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                         if (rbtree->comp(max_end, node->_right->max_end) < 0)
 386                                 max_end = node->_right->max_end;
 387                 }
 388                 if (!rcu_rbtree_is_nil(rbtree, node->_left)) {
 389                         if (rbtree->comp(max_end, node->_left->max_end) < 0)
 390                                 max_end = node->_left->max_end;
 391                 }
 392
 393                 if (rbtree->comp(max_end, node->max_end) != 0) {
 394                         if (prev && copy_parents) {
 395                                 node = dup_decay_node(rbtree, node);
 396                                 if (get_pos(prev) == IS_RIGHT)
 397                                         node->_right = prev;
 398                                 else
 399                                         node->_left = prev;
 400                                 set_parent(prev, node, get_pos(prev));
 401                         }
 402                         node->max_end = max_end;
 403                 } else {
 404                         /*
 405                          * We did not have to change the current node,
 406                          * so set the pointer to the prev node. If prev
 407                          * was null, this means we are coming in the
 408                          * first loop, and must update the parent of the
 409                          * node received as parameter (node).
 410                          */
 411                         if (prev)
 412                                 node = prev;
 413                         top = get_parent(node);
 414                         cmm_smp_wmb();  /* write into node before publish */
 415                         /* make new branch visible to readers */
 416                         if (rcu_rbtree_is_nil(rbtree, top))
 417                                 _CMM_STORE_SHARED(rbtree->root, node);
 418                         if (get_pos(node) == IS_LEFT)
 419                                 _CMM_STORE_SHARED(top->_left, node);
 420                         else
 421                                 _CMM_STORE_SHARED(top->_right, node);
 422                         goto end;
 423                 }
 424
 425                 /* Check for propagation stop */
 426                 if (node == stop)
 427                         return;
 428
 429                 prev = node;
 430                 node = get_parent(node);
 431         } while (!rcu_rbtree_is_nil(rbtree, node));
 432
 433         top = node;     /* nil */
 434         cmm_smp_wmb();  /* write into node before publish */
 435         /* make new branch visible to readers */
 436         _CMM_STORE_SHARED(rbtree->root, prev);
 437
 438 end:
 439         if (!copy_parents)
 440                 return;
 441         /* update children */
 442         node = orig_node;
 443         do {
 444                 assert(!rcu_rbtree_is_nil(rbtree, node));
 445                 set_parent(node->_left, get_decay(get_parent(node->_left)), IS_LEFT);
 446                 set_parent(node->_right, get_decay(get_parent(node->_right)), IS_RIGHT);
 447         } while ((node = get_parent(node)) != top);
 448 }
 449
 450 /*
 451  * We have to ensure these assumptions are correct for prev/next
 452  * traversal:
 453  *
 454  * with x being a right child, the assumption that:
 455  *   get_parent(x)->_right == x
 456  * or if x is a left child, the assumption that:
 457  *   get_parent(x)->_left == x
 458  *
 459  * This explains why we have to allocate a vc copy of the node for left_rotate,
 460  * right_rotate and transplant operations.
 461  *
 462  * We always ensure that the right/left child and correct parent is set in the
 463  * node copies *before* we reparent the children and make the upper-level point
 464  * to the copy.
