1 /* SPDX-License-Identifier: GPL-2.0-or-later * 1
2 /*
3 Red Black Trees
4 (C) 1999 Andrea Arcangeli <andrea@suse.de>
5 (C) 2002 David Woodhouse <dwmw2@infradead.o
6 (C) 2012 Michel Lespinasse <walken@google.c
7
8
9 linux/include/linux/rbtree_augmented.h
10 */
11
12 #ifndef _LINUX_RBTREE_AUGMENTED_H
13 #define _LINUX_RBTREE_AUGMENTED_H
14
15 #include <linux/compiler.h>
16 #include <linux/rbtree.h>
17 #include <linux/rcupdate.h>
18
19 /*
20 * Please note - only struct rb_augment_callba
21 * rb_insert_augmented() and rb_erase_augmente
22 * The rest are implementation details you are
23 *
24 * See Documentation/core-api/rbtree.rst for d
25 */
26
27 struct rb_augment_callbacks {
28 void (*propagate)(struct rb_node *node
29 void (*copy)(struct rb_node *old, stru
30 void (*rotate)(struct rb_node *old, st
31 };
32
33 extern void __rb_insert_augmented(struct rb_no
34 void (*augment_rotate)(struct rb_node
35
36 /*
37 * Fixup the rbtree and update the augmented i
38 *
39 * On insertion, the user must update the augm
40 * leading to the inserted node, then call rb_
41 * rb_insert_augmented() instead of the usual
42 * If rb_insert_augmented() rebalances the rbt
43 * a user provided function to update the augm
44 * affected subtrees.
45 */
46 static inline void
47 rb_insert_augmented(struct rb_node *node, stru
48 const struct rb_augment_ca
49 {
50 __rb_insert_augmented(node, root, augm
51 }
52
53 static inline void
54 rb_insert_augmented_cached(struct rb_node *nod
55 struct rb_root_cach
56 const struct rb_aug
57 {
58 if (newleft)
59 root->rb_leftmost = node;
60 rb_insert_augmented(node, &root->rb_ro
61 }
62
63 static __always_inline struct rb_node *
64 rb_add_augmented_cached(struct rb_node *node,
65 bool (*less)(struct rb
66 const struct rb_augmen
67 {
68 struct rb_node **link = &tree->rb_root
69 struct rb_node *parent = NULL;
70 bool leftmost = true;
71
72 while (*link) {
73 parent = *link;
74 if (less(node, parent)) {
75 link = &parent->rb_lef
76 } else {
77 link = &parent->rb_rig
78 leftmost = false;
79 }
80 }
81
82 rb_link_node(node, parent, link);
83 augment->propagate(parent, NULL); /* s
84 rb_insert_augmented_cached(node, tree,
85
86 return leftmost ? node : NULL;
87 }
88
89 /*
90 * Template for declaring augmented rbtree cal
91 *
92 * RBSTATIC: 'static' or empty
93 * RBNAME: name of the rb_augment_callbac
94 * RBSTRUCT: struct type of the tree nodes
95 * RBFIELD: name of struct rb_node field w
96 * RBAUGMENTED: name of field within RBSTRUCT
97 * RBCOMPUTE: name of function that recomput
98 */
99
100 #define RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME,
101 RBSTRUCT, RBFIELD
102 static inline void
103 RBNAME ## _propagate(struct rb_node *rb, struc
104 {
105 while (rb != stop) {
106 RBSTRUCT *node = rb_entry(rb,
107 if (RBCOMPUTE(node, true))
108 break;
109 rb = rb_parent(&node->RBFIELD)
110 }
111 }
112 static inline void
113 RBNAME ## _copy(struct rb_node *rb_old, struct
114 {
115 RBSTRUCT *old = rb_entry(rb_old, RBSTR
116 RBSTRUCT *new = rb_entry(rb_new, RBSTR
117 new->RBAUGMENTED = old->RBAUGMENTED;
118 }
119 static void
120 RBNAME ## _rotate(struct rb_node *rb_old, stru
121 {
122 RBSTRUCT *old = rb_entry(rb_old, RBSTR
123 RBSTRUCT *new = rb_entry(rb_new, RBSTR
124 new->RBAUGMENTED = old->RBAUGMENTED;
125 RBCOMPUTE(old, false);
126 }
127 RBSTATIC const struct rb_augment_callbacks RBN
128 .propagate = RBNAME ## _propagate,
129 .copy = RBNAME ## _copy,
130 .rotate = RBNAME ## _rotate
131 };
132
133 /*
134 * Template for declaring augmented rbtree cal
135 * computing RBAUGMENTED scalar as max(RBCOMPU
136 *
137 * RBSTATIC: 'static' or empty
138 * RBNAME: name of the rb_augment_callbac
139 * RBSTRUCT: struct type of the tree nodes
140 * RBFIELD: name of struct rb_node field w
141 * RBTYPE: type of the RBAUGMENTED field
142 * RBAUGMENTED: name of RBTYPE field within RB
143 * RBCOMPUTE: name of function that returns
144 */
145
146 #define RB_DECLARE_CALLBACKS_MAX(RBSTATIC, RBN
147 RBTYPE, RBAUG
148 static inline bool RBNAME ## _compute_max(RBST
149 {
150 RBSTRUCT *child;
151 RBTYPE max = RBCOMPUTE(node);
152 if (node->RBFIELD.rb_left) {
153 child = rb_entry(node->RBFIELD
154 if (child->RBAUGMENTED > max)
155 max = child->RBAUGMENT
156 }
