tools/include/linux/rbtree_augmented.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3   Red Black Trees
   4   (C) 1999  Andrea Arcangeli <andrea@suse.de>
   5   (C) 2002  David Woodhouse <dwmw2@infradead.org>
   6   (C) 2012  Michel Lespinasse <walken@google.com>
   7
   8
   9   tools/linux/include/linux/rbtree_augmented.h
  10
  11   Copied from:
  12   linux/include/linux/rbtree_augmented.h
  13 */
  14
  15 #ifndef _TOOLS_LINUX_RBTREE_AUGMENTED_H
  16 #define _TOOLS_LINUX_RBTREE_AUGMENTED_H
  17
  18 #include <linux/compiler.h>
  19 #include <linux/rbtree.h>
  20
  21 /*
  22  * Please note - only struct rb_augment_callbacks and the prototypes for
  23  * rb_insert_augmented() and rb_erase_augmented() are intended to be public.
  24  * The rest are implementation details you are not expected to depend on.
  25  *
  26  * See Documentation/rbtree.txt for documentation and samples.
  27  */
  28
  29 struct rb_augment_callbacks {
  30         void (*propagate)(struct rb_node *node, struct rb_node *stop);
  31         void (*copy)(struct rb_node *old, struct rb_node *new);
  32         void (*rotate)(struct rb_node *old, struct rb_node *new);
  33 };
  34
  35 extern void __rb_insert_augmented(struct rb_node *node,
  36                                   struct rb_root *root,
  37                                   bool newleft, struct rb_node **leftmost,
  38         void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
  39 /*
  40  * Fixup the rbtree and update the augmented information when rebalancing.
  41  *
  42  * On insertion, the user must update the augmented information on the path
  43  * leading to the inserted node, then call rb_link_node() as usual and
  44  * rb_augment_inserted() instead of the usual rb_insert_color() call.
  45  * If rb_augment_inserted() rebalances the rbtree, it will callback into
  46  * a user provided function to update the augmented information on the
  47  * affected subtrees.
  48  */
  49 static inline void
  50 rb_insert_augmented(struct rb_node *node, struct rb_root *root,
  51                     const struct rb_augment_callbacks *augment)
  52 {
  53         __rb_insert_augmented(node, root, false, NULL, augment->rotate);
  54 }
  55
  56 static inline void
  57 rb_insert_augmented_cached(struct rb_node *node,
  58                            struct rb_root_cached *root, bool newleft,
  59                            const struct rb_augment_callbacks *augment)
  60 {
  61         __rb_insert_augmented(node, &root->rb_root,
  62                               newleft, &root->rb_leftmost, augment->rotate);
  63 }
  64
  65 #define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield,       \
  66                              rbtype, rbaugmented, rbcompute)            \
  67 static inline void                                                      \
  68 rbname ## _propagate(struct rb_node *rb, struct rb_node *stop)          \
  69 {                                                                       \
  70         while (rb != stop) {                                            \
  71                 rbstruct *node = rb_entry(rb, rbstruct, rbfield);       \
  72                 rbtype augmented = rbcompute(node);                     \
  73                 if (node->rbaugmented == augmented)                     \
  74                         break;                                          \
  75                 node->rbaugmented = augmented;                          \
  76                 rb = rb_parent(&node->rbfield);                         \
  77         }                                                               \
  78 }                                                                       \
  79 static inline void                                                      \
  80 rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new)         \
  81 {                                                                       \
  82         rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);            \
  83         rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);            \
  84         new->rbaugmented = old->rbaugmented;                            \
  85 }                                                                       \
  86 static void                                                             \
  87 rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new)       \
  88 {                                                                       \
  89         rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);            \
  90         rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);            \
  91         new->rbaugmented = old->rbaugmented;                            \
  92         old->rbaugmented = rbcompute(old);                              \
  93 }                                                                       \
  94 rbstatic const struct rb_augment_callbacks rbname = {                   \
  95         .propagate = rbname ## _propagate,                              \
  96         .copy = rbname ## _copy,                                        \
  97         .rotate = rbname ## _rotate                                     \
  98 };
  99
 100
 101 #define RB_RED          0
 102 #define RB_BLACK        1
 103
 104 #define __rb_parent(pc)    ((struct rb_node *)(pc & ~3))
 105
 106 #define __rb_color(pc)     ((pc) & 1)
 107 #define __rb_is_black(pc)  __rb_color(pc)
 108 #define __rb_is_red(pc)    (!__rb_color(pc))
 109 #define rb_color(rb)       __rb_color((rb)->__rb_parent_color)
 110 #define rb_is_red(rb)      __rb_is_red((rb)->__rb_parent_color)
 111 #define rb_is_black(rb)    __rb_is_black((rb)->__rb_parent_color)
 112
 113 static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
 114 {
 115         rb->__rb_parent_color = rb_color(rb) | (unsigned long)p;
 116 }
 117
 118 static inline void rb_set_parent_color(struct rb_node *rb,
 119                                        struct rb_node *p, int color)
 120 {
 121         rb->__rb_parent_color = (unsigned long)p | color;
 122 }
 123
 124 static inline void
 125 __rb_change_child(struct rb_node *old, struct rb_node *new,
 126                   struct rb_node *parent, struct rb_root *root)
 127 {
 128         if (parent) {
 129                 if (parent->rb_left == old)
 130                         WRITE_ONCE(parent->rb_left, new);
 131                 else
 132                         WRITE_ONCE(parent->rb_right, new);
 133         } else
 134                 WRITE_ONCE(root->rb_node, new);
 135 }
 136
 137 extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
 138         void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
 139
 140 static __always_inline struct rb_node *
 141 __rb_erase_augmented(struct rb_node *node, struct rb_root *root,
 142                      struct rb_node **leftmost,
 143                      const struct rb_augment_callbacks *augment)
 144 {
 145         struct rb_node *child = node->rb_right;
 146         struct rb_node *tmp = node->rb_left;
 147         struct rb_node *parent, *rebalance;
 148         unsigned long pc;
 149
 150         if (leftmost && node == *leftmost)
 151                 *leftmost = rb_next(node);
 152
 153         if (!tmp) {
 154                 /*
 155                  * Case 1: node to erase has no more than 1 child (easy!)
