urcu-rbtree.c

   1 /*
   2  * urcu-rbtree.c
   3  *
   4  * Userspace RCU library - Red-Black Tree
   5  *
   6  * Copyright (c) 2010 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  *
  22  * Implementation of RCU-adapted data structures and operations based on the RB
  23  * tree algorithms found in chapter 12 of:
  24  *
  25  * Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest, and
  26  * Clifford Stein. Introduction to Algorithms, Third Edition. The MIT
  27  * Press, September 2009.
  28  */
  29
  30 #define _BSD_SOURCE
  31 #define _LGPL_SOURCE
  32
  33 #include <stdio.h>
  34 #include <pthread.h>
  35 #include <assert.h>
  36 #include <string.h>
  37 #include <unistd.h>
  38
  39 #include <urcu/rcurbtree.h>
  40 #include <urcu-pointer.h>
  41 #include <urcu-call-rcu.h>
  42 #include <urcu/compiler.h>
  43
  44 #ifdef DEBUG
  45 #define dbg_printf(args...)     printf(args)
  46 #define dbg_usleep(usecs)       usleep(usecs)
  47 #else
  48 #define dbg_printf(args...)
  49 #define dbg_usleep(usecs)
  50 #endif
  51
  52 /*
  53  * Undefine this to enable the non-RCU rotate and transplant functions
  54  * (for debugging).
  55  */
  56 #define RBTREE_RCU_SUPPORT_ROTATE_LEFT
  57 #define RBTREE_RCU_SUPPORT_ROTATE_RIGHT
  58 #define RBTREE_RCU_SUPPORT_TRANSPLANT
  59
  60 #ifdef EXTRA_DEBUG
  61 static pthread_mutex_t test_mutex = PTHREAD_MUTEX_INITIALIZER;
  62 static pthread_mutex_t outer_mutex = PTHREAD_MUTEX_INITIALIZER;
  63
  64 static
  65 void lock_outer_mutex(void)
  66 {
  67         pthread_mutex_lock(&outer_mutex);
  68 }
  69
  70 static
  71 void unlock_outer_mutex(void)
  72 {
  73         pthread_mutex_unlock(&outer_mutex);
  74 }
  75
  76 static
  77 void lock_test_mutex(void)
  78 {
  79         pthread_mutex_lock(&test_mutex);
  80 }
  81
  82 static
  83 void unlock_test_mutex(void)
  84 {
  85         pthread_mutex_unlock(&test_mutex);
  86 }
  87 #endif
  88
  89 static
  90 void set_parent(struct rcu_rbtree_node *node,
  91                 struct rcu_rbtree_node *parent,
  92                 unsigned int pos)
  93 {
  94         _CMM_STORE_SHARED(node->parent, ((unsigned long) parent) | pos);
  95 }
  96
  97 static
  98 struct rcu_rbtree_node *get_parent(struct rcu_rbtree_node *node)
  99 {
 100         return (struct rcu_rbtree_node *) (node->parent & ~1UL);
 101 }
 102
 103 static
 104 unsigned int get_pos(struct rcu_rbtree_node *node)
 105 {
 106         return (unsigned int) (node->parent & 1UL);
 107 }
 108
 109 static
 110 struct rcu_rbtree_node *get_parent_and_pos(struct rcu_rbtree_node *node,
 111                                 unsigned int *pos)
 112 {
 113         unsigned long parent_pos = rcu_dereference(node->parent);
 114
 115         *pos = (unsigned int) (parent_pos & 1UL);
 116         return (struct rcu_rbtree_node *) (parent_pos & ~1UL);
 117 }
 118
 119 static
 120 void set_decay(struct rcu_rbtree_node *x, struct rcu_rbtree_node *xc)
 121 {
 122         x->decay_next = xc;
 123 }
 124
 125 static
 126 struct rcu_rbtree_node *get_decay(struct rcu_rbtree_node *x)
 127 {
 128         if (!x)
 129                 return NULL;
 130         while (x->decay_next)
 131                 x = x->decay_next;
 132         return x;
 133 }
 134
 135 static
 136 struct rcu_rbtree_node *is_decay(struct rcu_rbtree_node *x)
 137 {
 138         return x->decay_next;
 139 }
 140
 141 static
 142 struct rcu_rbtree_node *dup_decay_node(struct rcu_rbtree *rbtree,
 143                                 struct rcu_rbtree_node *x)
 144 {
 145         struct rcu_rbtree_node *xc;
 146
 147         if (rcu_rbtree_is_nil(rbtree, x))
 148                 return x;
 149
 150         xc = rbtree->rballoc();
 151         memcpy(xc, x, sizeof(struct rcu_rbtree_node));
 152         xc->decay_next = NULL;
 153         set_decay(x, xc);
 154         call_rcu(&x->head, rbtree->rbfree);
 155         return xc;
 156 }
 157
 158 /*
 159  * Info for range lookups:
 160  * Range lookup information is only valid when used when searching for
 161  * ranges. It should never be used in next/prev traversal because the
 162  * pointers to parents are not in sync with the parent vision of the
 163  * children range.
