1 /* 2 Red Black Trees 3 (C) 1999 Andrea Arcangeli <andrea@suse.de> 4 5 This program is free software; you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 2 of the License, or 8 (at your option) any later version. 9 10 This program is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU General Public License for more details. 14 15 You should have received a copy of the GNU General Public License 16 along with this program; if not, write to the Free Software 17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 18 19 linux/include/linux/rbtree.h 20 21 To use rbtrees you'll have to implement your own insert and search cores. 22 This will avoid us to use callbacks and to drop drammatically performances. 23 I know it's not the cleaner way, but in C (not in C++) to get 24 performances and genericity... 25 26 See Documentation/rbtree.txt for documentation and samples. 27 */ 28 29 #ifndef _LINUX_RBTREE_H 30 #define _LINUX_RBTREE_H 31 32 #include <linux/kernel.h> 33 #include <linux/stddef.h> 34 #include <linux/rcupdate.h> 35 36 struct rb_node { 37 unsigned long __rb_parent_color; 38 struct rb_node *rb_right; 39 struct rb_node *rb_left; 40 } __attribute__((aligned(sizeof(long)))); 41 /* The alignment might seem pointless, but allegedly CRIS needs it */ 42 43 struct rb_root { 44 struct rb_node *rb_node; 45 }; 46 47 /* 48 * Leftmost-cached rbtrees. 49 * 50 * We do not cache the rightmost node based on footprint 51 * size vs number of potential users that could benefit 52 * from O(1) rb_last(). Just not worth it, users that want 53 * this feature can always implement the logic explicitly. 54 * Furthermore, users that want to cache both pointers may 55 * find it a bit asymmetric, but that's ok. 56 */ 57 struct rb_root_cached { 58 struct rb_root rb_root; 59 struct rb_node *rb_leftmost; 60 }; 61 62 #define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3)) 63 64 #define RB_ROOT (struct rb_root) { NULL, } 65 #define RB_ROOT_CACHED (struct rb_root_cached) { {NULL, }, NULL } 66 #define rb_entry(ptr, type, member) container_of(ptr, type, member) 67 68 #define RB_EMPTY_ROOT(root) (READ_ONCE((root)->rb_node) == NULL) 69 70 /* 'empty' nodes are nodes that are known not to be inserted in an rbtree */ 71 #define RB_EMPTY_NODE(node) \ 72 ((node)->__rb_parent_color == (unsigned long)(node)) 73 #define RB_CLEAR_NODE(node) \ 74 ((node)->__rb_parent_color = (unsigned long)(node)) 75 76 77 extern void rb_insert_color(struct rb_node *, struct rb_root *); 78 extern void rb_erase(struct rb_node *, struct rb_root *); 79 80 81 /* Find logical next and previous nodes in a tree */ 82 extern struct rb_node *rb_next(const struct rb_node *); 83 extern struct rb_node *rb_prev(const struct rb_node *); 84 extern struct rb_node *rb_first(const struct rb_root *); 85 extern struct rb_node *rb_last(const struct rb_root *); 86 87 extern void rb_insert_color_cached(struct rb_node *, 88 struct rb_root_cached *, bool); 89 extern void rb_erase_cached(struct rb_node *node, struct rb_root_cached *); 90 /* Same as rb_first(), but O(1) */ 91 #define rb_first_cached(root) (root)->rb_leftmost 92 93 /* Postorder iteration - always visit the parent after its children */ 94 extern struct rb_node *rb_first_postorder(const struct rb_root *); 95 extern struct rb_node *rb_next_postorder(const struct rb_node *); 96 97 /* Fast replacement of a single node without remove/rebalance/add/rebalance */ 98 extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, 99 struct rb_root *root); 100 extern void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new, 101 struct rb_root *root); 102 extern void rb_replace_node_cached(struct rb_node *victim, struct rb_node *new, 103 struct rb_root_cached *root); 104 105 static inline void rb_link_node(struct rb_node *node, struct rb_node *parent, 106 struct rb_node **rb_link) 107 { 108 node->__rb_parent_color = (unsigned long)parent; 109 node->rb_left = node->rb_right = NULL; 110 111 *rb_link = node; 112 } 113 114 static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent, 115 struct rb_node **rb_link) 116 { 117 node->__rb_parent_color = (unsigned long)parent; 118 node->rb_left = node->rb_right = NULL; 119 120 rcu_assign_pointer(*rb_link, node); 121 } 122 123 #define rb_entry_safe(ptr, type, member) \ 124 ({ typeof(ptr) ____ptr = (ptr); \ 125 ____ptr ? rb_entry(____ptr, type, member) : NULL; \ 126 }) 127 128 /** 129 * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of 130 * given type allowing the backing memory of @pos to be invalidated 131 * 132 * @pos: the 'type *' to use as a loop cursor. 133 * @n: another 'type *' to use as temporary storage 134 * @root: 'rb_root *' of the rbtree. 135 * @field: the name of the rb_node field within 'type'. 136 * 137 * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as 138 * list_for_each_entry_safe() and allows the iteration to continue independent 139 * of changes to @pos by the body of the loop. 140 * 141 * Note, however, that it cannot handle other modifications that re-order the 142 * rbtree it is iterating over. This includes calling rb_erase() on @pos, as 143 * rb_erase() may rebalance the tree, causing us to miss some nodes. 144 */ 145 #define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \ 146 for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \ 147 pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \ 148 typeof(*pos), field); 1; }); \ 149 pos = n) 150 151 #endif /* _LINUX_RBTREE_H */ 152