augmented rbtree: add new RB_DECLARE_CALLBACKS_MAX macro
[linux-2.6-block.git] / tools / include / linux / rbtree_augmented.h
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1a59d1b8 1/* SPDX-License-Identifier: GPL-2.0-or-later */
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2/*
3 Red Black Trees
4 (C) 1999 Andrea Arcangeli <andrea@suse.de>
5 (C) 2002 David Woodhouse <dwmw2@infradead.org>
6 (C) 2012 Michel Lespinasse <walken@google.com>
7
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8
9 tools/linux/include/linux/rbtree_augmented.h
10
11 Copied from:
12 linux/include/linux/rbtree_augmented.h
13*/
14
15#ifndef _TOOLS_LINUX_RBTREE_AUGMENTED_H
16#define _TOOLS_LINUX_RBTREE_AUGMENTED_H
17
18#include <linux/compiler.h>
19#include <linux/rbtree.h>
20
21/*
22 * Please note - only struct rb_augment_callbacks and the prototypes for
23 * rb_insert_augmented() and rb_erase_augmented() are intended to be public.
24 * The rest are implementation details you are not expected to depend on.
25 *
26 * See Documentation/rbtree.txt for documentation and samples.
27 */
28
29struct rb_augment_callbacks {
30 void (*propagate)(struct rb_node *node, struct rb_node *stop);
31 void (*copy)(struct rb_node *old, struct rb_node *new);
32 void (*rotate)(struct rb_node *old, struct rb_node *new);
33};
34
c7d4f7ee 35extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
307bc971 36 void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
c7d4f7ee 37
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38/*
39 * Fixup the rbtree and update the augmented information when rebalancing.
40 *
41 * On insertion, the user must update the augmented information on the path
42 * leading to the inserted node, then call rb_link_node() as usual and
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43 * rb_insert_augmented() instead of the usual rb_insert_color() call.
44 * If rb_insert_augmented() rebalances the rbtree, it will callback into
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45 * a user provided function to update the augmented information on the
46 * affected subtrees.
47 */
48static inline void
49rb_insert_augmented(struct rb_node *node, struct rb_root *root,
50 const struct rb_augment_callbacks *augment)
51{
c7d4f7ee 52 __rb_insert_augmented(node, root, augment->rotate);
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53}
54
55static inline void
56rb_insert_augmented_cached(struct rb_node *node,
57 struct rb_root_cached *root, bool newleft,
58 const struct rb_augment_callbacks *augment)
59{
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60 if (newleft)
61 root->rb_leftmost = node;
62 rb_insert_augmented(node, &root->rb_root, augment);
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63}
64
444b8a83 65/*
315cc066 66 * Template for declaring augmented rbtree callbacks (generic case)
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67 *
68 * RBSTATIC: 'static' or empty
69 * RBNAME: name of the rb_augment_callbacks structure
70 * RBSTRUCT: struct type of the tree nodes
71 * RBFIELD: name of struct rb_node field within RBSTRUCT
72 * RBTYPE: type of the RBAUGMENTED field
73 * RBAUGMENTED: name of RBTYPE field within RBSTRUCT holding data for subtree
74 * RBCOMPUTE: name of function that recomputes the RBAUGMENTED data
75 */
76
77#define RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME, RBSTRUCT, RBFIELD, \
78 RBTYPE, RBAUGMENTED, RBCOMPUTE) \
307bc971 79static inline void \
444b8a83 80RBNAME ## _propagate(struct rb_node *rb, struct rb_node *stop) \
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81{ \
82 while (rb != stop) { \
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83 RBSTRUCT *node = rb_entry(rb, RBSTRUCT, RBFIELD); \
84 RBTYPE augmented = RBCOMPUTE(node); \
85 if (node->RBAUGMENTED == augmented) \
307bc971 86 break; \
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87 node->RBAUGMENTED = augmented; \
88 rb = rb_parent(&node->RBFIELD); \
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89 } \
90} \
91static inline void \
444b8a83 92RBNAME ## _copy(struct rb_node *rb_old, struct rb_node *rb_new) \
307bc971 93{ \
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94 RBSTRUCT *old = rb_entry(rb_old, RBSTRUCT, RBFIELD); \
95 RBSTRUCT *new = rb_entry(rb_new, RBSTRUCT, RBFIELD); \
96 new->RBAUGMENTED = old->RBAUGMENTED; \
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97} \
98static void \
444b8a83 99RBNAME ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new) \
307bc971 100{ \
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101 RBSTRUCT *old = rb_entry(rb_old, RBSTRUCT, RBFIELD); \
102 RBSTRUCT *new = rb_entry(rb_new, RBSTRUCT, RBFIELD); \
103 new->RBAUGMENTED = old->RBAUGMENTED; \
104 old->RBAUGMENTED = RBCOMPUTE(old); \
307bc971 105} \
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106RBSTATIC const struct rb_augment_callbacks RBNAME = { \
107 .propagate = RBNAME ## _propagate, \
108 .copy = RBNAME ## _copy, \
109 .rotate = RBNAME ## _rotate \
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110};
111
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112/*
113 * Template for declaring augmented rbtree callbacks,
114 * computing RBAUGMENTED scalar as max(RBCOMPUTE(node)) for all subtree nodes.