 164  */
 165 static
 166 void set_left(struct rcu_rbtree *rbtree, struct rcu_rbtree_node *node,
 167                         struct rcu_rbtree_node *left)
 168 {
 169         node->_left = left;
 170 }
 171
 172 static
 173 void set_right(struct rcu_rbtree *rbtree, struct rcu_rbtree_node *node,
 174                         struct rcu_rbtree_node *right)
 175 {
 176         node->_right = right;
 177 }
 178
 179 /*
 180  * TODO
 181  * Deal with memory allocation errors.
 182  * Can be ensured by reserving a pool of memory entries before doing the
 183  * insertion, which will have to be function of number of
 184  * transplantations/rotations required for the operation.
 185  */
 186
 187 #ifdef DEBUG
 188 static
 189 void show_tree(struct rcu_rbtree *rbtree)
 190 {
 191         struct rcu_rbtree_node *node;
 192
 193         node = rcu_rbtree_min(rbtree, rbtree->root);
 194         while (!rcu_rbtree_is_nil(rbtree, node)) {
 195                 assert(!is_decay(node));
 196                 printf("{ b:%lX e:%lX pb: %lX r:%lX l:%lX %s %s %s} ",
 197                         (unsigned long) node->begin,
 198                         (unsigned long) node->end,
 199                         (unsigned long) get_parent(node)->begin,
 200                         (unsigned long) node->_right->begin,
 201                         (unsigned long) node->_left->begin,
 202                         node->color ? "red" : "black",
 203                         get_pos(node) ? "right" : "left",
 204                         rcu_rbtree_is_nil(rbtree, node) ? "nil" : "");
 205                 node = rcu_rbtree_next(rbtree, node);
 206         }
 207         printf("\n");
 208 }
 209 #else /* DEBUG */
 210 static
 211 void show_tree(struct rcu_rbtree *rbtree)
 212 {
 213 }
 214 #endif /* DEBUG */
 215
 216 static
 217 struct rcu_rbtree_node *make_nil(struct rcu_rbtree *rbtree)
 218 {
 219         return &rbtree->nil_node;
 220 }
 221
 222 /*
 223  * Iterative rbtree search.
 224  */
 225 struct rcu_rbtree_node *rcu_rbtree_search(struct rcu_rbtree *rbtree,
 226                                           struct rcu_rbtree_node *x,
 227                                           void *k)
 228 {
 229         x = rcu_dereference(x);
 230         int comp;
 231
 232         while (!rcu_rbtree_is_nil(rbtree, x) && (comp = rbtree->comp(k, x->begin)) != 0) {
 233                 dbg_usleep(10);
 234                 if (comp < 0)
 235                         x = rcu_dereference(x->_left);
 236                 else
 237                         x = rcu_dereference(x->_right);
 238         }
 239         return x;
 240 }
 241
 242 static
 243 struct rcu_rbtree_node *rcu_rbtree_min_dup_decay(struct rcu_rbtree *rbtree,
 244                                                  struct rcu_rbtree_node *x,
 245                                                  struct rcu_rbtree_node **zr)
 246 {
 247         struct rcu_rbtree_node *xl;
 248
 249         x = rcu_dereference(x);
 250
 251         if (rcu_rbtree_is_nil(rbtree, x)) {
 252                 *zr = x;
 253                 return x;
 254         } else
 255                 *zr = x = dup_decay_node(rbtree, x);
 256
 257         while (!rcu_rbtree_is_nil(rbtree, xl = rcu_dereference(x->_left))) {
 258                 x = dup_decay_node(rbtree, xl);
 259                 set_parent(x, get_decay(get_parent(x)), get_pos(x));
 260                 get_parent(x)->_left = get_decay(get_parent(x)->_left);
 261         }
 262         return x;
 263 }
 264
 265 static
 266 struct rcu_rbtree_node *rcu_rbtree_min_update_decay(struct rcu_rbtree *rbtree,
 267                                                     struct rcu_rbtree_node *x)
 268 {
 269         struct rcu_rbtree_node *xl;
 270
 271         x = rcu_dereference(x);
 272
 273         if (rcu_rbtree_is_nil(rbtree, x))
 274                 return x;
 275         else {
 276                 set_parent(x->_right, get_decay(get_parent(x->_right)),
 277                            get_pos(x->_right));
 278                 set_parent(x->_left, get_decay(get_parent(x->_left)),
 279                            get_pos(x->_left));
 280         }
 281
 282         while (!rcu_rbtree_is_nil(rbtree, xl = rcu_dereference(x->_left))) {
 283                 x = xl;
 284                 set_parent(x->_right, get_decay(get_parent(x->_right)),
 285                            get_pos(x->_right));
 286                 set_parent(x->_left, get_decay(get_parent(x->_left)),
 287                            get_pos(x->_left));
 288         }
 289         return x;
 290 }
 291
 292 struct rcu_rbtree_node *rcu_rbtree_min(struct rcu_rbtree *rbtree,
 293                                        struct rcu_rbtree_node *x)
 294 {
 295         struct rcu_rbtree_node *xl;
 296
 297         x = rcu_dereference(x);
 298
 299         if (rcu_rbtree_is_nil(rbtree, x))
 300                 return x;
 301
 302         while (!rcu_rbtree_is_nil(rbtree, xl = rcu_dereference(x->_left)))
 303                 x = xl;
 304         return x;
 305 }
 306
 307 struct rcu_rbtree_node *rcu_rbtree_max(struct rcu_rbtree *rbtree,
 308                                        struct rcu_rbtree_node *x)
 309 {
 310         struct rcu_rbtree_node *xr;
 311
 312         x = rcu_dereference(x);
 313
 314         if (rcu_rbtree_is_nil(rbtree, x))
 315                 return x;
 316
 317         while (!rcu_rbtree_is_nil(rbtree, xr = rcu_dereference(x->_right)))
 318                 x = xr;
 319         return x;
 320 }
 321
 322 /*
 323  * FIXME:
 324  * Updates should wait for a grace period between update of the
 325  * redirect pointer and update of the parent child pointer. This is to make sure
 326  * that no reference to the old entry exist.
