LXR linux/tools/include/linux/rbtree.h

   1/* SPDX-License-Identifier: GPL-2.0-or-later */
   2/*
   3  Red Black Trees
   4  (C) 1999  Andrea Arcangeli <andrea@suse.de>
   5
   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 __TOOLS_LINUX_PERF_RBTREE_H
  18#define __TOOLS_LINUX_PERF_RBTREE_H
  19
  20#include <linux/kernel.h>
  21#include <linux/stddef.h>
  22
  23struct rb_node {
  24        unsigned long  __rb_parent_color;
  25        struct rb_node *rb_right;
  26        struct rb_node *rb_left;
  27} __attribute__((aligned(sizeof(long))));
  28    /* The alignment might seem pointless, but allegedly CRIS needs it */
  29
  30struct rb_root {
  31        struct rb_node *rb_node;
  32};
  33
  34/*
  35 * Leftmost-cached rbtrees.
  36 *
  37 * We do not cache the rightmost node based on footprint
  38 * size vs number of potential users that could benefit
  39 * from O(1) rb_last(). Just not worth it, users that want
  40 * this feature can always implement the logic explicitly.
  41 * Furthermore, users that want to cache both pointers may
  42 * find it a bit asymmetric, but that's ok.
  43 */
  44struct rb_root_cached {
  45        struct rb_root rb_root;
  46        struct rb_node *rb_leftmost;
  47};
  48
  49#define rb_parent(r)   ((struct rb_node *)((r)->__rb_parent_color & ~3))
  50
  51#define RB_ROOT (struct rb_root) { NULL, }
  52#define RB_ROOT_CACHED (struct rb_root_cached) { {NULL, }, NULL }
  53#define rb_entry(ptr, type, member) container_of(ptr, type, member)
  54
  55#define RB_EMPTY_ROOT(root)  (READ_ONCE((root)->rb_node) == NULL)
  56
  57/* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
  58#define RB_EMPTY_NODE(node)  \
  59        ((node)->__rb_parent_color == (unsigned long)(node))
  60#define RB_CLEAR_NODE(node)  \
  61        ((node)->__rb_parent_color = (unsigned long)(node))
  62
  63
  64extern void rb_insert_color(struct rb_node *, struct rb_root *);
  65extern void rb_erase(struct rb_node *, struct rb_root *);
  66
  67
  68/* Find logical next and previous nodes in a tree */
  69extern struct rb_node *rb_next(const struct rb_node *);
  70extern struct rb_node *rb_prev(const struct rb_node *);
  71extern struct rb_node *rb_first(const struct rb_root *);
  72extern struct rb_node *rb_last(const struct rb_root *);
  73
  74extern void rb_insert_color_cached(struct rb_node *,
  75                                   struct rb_root_cached *, bool);
  76extern void rb_erase_cached(struct rb_node *node, struct rb_root_cached *);
  77/* Same as rb_first(), but O(1) */
  78#define rb_first_cached(root) (root)->rb_leftmost
  79
  80/* Postorder iteration - always visit the parent after its children */
  81extern struct rb_node *rb_first_postorder(const struct rb_root *);
  82extern struct rb_node *rb_next_postorder(const struct rb_node *);
  83
  84/* Fast replacement of a single node without remove/rebalance/add/rebalance */
  85extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
  86                            struct rb_root *root);
  87extern void rb_replace_node_cached(struct rb_node *victim, struct rb_node *new,
  88                                   struct rb_root_cached *root);
  89
  90static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
  91                                struct rb_node **rb_link)
  92{
  93        node->__rb_parent_color = (unsigned long)parent;
  94        node->rb_left = node->rb_right = NULL;
  95
  96        *rb_link = node;
  97}
  98
  99#define rb_entry_safe(ptr, type, member) \
 100        ({ typeof(ptr) ____ptr = (ptr); \
 101           ____ptr ? rb_entry(____ptr, type, member) : NULL; \
 102        })
 103
 104/**
 105 * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
 106 * given type allowing the backing memory of @pos to be invalidated
 107 *
 108 * @pos:        the 'type *' to use as a loop cursor.
 109 * @n:          another 'type *' to use as temporary storage
 110 * @root:       'rb_root *' of the rbtree.
 111 * @field:      the name of the rb_node field within 'type'.
 112 *
 113 * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
 114 * list_for_each_entry_safe() and allows the iteration to continue independent
 115 * of changes to @pos by the body of the loop.
 116 *
 117 * Note, however, that it cannot handle other modifications that re-order the
 118 * rbtree it is iterating over. This includes calling rb_erase() on @pos, as
 119 * rb_erase() may rebalance the tree, causing us to miss some nodes.
 120 */
 121#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
 122        for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
 123             pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
 124                        typeof(*pos), field); 1; }); \
 125             pos = n)
 126
 127static inline void rb_erase_init(struct rb_node *n, struct rb_root *root)
 128{
 129        rb_erase(n, root);
 130        RB_CLEAR_NODE(n);
 131}
 132#endif /* __TOOLS_LINUX_PERF_RBTREE_H */
 133