root/tools/include/linux/rbtree.h

INCLUDED FROM

DEFINITIONS

1. rb_link_node
2. rb_erase_init
3. rb_insert_color_cached
4. rb_erase_cached
5. rb_replace_node_cached

   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 
  23 struct 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 
  30 struct 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 
  48 extern void rb_insert_color(struct rb_node *, struct rb_root *);
  49 extern void rb_erase(struct rb_node *, struct rb_root *);
  50 
  51 
  52 /* Find logical next and previous nodes in a tree */
  53 extern struct rb_node *rb_next(const struct rb_node *);
  54 extern struct rb_node *rb_prev(const struct rb_node *);
  55 extern struct rb_node *rb_first(const struct rb_root *);
  56 extern struct rb_node *rb_last(const struct rb_root *);
  57 
  58 /* Postorder iteration - always visit the parent after its children */
  59 extern struct rb_node *rb_first_postorder(const struct rb_root *);
  60 extern struct rb_node *rb_next_postorder(const struct rb_node *);
  61 
  62 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
  63 extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
  64                             struct rb_root *root);
  65 
  66 static 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 
 103 static 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  */
 119 struct 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 
 129 static 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 
 138 static 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 
 146 static 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 */