 327  */
 328
 329 /*
 330  * RCU read lock must be held across the next/prev calls to ensure validity of
 331  * the returned node.
 332  */
 333 struct rcu_rbtree_node *rcu_rbtree_next(struct rcu_rbtree *rbtree,
 334                                         struct rcu_rbtree_node *x)
 335 {
 336         struct rcu_rbtree_node *xr, *y;
 337         unsigned int x_pos;
 338
 339         x = rcu_dereference(x);
 340
 341         if (!rcu_rbtree_is_nil(rbtree, xr = rcu_dereference(x->_right)))
 342                 return rcu_rbtree_min(rbtree, xr);
 343         y = get_parent_and_pos(x, &x_pos);
 344         while (!rcu_rbtree_is_nil(rbtree, y) && x_pos == IS_RIGHT) {
 345                 x = y;
 346                 y = get_parent_and_pos(y, &x_pos);
 347         }
 348         return y;
 349 }
 350
 351 struct rcu_rbtree_node *rcu_rbtree_prev(struct rcu_rbtree *rbtree,
 352                                         struct rcu_rbtree_node *x)
 353 {
 354         struct rcu_rbtree_node *xl, *y;
 355         unsigned int x_pos;
 356
 357         x = rcu_dereference(x);
 358
 359         if (!rcu_rbtree_is_nil(rbtree, xl = rcu_dereference(x->_left)))
 360                 return rcu_rbtree_max(rbtree, xl);
 361         y = get_parent_and_pos(x, &x_pos);
 362         while (!rcu_rbtree_is_nil(rbtree, y) && x_pos == IS_LEFT) {
 363                 x = y;
 364                 y = get_parent_and_pos(y, &x_pos);
 365         }
 366         return y;
 367 }
 368
 369 /*
 370  * "node" needs to be non-visible by readers.
 371  */
 372 static
 373 void populate_node_end(struct rcu_rbtree *rbtree, struct rcu_rbtree_node *node,
 374                 unsigned int copy_parents, struct rcu_rbtree_node *stop)
 375 {
 376         struct rcu_rbtree_node *prev = NULL, *orig_node = node, *top;
 377
 378         do {
 379                 void *max_end;
 380
 381                 assert(node);
 382                 assert(!rcu_rbtree_is_nil(rbtree, node));
 383                 max_end = node->end;
 384                 if (!rcu_rbtree_is_nil(rbtree, node->_right))
 385                         max_end = max(max_end, node->_right->max_end);
 386                 if (!rcu_rbtree_is_nil(rbtree, node->_left))
 387                         max_end = max(max_end, node->_left->max_end);
 388
 389                 if (max_end != node->max_end) {
 390                         if (prev && copy_parents) {
 391                                 node = dup_decay_node(rbtree, node);
 392                                 if (get_pos(prev) == IS_RIGHT)
 393                                         node->_right = prev;
 394                                 else
 395                                         node->_left = prev;
 396                                 set_parent(prev, node, get_pos(prev));
 397                         }
 398                         node->max_end = max_end;
 399                 } else {
 400                         /*
 401                          * We did not have to change the current node,
 402                          * so set the pointer to the prev node. If prev
 403                          * was null, this means we are coming in the
 404                          * first loop, and must update the parent of the
 405                          * node received as parameter (node).
 406                          */
 407                         if (prev)
 408                                 node = prev;
 409                         top = get_parent(node);
 410                         cmm_smp_wmb();  /* write into node before publish */
 411                         /* make new branch visible to readers */
 412                         if (rcu_rbtree_is_nil(rbtree, top))
 413                                 _CMM_STORE_SHARED(rbtree->root, node);
 414                         if (get_pos(node) == IS_LEFT)
 415                                 _CMM_STORE_SHARED(top->_left, node);
 416                         else
 417                                 _CMM_STORE_SHARED(top->_right, node);
 418                         goto end;
 419                 }
 420
 421                 /* Check for propagation stop */
 422                 if (node == stop)
 423                         return;
 424
 425                 prev = node;
 426                 node = get_parent(node);
 427         } while (!rcu_rbtree_is_nil(rbtree, node));
 428
 429         top = node;     /* nil */
 430         cmm_smp_wmb();  /* write into node before publish */
 431         /* make new branch visible to readers */
 432         _CMM_STORE_SHARED(rbtree->root, prev);
 433
 434 end:
 435         if (!copy_parents)
 436                 return;
 437         /* update children */
 438         node = orig_node;
 439         do {
 440                 assert(!rcu_rbtree_is_nil(rbtree, node));
 441                 set_parent(node->_left, get_decay(get_parent(node->_left)), IS_LEFT);
 442                 set_parent(node->_right, get_decay(get_parent(node->_right)), IS_RIGHT);
 443         } while ((node = get_parent(node)) != top);
 444 }
 445
 446 /*
 447  * We have to ensure these assumptions are correct for prev/next
 448  * traversal:
 449  *
 450  * with x being a right child, the assumption that:
 451  *   get_parent(x)->_right == x
 452  * or if x is a left child, the assumption that:
 453  *   get_parent(x)->_left == x
 454  *
 455  * This explains why we have to allocate a vc copy of the node for left_rotate,
 456  * right_rotate and transplant operations.