115 *
116 * RBSTATIC: 'static' or empty
117 * RBNAME: name of the rb_augment_callbacks structure
118 * RBSTRUCT: struct type of the tree nodes
119 * RBFIELD: name of struct rb_node field within RBSTRUCT
120 * RBTYPE: type of the RBAUGMENTED field
121 * RBAUGMENTED: name of RBTYPE field within RBSTRUCT holding data for subtree
122 * RBCOMPUTE: name of function that returns the per-node RBTYPE scalar
123 */
124
125#define RB_DECLARE_CALLBACKS_MAX(RBSTATIC, RBNAME, RBSTRUCT, RBFIELD, \
126 RBTYPE, RBAUGMENTED, RBCOMPUTE) \
127static inline RBTYPE RBNAME ## _compute_max(RBSTRUCT *node) \
128{ \
129 RBSTRUCT *child; \
130 RBTYPE max = RBCOMPUTE(node); \
131 if (node->RBFIELD.rb_left) { \
132 child = rb_entry(node->RBFIELD.rb_left, RBSTRUCT, RBFIELD); \
133 if (child->RBAUGMENTED > max) \
134 max = child->RBAUGMENTED; \
135 } \
136 if (node->RBFIELD.rb_right) { \
137 child = rb_entry(node->RBFIELD.rb_right, RBSTRUCT, RBFIELD); \
138 if (child->RBAUGMENTED > max) \
139 max = child->RBAUGMENTED; \
140 } \
141 return max; \
142} \
143RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME, RBSTRUCT, RBFIELD, \
144 RBTYPE, RBAUGMENTED, RBNAME ## _compute_max)
145
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146
147#define RB_RED 0
148#define RB_BLACK 1
149
150#define __rb_parent(pc) ((struct rb_node *)(pc & ~3))
151
152#define __rb_color(pc) ((pc) & 1)
153#define __rb_is_black(pc) __rb_color(pc)
154#define __rb_is_red(pc) (!__rb_color(pc))
155#define rb_color(rb) __rb_color((rb)->__rb_parent_color)
156#define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color)
157#define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color)
158
159static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
160{
161 rb->__rb_parent_color = rb_color(rb) | (unsigned long)p;
162}
163
164static inline void rb_set_parent_color(struct rb_node *rb,
165 struct rb_node *p, int color)
166{
167 rb->__rb_parent_color = (unsigned long)p | color;
168}
169
170static inline void
171__rb_change_child(struct rb_node *old, struct rb_node *new,
172 struct rb_node *parent, struct rb_root *root)
173{
174 if (parent) {
175 if (parent->rb_left == old)
3aef2cad 176 WRITE_ONCE(parent->rb_left, new);
307bc971 177 else
3aef2cad 178 WRITE_ONCE(parent->rb_right, new);
307bc971 179 } else
3aef2cad 180 WRITE_ONCE(root->rb_node, new);
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181}
182
183extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
184 void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
185
186static __always_inline struct rb_node *
187__rb_erase_augmented(struct rb_node *node, struct rb_root *root,
188 const struct rb_augment_callbacks *augment)
189{
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190 struct rb_node *child = node->rb_right;
191 struct rb_node *tmp = node->rb_left;
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192 struct rb_node *parent, *rebalance;
193 unsigned long pc;
194
195 if (!tmp) {
196 /*
197 * Case 1: node to erase has no more than 1 child (easy!)
