1 /* 2 Red Black Trees 3 (C) 1999 Andrea Arcangeli <andrea@suse.de> 4 (C) 2002 David Woodhouse <dwmw2@infradead.org> 5 (C) 2012 Michel Lespinasse <walken@google.com> 6 7 This program is free software; you can redistribute it and/or modify 8 it under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 2 of the License, or 10 (at your option) any later version. 11 12 This program is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 GNU General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with this program; if not, write to the Free Software 19 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20 21 linux/include/linux/rbtree_augmented.h 22 */ 23 24 #ifndef _LINUX_RBTREE_AUGMENTED_H 25 #define _LINUX_RBTREE_AUGMENTED_H 26 27 #include <linux/compiler.h> 28 #include <linux/rbtree.h> 29 30 /* 31 * Please note - only struct rb_augment_callbacks and the prototypes for 32 * rb_insert_augmented() and rb_erase_augmented() are intended to be public. 33 * The rest are implementation details you are not expected to depend on. 34 * 35 * See Documentation/rbtree.txt for documentation and samples. 36 */ 37 38 struct rb_augment_callbacks { 39 void (*propagate)(struct rb_node *node, struct rb_node *stop); 40 void (*copy)(struct rb_node *old, struct rb_node *new); 41 void (*rotate)(struct rb_node *old, struct rb_node *new); 42 }; 43 44 extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root, 45 void (*augment_rotate)(struct rb_node *old, struct rb_node *new)); 46 /* 47 * Fixup the rbtree and update the augmented information when rebalancing. 48 * 49 * On insertion, the user must update the augmented information on the path 50 * leading to the inserted node, then call rb_link_node() as usual and 51 * rb_augment_inserted() instead of the usual rb_insert_color() call. 52 * If rb_augment_inserted() rebalances the rbtree, it will callback into 53 * a user provided function to update the augmented information on the 54 * affected subtrees. 55 */ 56 static inline void 57 rb_insert_augmented(struct rb_node *node, struct rb_root *root, 58 const struct rb_augment_callbacks *augment) 59 { 60 __rb_insert_augmented(node, root, augment->rotate); 61 } 62 63 #define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield, \ 64 rbtype, rbaugmented, rbcompute) \ 65 static inline void \ 66 rbname ## _propagate(struct rb_node *rb, struct rb_node *stop) \ 67 { \ 68 while (rb != stop) { \ 69 rbstruct *node = rb_entry(rb, rbstruct, rbfield); \ 70 rbtype augmented = rbcompute(node); \ 71 if (node->rbaugmented == augmented) \ 72 break; \ 73 node->rbaugmented = augmented; \ 74 rb = rb_parent(&node->rbfield); \ 75 } \ 76 } \ 77 static inline void \ 78 rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new) \ 79 { \ 80 rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \ 81 rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \ 82 new->rbaugmented = old->rbaugmented; \ 83 } \ 84 static void \ 85 rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new) \ 86 { \ 87 rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \ 88 rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \ 89 new->rbaugmented = old->rbaugmented; \ 90 old->rbaugmented = rbcompute(old); \ 91 } \ 92 rbstatic const struct rb_augment_callbacks rbname = { \ 93 rbname ## _propagate, rbname ## _copy, rbname ## _rotate \ 94 }; 95 96 97 #define RB_RED 0 98 #define RB_BLACK 1 99 100 #define __rb_parent(pc) ((struct rb_node *)(pc & ~3)) 101 102 #define __rb_color(pc) ((pc) & 1) 103 #define __rb_is_black(pc) __rb_color(pc) 104 #define __rb_is_red(pc) (!