 457  *
 458  * We always ensure that the right/left child and correct parent is set in the
 459  * node copies *before* we reparent the children and make the upper-level point
 460  * to the copy.
 461  */
 462
 463 /* RCU: copy x and y, atomically point to new versions. GC old. */
 464 /* Should be eventually followed by a cmm_smp_wmc() */
 465
 466 #ifdef RBTREE_RCU_SUPPORT_ROTATE_LEFT
 467
 468 static
 469 void left_rotate(struct rcu_rbtree *rbtree,
 470                  struct rcu_rbtree_node *x)
 471 {
 472         struct rcu_rbtree_node *y, *y_left;
 473
 474         y = x->_right;
 475         y_left = y->_left;
 476
 477         /* Now operate on new copy, decay old versions */
 478         x = dup_decay_node(rbtree, x);
 479         y = dup_decay_node(rbtree, y);
 480         y_left = dup_decay_node(rbtree, y_left);
 481
 482         /* Internal node modifications */
 483         set_parent(y, get_parent(x), get_pos(x));
 484         set_parent(x, y, IS_LEFT);
 485         set_left(rbtree, y, x);
 486         set_right(rbtree, x, y_left);
 487
 488         if (!rcu_rbtree_is_nil(rbtree, y_left))
 489                 set_parent(y_left, x, IS_RIGHT);
 490
 491         cmm_smp_wmb();  /* write into node before publish */
 492
 493         /* External references update (visible by readers) */
 494         if (rcu_rbtree_is_nil(rbtree, get_parent(y)))
 495                 _CMM_STORE_SHARED(rbtree->root, y);
 496         else if (get_pos(y) == IS_LEFT)
 497                 _CMM_STORE_SHARED(get_parent(y)->_left, y);
 498         else
 499                 _CMM_STORE_SHARED(get_parent(y)->_right, y);
 500
 501         /* Point children to new copy (parent only used by updates/next/prev) */
 502         set_parent(x->_left, get_decay(get_parent(x->_left)),
 503                 get_pos(x->_left));
 504         set_parent(y->_right, get_decay(get_parent(y->_right)),
 505                 get_pos(y->_right));
 506         if (!rcu_rbtree_is_nil(rbtree, y_left)) {
 507                 set_parent(y_left->_right,
 508                         get_decay(get_parent(y_left->_right)),
 509                         get_pos(y_left->_right));
 510                 set_parent(y_left->_left,
 511                         get_decay(get_parent(y_left->_left)),
 512                         get_pos(y_left->_left));
 513         }
 514
 515         /* Sanity checks */
 516         assert(y == rbtree->root || get_parent(y)->_left == y
 517                 || get_parent(y)->_right == y);
 518         assert(x == rbtree->root || get_parent(x)->_left == x
 519                 || get_parent(x)->_right == x);
 520         assert(rcu_rbtree_is_nil(rbtree, x->_right) || get_parent(x->_right) == x);
 521         assert(rcu_rbtree_is_nil(rbtree, x->_left) || get_parent(x->_left) == x);
 522         assert(rcu_rbtree_is_nil(rbtree, y->_right) || get_parent(y->_right) == y);
 523         assert(rcu_rbtree_is_nil(rbtree, y->_left) || get_parent(y->_left) == y);
 524         assert(!is_decay(rbtree->root));
 525         assert(!is_decay(x));
 526         assert(!is_decay(y));
 527         assert(!is_decay(x->_right));
 528         assert(!is_decay(x->_left));
 529         assert(!is_decay(y->_right));
 530         assert(!is_decay(y->_left));
 531 }
 532
 533 #else
 534
 535 /* non-rcu version */
 536 static
 537 void left_rotate(struct rcu_rbtree *rbtree,
 538                  struct rcu_rbtree_node *x)
 539 {
 540         struct rcu_rbtree_node *y;
 541
 542         lock_test_mutex();
 543         y = x->_right;
 544         x->_right = y->_left;
 545         if (!rcu_rbtree_is_nil(rbtree, y->_left))
 546                 set_parent(y->_left, x, IS_RIGHT);
 547         set_parent(y, get_parent(x), get_pos(x));
 548         if (rcu_rbtree_is_nil(rbtree, get_parent(x)))
 549                 rbtree->root = y;
 550         else if (x == get_parent(x)->_left) {
 551                 get_parent(x)->_left = y;
 552         } else {
 553                 get_parent(x)->_right = y;
 554         }
 555         y->_left = x;
 556         set_parent(x, y, IS_LEFT);
 557         unlock_test_mutex();
 558 }
 559
 560 #endif
 561
 562 #ifdef RBTREE_RCU_SUPPORT_ROTATE_RIGHT
 563 static
 564 void right_rotate(struct rcu_rbtree *rbtree,
 565                   struct rcu_rbtree_node *x)
 566 {
 567         struct rcu_rbtree_node *y, *y_right;
 568
 569         y = x->_left;
 570         y_right = y->_right;
 571
 572         /* Now operate on new copy, decay old versions */
 573         x = dup_decay_node(rbtree, x);
 574         y = dup_decay_node(rbtree, y);
