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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 
 36 struct 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 
 43 struct 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 
 62 extern void rb_insert_color(struct rb_node *, struct rb_root *);
 63 extern void rb_erase(struct rb_node *, struct rb_root *);
 64 
 65 
 66 /* Find logical next and previous nodes in a tree */
 67 extern struct rb_node *rb_next(const struct rb_node *);
 68 extern struct rb_node *rb_prev(const struct rb_node *);
 69 extern struct rb_node *rb_first(const struct rb_root *);
 70 extern struct rb_node *rb_last(const struct rb_root *);
 71 
 72 /* Postorder iteration - always visit the parent after its children */
 73 extern struct rb_node *rb_first_postorder(const struct rb_root *);
 74 extern struct rb_node *rb_next_postorder(const struct rb_node *);
 75 
 76 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
 77 extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
 78                             struct rb_root *root);
 79 extern void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new,
 80                                 struct rb_root *root);
 81 
 82 static 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 
 91 static 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 

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