 465  */
 466
 467 /* RCU: copy x and y, atomically point to new versions. GC old. */
 468 /* Should be eventually followed by a cmm_smp_wmc() */
 469
 470 #ifdef RBTREE_RCU_SUPPORT_ROTATE_LEFT
 471
 472 static
 473 void left_rotate(struct rcu_rbtree *rbtree,
 474                  struct rcu_rbtree_node *x)
 475 {
 476         struct rcu_rbtree_node *y, *y_left;
 477
 478         y = x->_right;
 479         y_left = y->_left;
 480
 481         /* Now operate on new copy, decay old versions */
 482         x = dup_decay_node(rbtree, x);
 483         y = dup_decay_node(rbtree, y);
 484         y_left = dup_decay_node(rbtree, y_left);
 485
 486         /* Internal node modifications */
 487         set_parent(y, get_parent(x), get_pos(x));
 488         set_parent(x, y, IS_LEFT);
 489         set_left(rbtree, y, x);
 490         set_right(rbtree, x, y_left);
 491
 492         if (!rcu_rbtree_is_nil(rbtree, y_left))
 493                 set_parent(y_left, x, IS_RIGHT);
 494
 495         cmm_smp_wmb();  /* write into node before publish */
 496
 497         /* External references update (visible by readers) */
 498         if (rcu_rbtree_is_nil(rbtree, get_parent(y)))
 499                 _CMM_STORE_SHARED(rbtree->root, y);
 500         else if (get_pos(y) == IS_LEFT)
 501                 _CMM_STORE_SHARED(get_parent(y)->_left, y);
 502         else
 503                 _CMM_STORE_SHARED(get_parent(y)->_right, y);
 504
 505         /* Point children to new copy (parent only used by updates/next/prev) */
 506         set_parent(x->_left, get_decay(get_parent(x->_left)),
 507                 get_pos(x->_left));
 508         set_parent(y->_right, get_decay(get_parent(y->_right)),
 509                 get_pos(y->_right));
 510         if (!rcu_rbtree_is_nil(rbtree, y_left)) {
 511                 set_parent(y_left->_right,
 512                         get_decay(get_parent(y_left->_right)),
 513                         get_pos(y_left->_right));
 514                 set_parent(y_left->_left,
 515                         get_decay(get_parent(y_left->_left)),
 516                         get_pos(y_left->_left));
 517         }
 518
 519         /* Sanity checks */
 520         assert(y == rbtree->root || get_parent(y)->_left == y
 521                 || get_parent(y)->_right == y);
 522         assert(x == rbtree->root || get_parent(x)->_left == x
 523                 || get_parent(x)->_right == x);
 524         assert(rcu_rbtree_is_nil(rbtree, x->_right) || get_parent(x->_right) == x);
 525         assert(rcu_rbtree_is_nil(rbtree, x->_left) || get_parent(x->_left) == x);
 526         assert(rcu_rbtree_is_nil(rbtree, y->_right) || get_parent(y->_right) == y);
 527         assert(rcu_rbtree_is_nil(rbtree, y->_left) || get_parent(y->_left) == y);
 528         assert(!is_decay(rbtree->root));
 529         assert(!is_decay(x));
 530         assert(!is_decay(y));
 531         assert(!is_decay(x->_right));
 532         assert(!is_decay(x->_left));
 533         assert(!is_decay(y->_right));
 534         assert(!is_decay(y->_left));
 535 }
 536
 537 #else
 538
 539 /* non-rcu version */
 540 static
 541 void left_rotate(struct rcu_rbtree *rbtree,
 542                  struct rcu_rbtree_node *x)
 543 {
 544         struct rcu_rbtree_node *y;
 545
 546         lock_test_mutex();
 547         y = x->_right;
 548         x->_right = y->_left;
 549         if (!rcu_rbtree_is_nil(rbtree, y->_left))
 550                 set_parent(y->_left, x, IS_RIGHT);
 551         set_parent(y, get_parent(x), get_pos(x));
 552         if (rcu_rbtree_is_nil(rbtree, get_parent(x)))
 553                 rbtree->root = y;
 554         else if (x == get_parent(x)->_left) {
 555                 get_parent(x)->_left = y;
 556         } else {
 557                 get_parent(x)->_right = y;
 558         }
 559         y->_left = x;
 560         set_parent(x, y, IS_LEFT);
 561         unlock_test_mutex();
 562 }
 563
 564 #endif
 565
 566 #ifdef RBTREE_RCU_SUPPORT_ROTATE_RIGHT
 567 static
 568 void right_rotate(struct rcu_rbtree *rbtree,