 156                  *
 157                  * Note that if there is one child it must be red due to 5)
 158                  * and node must be black due to 4). We adjust colors locally
 159                  * so as to bypass __rb_erase_color() later on.
 160                  */
 161                 pc = node->__rb_parent_color;
 162                 parent = __rb_parent(pc);
 163                 __rb_change_child(node, child, parent, root);
 164                 if (child) {
 165                         child->__rb_parent_color = pc;
 166                         rebalance = NULL;
 167                 } else
 168                         rebalance = __rb_is_black(pc) ? parent : NULL;
 169                 tmp = parent;
 170         } else if (!child) {
 171                 /* Still case 1, but this time the child is node->rb_left */
 172                 tmp->__rb_parent_color = pc = node->__rb_parent_color;
 173                 parent = __rb_parent(pc);
 174                 __rb_change_child(node, tmp, parent, root);
 175                 rebalance = NULL;
 176                 tmp = parent;
 177         } else {
 178                 struct rb_node *successor = child, *child2;
 179
 180                 tmp = child->rb_left;
 181                 if (!tmp) {
 182                         /*
 183                          * Case 2: node's successor is its right child
 184                          *
 185                          *    (n)          (s)
 186                          *    / \          / \
 187                          *  (x) (s)  ->  (x) (c)
 188                          *        \
 189                          *        (c)
 190                          */
 191                         parent = successor;
 192                         child2 = successor->rb_right;
 193
 194                         augment->copy(node, successor);
 195                 } else {
 196                         /*
 197                          * Case 3: node's successor is leftmost under
 198                          * node's right child subtree
 199                          *
 200                          *    (n)          (s)
 201                          *    / \          / \
 202                          *  (x) (y)  ->  (x) (y)
 203                          *      /            /
 204                          *    (p)          (p)
 205                          *    /            /
 206                          *  (s)          (c)
 207                          *    \
 208                          *    (c)
 209                          */
 210                         do {
 211                                 parent = successor;
 212                                 successor = tmp;
 213                                 tmp = tmp->rb_left;
 214                         } while (tmp);
 215                         child2 = successor->rb_right;
 216                         WRITE_ONCE(parent->rb_left, child2);
 217                         WRITE_ONCE(successor->rb_right, child);
 218                         rb_set_parent(child, successor);
 219
 220                         augment->copy(node, successor);
 221                         augment->propagate(parent, successor);
 222                 }
 223
 224                 tmp = node->rb_left;
 225                 WRITE_ONCE(successor->rb_left, tmp);
 226                 rb_set_parent(tmp, successor);
 227
 228                 pc = node->__rb_parent_color;
 229                 tmp = __rb_parent(pc);
 230                 __rb_change_child(node, successor, tmp, root);
 231
 232                 if (child2) {
 233                         successor->__rb_parent_color = pc;
 234                         rb_set_parent_color(child2, parent, RB_BLACK);
 235                         rebalance = NULL;
 236                 } else {
 237                         unsigned long pc2 = successor->__rb_parent_color;
 238                         successor->__rb_parent_color = pc;
 239                         rebalance = __rb_is_black(pc2) ? parent : NULL;
 240                 }
 241                 tmp = successor;
 242         }
 243
 244         augment->propagate(tmp, NULL);
 245         return rebalance;
 246 }
 247
 248 static __always_inline void
 249 rb_erase_augmented(struct rb_node *node, struct rb_root *root,
 250                    const struct rb_augment_callbacks *augment)
 251 {
 252         struct rb_node *rebalance = __rb_erase_augmented(node, root,
 253                                                          NULL, augment);
 254         if (rebalance)
 255                 __rb_erase_color(rebalance, root, augment->rotate);
 256 }
 257
 258 static __always_inline void
 259 rb_erase_augmented_cached(struct rb_node *node, struct rb_root_cached *root,
 260                           const struct rb_augment_callbacks *augment)
 261 {
 262         struct rb_node *rebalance = __rb_erase_augmented(node, &root->rb_root,
 263                                                          &root->rb_leftmost,
 264                                                          augment);
 265         if (rebalance)
 266                 __rb_erase_color(rebalance, &root->rb_root, augment->rotate);
 267 }
 268
 269 #endif /* _TOOLS_LINUX_RBTREE_AUGMENTED_H */