198 *
199 * Note that if there is one child it must be red due to 5)
200 * and node must be black due to 4). We adjust colors locally
201 * so as to bypass __rb_erase_color() later on.
202 */
203 pc = node->__rb_parent_color;
204 parent = __rb_parent(pc);
205 __rb_change_child(node, child, parent, root);
206 if (child) {
207 child->__rb_parent_color = pc;
208 rebalance = NULL;
209 } else
210 rebalance = __rb_is_black(pc) ? parent : NULL;
211 tmp = parent;
212 } else if (!child) {
213 /* Still case 1, but this time the child is node->rb_left */
214 tmp->__rb_parent_color = pc = node->__rb_parent_color;
215 parent = __rb_parent(pc);
216 __rb_change_child(node, tmp, parent, root);
217 rebalance = NULL;
218 tmp = parent;
219 } else {
220 struct rb_node *successor = child, *child2;
3aef2cad 221
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222 tmp = child->rb_left;
223 if (!tmp) {
224 /*
225 * Case 2: node's successor is its right child
226 *
227 * (n) (s)
228 * / \ / \
229 * (x) (s) -> (x) (c)
230 * \
231 * (c)
232 */
233 parent = successor;
234 child2 = successor->rb_right;
3aef2cad 235
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236 augment->copy(node, successor);
237 } else {
238 /*
239 * Case 3: node's successor is leftmost under
240 * node's right child subtree
241 *
242 * (n) (s)
243 * / \ / \
244 * (x) (y) -> (x) (y)
245 * / /
246 * (p) (p)
247 * / /
248 * (s) (c)
249 * \
250 * (c)
251 */
252 do {
253 parent = successor;
254 successor = tmp;
255 tmp = tmp->rb_left;
256 } while (tmp);
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257 child2 = successor->rb_right;
258 WRITE_ONCE(parent->rb_left, child2);
259 WRITE_ONCE(successor->rb_right, child);
307bc971 260 rb_set_parent(child, successor);
3aef2cad 261
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262 augment->copy(node, successor);
263 augment->propagate(parent, successor);
264 }
265
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266 tmp = node->rb_left;
267 WRITE_ONCE(successor->rb_left, tmp);
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268 rb_set_parent(tmp, successor);
269
270 pc = node->__rb_parent_color;
271 tmp = __rb_parent(pc);
272 __rb_change_child(node, successor, tmp, root);
3aef2cad 273
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274 if (child2) {
275 successor->__rb_parent_color = pc;
276 rb_set_parent_color(child2, parent, RB_BLACK);
277 rebalance = NULL;
278 } else {
279 unsigned long pc2 = successor->__rb_parent_color;
280 successor->__rb_parent_color = pc;
281 rebalance = __rb_is_black(pc2) ? parent : NULL;
282 }
283 tmp = successor;
284 }
285
286 augment->propagate(tmp, NULL);
287 return rebalance;
288}
289
290static __always_inline void
291rb_erase_augmented(struct rb_node *node, struct rb_root *root,
292 const struct rb_augment_callbacks *augment)
293{
c7d4f7ee 294 struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);
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295 if (rebalance)
296 __rb_erase_color(rebalance, root, augment->rotate);
297}
298
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299static __always_inline void
300rb_erase_augmented_cached(struct rb_node *node, struct rb_root_cached *root,
301 const struct rb_augment_callbacks *augment)
302{
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303 if (root->rb_leftmost == node)
304 root->rb_leftmost = rb_next(node);
305 rb_erase_augmented(node, &root->rb_root, augment);
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306}
307
308#endif /* _TOOLS_LINUX_RBTREE_AUGMENTED_H */