1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 Red Black Trees 4 (C) 1999 Andrea Arcangeli <[email protected]> 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 */ 156