rbtree.h 5.1 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 _LINUX_RBTREE_H
  13. #define _LINUX_RBTREE_H
  14. #include <linux/kernel.h>
  15. #include <linux/stddef.h>
  16. #include <linux/rcupdate.h>
  17. struct rb_node {
  18. unsigned long __rb_parent_color;
  19. struct rb_node *rb_right;
  20. struct rb_node *rb_left;
  21. } __attribute__((aligned(sizeof(long))));
  22. /* The alignment might seem pointless, but allegedly CRIS needs it */
  23. struct rb_root {
  24. struct rb_node *rb_node;
  25. };
  26. #define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3))
  27. #define RB_ROOT (struct rb_root) { NULL, }
  28. #define rb_entry(ptr, type, member) container_of(ptr, type, member)
  29. #define RB_EMPTY_ROOT(root) (READ_ONCE((root)->rb_node) == NULL)
  30. /* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
  31. #define RB_EMPTY_NODE(node) \
  32. ((node)->__rb_parent_color == (unsigned long)(node))
  33. #define RB_CLEAR_NODE(node) \
  34. ((node)->__rb_parent_color = (unsigned long)(node))
  35. extern void rb_insert_color(struct rb_node *, struct rb_root *);
  36. extern void rb_erase(struct rb_node *, struct rb_root *);
  37. /* Find logical next and previous nodes in a tree */
  38. extern struct rb_node *rb_next(const struct rb_node *);
  39. extern struct rb_node *rb_prev(const struct rb_node *);
  40. extern struct rb_node *rb_first(const struct rb_root *);
  41. extern struct rb_node *rb_last(const struct rb_root *);
  42. /* Postorder iteration - always visit the parent after its children */
  43. extern struct rb_node *rb_first_postorder(const struct rb_root *);
  44. extern struct rb_node *rb_next_postorder(const struct rb_node *);
  45. /* Fast replacement of a single node without remove/rebalance/add/rebalance */
  46. extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
  47. struct rb_root *root);
  48. extern void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new,
  49. struct rb_root *root);
  50. static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
  51. struct rb_node **rb_link)
  52. {
  53. node->__rb_parent_color = (unsigned long)parent;
  54. node->rb_left = node->rb_right = NULL;
  55. *rb_link = node;
  56. }
  57. static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent,
  58. struct rb_node **rb_link)
  59. {
  60. node->__rb_parent_color = (unsigned long)parent;
  61. node->rb_left = node->rb_right = NULL;
  62. rcu_assign_pointer(*rb_link, node);
  63. }
  64. #define rb_entry_safe(ptr, type, member) \
  65. ({ typeof(ptr) ____ptr = (ptr); \
  66. ____ptr ? rb_entry(____ptr, type, member) : NULL; \
  67. })
  68. /**
  69. * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
  70. * given type allowing the backing memory of @pos to be invalidated
  71. *
  72. * @pos: the 'type *' to use as a loop cursor.
  73. * @n: another 'type *' to use as temporary storage
  74. * @root: 'rb_root *' of the rbtree.
  75. * @field: the name of the rb_node field within 'type'.
  76. *
  77. * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
  78. * list_for_each_entry_safe() and allows the iteration to continue independent
  79. * of changes to @pos by the body of the loop.
  80. *
  81. * Note, however, that it cannot handle other modifications that re-order the
  82. * rbtree it is iterating over. This includes calling rb_erase() on @pos, as
  83. * rb_erase() may rebalance the tree, causing us to miss some nodes.
  84. */
  85. #define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
  86. for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
  87. pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
  88. typeof(*pos), field); 1; }); \
  89. pos = n)
  90. /*
  91. * Leftmost-cached rbtrees.
  92. *
  93. * We do not cache the rightmost node based on footprint
  94. * size vs number of potential users that could benefit
  95. * from O(1) rb_last(). Just not worth it, users that want
  96. * this feature can always implement the logic explicitly.
  97. * Furthermore, users that want to cache both pointers may
  98. * find it a bit asymmetric, but that's ok.
  99. */
  100. struct rb_root_cached {
  101. struct rb_root rb_root;
  102. struct rb_node *rb_leftmost;
  103. };
  104. #define RB_ROOT_CACHED (struct rb_root_cached) { {NULL, }, NULL }
  105. /* Same as rb_first(), but O(1) */
  106. #define rb_first_cached(root) (root)->rb_leftmost
  107. static inline void rb_insert_color_cached(struct rb_node *node,
  108. struct rb_root_cached *root,
  109. bool leftmost)
  110. {
  111. if (leftmost)
  112. root->rb_leftmost = node;
  113. rb_insert_color(node, &root->rb_root);
  114. }
  115. static inline void rb_erase_cached(struct rb_node *node,
  116. struct rb_root_cached *root)
  117. {
  118. if (root->rb_leftmost == node)
  119. root->rb_leftmost = rb_next(node);
  120. rb_erase(node, &root->rb_root);
  121. }
  122. static inline void rb_replace_node_cached(struct rb_node *victim,
  123. struct rb_node *new,
  124. struct rb_root_cached *root)
  125. {
  126. if (root->rb_leftmost == victim)
  127. root->rb_leftmost = new;
  128. rb_replace_node(victim, new, &root->rb_root);
  129. }
  130. #endif /* _LINUX_RBTREE_H */