rbtree.h 4.9 KB

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  1. /* SPDX-License-Identifier: GPL-2.0-or-later */
  2. /*
  3. Red Black Trees
  4. (C) 1999 Andrea Arcangeli <andrea@suse.de>
  5. linux/include/linux/rbtree.h
  6. To use rbtrees you'll have to implement your own insert and search cores.
  7. This will avoid us to use callbacks and to drop drammatically performances.
  8. I know it's not the cleaner way, but in C (not in C++) to get
  9. performances and genericity...
  10. See Documentation/core-api/rbtree.rst for documentation and samples.
  11. */
  12. #ifndef __TOOLS_LINUX_PERF_RBTREE_H
  13. #define __TOOLS_LINUX_PERF_RBTREE_H
  14. #include <linux/kernel.h>
  15. #include <linux/stddef.h>
  16. struct rb_node {
  17. unsigned long __rb_parent_color;
  18. struct rb_node *rb_right;
  19. struct rb_node *rb_left;
  20. } __attribute__((aligned(sizeof(long))));
  21. /* The alignment might seem pointless, but allegedly CRIS needs it */
  22. struct rb_root {
  23. struct rb_node *rb_node;
  24. };
  25. #define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3))
  26. #define RB_ROOT (struct rb_root) { NULL, }
  27. #define rb_entry(ptr, type, member) container_of(ptr, type, member)
  28. #define RB_EMPTY_ROOT(root) (READ_ONCE((root)->rb_node) == NULL)
  29. /* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
  30. #define RB_EMPTY_NODE(node) \
  31. ((node)->__rb_parent_color == (unsigned long)(node))
  32. #define RB_CLEAR_NODE(node) \
  33. ((node)->__rb_parent_color = (unsigned long)(node))
  34. extern void rb_insert_color(struct rb_node *, struct rb_root *);
  35. extern void rb_erase(struct rb_node *, struct rb_root *);
  36. /* Find logical next and previous nodes in a tree */
  37. extern struct rb_node *rb_next(const struct rb_node *);
  38. extern struct rb_node *rb_prev(const struct rb_node *);
  39. extern struct rb_node *rb_first(const struct rb_root *);
  40. extern struct rb_node *rb_last(const struct rb_root *);
  41. /* Postorder iteration - always visit the parent after its children */
  42. extern struct rb_node *rb_first_postorder(const struct rb_root *);
  43. extern struct rb_node *rb_next_postorder(const struct rb_node *);
  44. /* Fast replacement of a single node without remove/rebalance/add/rebalance */
  45. extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
  46. struct rb_root *root);
  47. static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
  48. struct rb_node **rb_link)
  49. {
  50. node->__rb_parent_color = (unsigned long)parent;
  51. node->rb_left = node->rb_right = NULL;
  52. *rb_link = node;
  53. }
  54. #define rb_entry_safe(ptr, type, member) \
  55. ({ typeof(ptr) ____ptr = (ptr); \
  56. ____ptr ? rb_entry(____ptr, type, member) : NULL; \
  57. })
  58. /**
  59. * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
  60. * given type allowing the backing memory of @pos to be invalidated
  61. *
  62. * @pos: the 'type *' to use as a loop cursor.
  63. * @n: another 'type *' to use as temporary storage
  64. * @root: 'rb_root *' of the rbtree.
  65. * @field: the name of the rb_node field within 'type'.
  66. *
  67. * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
  68. * list_for_each_entry_safe() and allows the iteration to continue independent
  69. * of changes to @pos by the body of the loop.
  70. *
  71. * Note, however, that it cannot handle other modifications that re-order the
  72. * rbtree it is iterating over. This includes calling rb_erase() on @pos, as
  73. * rb_erase() may rebalance the tree, causing us to miss some nodes.
  74. */
  75. #define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
  76. for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
  77. pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
  78. typeof(*pos), field); 1; }); \
  79. pos = n)
  80. static inline void rb_erase_init(struct rb_node *n, struct rb_root *root)
  81. {
  82. rb_erase(n, root);
  83. RB_CLEAR_NODE(n);
  84. }
  85. /*
  86. * Leftmost-cached rbtrees.
  87. *
  88. * We do not cache the rightmost node based on footprint
  89. * size vs number of potential users that could benefit
  90. * from O(1) rb_last(). Just not worth it, users that want
  91. * this feature can always implement the logic explicitly.
  92. * Furthermore, users that want to cache both pointers may
  93. * find it a bit asymmetric, but that's ok.
  94. */
  95. struct rb_root_cached {
  96. struct rb_root rb_root;
  97. struct rb_node *rb_leftmost;
  98. };
  99. #define RB_ROOT_CACHED (struct rb_root_cached) { {NULL, }, NULL }
  100. /* Same as rb_first(), but O(1) */
  101. #define rb_first_cached(root) (root)->rb_leftmost
  102. static inline void rb_insert_color_cached(struct rb_node *node,
  103. struct rb_root_cached *root,
  104. bool leftmost)
  105. {
  106. if (leftmost)
  107. root->rb_leftmost = node;
  108. rb_insert_color(node, &root->rb_root);
  109. }
  110. static inline void rb_erase_cached(struct rb_node *node,
  111. struct rb_root_cached *root)
  112. {
  113. if (root->rb_leftmost == node)
  114. root->rb_leftmost = rb_next(node);
  115. rb_erase(node, &root->rb_root);
  116. }
  117. static inline void rb_replace_node_cached(struct rb_node *victim,
  118. struct rb_node *new,
  119. struct rb_root_cached *root)
  120. {
  121. if (root->rb_leftmost == victim)
  122. root->rb_leftmost = new;
  123. rb_replace_node(victim, new, &root->rb_root);
  124. }
  125. #endif /* __TOOLS_LINUX_PERF_RBTREE_H */