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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/rbtree.txt 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
;
36 * Leftmost-cached rbtrees.
38 * We do not cache the rightmost node based on footprint
39 * size vs number of potential users that could benefit
40 * from O(1) rb_last(). Just not worth it, users that want
41 * this feature can always implement the logic explicitly.
42 * Furthermore, users that want to cache both pointers may
43 * find it a bit asymmetric, but that's ok.
45 struct rb_root_cached
{
46 struct rb_root rb_root
;
47 struct rb_node
*rb_leftmost
;
50 #define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3))
52 #define RB_ROOT (struct rb_root) { NULL, }
53 #define RB_ROOT_CACHED (struct rb_root_cached) { {NULL, }, NULL }
54 #define rb_entry(ptr, type, member) container_of(ptr, type, member)
56 #define RB_EMPTY_ROOT(root) (READ_ONCE((root)->rb_node) == NULL)
58 /* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
59 #define RB_EMPTY_NODE(node) \
60 ((node)->__rb_parent_color == (unsigned long)(node))
61 #define RB_CLEAR_NODE(node) \
62 ((node)->__rb_parent_color = (unsigned long)(node))
65 extern void rb_insert_color(struct rb_node
*, struct rb_root
*);
66 extern void rb_erase(struct rb_node
*, struct rb_root
*);
69 /* Find logical next and previous nodes in a tree */
70 extern struct rb_node
*rb_next(const struct rb_node
*);
71 extern struct rb_node
*rb_prev(const struct rb_node
*);
72 extern struct rb_node
*rb_first(const struct rb_root
*);
73 extern struct rb_node
*rb_last(const struct rb_root
*);
75 extern void rb_insert_color_cached(struct rb_node
*,
76 struct rb_root_cached
*, bool);
77 extern void rb_erase_cached(struct rb_node
*node
, struct rb_root_cached
*);
78 /* Same as rb_first(), but O(1) */
79 #define rb_first_cached(root) (root)->rb_leftmost
81 /* Postorder iteration - always visit the parent after its children */
82 extern struct rb_node
*rb_first_postorder(const struct rb_root
*);
83 extern struct rb_node
*rb_next_postorder(const struct rb_node
*);
85 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
86 extern void rb_replace_node(struct rb_node
*victim
, struct rb_node
*new,
87 struct rb_root
*root
);
88 extern void rb_replace_node_rcu(struct rb_node
*victim
, struct rb_node
*new,
89 struct rb_root
*root
);
90 extern void rb_replace_node_cached(struct rb_node
*victim
, struct rb_node
*new,
91 struct rb_root_cached
*root
);
93 static inline void rb_link_node(struct rb_node
*node
, struct rb_node
*parent
,
94 struct rb_node
**rb_link
)
96 node
->__rb_parent_color
= (unsigned long)parent
;
97 node
->rb_left
= node
->rb_right
= NULL
;
102 static inline void rb_link_node_rcu(struct rb_node
*node
, struct rb_node
*parent
,
103 struct rb_node
**rb_link
)
105 node
->__rb_parent_color
= (unsigned long)parent
;
106 node
->rb_left
= node
->rb_right
= NULL
;
108 rcu_assign_pointer(*rb_link
, node
);
111 #define rb_entry_safe(ptr, type, member) \
112 ({ typeof(ptr) ____ptr = (ptr); \
113 ____ptr ? rb_entry(____ptr, type, member) : NULL; \
117 * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
118 * given type allowing the backing memory of @pos to be invalidated
120 * @pos: the 'type *' to use as a loop cursor.
121 * @n: another 'type *' to use as temporary storage
122 * @root: 'rb_root *' of the rbtree.
123 * @field: the name of the rb_node field within 'type'.
125 * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
126 * list_for_each_entry_safe() and allows the iteration to continue independent
127 * of changes to @pos by the body of the loop.
129 * Note, however, that it cannot handle other modifications that re-order the
130 * rbtree it is iterating over. This includes calling rb_erase() on @pos, as
131 * rb_erase() may rebalance the tree, causing us to miss some nodes.
133 #define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
134 for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
135 pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
136 typeof(*pos), field); 1; }); \
139 #endif /* _LINUX_RBTREE_H */