 569                   struct rcu_rbtree_node *x)
 570 {
 571         struct rcu_rbtree_node *y, *y_right;
 572
 573         y = x->_left;
 574         y_right = y->_right;
 575
 576         /* Now operate on new copy, decay old versions */
 577         x = dup_decay_node(rbtree, x);
 578         y = dup_decay_node(rbtree, y);
 579         y_right = dup_decay_node(rbtree, y_right);
 580
 581         /* Internal node modifications */
 582         set_parent(y, get_parent(x), get_pos(x));
 583         set_parent(x, y, IS_RIGHT);
 584         set_right(rbtree, y, x);
 585         set_left(rbtree, x, y_right);
 586
 587         if (!rcu_rbtree_is_nil(rbtree, y_right))
 588                 set_parent(y_right, x, IS_LEFT);
 589
 590         cmm_smp_wmb();  /* write into node before publish */
 591
 592         /* External references update (visible by readers) */
 593         if (rcu_rbtree_is_nil(rbtree, get_parent(y)))
 594                 _CMM_STORE_SHARED(rbtree->root, y);
 595         else if (get_pos(y) == IS_RIGHT)
 596                 _CMM_STORE_SHARED(get_parent(y)->_right, y);
 597         else
 598                 _CMM_STORE_SHARED(get_parent(y)->_left, y);
 599
 600         /* Point children to new copy (parent only used by updates/next/prev) */
 601         set_parent(x->_right, get_decay(get_parent(x->_right)),
 602                 get_pos(x->_right));
 603         set_parent(y->_left, get_decay(get_parent(y->_left)),
 604                 get_pos(y->_left));
 605         if (!rcu_rbtree_is_nil(rbtree, y_right)) {
 606                 set_parent(y_right->_left,
 607                         get_decay(get_parent(y_right->_left)),
 608                         get_pos(y_right->_left));
 609                 set_parent(y_right->_right,
 610                         get_decay(get_parent(y_right->_right)),
 611                         get_pos(y_right->_right));
 612         }
 613
 614         /* Sanity checks */
 615         assert(y == rbtree->root || get_parent(y)->_right == y
 616                 || get_parent(y)->_left == y);
 617         assert(x == rbtree->root || get_parent(x)->_right == x
 618                 || get_parent(x)->_left == x);
 619         assert(rcu_rbtree_is_nil(rbtree, x->_left) || get_parent(x->_left) == x);
 620         assert(rcu_rbtree_is_nil(rbtree, x->_right) || get_parent(x->_right) == x);
 621         assert(rcu_rbtree_is_nil(rbtree, y->_left) || get_parent(y->_left) == y);
 622         assert(rcu_rbtree_is_nil(rbtree, y->_right) || get_parent(y->_right) == y);
 623         assert(!is_decay(rbtree->root));
 624         assert(!is_decay(x));
 625         assert(!is_decay(y));
 626         assert(!is_decay(x->_left));
 627         assert(!is_decay(x->_right));
 628         assert(!is_decay(y->_left));
 629         assert(!is_decay(y->_right));
 630 }
 631
 632 #else
 633
 634 /* non-rcu version */
 635 static
 636 void right_rotate(struct rcu_rbtree *rbtree,
 637                   struct rcu_rbtree_node *x)
 638 {
 639         struct rcu_rbtree_node *y;
 640
 641         lock_test_mutex();
 642         y = x->_left;
 643         x->_left = y->_right;
 644         if (!rcu_rbtree_is_nil(rbtree, y->_right))
 645                 set_parent(y->_right, x, IS_LEFT);
 646         set_parent(y, get_parent(x), get_pos(x));
 647         if (rcu_rbtree_is_nil(rbtree, get_parent(x)))
 648                 rbtree->root = y;
 649         else if (x == get_parent(x)->_right) {
 650                 get_parent(x)->_right = y;
 651         } else {
 652                 get_parent(x)->_left = y;
 653         }
 654         y->_right = x;
 655         set_parent(x, y, IS_RIGHT);
 656         unlock_test_mutex();
 657 }
 658
 659 #endif
 660
 661 static void rcu_rbtree_insert_fixup(struct rcu_rbtree *rbtree,
 662                                     struct rcu_rbtree_node *z)
 663 {
 664         struct rcu_rbtree_node *y;
 665
 666         dbg_printf("insert fixup %p\n", z->begin);
 667         assert(!is_decay(rbtree->root));
 668
 669         while (get_parent(z)->color == COLOR_RED) {
 670                 if (get_parent(z) == get_parent(get_parent(z))->_left) {
