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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 Red Black Trees
3 (C) 1999 Andrea Arcangeli <andrea@suse.de>
4
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2 of the License, or
8 (at your option) any later version.
9
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software
17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18
19 linux/include/linux/rbtree.h
20
21 To use rbtrees you'll have to implement your own insert and search cores.
22 This will avoid us to use callbacks and to drop drammatically performances.
23 I know it's not the cleaner way, but in C (not in C++) to get
24 performances and genericity...
25
Michel Lespinasse1457d282012-10-08 16:30:28 -070026 See Documentation/rbtree.txt for documentation and samples.
Linus Torvalds1da177e2005-04-16 15:20:36 -070027*/
28
29#ifndef _LINUX_RBTREE_H
30#define _LINUX_RBTREE_H
31
32#include <linux/kernel.h>
33#include <linux/stddef.h>
Peter Zijlstrad72da4a2015-05-27 11:09:36 +093034#include <linux/rcupdate.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035
Michel Lespinassebf7ad8e2012-10-08 16:30:37 -070036struct rb_node {
37 unsigned long __rb_parent_color;
Linus Torvalds1da177e2005-04-16 15:20:36 -070038 struct rb_node *rb_right;
39 struct rb_node *rb_left;
David Woodhousee9771452006-04-21 23:15:39 +010040} __attribute__((aligned(sizeof(long))));
41 /* The alignment might seem pointless, but allegedly CRIS needs it */
Linus Torvalds1da177e2005-04-16 15:20:36 -070042
Michel Lespinassebf7ad8e2012-10-08 16:30:37 -070043struct rb_root {
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 struct rb_node *rb_node;
45};
46
David Woodhouse55a98102006-04-21 13:35:51 +010047
Michel Lespinassebf7ad8e2012-10-08 16:30:37 -070048#define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3))
David Woodhouse55a98102006-04-21 13:35:51 +010049
Peter Zijlstrab945d6b2010-05-29 15:31:43 +020050#define RB_ROOT (struct rb_root) { NULL, }
Linus Torvalds1da177e2005-04-16 15:20:36 -070051#define rb_entry(ptr, type, member) container_of(ptr, type, member)
52
Davidlohr Buesoa460bec2016-01-20 15:00:42 -080053#define RB_EMPTY_ROOT(root) (READ_ONCE((root)->rb_node) == NULL)
Jens Axboedd67d052006-06-21 09:36:18 +020054
John de la Garza7647f142015-02-17 13:46:04 -080055/* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
Michel Lespinassebf7ad8e2012-10-08 16:30:37 -070056#define RB_EMPTY_NODE(node) \
57 ((node)->__rb_parent_color == (unsigned long)(node))
58#define RB_CLEAR_NODE(node) \
59 ((node)->__rb_parent_color = (unsigned long)(node))
Michel Lespinasse4c199a92012-10-08 16:30:32 -070060
John Stultz88d19cf2011-01-03 18:59:43 -080061
Linus Torvalds1da177e2005-04-16 15:20:36 -070062extern void rb_insert_color(struct rb_node *, struct rb_root *);
63extern void rb_erase(struct rb_node *, struct rb_root *);
64
Michel Lespinasse14b94af2012-10-08 16:31:17 -070065
Linus Torvalds1da177e2005-04-16 15:20:36 -070066/* Find logical next and previous nodes in a tree */
Artem Bityutskiyf4b477c2009-01-10 11:12:09 +000067extern struct rb_node *rb_next(const struct rb_node *);
68extern struct rb_node *rb_prev(const struct rb_node *);
69extern struct rb_node *rb_first(const struct rb_root *);
70extern struct rb_node *rb_last(const struct rb_root *);
Linus Torvalds1da177e2005-04-16 15:20:36 -070071
Cody P Schafer9dee5c52013-09-11 14:25:10 -070072/* Postorder iteration - always visit the parent after its children */
73extern struct rb_node *rb_first_postorder(const struct rb_root *);
74extern struct rb_node *rb_next_postorder(const struct rb_node *);
75
Linus Torvalds1da177e2005-04-16 15:20:36 -070076/* Fast replacement of a single node without remove/rebalance/add/rebalance */
Peter Zijlstrad72da4a2015-05-27 11:09:36 +093077extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
Linus Torvalds1da177e2005-04-16 15:20:36 -070078 struct rb_root *root);
79
Peter Zijlstrad72da4a2015-05-27 11:09:36 +093080static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
81 struct rb_node **rb_link)
Linus Torvalds1da177e2005-04-16 15:20:36 -070082{
Michel Lespinassebf7ad8e2012-10-08 16:30:37 -070083 node->__rb_parent_color = (unsigned long)parent;
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 node->rb_left = node->rb_right = NULL;
85
86 *rb_link = node;
87}
88
Peter Zijlstrad72da4a2015-05-27 11:09:36 +093089static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent,
90 struct rb_node **rb_link)
91{
92 node->__rb_parent_color = (unsigned long)parent;
93 node->rb_left = node->rb_right = NULL;
94
95 rcu_assign_pointer(*rb_link, node);
96}
97
Jan Kara1310a5a2013-11-12 15:11:19 -080098#define rb_entry_safe(ptr, type, member) \
99 ({ typeof(ptr) ____ptr = (ptr); \
100 ____ptr ? rb_entry(____ptr, type, member) : NULL; \
101 })
102
Cody P Schafer2b529082013-09-11 14:25:11 -0700103/**
Cody P Schafer8de1ee72015-11-06 16:31:28 -0800104 * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
105 * given type allowing the backing memory of @pos to be invalidated
Cody P Schafer2b529082013-09-11 14:25:11 -0700106 *
107 * @pos: the 'type *' to use as a loop cursor.
108 * @n: another 'type *' to use as temporary storage
109 * @root: 'rb_root *' of the rbtree.
110 * @field: the name of the rb_node field within 'type'.
Cody P Schafer8de1ee72015-11-06 16:31:28 -0800111 *
112 * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
113 * list_for_each_entry_safe() and allows the iteration to continue independent
114 * of changes to @pos by the body of the loop.
115 *
116 * Note, however, that it cannot handle other modifications that re-order the
117 * rbtree it is iterating over. This includes calling rb_erase() on @pos, as
118 * rb_erase() may rebalance the tree, causing us to miss some nodes.
Cody P Schafer2b529082013-09-11 14:25:11 -0700119 */
120#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
Jan Kara1310a5a2013-11-12 15:11:19 -0800121 for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
122 pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
123 typeof(*pos), field); 1; }); \
124 pos = n)
Cody P Schafer2b529082013-09-11 14:25:11 -0700125
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126#endif /* _LINUX_RBTREE_H */