 545
510 /* 546 /*
511 * No right-hand children. Everything 547 * No right-hand children. Everything down and left is smaller than us,
512 * so any 'next' node must be in the g 548 * so any 'next' node must be in the general direction of our parent.
513 * Go up the tree; any time the ancest 549 * Go up the tree; any time the ancestor is a right-hand child of its
514 * parent, keep going up. First time i 550 * parent, keep going up. First time it's a left-hand child of its
515 * parent, said parent is our 'next' n 551 * parent, said parent is our 'next' node.
516 */ 552 */
517 while ((parent = rb_parent(node)) && n 553 while ((parent = rb_parent(node)) && node == parent->rb_right)
518 node = parent; 554 node = parent;
519 555
520 return parent; 556 return parent;
521 } 557 }
522 EXPORT_SYMBOL(rb_next); 558 EXPORT_SYMBOL(rb_next);
523 559
524 struct rb_node *rb_prev(const struct rb_node * 560 struct rb_node *rb_prev(const struct rb_node *node)
525 { 561 {
526 struct rb_node *parent; 562 struct rb_node *parent;
527 563
528 if (RB_EMPTY_NODE(node)) 564 if (RB_EMPTY_NODE(node))
529 return NULL; 565 return NULL;
530 566
531 /* 567 /*
532 * If we have a left-hand child, go do 568 * If we have a left-hand child, go down and then right as far
533 * as we can. 569 * as we can.
534 */ 570 */
535 if (node->rb_left) { 571 if (node->rb_left) {
536 node = node->rb_left; 572 node = node->rb_left;
537 while (node->rb_right) 573 while (node->rb_right)
538 node = node->rb_right; !! 574 node=node->rb_right;
539 return (struct rb_node *)node; 575 return (struct rb_node *)node;
540 } 576 }
541 577
542 /* 578 /*
543 * No left-hand children. Go up till w 579 * No left-hand children. Go up till we find an ancestor which
544 * is a right-hand child of its parent 580 * is a right-hand child of its parent.
545 */ 581 */
546 while ((parent = rb_parent(node)) && n 582 while ((parent = rb_parent(node)) && node == parent->rb_left)
547 node = parent; 583 node = parent;
548 584
549 return parent; 585 return parent;
550 } 586 }
551 EXPORT_SYMBOL(rb_prev); 587 EXPORT_SYMBOL(rb_prev);
552 588
553 void rb_replace_node(struct rb_node *victim, s 589 void rb_replace_node(struct rb_node *victim, struct rb_node *new,
554 struct rb_root *root) 590 struct rb_root *root)
555 { 591 {
556 struct rb_node *parent = rb_parent(vic 592 struct rb_node *parent = rb_parent(victim);
557 593
558 /* Copy the pointers/colour from the v 594 /* Copy the pointers/colour from the victim to the replacement */
559 *new = *victim; 595 *new = *victim;
560 596
561 /* Set the surrounding nodes to point 597 /* Set the surrounding nodes to point to the replacement */
562 if (victim->rb_left) 598 if (victim->rb_left)
563 rb_set_parent(victim->rb_left, 599 rb_set_parent(victim->rb_left, new);
564 if (victim->rb_right) 600 if (victim->rb_right)
565 rb_set_parent(victim->rb_right 601 rb_set_parent(victim->rb_right, new);
566 __rb_change_child(victim, new, parent, 602 __rb_change_child(victim, new, parent, root);
567 } 603 }
568 EXPORT_SYMBOL(rb_replace_node); 604 EXPORT_SYMBOL(rb_replace_node);
>> 605
>> 606 void rb_replace_node_cached(struct rb_node *victim, struct rb_node *new,
>> 607 struct rb_root_cached *root)
>> 608 {
>> 609 rb_replace_node(victim, new, &root->rb_root);
>> 610
>> 611 if (root->rb_leftmost == victim)
>> 612 root->rb_leftmost = new;
>> 613 }
>> 614 EXPORT_SYMBOL(rb_replace_node_cached);
569 615
