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