157 if (node->RBFIELD.rb_right) {
158 child = rb_entry(node->RBFIELD
159 if (child->RBAUGMENTED > max)
160 max = child->RBAUGMENT
161 }
162 if (exit && node->RBAUGMENTED == max)
163 return true;
164 node->RBAUGMENTED = max;
165 return false;
166 }
167 RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME,
168 RBSTRUCT, RBFIELD, RBAUGM
169
170
171 #define RB_RED 0
172 #define RB_BLACK 1
173
174 #define __rb_parent(pc) ((struct rb_node *)
175
176 #define __rb_color(pc) ((pc) & 1)
177 #define __rb_is_black(pc) __rb_color(pc)
178 #define __rb_is_red(pc) (!__rb_color(pc))
179 #define rb_color(rb) __rb_color((rb)->__
180 #define rb_is_red(rb) __rb_is_red((rb)->_
181 #define rb_is_black(rb) __rb_is_black((rb)-
182
183 static inline void rb_set_parent(struct rb_nod
184 {
185 rb->__rb_parent_color = rb_color(rb) +
186 }
187
188 static inline void rb_set_parent_color(struct
189 struct
190 {
191 rb->__rb_parent_color = (unsigned long
192 }
193
194 static inline void
195 __rb_change_child(struct rb_node *old, struct
196 struct rb_node *parent, stru
197 {
198 if (parent) {
199 if (parent->rb_left == old)
200 WRITE_ONCE(parent->rb_
201 else
202 WRITE_ONCE(parent->rb_
203 } else
204 WRITE_ONCE(root->rb_node, new)
205 }
206
207 static inline void
208 __rb_change_child_rcu(struct rb_node *old, str
209 struct rb_node *parent,
210 {
211 if (parent) {
212 if (parent->rb_left == old)
213 rcu_assign_pointer(par
214 else
215 rcu_assign_pointer(par
216 } else
217 rcu_assign_pointer(root->rb_no
218 }
219
220 extern void __rb_erase_color(struct rb_node *p
221 void (*augment_rotate)(struct rb_node
222
223 static __always_inline struct rb_node *
224 __rb_erase_augmented(struct rb_node *node, str
225 const struct rb_augment_c
226 {
227 struct rb_node *child = node->rb_right
228 struct rb_node *tmp = node->rb_left;
229 struct rb_node *parent, *rebalance;
230 unsigned long pc;
231
232 if (!tmp) {
233 /*
234 * Case 1: node to erase has n
235 *
236 * Note that if there is one c
237 * and node must be black due
238 * so as to bypass __rb_erase_
239 */
240 pc = node->__rb_parent_color;
241 parent = __rb_parent(pc);
242 __rb_change_child(node, child,
243 if (child) {
244 child->__rb_parent_col
245 rebalance = NULL;
246 } else
247 rebalance = __rb_is_bl
248 tmp = parent;
249 } else if (!child) {
250 /* Still case 1, but this time
251 tmp->__rb_parent_color = pc =
252 parent = __rb_parent(pc);
253 __rb_change_child(node, tmp, p
254 rebalance = NULL;
255 tmp = parent;
256 } else {
257 struct rb_node *successor = ch
258
259 tmp = child->rb_left;
260 if (!tmp) {
261 /*
262 * Case 2: node's succ
263 *
264 * (n) (s)
265 * / \ / \
266 * (x) (s) -> (x) (
267 * \
268 * (c)
269 */
270 parent = successor;
271 child2 = successor->rb
272
273 augment->copy(node, su
274 } else {
275 /*
276 * Case 3: node's succ
277 * node's right child
278 *
279 * (n) (s)
280 * / \ / \
281 * (x) (y) -> (x) (
282 * / /
283 * (p) (p)
284 * / /
285 * (s) (c)
286 * \
287 * (c)
288 */
289 do {
290 parent = succe
291 successor = tm
292 tmp = tmp->rb_
293 } while (tmp);
294 child2 = successor->rb
295 WRITE_ONCE(parent->rb_
296 WRITE_ONCE(successor->
297 rb_set_parent(child, s
298
299 augment->copy(node, su
300 augment->propagate(par
301 }
302
303 tmp = node->rb_left;
304 WRITE_ONCE(successor->rb_left,
305 rb_set_parent(tmp, successor);
306
307 pc = node->__rb_parent_color;
308 tmp = __rb_parent(pc);
309 __rb_change_child(node, succes
310
311 if (child2) {
312 rb_set_parent_color(ch
313 rebalance = NULL;
314 } else {
315 rebalance = rb_is_blac
316 }
317 successor->__rb_parent_color =
318 tmp = successor;
319 }
320
321 augment->propagate(tmp, NULL);
322 return rebalance;
323 }
324
325 static __always_inline void
326 rb_erase_augmented(struct rb_node *node, struc
327 const struct rb_augment_cal
328 {
329 struct rb_node *rebalance = __rb_erase
330 if (rebalance)
331 __rb_erase_color(rebalance, ro
332 }
333
334 static __always_inline void
335 rb_erase_augmented_cached(struct rb_node *node
336 const struct rb_augm
337 {
338 if (root->rb_leftmost == node)
339 root->rb_leftmost = rb_next(no
340 rb_erase_augmented(node, &root->rb_roo
341 }
342
343 #endif /* _LINUX_RBTREE_AUGMENTED_H */
344
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