LXR linux/include/linux/rbtree.h

   1/*
   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
  26  See Documentation/rbtree.txt for documentation and samples.
  27*/
  28
  29#ifndef _LINUX_RBTREE_H
  30#define _LINUX_RBTREE_H
  31
  32#include <linux/kernel.h>
  33#include <linux/stddef.h>
  34#include <linux/rcupdate.h>
  35
  36struct rb_node {
  37        unsigned long  __rb_parent_color;
  38        struct rb_node *rb_right;
  39        struct rb_node *rb_left;
  40} __attribute__((aligned(sizeof(long))));
  41    /* The alignment might seem pointless, but allegedly CRIS needs it */
  42
  43struct rb_root {
  44        struct rb_node *rb_node;
  45};
  46
  47
  48#define rb_parent(r)   ((struct rb_node *)((r)->__rb_parent_color & ~3))
  49
  50#define RB_ROOT (struct rb_root) { NULL, }
  51#define rb_entry(ptr, type, member) container_of(ptr, type, member)
  52
  53#define RB_EMPTY_ROOT(root)  (READ_ONCE((root)->rb_node) == NULL)
  54
  55/* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
  56#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))
  60
  61
  62extern void rb_insert_color(struct rb_node *, struct rb_root *);
  63extern void rb_erase(struct rb_node *, struct rb_root *);
  64
  65
  66/* Find logical next and previous nodes in a tree */
  67extern 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 *);
  71
  72/* 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
  76/* Fast replacement of a single node without remove/rebalance/add/rebalance */
  77extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
  78                            struct rb_root *root);
  79extern void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new,
  80                                struct rb_root *root);
  81
  82static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
  83                                struct rb_node **rb_link)
  84{
  85        node->__rb_parent_color = (unsigned long)parent;
  86        node->rb_left = node->rb_right = NULL;
  87
  88        *rb_link = node;
  89}
  90
  91static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent,
  92                                    struct rb_node **rb_link)
  93{
  94        node->__rb_parent_color = (unsigned long)parent;
  95        node->rb_left = node->rb_right = NULL;
  96
  97        rcu_assign_pointer(*rb_link, node);
  98}
  99
 100#define rb_entry_safe(ptr, type, member) \
 101        ({ typeof(ptr) ____ptr = (ptr); \
 102           ____ptr ? rb_entry(____ptr, type, member) : NULL; \
 103        })
 104
 105/**
 106 * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
 107 * given type allowing the backing memory of @pos to be invalidated
 108 *
 109 * @pos:        the 'type *' to use as a loop cursor.
 110 * @n:          another 'type *' to use as temporary storage
 111 * @root:       'rb_root *' of the rbtree.
 112 * @field:      the name of the rb_node field within 'type'.
 113 *
 114 * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
 115 * list_for_each_entry_safe() and allows the iteration to continue independent
 116 * of changes to @pos by the body of the loop.
 117 *
 118 * Note, however, that it cannot handle other modifications that re-order the
 119 * rbtree it is iterating over. This includes calling rb_erase() on @pos, as
 120 * rb_erase() may rebalance the tree, causing us to miss some nodes.
 121 */
 122#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
 123        for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
 124             pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
 125                        typeof(*pos), field); 1; }); \
 126             pos = n)
 127
 128#endif  /* _LINUX_RBTREE_H */
 129