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)  ((root)->rb_node == NULL)
  54
  55/* 'empty' nodes are nodes that are known not to be inserted in an rbree */
  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);
  79
  80static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
  81                                struct rb_node **rb_link)
  82{
  83        node->__rb_parent_color = (unsigned long)parent;
  84        node->rb_left = node->rb_right = NULL;
  85
  86        *rb_link = node;
  87}
  88
  89static 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
  98#define rb_entry_safe(ptr, type, member) \
  99        ({ typeof(ptr) ____ptr = (ptr); \
 100           ____ptr ? rb_entry(____ptr, type, member) : NULL; \
 101        })
 102
 103/**
 104 * rbtree_postorder_for_each_entry_safe - iterate over rb_root in post order of
 105 * given type safe against removal of rb_node entry
 106 *
 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'.
 111 */
 112#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
 113        for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
 114             pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
 115                        typeof(*pos), field); 1; }); \
 116             pos = n)
 117
 118#endif  /* _LINUX_RBTREE_H */
 119