570 void rb_replace_node_rcu(struct rb_node *victi 616 void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new,
571 struct rb_root *root) 617 struct rb_root *root)
572 { 618 {
573 struct rb_node *parent = rb_parent(vic 619 struct rb_node *parent = rb_parent(victim);
574 620
575 /* Copy the pointers/colour from the v 621 /* Copy the pointers/colour from the victim to the replacement */
576 *new = *victim; 622 *new = *victim;
577 623
578 /* Set the surrounding nodes to point 624 /* Set the surrounding nodes to point to the replacement */
579 if (victim->rb_left) 625 if (victim->rb_left)
580 rb_set_parent(victim->rb_left, 626 rb_set_parent(victim->rb_left, new);
581 if (victim->rb_right) 627 if (victim->rb_right)
582 rb_set_parent(victim->rb_right 628 rb_set_parent(victim->rb_right, new);
583 629
584 /* Set the parent's pointer to the new 630 /* Set the parent's pointer to the new node last after an RCU barrier
585 * so that the pointers onwards are se 631 * so that the pointers onwards are seen to be set correctly when doing
586 * an RCU walk over the tree. 632 * an RCU walk over the tree.
587 */ 633 */
588 __rb_change_child_rcu(victim, new, par 634 __rb_change_child_rcu(victim, new, parent, root);
589 } 635 }
590 EXPORT_SYMBOL(rb_replace_node_rcu); 636 EXPORT_SYMBOL(rb_replace_node_rcu);
591 637
592 static struct rb_node *rb_left_deepest_node(co 638 static struct rb_node *rb_left_deepest_node(const struct rb_node *node)
593 { 639 {
594 for (;;) { 640 for (;;) {
595 if (node->rb_left) 641 if (node->rb_left)
596 node = node->rb_left; 642 node = node->rb_left;
597 else if (node->rb_right) 643 else if (node->rb_right)
598 node = node->rb_right; 644 node = node->rb_right;
599 else 645 else
600 return (struct rb_node 646 return (struct rb_node *)node;
601 } 647 }
602 } 648 }
603 649
604 struct rb_node *rb_next_postorder(const struct 650 struct rb_node *rb_next_postorder(const struct rb_node *node)
605 { 651 {
606 const struct rb_node *parent; 652 const struct rb_node *parent;
607 if (!node) 653 if (!node)
608 return NULL; 654 return NULL;
609 parent = rb_parent(node); 655 parent = rb_parent(node);
610 656
611 /* If we're sitting on node, we've alr 657 /* If we're sitting on node, we've already seen our children */
612 if (parent && node == parent->rb_left 658 if (parent && node == parent->rb_left && parent->rb_right) {
613 /* If we are the parent's left 659 /* If we are the parent's left node, go to the parent's right
614 * node then all the way down 660 * node then all the way down to the left */
615 return rb_left_deepest_node(pa 661 return rb_left_deepest_node(parent->rb_right);
616 } else 662 } else
617 /* Otherwise we are the parent 663 /* Otherwise we are the parent's right node, and the parent
618 * should be next */ 664 * should be next */
619 return (struct rb_node *)paren 665 return (struct rb_node *)parent;
620 } 666 }
621 EXPORT_SYMBOL(rb_next_postorder); 667 EXPORT_SYMBOL(rb_next_postorder);
622 668
623 struct rb_node *rb_first_postorder(const struc 669 struct rb_node *rb_first_postorder(const struct rb_root *root)
624 { 670 {
625 if (!root->rb_node) 671 if (!root->rb_node)
626 return NULL; 672 return NULL;
627 673
628 return rb_left_deepest_node(root->rb_n 674 return rb_left_deepest_node(root->rb_node);
629 } 675 }
630 EXPORT_SYMBOL(rb_first_postorder); 676 EXPORT_SYMBOL(rb_first_postorder);
631 677
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