include/linux/rbtree.h

   1 /*
   2   Red Black Trees
   3   (C) 1999  Andrea Arcangeli <andrea@suse.de>
   4
   5  * SPDX-License-Identifier:     GPL-2.0+
   6
   7   linux/include/linux/rbtree.h
   8
   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...
  13
  14   See Documentation/rbtree.txt for documentation and samples.
  15 */
  16
  17 #ifndef _LINUX_RBTREE_H
  18 #define _LINUX_RBTREE_H
  19
  20 #ifndef __UBOOT__
  21 #include <linux/kernel.h>
  22 #endif
  23 #include <linux/stddef.h>
  24
  25 struct rb_node {
  26         unsigned long  __rb_parent_color;
  27         struct rb_node *rb_right;
  28         struct rb_node *rb_left;
  29 } __attribute__((aligned(sizeof(long))));
  30     /* The alignment might seem pointless, but allegedly CRIS needs it */
  31
  32 struct rb_root {
  33         struct rb_node *rb_node;
  34 };
  35
  36
  37 #define rb_parent(r)   ((struct rb_node *)((r)->__rb_parent_color & ~3))
  38
  39 #define RB_ROOT (struct rb_root) { NULL, }
  40 #define rb_entry(ptr, type, member) container_of(ptr, type, member)
  41
  42 #define RB_EMPTY_ROOT(root)  ((root)->rb_node == NULL)
  43
  44 /* 'empty' nodes are nodes that are known not to be inserted in an rbree */
  45 #define RB_EMPTY_NODE(node)  \
  46         ((node)->__rb_parent_color == (unsigned long)(node))
  47 #define RB_CLEAR_NODE(node)  \
  48         ((node)->__rb_parent_color = (unsigned long)(node))
  49
  50
  51 extern void rb_insert_color(struct rb_node *, struct rb_root *);
  52 extern void rb_erase(struct rb_node *, struct rb_root *);
  53
  54
  55 /* Find logical next and previous nodes in a tree */
  56 extern struct rb_node *rb_next(const struct rb_node *);
  57 extern struct rb_node *rb_prev(const struct rb_node *);
  58 extern struct rb_node *rb_first(const struct rb_root *);
  59 extern struct rb_node *rb_last(const struct rb_root *);
  60
  61 /* Postorder iteration - always visit the parent after its children */
  62 extern struct rb_node *rb_first_postorder(const struct rb_root *);
  63 extern struct rb_node *rb_next_postorder(const struct rb_node *);
  64
  65 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
  66 extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
  67                             struct rb_root *root);
  68
  69 static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
  70                                 struct rb_node ** rb_link)
  71 {
  72         node->__rb_parent_color = (unsigned long)parent;
  73         node->rb_left = node->rb_right = NULL;
  74
  75         *rb_link = node;
  76 }
  77
  78 #define rb_entry_safe(ptr, type, member) \
  79         ({ typeof(ptr) ____ptr = (ptr); \
  80            ____ptr ? rb_entry(____ptr, type, member) : NULL; \
  81         })
  82
  83 /**
  84  * rbtree_postorder_for_each_entry_safe - iterate over rb_root in post order of
  85  * given type safe against removal of rb_node entry
  86  *
  87  * @pos:        the 'type *' to use as a loop cursor.
  88  * @n:          another 'type *' to use as temporary storage
  89  * @root:       'rb_root *' of the rbtree.
  90  * @field:      the name of the rb_node field within 'type'.
  91  */
  92 #define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
  93         for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
  94              pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
  95                         typeof(*pos), field); 1; }); \
  96              pos = n)
  97
  98 #endif  /* _LINUX_RBTREE_H */