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 #include <linux/rcupdate.h> 30 31 /* 32 * Please note - only struct rb_augment_callbacks and the prototypes for 33 * rb_insert_augmented() and rb_erase_augmented() are intended to be public. 34 * The rest are implementation details you are not expected to depend on. 35 * 36 * See Documentation/rbtree.txt for documentation and samples. 37 */ 38 39 struct rb_augment_callbacks { 40 void (*propagate)(struct rb_node *node, struct rb_node *stop); 41 void (*copy)(struct rb_node *old, struct rb_node *new); 42 void (*rotate)(struct rb_node *old, struct rb_node *new); 43 }; 44 45 extern void __rb_insert_augmented(struct rb_node *node, 46 struct rb_root *root, 47 bool newleft, struct rb_node **leftmost, 48 void (*augment_rotate)(struct rb_node *old, struct rb_node *new)); 49 /* 50 * Fixup the rbtree and update the augmented information when rebalancing. 51 * 52 * On insertion, the user must update the augmented information on the path 53 * leading to the inserted node, then call rb_link_node() as usual and 54 * rb_insert_augmented() instead of the usual rb_insert_color() call. 55 * If rb_insert_augmented() rebalances the rbtree, it will callback into 56 * a user provided function to update the augmented information on the 57 * affected subtrees. 58 */ 59 static inline void 60 rb_insert_augmented(struct rb_node *node, struct rb_root *root, 61 const struct rb_augment_callbacks *augment) 62 { 63 __rb_insert_augmented(node, root, false, NULL, augment->rotate); 64 } 65 66 static inline void 67 rb_insert_augmented_cached(struct rb_node *node, 68 struct rb_root_cached *root, bool newleft, 69 const struct rb_augment_callbacks *augment) 70 { 71 __rb_insert_augmented(node, &root->rb_root, 72 newleft, &root->rb_leftmost, augment->rotate); 73 } 74 75 #define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield, \ 76 rbtype, rbaugmented, rbcompute) \ 77 static inline void \ 78 rbname ## _propagate(struct rb_node *rb, struct rb_node *stop) \ 79 { \ 80 while (rb != stop) { \ 81 rbstruct *node = rb_entry(rb, rbstruct, rbfield); \ 82 rbtype augmented = rbcompute(node); \ 83 if (node->rbaugmented == augmented) \ 84 break; \ 85 node->rbaugmented = augmented; \ 86 rb = rb_parent(&node->rbfield); \ 87 } \ 88 } \ 89 static inline void \ 90 rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new) \ 91 { \ 92 rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \ 93 rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \ 94 new->rbaugmented = old->rbaugmented; \ 95 } \ 96 static void \ 97 rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new) \ 98 { \ 99 rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \ 100 rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \ 101 new->rbaugmented = old->rbaugmented; \ 102 old->rbaugmented = rbcompute(old); \ 103 } \ 104 rbstatic const struct rb_augment_callbacks rbname = { \ 105 .propagate = rbname ## _propagate, \ 106 .copy = rbname ## _copy, \ 107 .rotate = rbname ## _rotate \ 108 }; 109 110 111 #define RB_RED 0 112 #define RB_BLACK 1 113 114 #define __rb_parent(pc) ((struct rb_node *)(pc & ~3)) 115 116 #define __rb_color(pc) ((pc) & 1) 117 #define __rb_is_black(pc) __rb_color(pc) 118 #define __rb_is_red(pc) (!__rb_color(pc)) 119 #define rb_color(rb) __rb_color((rb)->__rb_parent_color) 120 #define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color) 121 #define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color) 122 123 static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p) 124 { 125 rb->__rb_parent_color = rb_color(rb) | (unsigned long)p; 126 } 127 128 static inline void rb_set_parent_color(struct rb_node *rb, 129 struct rb_node *p, int color) 130 { 131 rb->__rb_parent_color = (unsigned long)p | color; 132 } 133 134 static inline void 135 __rb_change_child(struct rb_node *old, struct rb_node *new, 136 struct rb_node *parent, struct rb_root *root) 137 { 138 if (parent) { 139 if (parent->rb_left == old) 140 WRITE_ONCE(parent->rb_left, new); 141 else 142 WRITE_ONCE(parent->rb_right, new); 143 } else 