 575         y_right = dup_decay_node(rbtree, y_right);
 576
 577         /* Internal node modifications */
 578         set_parent(y, get_parent(x), get_pos(x));
 579         set_parent(x, y, IS_RIGHT);
 580         set_right(rbtree, y, x);
 581         set_left(rbtree, x, y_right);
 582
 583         if (!rcu_rbtree_is_nil(rbtree, y_right))
 584                 set_parent(y_right, x, IS_LEFT);
 585
 586         cmm_smp_wmb();  /* write into node before publish */
 587
 588         /* External references update (visible by readers) */
 589         if (rcu_rbtree_is_nil(rbtree, get_parent(y)))
 590                 _CMM_STORE_SHARED(rbtree->root, y);
 591         else if (get_pos(y) == IS_RIGHT)
 592                 _CMM_STORE_SHARED(get_parent(y)->_right, y);
 593         else
 594                 _CMM_STORE_SHARED(get_parent(y)->_left, y);
 595
 596         /* Point children to new copy (parent only used by updates/next/prev) */
 597         set_parent(x->_right, get_decay(get_parent(x->_right)),
 598                 get_pos(x->_right));
 599         set_parent(y->_left, get_decay(get_parent(y->_left)),
 600                 get_pos(y->_left));
 601         if (!rcu_rbtree_is_nil(rbtree, y_right)) {
 602                 set_parent(y_right->_left,
 603                         get_decay(get_parent(y_right->_left)),
 604                         get_pos(y_right->_left));
 605                 set_parent(y_right->_right,
 606                         get_decay(get_parent(y_right->_right)),
 607                         get_pos(y_right->_right));
 608         }
 609
 610         /* Sanity checks */
 611         assert(y == rbtree->root || get_parent(y)->_right == y
 612                 || get_parent(y)->_left == y);
 613         assert(x == rbtree->root || get_parent(x)->_right == x
 614                 || get_parent(x)->_left == x);
 615         assert(rcu_rbtree_is_nil(rbtree, x->_left) || get_parent(x->_left) == x);
 616         assert(rcu_rbtree_is_nil(rbtree, x->_right) || get_parent(x->_right) == x);
 617         assert(rcu_rbtree_is_nil(rbtree, y->_left) || get_parent(y->_left) == y);
 618         assert(rcu_rbtree_is_nil(rbtree, y->_right) || get_parent(y->_right) == y);
 619         assert(!is_decay(rbtree->root));
 620         assert(!is_decay(x));
 621         assert(!is_decay(y));
 622         assert(!is_decay(x->_left));
 623         assert(!is_decay(x->_right));
 624         assert(!is_decay(y->_left));
 625         assert(!is_decay(y->_right));
 626 }
 627
 628 #else
 629
 630 /* non-rcu version */
 631 static
 632 void right_rotate(struct rcu_rbtree *rbtree,
 633                   struct rcu_rbtree_node *x)
 634 {
 635         struct rcu_rbtree_node *y;
 636
 637         lock_test_mutex();
 638         y = x->_left;
 639         x->_left = y->_right;
 640         if (!rcu_rbtree_is_nil(rbtree, y->_right))
 641                 set_parent(y->_right, x, IS_LEFT);
 642         set_parent(y, get_parent(x), get_pos(x));
 643         if (rcu_rbtree_is_nil(rbtree, get_parent(x)))
 644                 rbtree->root = y;
 645         else if (x == get_parent(x)->_right) {
 646                 get_parent(x)->_right = y;
 647         } else {
 648                 get_parent(x)->_left = y;
 649         }
 650         y->_right = x;
 651         set_parent(x, y, IS_RIGHT);
 652         unlock_test_mutex();
 653 }
 654
 655 #endif
 656
 657 static void rcu_rbtree_insert_fixup(struct rcu_rbtree *rbtree,
 658                                     struct rcu_rbtree_node *z)
 659 {
 660         struct rcu_rbtree_node *y;
 661
 662         dbg_printf("insert fixup %p\n", z->begin);
 663         assert(!is_decay(rbtree->root));
 664
 665         while (get_parent(z)->color == COLOR_RED) {
 666                 if (get_parent(z) == get_parent(get_parent(z))->_left) {
 667                         y = get_parent(get_parent(z))->_right;
 668                         if (y->color == COLOR_RED) {
 669                                 get_parent(z)->color = COLOR_BLACK;
 670                                 y->color = COLOR_BLACK;
 671                                 get_parent(get_parent(z))->color = COLOR_RED;
 672                                 z = get_parent(get_parent(z));
 673                         } else {
 674                                 if (z == get_parent(z)->_right) {
 675                                         z = get_parent(z);
 676                                         left_rotate(rbtree, z);
 677                                         z = get_decay(z);