__rb_color(pc)) 105 #define rb_color(rb) __rb_color((rb)->__rb_parent_color) 106 #define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color) 107 #define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color) 108 109 static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p) 110 { 111 rb->__rb_parent_color = rb_color(rb) | (unsigned long)p; 112 } 113 114 static inline void rb_set_parent_color(struct rb_node *rb, 115 struct rb_node *p, int color) 116 { 117 rb->__rb_parent_color = (unsigned long)p | color; 118 } 119 120 static inline void 121 __rb_change_child(struct rb_node *old, struct rb_node *new, 122 struct rb_node *parent, struct rb_root *root) 123 { 124 if (parent) { 125 if (parent->rb_left == old) 126 WRITE_ONCE(parent->rb_left, new); 127 else 128 WRITE_ONCE(parent->rb_right, new); 129 } else 130 WRITE_ONCE(root->rb_node, new); 131 } 132 133 static inline void 134 __rb_change_child_rcu(struct rb_node *old, struct rb_node *new, 135 struct rb_node *parent, struct rb_root *root) 136 { 137 if (parent) { 138 if (parent->rb_left == old) 139 rcu_assign_pointer(parent->rb_left, new); 140 else 141 rcu_assign_pointer(parent->rb_right, new); 142 } else 143 rcu_assign_pointer(root->rb_node, new); 144 } 145 146 extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root, 147 void (*augment_rotate)(struct rb_node *old, struct rb_node *new)); 148 149 static __always_inline struct rb_node * 150 __rb_erase_augmented(struct rb_node *node, struct rb_root *root, 151 const struct rb_augment_callbacks *augment) 152 { 153 struct rb_node *child = node->rb_right; 154 struct rb_node *tmp = node->rb_left; 155 struct rb_node *parent, *rebalance; 156 unsigned long pc; 157 158 if (!tmp) { 159 /* 160 * Case 1: node to erase has no more than 1 child (easy!) 161 * 162 * Note that if there is one child it must be red due to 5) 163 * and node must be black due to 4). We adjust colors locally 164 * so as to bypass __rb_erase_color() later on. 165 */ 166 pc = node->__rb_parent_color; 167 parent = __rb_parent(pc); 168 __rb_change_child(node, child, parent, root); 169 if (child) { 170 child->__rb_parent_color = pc; 171 rebalance = NULL; 172 } else 173 rebalance = __rb_is_black(pc) ? parent : NULL; 174 tmp = parent; 175 } else if (!child) { 176 /* Still case 1, but this time the child is node->rb_left */ 177 tmp->__rb_parent_color = pc = node->__rb_parent_color; 178 parent = __rb_parent(pc); 179 __rb_change_child(node, tmp, parent, root); 180 rebalance = NULL; 181 tmp = parent; 182 } else { 183 struct rb_node *successor = child, *child2; 184 185 tmp = child->rb_left; 186 if (!tmp) { 187 /* 188 * Case 2: node's successor is its right child 189 * 190 * (n) (s) 191 * / \ / \ 192 * (x) (s) -> (x) (c) 193 * \ 194 * (c) 195 */ 196 parent = successor; 197 child2 = successor->rb_right; 198 199 augment->copy(node, successor); 200 } else { 201 /* 202 * Case 3: node's successor is leftmost under 203 * node's right child subtree 204 * 205 * (n) (s) 206 * / \ / \ 207 * (x) (y) -> (x) (y) 208 * / / 209 * (p) (p) 210 * / / 211 * (s) (c) 212 * \ 213 * (c) 214 */ 215 do { 216 parent = successor; 217 successor = tmp; 218 tmp = tmp->rb_left; 219 } while (tmp); 220 child2 = successor->rb_right; 221 WRITE_ONCE(parent->rb_left, child2); 222 WRITE_ONCE(successor->rb_right, child); 223 rb_set_parent(child, successor); 224 225 augment->copy(node, successor); 226 augment->propagate(parent, successor); 227 } 228 229 tmp = node->rb_left; 230 WRITE_ONCE(successor->rb_left, tmp); 231 rb_set_parent(tmp, successor); 232 233 pc = node->__rb_parent_color; 234 tmp = __rb_parent(pc); 235 __rb_change_child(node, successor, tmp, root); 236 237 if (child2) { 238 successor->__rb_parent_color = pc; 239 rb_set_parent_color(child2, parent, RB_BLACK); 240 rebalance = NULL; 241 } else { 242 unsigned long pc2 = successor->__rb_parent_color; 243 successor->__rb_parent_color = pc; 244 rebalance = __rb_is_black(pc2) ? parent : NULL; 245 } 246 tmp = successor; 247 } 248 249 augment->propagate(tmp, NULL); 250 return rebalance; 251 } 252 253 static __always_inline void 254 rb_erase_augmented(struct rb_node *node, struct rb_root *root, 255 const struct rb_augment_callbacks *augment) 256 { 257 struct rb_node *rebalance = __rb_erase_augmented(node, root, augment); 258 if (rebalance) 259 __rb_erase_color(rebalance, root, augment->rotate); 260 } 261 262 #endif /* _LINUX_RBTREE_AUGMENTED_H */ 263