 671                         y = get_parent(get_parent(z))->_right;
 672                         if (y->color == COLOR_RED) {
 673                                 get_parent(z)->color = COLOR_BLACK;
 674                                 y->color = COLOR_BLACK;
 675                                 get_parent(get_parent(z))->color = COLOR_RED;
 676                                 z = get_parent(get_parent(z));
 677                         } else {
 678                                 if (z == get_parent(z)->_right) {
 679                                         z = get_parent(z);
 680                                         left_rotate(rbtree, z);
 681                                         z = get_decay(z);
 682                                         assert(!is_decay(rbtree->root));
 683                                 }
 684                                 get_parent(z)->color = COLOR_BLACK;
 685                                 get_parent(get_parent(z))->color = COLOR_RED;
 686                                 assert(!is_decay(z));
 687                                 assert(!is_decay(get_parent(z)));
 688                                 assert(!is_decay(get_parent(get_parent(z))));
 689                                 right_rotate(rbtree, get_parent(get_parent(z)));
 690                                 assert(!is_decay(z));
 691                                 assert(!is_decay(rbtree->root));
 692                         }
 693                 } else {
 694                         y = get_parent(get_parent(z))->_left;
 695                         if (y->color == COLOR_RED) {
 696                                 get_parent(z)->color = COLOR_BLACK;
 697                                 y->color = COLOR_BLACK;
 698                                 get_parent(get_parent(z))->color = COLOR_RED;
 699                                 z = get_parent(get_parent(z));
 700                         } else {
 701                                 if (z == get_parent(z)->_left) {
 702                                         z = get_parent(z);
 703                                         right_rotate(rbtree, z);
 704                                         z = get_decay(z);
 705                                         assert(!is_decay(rbtree->root));
 706                                 }
 707                                 get_parent(z)->color = COLOR_BLACK;
 708                                 get_parent(get_parent(z))->color = COLOR_RED;
 709                                 left_rotate(rbtree, get_parent(get_parent(z)));
 710                                 assert(!is_decay(z));
 711                                 assert(!is_decay(rbtree->root));
 712                         }
 713                 }
 714         }
 715         rbtree->root->color = COLOR_BLACK;
 716 }
 717
 718 /*
 719  * rcu_rbtree_insert - Insert a node in the RCU rbtree
 720  *
 721  * Returns 0 on success, or < 0 on error.
 722  */
 723 int rcu_rbtree_insert(struct rcu_rbtree *rbtree,
 724                       struct rcu_rbtree_node *z)
 725 {
 726         struct rcu_rbtree_node *x, *y;
 727
 728         dbg_printf("insert %p\n", z->begin);
 729         assert(!is_decay(rbtree->root));
 730
 731         y = make_nil(rbtree);
 732         x = rbtree->root;
 733         while (!rcu_rbtree_is_nil(rbtree, x)) {
 734                 y = x;
 735                 if (rbtree->comp(z->begin, x->begin) < 0)
 736                         x = x->_left;
 737                 else
 738                         x = x->_right;
 739         }
 740
 741         z->_left = make_nil(rbtree);
 742         z->_right = make_nil(rbtree);
 743         z->color = COLOR_RED;
 744         z->decay_next = NULL;
 745         z->max_end = z->end;
 746
 747         if (rcu_rbtree_is_nil(rbtree, y)) {
 748                 set_parent(z, y, IS_RIGHT); /* pos arbitrary for root node */
 749                 /*
 750                  * Order stores to z (children/parents) before stores
 751                  * that will make it visible to the rest of the tree.