 678                                         assert(!is_decay(rbtree->root));
 679                                 }
 680                                 get_parent(z)->color = COLOR_BLACK;
 681                                 get_parent(get_parent(z))->color = COLOR_RED;
 682                                 assert(!is_decay(z));
 683                                 assert(!is_decay(get_parent(z)));
 684                                 assert(!is_decay(get_parent(get_parent(z))));
 685                                 right_rotate(rbtree, get_parent(get_parent(z)));
 686                                 assert(!is_decay(z));
 687                                 assert(!is_decay(rbtree->root));
 688                         }
 689                 } else {
 690                         y = get_parent(get_parent(z))->_left;
 691                         if (y->color == COLOR_RED) {
 692                                 get_parent(z)->color = COLOR_BLACK;
 693                                 y->color = COLOR_BLACK;
 694                                 get_parent(get_parent(z))->color = COLOR_RED;
 695                                 z = get_parent(get_parent(z));
 696                         } else {
 697                                 if (z == get_parent(z)->_left) {
 698                                         z = get_parent(z);
 699                                         right_rotate(rbtree, z);
 700                                         z = get_decay(z);
 701                                         assert(!is_decay(rbtree->root));
 702                                 }
 703                                 get_parent(z)->color = COLOR_BLACK;
 704                                 get_parent(get_parent(z))->color = COLOR_RED;
 705                                 left_rotate(rbtree, get_parent(get_parent(z)));
 706                                 assert(!is_decay(z));
 707                                 assert(!is_decay(rbtree->root));
 708                         }
 709                 }
 710         }
 711         rbtree->root->color = COLOR_BLACK;
 712 }
 713
 714 /*
 715  * rcu_rbtree_insert - Insert a node in the RCU rbtree
 716  *
 717  * Returns 0 on success, or < 0 on error.
 718  */
 719 int rcu_rbtree_insert(struct rcu_rbtree *rbtree,
 720                       struct rcu_rbtree_node *z)
 721 {
 722         struct rcu_rbtree_node *x, *y;
 723
 724         dbg_printf("insert %p\n", z->begin);
 725         assert(!is_decay(rbtree->root));
 726
 727         y = make_nil(rbtree);
 728         x = rbtree->root;
 729         while (!rcu_rbtree_is_nil(rbtree, x)) {
 730                 y = x;
 731                 if (rbtree->comp(z->begin, x->begin) < 0)
 732                         x = x->_left;
 733                 else
 734                         x = x->_right;
 735         }
 736
 737         z->_left = make_nil(rbtree);
 738         z->_right = make_nil(rbtree);
 739         z->color = COLOR_RED;
 740         z->decay_next = NULL;
 741         z->max_end = z->end;
 742
 743         if (rcu_rbtree_is_nil(rbtree, y)) {
 744                 set_parent(z, y, IS_RIGHT); /* pos arbitrary for root node */
 745                 /*
 746                  * Order stores to z (children/parents) before stores
 747                  * that will make it visible to the rest of the tree.
 748                  */
 749                 cmm_smp_wmb();
 750                 _CMM_STORE_SHARED(rbtree->root, z);
 751         } else if (rbtree->comp(z->begin, y->begin) < 0) {
 752                 y = dup_decay_node(rbtree, y);
 753                 set_parent(z, y, IS_LEFT);
 754                 if (get_pos(z) == IS_LEFT)
 755                         _CMM_STORE_SHARED(y->_left, z);
 756                 else
 757                         _CMM_STORE_SHARED(y->_right, z);
 758                 populate_node_end(rbtree, y, 1, NULL);
 759         } else {
 760                 y = dup_decay_node(rbtree, y);
 761                 set_parent(z, y, IS_RIGHT);
 762                 if (get_pos(z) == IS_LEFT)
 763                         _CMM_STORE_SHARED(y->_left, z);
 764                 else
 765                         _CMM_STORE_SHARED(y->_right, z);
 766                 populate_node_end(rbtree, y, 1, NULL);
 767         }
 768         rcu_rbtree_insert_fixup(rbtree, z);
 769         /*
 770          * Make sure to commit all _CMM_STORE_SHARED() for non-coherent caches.
 771          */
 772         cmm_smp_wmc();
 773         show_tree(rbtree);
 774
 775         return 0;
 776 }
 777
 778 /*
 779  * Transplant v into u position.
