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#define rb_parent(r)   ((struct rb_node *)((r)->__rb_parent_color & ~3))
  35
  36#define RB_ROOT (struct rb_root) { NULL, }
  37#define rb_entry(ptr, type, member) container_of(ptr, type, member)
  38
  39#define RB_EMPTY_ROOT(root)  (READ_ONCE((root)->rb_node) == NULL)
  40
  41/* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
  42#define RB_EMPTY_NODE(node)  \
  43        ((node)->__rb_parent_color == (unsigned long)(node))
  44#define RB_CLEAR_NODE(node)  \
  45        ((node)->__rb_parent_color = (unsigned long)(node))
  46
  47
  48extern void rb_insert_color(struct rb_node *, struct rb_root *);
  49extern void rb_erase(struct rb_node *, struct rb_root *);
  50
  51
  52/* Find logical next and previous nodes in a tree */
  53extern struct rb_node *rb_next(const struct rb_node *);
  54extern struct rb_node *rb_prev(const struct rb_node *);
  55extern struct rb_node *rb_first(const struct rb_root *);
  56extern struct rb_node *rb_last(const struct rb_root *);
  57
  58/* Postorder iteration - always visit the parent after its children */
  59extern struct rb_node *rb_first_postorder(const struct rb_root *);
  60extern struct rb_node *rb_next_postorder(const struct rb_node *);
  61
  62/* Fast replacement of a single node without remove/rebalance/add/rebalance */
  63extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
  64                            struct rb_root *root);
  65
  66static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
  67                                struct rb_node **rb_link)
  68{
  69        node->__rb_parent_color = (unsigned long)parent;
  70        node->rb_left = node->rb_right = NULL;
  71
  72        *rb_link = node;
  73}
  74
  75#define rb_entry_safe(ptr, type, member) \
  76        ({ typeof(ptr) ____ptr = (ptr); \
  77           ____ptr ? rb_entry(____ptr, type, member) : NULL; \
  78        })
  79
  80/**
  81 * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
  82 * given type allowing the backing memory of @pos to be invalidated
  83 *
  84 * @pos:        the 'type *' to use as a loop cursor.
  85 * @n:          another 'type *' to use as temporary storage
  86 * @root:       'rb_root *' of the rbtree.
  87 * @field:      the name of the rb_node field within 'type'.
  88 *
  89 * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
  90 * list_for_each_entry_safe() and allows the iteration to continue independent
  91 * of changes to @pos by the body of the loop.
  92 *
  93 * Note, however, that it cannot handle other modifications that re-order the
  94 * rbtree it is iterating over. This includes calling rb_erase() on @pos, as
  95 * rb_erase() may rebalance the tree, causing us to miss some nodes.
  96 */
  97#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
  98        for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
  99             pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
 100                        typeof(*pos), field); 1; }); \
 101             pos = n)
 102
 103static inline void rb_erase_init(struct rb_node *n, struct rb_root *root)
 104{
 105        rb_erase(n, root);
 106        RB_CLEAR_NODE(n);
 107}
 108
 109/*
 110 * Leftmost-cached rbtrees.
 111 *
 112 * We do not cache the rightmost node based on footprint
 113 * size vs number of potential users that could benefit
 114 * from O(1) rb_last(). Just not worth it, users that want
 115 * this feature can always implement the logic explicitly.
 116 * Furthermore, users that want to cache both pointers may
 117 * find it a bit asymmetric, but that's ok.
 118 */
 119struct rb_root_cached {
 120        struct rb_root rb_root;
 121        struct rb_node *rb_leftmost;
 122};
 123
 124#define RB_ROOT_CACHED (struct rb_root_cached) { {NULL, }, NULL }
 125
 126/* Same as rb_first(), but O(1) */
 127#define rb_first_cached(root) (root)->rb_leftmost
 128
 129static inline void rb_insert_color_cached(struct rb_node *node,
 130                                          struct rb_root_cached *root,
 131                                          bool leftmost)
 132{
 133        if (leftmost)
 134                root->rb_leftmost = node;
 135        rb_insert_color(node, &root->rb_root);
 136}
 137
 138static inline void rb_erase_cached(struct rb_node *node,
 139                                   struct rb_root_cached *root)
 140{
 141        if (root->rb_leftmost == node)
 142                root->rb_leftmost = rb_next(node);
 143        rb_erase(node, &root->rb_root);
 144}
 145
 146static inline void rb_replace_node_cached(struct rb_node *victim,
 147                                          struct rb_node *new,
 148                                          struct rb_root_cached *root)
 149{
 150        if (root->rb_leftmost == victim)
 151                root->rb_leftmost = new;
 152        rb_replace_node(victim, new, &root->rb_root);
 153}
 154
 155#endif /* __TOOLS_LINUX_PERF_RBTREE_H */
 156