144 WRITE_ONCE(root->rb_node, new); 145 } 146 147 static inline void 148 __rb_change_child_rcu(struct rb_node *old, struct rb_node *new, 149 struct rb_node *parent, struct rb_root *root) 150 { 151 if (parent) { 152 if (parent->rb_left == old) 153 rcu_assign_pointer(parent->rb_left, new); 154 else 155 rcu_assign_pointer(parent->rb_right, new); 156 } else 157 rcu_assign_pointer(root->rb_node, new); 158 } 159 160 extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root, 161 void (*augment_rotate)(struct rb_node *old, struct rb_node *new)); 162 163 static __always_inline struct rb_node * 164 __rb_erase_augmented(struct rb_node *node, struct rb_root *root, 165 struct rb_node **leftmost, 166 const struct rb_augment_callbacks *augment) 167 { 168 struct rb_node *child = node->rb_right; 169 struct rb_node *tmp = node->rb_left; 170 struct rb_node *parent, *rebalance; 171 unsigned long pc; 172 173 if (leftmost && node == *leftmost) 174 *leftmost = rb_next(node); 175 176 if (!tmp) { 177 /* 178 * Case 1: node to erase has no more than 1 child (easy!) 179 * 180 * Note that if there is one child it must be red due to 5) 181 * and node must be black due to 4). We adjust colors locally 182 * so as to bypass __rb_erase_color() later on. 183 */ 184 pc = node->__rb_parent_color; 185 parent = __rb_parent(pc); 186 __rb_change_child(node, child, parent, root); 187 if (child) { 188 child->__rb_parent_color = pc; 189 rebalance = NULL; 190 } else 191 rebalance = __rb_is_black(pc) ? parent : NULL; 192 tmp = parent; 193 } else if (!child) { 194 /* Still case 1, but this time the child is node->rb_left */ 195 tmp->__rb_parent_color = pc = node->__rb_parent_color; 196 parent = __rb_parent(pc); 197 __rb_change_child(node, tmp, parent, root); 198 rebalance = NULL; 199 tmp = parent; 200 } else { 201 struct rb_node *successor = child, *child2; 202 203 tmp = child->rb_left; 204 if (!tmp) { 205 /* 206 * Case 2: node's successor is its right child 207 * 208 * (n) (s) 209 * / \ / \ 210 * (x) (s) -> (x) (c) 211 * \ 212 * (c) 213 */ 214 parent = successor; 215 child2 = successor->rb_right; 216 217 augment->copy(node, successor); 218 } else { 219 /* 220 * Case 3: node's successor is leftmost under 221 * node's right child subtree 222 * 223 * (n) (s) 224 * / \ / \ 225 * (x) (y) -> (x) (y) 226 * / / 227 * (p) (p) 228 * / / 229 * (s) (c) 230 * \ 231 * (c) 232 */ 233 do { 234 parent = successor; 235 successor = tmp; 236 tmp = tmp->rb_left; 237 } while (tmp); 238 child2 = successor->rb_right; 239 WRITE_ONCE(parent->rb_left, child2); 240 WRITE_ONCE(successor->rb_right, child); 241 rb_set_parent(child, successor); 242 243 augment->copy(node, successor); 244 augment->propagate(parent, successor); 245 } 246 247 tmp = node->rb_left; 248 WRITE_ONCE(successor->rb_left, tmp); 249 rb_set_parent(tmp, successor); 250 251 pc = node->__rb_parent_color; 252 tmp = __rb_parent(pc); 253 __rb_change_child(node, successor, tmp, root); 254 255 if (child2) { 256 successor->__rb_parent_color = pc; 257 rb_set_parent_color(child2, parent, RB_BLACK); 258 rebalance = NULL; 259 } else { 260 unsigned long pc2 = successor->__rb_parent_color; 261 successor->__rb_parent_color = pc; 262 rebalance = __rb_is_black(pc2) ? parent : NULL; 263 } 264 tmp = successor; 265 } 266 267 augment->propagate(tmp, NULL); 268 return rebalance; 269 } 270 271 static __always_inline void 272 rb_erase_augmented(struct rb_node *node, struct rb_root *root, 273 const struct rb_augment_callbacks *augment) 274 { 275 struct rb_node *rebalance = __rb_erase_augmented(node, root, 276 NULL, augment); 277 if (rebalance) 278 __rb_erase_color(rebalance, root, augment->rotate); 279 } 280 281 static __always_inline void 282 rb_erase_augmented_cached(struct rb_node *node, struct rb_root_cached *root, 283 const struct rb_augment_callbacks *augment) 284 { 285 struct rb_node *rebalance = __rb_erase_augmented(node, &root->rb_root, 286 &root->rb_leftmost, 287 augment); 288 if (rebalance) 289 __rb_erase_color(rebalance, &root->rb_root, augment->rotate); 290 } 291 292 #endif /* _LINUX_RBTREE_AUGMENTED_H */ 293