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 _LINUX_RBTREE_H 18 #define _LINUX_RBTREE_H 19 20 #include <linux/kernel.h> 21 #include <linux/stddef.h> 22 #include <linux/rcupdate.h> 23 24 struct rb_node { 25 unsigned long __rb_parent_color; 26 struct rb_node *rb_right; 27 struct rb_node *rb_left; 28 } __attribute__((aligned(sizeof(long)))); 29 /* The alignment might seem pointless, but allegedly CRIS needs it */ 30 31 struct rb_root { 32 struct rb_node *rb_node; 33 }; 34 35 #define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3)) 36 37 #define RB_ROOT (struct rb_root) { NULL, } 38 #define rb_entry(ptr, type, member) container_of(ptr, type, member) 39 40 #define RB_EMPTY_ROOT(root) (READ_ONCE((root)->rb_node) == NULL) 41 42 /* 'empty' nodes are nodes that are known not to be inserted in an rbtree */ 43 #define RB_EMPTY_NODE(node) \ 44 ((node)->__rb_parent_color == (unsigned long)(node)) 45 #define RB_CLEAR_NODE(node) \ 46 ((node)->__rb_parent_color = (unsigned long)(node)) 47 48 49 extern void rb_insert_color(struct rb_node *, struct rb_root *); 50 extern void rb_erase(struct rb_node *, struct rb_root *); 51 52 53 /* Find logical next and previous nodes in a tree */ 54 extern struct rb_node *rb_next(const struct rb_node *); 55 extern struct rb_node *rb_prev(const struct rb_node *); 56 extern struct rb_node *rb_first(const struct rb_root *); 57 extern struct rb_node *rb_last(const struct rb_root *); 58 59 /* Postorder iteration - always visit the parent after its children */ 60 extern struct rb_node *rb_first_postorder(const struct rb_root *); 61 extern struct rb_node *rb_next_postorder(const struct rb_node *); 62 63 /* Fast replacement of a single node without remove/rebalance/add/rebalance */ 64 extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, 65 struct rb_root *root); 66 extern void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new, 67 struct rb_root *root); 68 69 static inline void rb_link_node(struct rb_node *node, struct rb_node *parent, 70 struct rb_node **rb_link) 71 { 72 node->__rb_parent_color = (unsigned long)parent; 73 node->rb_left = node->rb_right = NULL; 74 75 *rb_link = node; 76 } 77 78 static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent, 79 struct rb_node **rb_link) 80 { 81 node->__rb_parent_color = (unsigned long)parent; 82 node->rb_left = node->rb_right = NULL; 83 84 rcu_assign_pointer(*rb_link, node); 85 } 86 87 #define rb_entry_safe(ptr, type, member) \ 88 ({ typeof(ptr) ____ptr = (ptr); \ 89 ____ptr ? rb_entry(____ptr, type, member) : NULL; \ 90 }) 91 92 /** 93 * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of 94 * given type allowing the backing memory of @pos to be invalidated 95 * 96 * @pos: the 'type *' to use as a loop cursor. 97 * @n: another 'type *' to use as temporary storage 98 * @root: 'rb_root *' of the rbtree. 99 * @field: the name of the rb_node field within 'type'. 100 * 101 * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as 102 * list_for_each_entry_safe() and allows the iteration to continue independent 103 * of changes to @pos by the body of the loop. 104 * 105 * Note, however, that it cannot handle other modifications that re-order the 106 * rbtree it is iterating over. This includes calling rb_erase() on @pos, as 107 * rb_erase() may rebalance the tree, causing us to miss some nodes. 108 */ 109 #define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \ 110 for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \ 111 pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \ 112 typeof(*pos), field); 1; }); \ 113 pos = n) 114 115 /* 116 * Leftmost-cached rbtrees. 117 * 118 * We do not cache the rightmost node based on footprint 119 * size vs number of potential users that could benefit 120 * from O(1) rb_last(). Just not worth it, users that want 121 * this feature can always implement the logic explicitly. 122 * Furthermore, users that want to cache both pointers may 123 * find it a bit asymmetric, but that's ok. 124 */ 125 struct rb_root_cached { 126 struct rb_root rb_root; 127 struct rb_node *rb_leftmost; 128 }; 129 130 #define RB_ROOT_CACHED (struct rb_root_cached) { {NULL, }, NULL } 131 132 /* Same as rb_first(), but O(1) */ 133 #define rb_first_cached(root) (root)->rb_leftmost 134 135 static inline void rb_insert_color_cached(struct rb_node *node, 136 struct rb_root_cached *root, 137 bool leftmost) 138 { 139 if (leftmost) 140 root->rb_leftmost = node; 141 rb_insert_color(node, &root->rb_root); 142 } 143 144 static inline void rb_erase_cached(struct rb_node *node, 145 struct rb_root_cached *root) 146 { 147 if (root->rb_leftmost == node) 148 root->rb_leftmost = rb_next(node); 149 rb_erase(node, &root->rb_root); 150 } 151 152 static inline void rb_replace_node_cached(struct rb_node *victim, 153 struct rb_node *new, 154 struct rb_root_cached *root) 155 { 156 if (root->rb_leftmost == victim) 157 root->rb_leftmost = new; 158 rb_replace_node(victim, new, &root->rb_root); 159 } 160 161 #endif /* _LINUX_RBTREE_H */ 162