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