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Michel Lespinasse9c079ad2012-10-08 16:31:33 -07001/*
2 Red Black Trees
3 (C) 1999 Andrea Arcangeli <andrea@suse.de>
4 (C) 2002 David Woodhouse <dwmw2@infradead.org>
5 (C) 2012 Michel Lespinasse <walken@google.com>
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
20
21 linux/include/linux/rbtree_augmented.h
22*/
23
24#ifndef _LINUX_RBTREE_AUGMENTED_H
25#define _LINUX_RBTREE_AUGMENTED_H
26
Will Deacon29fc7c52012-10-25 13:37:53 -070027#include <linux/compiler.h>
Michel Lespinasse9c079ad2012-10-08 16:31:33 -070028#include <linux/rbtree.h>
29
30/*
31 * Please note - only struct rb_augment_callbacks and the prototypes for
32 * rb_insert_augmented() and rb_erase_augmented() are intended to be public.
33 * The rest are implementation details you are not expected to depend on.
34 *
35 * See Documentation/rbtree.txt for documentation and samples.
36 */
37
38struct rb_augment_callbacks {
39 void (*propagate)(struct rb_node *node, struct rb_node *stop);
40 void (*copy)(struct rb_node *old, struct rb_node *new);
41 void (*rotate)(struct rb_node *old, struct rb_node *new);
42};
43
44extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
45 void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
Lai Jiangshana841b652014-10-13 15:53:48 -070046/*
47 * Fixup the rbtree and update the augmented information when rebalancing.
48 *
49 * On insertion, the user must update the augmented information on the path
50 * leading to the inserted node, then call rb_link_node() as usual and
51 * rb_augment_inserted() instead of the usual rb_insert_color() call.
52 * If rb_augment_inserted() rebalances the rbtree, it will callback into
53 * a user provided function to update the augmented information on the
54 * affected subtrees.
55 */
Michel Lespinasse9c079ad2012-10-08 16:31:33 -070056static inline void
57rb_insert_augmented(struct rb_node *node, struct rb_root *root,
58 const struct rb_augment_callbacks *augment)
59{
60 __rb_insert_augmented(node, root, augment->rotate);
61}
62
63#define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield, \
64 rbtype, rbaugmented, rbcompute) \
65static inline void \
66rbname ## _propagate(struct rb_node *rb, struct rb_node *stop) \
67{ \
68 while (rb != stop) { \
69 rbstruct *node = rb_entry(rb, rbstruct, rbfield); \
70 rbtype augmented = rbcompute(node); \
71 if (node->rbaugmented == augmented) \
72 break; \
73 node->rbaugmented = augmented; \
74 rb = rb_parent(&node->rbfield); \
75 } \
76} \
77static inline void \
78rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new) \
79{ \
80 rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \
81 rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \
82 new->rbaugmented = old->rbaugmented; \
83} \
84static void \
85rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new) \
86{ \
87 rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \
88 rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \
89 new->rbaugmented = old->rbaugmented; \
90 old->rbaugmented = rbcompute(old); \
91} \
92rbstatic const struct rb_augment_callbacks rbname = { \
93 rbname ## _propagate, rbname ## _copy, rbname ## _rotate \
94};
95
96
97#define RB_RED 0
98#define RB_BLACK 1
99
100#define __rb_parent(pc) ((struct rb_node *)(pc & ~3))
101
102#define __rb_color(pc) ((pc) & 1)
103#define __rb_is_black(pc) __rb_color(pc)
104#define __rb_is_red(pc) (!__rb_color(pc))
105#define rb_color(rb) __rb_color((rb)->__rb_parent_color)
106#define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color)
107#define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color)
108
109static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
110{
111 rb->__rb_parent_color = rb_color(rb) | (unsigned long)p;
112}
113
114static inline void rb_set_parent_color(struct rb_node *rb,
115 struct rb_node *p, int color)
116{
117 rb->__rb_parent_color = (unsigned long)p | color;
118}
119
120static inline void
121__rb_change_child(struct rb_node *old, struct rb_node *new,
122 struct rb_node *parent, struct rb_root *root)
123{
124 if (parent) {
125 if (parent->rb_left == old)
Peter Zijlstrad72da4a2015-05-27 11:09:36 +0930126 WRITE_ONCE(parent->rb_left, new);
Michel Lespinasse9c079ad2012-10-08 16:31:33 -0700127 else
Peter Zijlstrad72da4a2015-05-27 11:09:36 +0930128 WRITE_ONCE(parent->rb_right, new);
Michel Lespinasse9c079ad2012-10-08 16:31:33 -0700129 } else
Peter Zijlstrad72da4a2015-05-27 11:09:36 +0930130 WRITE_ONCE(root->rb_node, new);
Michel Lespinasse9c079ad2012-10-08 16:31:33 -0700131}
132
David Howellsc1adf202016-07-01 07:53:51 +0100133static inline void
134__rb_change_child_rcu(struct rb_node *old, struct rb_node *new,
135 struct rb_node *parent, struct rb_root *root)
136{
137 if (parent) {
138 if (parent->rb_left == old)
139 rcu_assign_pointer(parent->rb_left, new);
140 else
141 rcu_assign_pointer(parent->rb_right, new);
142 } else
143 rcu_assign_pointer(root->rb_node, new);
144}
145
Michel Lespinasse9c079ad2012-10-08 16:31:33 -0700146extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
147 void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
148
Michel Lespinasse3cb7a562013-01-11 14:32:20 -0800149static __always_inline struct rb_node *
150__rb_erase_augmented(struct rb_node *node, struct rb_root *root,
151 const struct rb_augment_callbacks *augment)
Michel Lespinasse9c079ad2012-10-08 16:31:33 -0700152{
Peter Zijlstrad72da4a2015-05-27 11:09:36 +0930153 struct rb_node *child = node->rb_right;
154 struct rb_node *tmp = node->rb_left;
Michel Lespinasse9c079ad2012-10-08 16:31:33 -0700155 struct rb_node *parent, *rebalance;
156 unsigned long pc;
157
158 if (!tmp) {
159 /*
160 * Case 1: node to erase has no more than 1 child (easy!)
