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1 /* SPDX-License-Identifier: GPL-2.0-or-later */
4 (C) 1999 Andrea Arcangeli <andrea@suse.de>
7 linux/include/linux/rbtree.h
9 To use rbtrees you'll have to implement your own insert and search cores.
10 This will avoid us to use callbacks and to drop drammatically performances.
11 I know it's not the cleaner way, but in C (not in C++) to get
12 performances and genericity...
14 See Documentation/core-api/rbtree.rst for documentation and samples.
17 #ifndef _LINUX_RBTREE_H
18 #define _LINUX_RBTREE_H
20 #include <linux/kernel.h>
21 #include <linux/stddef.h>
22 #include <linux/rcupdate.h>
25 unsigned long __rb_parent_color
;
26 struct rb_node
*rb_right
;
27 struct rb_node
*rb_left
;
28 } __attribute__((aligned(sizeof(long))));
29 /* The alignment might seem pointless, but allegedly CRIS needs it */
32 struct rb_node
*rb_node
;
35 #define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3))
37 #define RB_ROOT (struct rb_root) { NULL, }
38 #define rb_entry(ptr, type, member) container_of(ptr, type, member)
40 #define RB_EMPTY_ROOT(root) (READ_ONCE((root)->rb_node) == NULL)
42 /* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
43 #define RB_EMPTY_NODE(node) \
44 ((node)->__rb_parent_color == (unsigned long)(node))
45 #define RB_CLEAR_NODE(node) \
46 ((node)->__rb_parent_color = (unsigned long)(node))
49 extern void rb_insert_color(struct rb_node
*, struct rb_root
*);
50 extern void rb_erase(struct rb_node
*, struct rb_root
*);
53 /* Find logical next and previous nodes in a tree */
54 extern struct rb_node
*rb_next(const struct rb_node
*);
55 extern struct rb_node
*rb_prev(const struct rb_node
*);
56 extern struct rb_node
*rb_first(const struct rb_root
*);
57 extern struct rb_node
*rb_last(const struct rb_root
*);
59 /* Postorder iteration - always visit the parent after its children */
60 extern struct rb_node
*rb_first_postorder(const struct rb_root
*);
61 extern struct rb_node
*rb_next_postorder(const struct rb_node
*);
63 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
64 extern void rb_replace_node(struct rb_node
*victim
, struct rb_node
*new,
65 struct rb_root
*root
);
66 extern void rb_replace_node_rcu(struct rb_node
*victim
, struct rb_node
*new,
67 struct rb_root
*root
);
69 static inline void rb_link_node(struct rb_node
*node
, struct rb_node
*parent
,
70 struct rb_node
**rb_link
)
72 node
->__rb_parent_color
= (unsigned long)parent
;
73 node
->rb_left
= node
->rb_right
= NULL
;
78 static inline void rb_link_node_rcu(struct rb_node
*node
, struct rb_node
*parent
,
79 struct rb_node
**rb_link
)
81 node
->__rb_parent_color
= (unsigned long)parent
;
82 node
->rb_left
= node
->rb_right
= NULL
;
84 rcu_assign_pointer(*rb_link
, node
);
87 #define rb_entry_safe(ptr, type, member) \
88 ({ typeof(ptr) ____ptr = (ptr); \
89 ____ptr ? rb_entry(____ptr, type, member) : NULL; \
93 * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
94 * given type allowing the backing memory of @pos to be invalidated
96 * @pos: the 'type *' to use as a loop cursor.
97 * @n: another 'type *' to use as temporary storage
98 * @root: 'rb_root *' of the rbtree.
99 * @field: the name of the rb_node field within 'type'.
101 * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
102 * list_for_each_entry_safe() and allows the iteration to continue independent
103 * of changes to @pos by the body of the loop.
105 * Note, however, that it cannot handle other modifications that re-order the
106 * rbtree it is iterating over. This includes calling rb_erase() on @pos, as
107 * rb_erase() may rebalance the tree, causing us to miss some nodes.
109 #define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
110 for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
111 pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
112 typeof(*pos), field); 1; }); \
116 * Leftmost-cached rbtrees.
118 * We do not cache the rightmost node based on footprint
119 * size vs number of potential users that could benefit
120 * from O(1) rb_last(). Just not worth it, users that want
121 * this feature can always implement the logic explicitly.
122 * Furthermore, users that want to cache both pointers may
123 * find it a bit asymmetric, but that's ok.
125 struct rb_root_cached
{
126 struct rb_root rb_root
;
127 struct rb_node
*rb_leftmost
;
130 #define RB_ROOT_CACHED (struct rb_root_cached) { {NULL, }, NULL }
132 /* Same as rb_first(), but O(1) */
133 #define rb_first_cached(root) (root)->rb_leftmost
135 static inline void rb_insert_color_cached(struct rb_node
*node
,
136 struct rb_root_cached
*root
,
140 root
->rb_leftmost
= node
;
141 rb_insert_color(node
, &root
->rb_root
);
144 static inline void rb_erase_cached(struct rb_node
*node
,
145 struct rb_root_cached
*root
)
147 if (root
->rb_leftmost
== node
)
148 root
->rb_leftmost
= rb_next(node
);
149 rb_erase(node
, &root
->rb_root
);
152 static inline void rb_replace_node_cached(struct rb_node
*victim
,
154 struct rb_root_cached
*root
)
156 if (root
->rb_leftmost
== victim
)
157 root
->rb_leftmost
= new;
158 rb_replace_node(victim
, new, &root
->rb_root
);
161 #endif /* _LINUX_RBTREE_H */