 780  */
 781
 782 #ifdef RBTREE_RCU_SUPPORT_TRANSPLANT
 783
 784 static
 785 void rcu_rbtree_transplant(struct rcu_rbtree *rbtree,
 786                         struct rcu_rbtree_node *u,
 787                         struct rcu_rbtree_node *v,
 788                         unsigned int copy_parents,
 789                         struct rcu_rbtree_node *stop)
 790 {
 791         dbg_printf("transplant %p\n", v->begin);
 792
 793         if (!rcu_rbtree_is_nil(rbtree, v))
 794                 v = dup_decay_node(rbtree, v);
 795
 796         if (rcu_rbtree_is_nil(rbtree, get_parent(u))) {
 797                 /* pos is arbitrary for root node */
 798                 set_parent(v, get_parent(u), IS_RIGHT);
 799                 cmm_smp_wmb();  /* write into node before publish */
 800                 _CMM_STORE_SHARED(rbtree->root, v);
 801         } else {
 802                 struct rcu_rbtree_node *vp;
 803
 804                 vp = get_parent(u);
 805                 if (copy_parents)
 806                         vp = dup_decay_node(rbtree, vp);
 807                 set_parent(v, vp, get_pos(u));
 808                 if (get_pos(v) == IS_LEFT)
 809                         _CMM_STORE_SHARED(vp->_left, v);
 810                 else
 811                         _CMM_STORE_SHARED(vp->_right, v);
 812                 populate_node_end(rbtree, vp, copy_parents, stop);
 813         }
 814
 815         /* Point children to new copy (parent only used by updates/next/prev) */
 816         if (!rcu_rbtree_is_nil(rbtree, v)) {
 817                 set_parent(v->_right, get_decay(get_parent(v->_right)),
 818                         get_pos(v->_right));
 819                 set_parent(v->_left, get_decay(get_parent(v->_left)),
 820                         get_pos(v->_left));
 821         }
 822         assert(!is_decay(rbtree->root));
 823 }
 824
 825 #else
 826
 827 /* Non-RCU version */
 828 static
 829 void rcu_rbtree_transplant(struct rcu_rbtree *rbtree,
 830                            struct rcu_rbtree_node *u,
 831                            struct rcu_rbtree_node *v,
 832                            unsigned int copy_parents,
 833                            struct rcu_rbtree_node *stop)
 834 {
 835         dbg_printf("transplant %p\n", v->begin);
 836
 837         lock_test_mutex();
 838         if (rcu_rbtree_is_nil(rbtree, get_parent(u)))
 839                 rbtree->root = v;
 840         else if (u == get_parent(u)->_left)
 841                 get_parent(u)->_left = v;
 842         else
 843                 get_parent(u)->_right = v;
 844         set_parent(v, get_parent(u), get_pos(u));
 845         unlock_test_mutex();
 846 }
 847
 848 #endif
 849
 850 static void rcu_rbtree_remove_fixup(struct rcu_rbtree *rbtree,
 851                                     struct rcu_rbtree_node *x)
 852 {
 853         dbg_printf("remove fixup %p\n", x->begin);
 854
 855         while (x != rbtree->root && x->color == COLOR_BLACK) {
 856                 assert(!is_decay(get_parent(x)));
 857                 assert(!is_decay(get_parent(x)->_left));
 858                 if (x == get_parent(x)->_left) {
 859                         struct rcu_rbtree_node *w;
 860
 861                         w = get_parent(x)->_right;
 862
 863                         if (w->color == COLOR_RED) {
 864                                 w->color = COLOR_BLACK;
 865                                 get_parent(x)->color = COLOR_RED;
 866                                 left_rotate(rbtree, get_parent(x));
 867                                 x = get_decay(x);
 868                                 assert(!is_decay(rbtree->root));
 869                                 w = get_parent(x)->_right;
 870                         }
 871                         if (w->_left->color == COLOR_BLACK
 872                             && w->_right->color == COLOR_BLACK) {
 873                                 w->color = COLOR_RED;
 874                                 x = get_parent(x);
 875                                 assert(!is_decay(rbtree->root));
 876                                 assert(!is_decay(x));
 877                         } else {
 878                                 if (w->_right->color == COLOR_BLACK) {
 879                                         w->_left->color = COLOR_BLACK;
 880                                         w->color = COLOR_RED;
 881                                         right_rotate(rbtree, w);
 882                                         assert(!is_decay(rbtree->root));
 883                                         x = get_decay(x);
 884                                         w = get_parent(x)->_right;
 885                                 }
 886                                 w->color = get_parent(x)->color;
 887                                 get_parent(x)->color = COLOR_BLACK;
 888                                 w->_right->color = COLOR_BLACK;
 889                                 left_rotate(rbtree, get_parent(x));
 890                                 assert(!is_decay(rbtree->root));
 891                                 x = rbtree->root;
 892                         }
 893                 } else {
 894                         struct rcu_rbtree_node *w;
 895
 896                         w = get_parent(x)->_left;
 897
 898                         if (w->color == COLOR_RED) {
 899                                 w->color = COLOR_BLACK;
 900                                 get_parent(x)->color = COLOR_RED;
 901                                 right_rotate(rbtree, get_parent(x));
 902                                 assert(!is_decay(rbtree->root));
 903                                 x = get_decay(x);
 904                                 w = get_parent(x)->_left;
 905                         }
 906                         if (w->_right->color == COLOR_BLACK
 907                             && w->_left->color == COLOR_BLACK) {
 908                                 w->color = COLOR_RED;
 909                                 x = get_parent(x);
 910                                 assert(!is_decay(rbtree->root));
 911                                 assert(!is_decay(x));
 912                         } else {
 913                                 if (w->_left->color == COLOR_BLACK) {
 914                                         w->_right->color = COLOR_BLACK;
 915                                         w->color = COLOR_RED;
 916                                         left_rotate(rbtree, w);
 917                                         assert(!is_decay(rbtree->root));
 918                                         x = get_decay(x);
 919                                         w = get_parent(x)->_left;
 920                                 }
 921                                 w->color = get_parent(x)->color;
 922                                 get_parent(x)->color = COLOR_BLACK;
 923                                 w->_left->color = COLOR_BLACK;
 924                                 right_rotate(rbtree, get_parent(x));
 925                                 assert(!is_decay(rbtree->root));
 926                                 x = rbtree->root;
 927                         }
 928                 }
 929         }
 930         x->color = COLOR_BLACK;
 931 }
 932
 933 /*
 934  * Delete z. All non-copied children left/right positions are unchanged.