161 *
162 * Note that if there is one child it must be red due to 5)
163 * and node must be black due to 4). We adjust colors locally
164 * so as to bypass __rb_erase_color() later on.
165 */
166 pc = node->__rb_parent_color;
167 parent = __rb_parent(pc);
168 __rb_change_child(node, child, parent, root);
169 if (child) {
170 child->__rb_parent_color = pc;
171 rebalance = NULL;
172 } else
173 rebalance = __rb_is_black(pc) ? parent : NULL;
174 tmp = parent;
175 } else if (!child) {
176 /* Still case 1, but this time the child is node->rb_left */
177 tmp->__rb_parent_color = pc = node->__rb_parent_color;
178 parent = __rb_parent(pc);
179 __rb_change_child(node, tmp, parent, root);
180 rebalance = NULL;
181 tmp = parent;
182 } else {
183 struct rb_node *successor = child, *child2;
Peter Zijlstrad72da4a2015-05-27 11:09:36 +0930184
Michel Lespinasse9c079ad2012-10-08 16:31:33 -0700185 tmp = child->rb_left;
186 if (!tmp) {
187 /*
188 * Case 2: node's successor is its right child
189 *
190 * (n) (s)
191 * / \ / \
192 * (x) (s) -> (x) (c)
193 * \
194 * (c)
195 */
196 parent = successor;
197 child2 = successor->rb_right;
Peter Zijlstrad72da4a2015-05-27 11:09:36 +0930198
Michel Lespinasse9c079ad2012-10-08 16:31:33 -0700199 augment->copy(node, successor);
200 } else {
201 /*
202 * Case 3: node's successor is leftmost under
203 * node's right child subtree
204 *
205 * (n) (s)
206 * / \ / \
207 * (x) (y) -> (x) (y)
208 * / /
209 * (p) (p)
210 * / /
211 * (s) (c)
212 * \
213 * (c)
214 */
215 do {
216 parent = successor;
217 successor = tmp;
218 tmp = tmp->rb_left;
219 } while (tmp);
Peter Zijlstrad72da4a2015-05-27 11:09:36 +0930220 child2 = successor->rb_right;
221 WRITE_ONCE(parent->rb_left, child2);
222 WRITE_ONCE(successor->rb_right, child);
Michel Lespinasse9c079ad2012-10-08 16:31:33 -0700223 rb_set_parent(child, successor);
Peter Zijlstrad72da4a2015-05-27 11:09:36 +0930224
Michel Lespinasse9c079ad2012-10-08 16:31:33 -0700225 augment->copy(node, successor);
226 augment->propagate(parent, successor);
227 }
228
Peter Zijlstrad72da4a2015-05-27 11:09:36 +0930229 tmp = node->rb_left;
230 WRITE_ONCE(successor->rb_left, tmp);
Michel Lespinasse9c079ad2012-10-08 16:31:33 -0700231 rb_set_parent(tmp, successor);
232
233 pc = node->__rb_parent_color;
234 tmp = __rb_parent(pc);
235 __rb_change_child(node, successor, tmp, root);
Peter Zijlstrad72da4a2015-05-27 11:09:36 +0930236
Michel Lespinasse9c079ad2012-10-08 16:31:33 -0700237 if (child2) {
238 successor->__rb_parent_color = pc;
239 rb_set_parent_color(child2, parent, RB_BLACK);
240 rebalance = NULL;
241 } else {
242 unsigned long pc2 = successor->__rb_parent_color;
243 successor->__rb_parent_color = pc;
244 rebalance = __rb_is_black(pc2) ? parent : NULL;
245 }
246 tmp = successor;
247 }
248
249 augment->propagate(tmp, NULL);
Michel Lespinasse3cb7a562013-01-11 14:32:20 -0800250 return rebalance;
251}
252
253static __always_inline void
254rb_erase_augmented(struct rb_node *node, struct rb_root *root,
255 const struct rb_augment_callbacks *augment)
256{
257 struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);
Michel Lespinasse9c079ad2012-10-08 16:31:33 -0700258 if (rebalance)
259 __rb_erase_color(rebalance, root, augment->rotate);
260}
261
262#endif /* _LINUX_RBTREE_AUGMENTED_H */