1 /* SPDX-License-Identifier: GPL-2.0-or-later */
4 (C) 1999 Andrea Arcangeli <andrea@suse.de>
5 (C) 2002 David Woodhouse <dwmw2@infradead.org>
6 (C) 2012 Michel Lespinasse <walken@google.com>
9 linux/include/linux/rbtree_augmented.h
12 #ifndef _LINUX_RBTREE_AUGMENTED_H
13 #define _LINUX_RBTREE_AUGMENTED_H
15 #include <linux/compiler.h>
16 #include <linux/rbtree.h>
17 #include <linux/rcupdate.h>
20 * Please note - only struct rb_augment_callbacks and the prototypes for
21 * rb_insert_augmented() and rb_erase_augmented() are intended to be public.
22 * The rest are implementation details you are not expected to depend on.
24 * See Documentation/rbtree.txt for documentation and samples.
27 struct rb_augment_callbacks {
28 void (*propagate)(struct rb_node *node, struct rb_node *stop);
29 void (*copy)(struct rb_node *old, struct rb_node *new);
30 void (*rotate)(struct rb_node *old, struct rb_node *new);
33 extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
34 void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
37 * Fixup the rbtree and update the augmented information when rebalancing.
39 * On insertion, the user must update the augmented information on the path
40 * leading to the inserted node, then call rb_link_node() as usual and
41 * rb_insert_augmented() instead of the usual rb_insert_color() call.
42 * If rb_insert_augmented() rebalances the rbtree, it will callback into
43 * a user provided function to update the augmented information on the
47 rb_insert_augmented(struct rb_node *node, struct rb_root *root,
48 const struct rb_augment_callbacks *augment)
50 __rb_insert_augmented(node, root, augment->rotate);
54 rb_insert_augmented_cached(struct rb_node *node,
55 struct rb_root_cached *root, bool newleft,
56 const struct rb_augment_callbacks *augment)
59 root->rb_leftmost = node;
60 rb_insert_augmented(node, &root->rb_root, augment);
63 #define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield, \
64 rbtype, rbaugmented, rbcompute) \
66 rbname ## _propagate(struct rb_node *rb, struct rb_node *stop) \
68 while (rb != stop) { \
69 rbstruct *node = rb_entry(rb, rbstruct, rbfield); \
70 rbtype augmented = rbcompute(node); \
71 if (node->rbaugmented == augmented) \
73 node->rbaugmented = augmented; \
74 rb = rb_parent(&node->rbfield); \
78 rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new) \
80 rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \
81 rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \
82 new->rbaugmented = old->rbaugmented; \
85 rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new) \
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); \
92 rbstatic const struct rb_augment_callbacks rbname = { \
93 .propagate = rbname ## _propagate, \
94 .copy = rbname ## _copy, \
95 .rotate = rbname ## _rotate \
102 #define __rb_parent(pc) ((struct rb_node *)(pc & ~3))
104 #define __rb_color(pc) ((pc) & 1)
105 #define __rb_is_black(pc) __rb_color(pc)
106 #define __rb_is_red(pc) (!__rb_color(pc))
107 #define rb_color(rb) __rb_color((rb)->__rb_parent_color)
108 #define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color)
109 #define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color)
111 static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
113 rb->__rb_parent_color = rb_color(rb) | (unsigned long)p;
116 static inline void rb_set_parent_color(struct rb_node *rb,
117 struct rb_node *p, int color)
119 rb->__rb_parent_color = (unsigned long)p | color;
123 __rb_change_child(struct rb_node *old, struct rb_node *new,
124 struct rb_node *parent, struct rb_root *root)
127 if (parent->rb_left == old)
128 WRITE_ONCE(parent->rb_left, new);
130 WRITE_ONCE(parent->rb_right, new);
132 WRITE_ONCE(root->rb_node, new);
136 __rb_change_child_rcu(struct rb_node *old, struct rb_node *new,
137 struct rb_node *parent, struct rb_root *root)
140 if (parent->rb_left == old)
141 rcu_assign_pointer(parent->rb_left, new);
143 rcu_assign_pointer(parent->rb_right, new);
145 rcu_assign_pointer(root->rb_node, new);
148 extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
149 void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
151 static __always_inline struct rb_node *
152 __rb_erase_augmented(struct rb_node *node, struct rb_root *root,
153 const struct rb_augment_callbacks *augment)
155 struct rb_node *child = node->rb_right;
156 struct rb_node *tmp = node->rb_left;
157 struct rb_node *parent, *rebalance;
162 * Case 1: node to erase has no more than 1 child (easy!)
164 * Note that if there is one child it must be red due to 5)
165 * and node must be black due to 4). We adjust colors locally
166 * so as to bypass __rb_erase_color() later on.
168 pc = node->__rb_parent_color;
169 parent = __rb_parent(pc);
170 __rb_change_child(node, child, parent, root);
172 child->__rb_parent_color = pc;
175 rebalance = __rb_is_black(pc) ? parent : NULL;
178 /* Still case 1, but this time the child is node->rb_left */
179 tmp->__rb_parent_color = pc = node->__rb_parent_color;
180 parent = __rb_parent(pc);
181 __rb_change_child(node, tmp, parent, root);
185 struct rb_node *successor = child, *child2;
187 tmp = child->rb_left;
190 * Case 2: node's successor is its right child
199 child2 = successor->rb_right;
201 augment->copy(node, successor);
204 * Case 3: node's successor is leftmost under
205 * node's right child subtree
222 child2 = successor->rb_right;
223 WRITE_ONCE(parent->rb_left, child2);
224 WRITE_ONCE(successor->rb_right, child);
225 rb_set_parent(child, successor);
227 augment->copy(node, successor);
228 augment->propagate(parent, successor);
232 WRITE_ONCE(successor->rb_left, tmp);
233 rb_set_parent(tmp, successor);
235 pc = node->__rb_parent_color;
236 tmp = __rb_parent(pc);
237 __rb_change_child(node, successor, tmp, root);
240 successor->__rb_parent_color = pc;
241 rb_set_parent_color(child2, parent, RB_BLACK);
244 unsigned long pc2 = successor->__rb_parent_color;
245 successor->__rb_parent_color = pc;
246 rebalance = __rb_is_black(pc2) ? parent : NULL;
251 augment->propagate(tmp, NULL);
255 static __always_inline void
256 rb_erase_augmented(struct rb_node *node, struct rb_root *root,
257 const struct rb_augment_callbacks *augment)
259 struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);
261 __rb_erase_color(rebalance, root, augment->rotate);
264 static __always_inline void
265 rb_erase_augmented_cached(struct rb_node *node, struct rb_root_cached *root,
266 const struct rb_augment_callbacks *augment)
268 if (root->rb_leftmost == node)
269 root->rb_leftmost = rb_next(node);
270 rb_erase_augmented(node, &root->rb_root, augment);
273 #endif /* _LINUX_RBTREE_AUGMENTED_H */