 935  */
 936 static
 937 void rcu_rbtree_remove_nonil(struct rcu_rbtree *rbtree,
 938                              struct rcu_rbtree_node *z,
 939                              struct rcu_rbtree_node *y)
 940 {
 941         struct rcu_rbtree_node *x;
 942
 943         dbg_printf("remove nonil %p\n", z->begin);
 944         show_tree(rbtree);
 945
 946         assert(!is_decay(z));
 947         assert(!is_decay(y));
 948         assert(!is_decay(y->_right));
 949         assert(!is_decay(get_parent(y)));
 950         x = y->_right;
 951         assert(!is_decay(x));
 952         if (get_parent(y) == z) {
 953                 y = dup_decay_node(rbtree, y);
 954                 set_parent(x, y, get_pos(x));   /* parent for nil */
 955                 /* y is z's right node: set left will just update y */
 956                 set_left(rbtree, y, z->_left);
 957                 rcu_rbtree_transplant(rbtree, z, y, 1, NULL);
 958         } else {
 959                 struct rcu_rbtree_node *oy_right, *z_right;
 960
 961                 /*
 962                  * Need to make sure y is always visible by readers.
 963                  */
 964                 y = rcu_rbtree_min_dup_decay(rbtree, z->_right, &z_right);
 965                 assert(!is_decay(y));
 966                 assert(!is_decay(z));
 967                 oy_right = y->_right;
 968
 969                 /*
 970                  * The max child begin of z_right does not change, because
 971                  * we're only changing its left children.
 972                  */
 973                 y->_right = z_right;
 974                 set_parent(y->_right, y, IS_RIGHT);
 975                 assert(!is_decay(z->_left));
 976                 y->_left = z->_left;
 977                 assert(!is_decay(oy_right));
 978                 /*
 979                  * Transplant of oy_right to old y's location will only
 980                  * trigger a "end" value update of the already copied branch
 981                  * (which is not visible yet). We are transplanting
 982                  * oy_right as a left child of old y's parent, so the
 983                  * min values update propagated upward necessarily stops
 984                  * at z_right.
 985                  */
 986                 rcu_rbtree_transplant(rbtree, y, oy_right, 0, y);
 987                 rcu_rbtree_transplant(rbtree, z, y, 1, NULL);
 988                 /* Update children */
 989                 (void) rcu_rbtree_min_update_decay(rbtree, y->_right);
 990         }
 991         y = get_decay(y);
 992         assert(!is_decay(z));
 993         assert(!is_decay(z->_left));
 994         y->color = z->color;
 995         set_parent(y->_left, y, IS_LEFT);
 996         set_parent(y->_right, get_decay(get_parent(y->_right)), IS_RIGHT);
 997         assert(!is_decay(y->_left));
 998         assert(!is_decay(y->_right));
 999 }
1000
1001 int rcu_rbtree_remove(struct rcu_rbtree *rbtree,
1002                       struct rcu_rbtree_node *z)
1003 {
1004         struct rcu_rbtree_node *x, *y;
1005         unsigned int y_original_color;
1006
1007         assert(!is_decay(rbtree->root));
1008         dbg_printf("remove %p\n", z->begin);
1009         show_tree(rbtree);
1010
1011         assert(!is_decay(z));
1012         y = z;
1013         y_original_color = y->color;
1014
1015         if (rcu_rbtree_is_nil(rbtree, z->_left)) {
1016                 rcu_rbtree_transplant(rbtree, z, z->_right, 1, NULL);
1017                 assert(!is_decay(z));
1018                 x = get_decay(z->_right);
1019                 show_tree(rbtree);
1020         } else if (rcu_rbtree_is_nil(rbtree, z->_right)) {
1021                 rcu_rbtree_transplant(rbtree, z, z->_left, 1, NULL);
1022                 assert(!is_decay(z));
1023                 x = get_decay(z->_left);
1024                 show_tree(rbtree);
1025         } else {
1026                 y = rcu_rbtree_min(rbtree, z->_right);
1027                 assert(!is_decay(y));
1028                 y_original_color = y->color;
1029                 x = y->_right;
1030                 rcu_rbtree_remove_nonil(rbtree, z, y);
1031                 x = get_decay(x);
1032                 show_tree(rbtree);
1033         }
1034         if (y_original_color == COLOR_BLACK)
1035                 rcu_rbtree_remove_fixup(rbtree, x);
1036         show_tree(rbtree);
1037         /*
1038          * Commit all _CMM_STORE_SHARED().
1039          */
1040         cmm_smp_wmc();
1041
1042         return 0;
1043 }