 752                  */
 753                 cmm_smp_wmb();
 754                 _CMM_STORE_SHARED(rbtree->root, z);
 755         } else if (rbtree->comp(z->begin, y->begin) < 0) {
 756                 y = dup_decay_node(rbtree, y);
 757                 set_parent(z, y, IS_LEFT);
 758                 if (get_pos(z) == IS_LEFT)
 759                         _CMM_STORE_SHARED(y->_left, z);
 760                 else
 761                         _CMM_STORE_SHARED(y->_right, z);
 762                 populate_node_end(rbtree, y, 1, NULL);
 763         } else {
 764                 y = dup_decay_node(rbtree, y);
 765                 set_parent(z, y, IS_RIGHT);
 766                 if (get_pos(z) == IS_LEFT)
 767                         _CMM_STORE_SHARED(y->_left, z);
 768                 else
 769                         _CMM_STORE_SHARED(y->_right, z);
 770                 populate_node_end(rbtree, y, 1, NULL);
 771         }
 772         rcu_rbtree_insert_fixup(rbtree, z);
 773         /*
 774          * Make sure to commit all _CMM_STORE_SHARED() for non-coherent caches.
 775          */
 776         cmm_smp_wmc();
 777         show_tree(rbtree);
 778
 779         return 0;
 780 }
 781
 782 /*
 783  * Transplant v into u position.
 784  */
 785
 786 #ifdef RBTREE_RCU_SUPPORT_TRANSPLANT
 787
 788 static
 789 void rcu_rbtree_transplant(struct rcu_rbtree *rbtree,
 790                         struct rcu_rbtree_node *u,
 791                         struct rcu_rbtree_node *v,
 792                         unsigned int copy_parents,
 793                         struct rcu_rbtree_node *stop)
 794 {
 795         dbg_printf("transplant %p\n", v->begin);
 796
 797         if (!rcu_rbtree_is_nil(rbtree, v))
 798                 v = dup_decay_node(rbtree, v);
 799
 800         if (rcu_rbtree_is_nil(rbtree, get_parent(u))) {
 801                 /* pos is arbitrary for root node */
 802                 set_parent(v, get_parent(u), IS_RIGHT);
 803                 cmm_smp_wmb();  /* write into node before publish */
 804                 _CMM_STORE_SHARED(rbtree->root, v);
 805         } else {
 806                 struct rcu_rbtree_node *vp;
 807
 808                 vp = get_parent(u);
 809                 if (copy_parents)
 810                         vp = dup_decay_node(rbtree, vp);
 811                 set_parent(v, vp, get_pos(u));
 812                 if (get_pos(v) == IS_LEFT)
 813                         _CMM_STORE_SHARED(vp->_left, v);
 814                 else
 815                         _CMM_STORE_SHARED(vp->_right, v);
 816                 populate_node_end(rbtree, vp, copy_parents, stop);
 817         }
 818
 819         /* Point children to new copy (parent only used by updates/next/prev) */
 820         if (!rcu_rbtree_is_nil(rbtree, v)) {
 821                 set_parent(v->_right, get_decay(get_parent(v->_right)),
 822                         get_pos(v->_right));
 823                 set_parent(v->_left, get_decay(get_parent(v->_left)),
 824                         get_pos(v->_left));
 825         }
 826         assert(!is_decay(rbtree->root));
 827 }
 828
 829 #else
 830
 831 /* Non-RCU version */
 832 static
 833 void rcu_rbtree_transplant(struct rcu_rbtree *rbtree,
 834                            struct rcu_rbtree_node *u,
 835                            struct rcu_rbtree_node *v,
 836                            unsigned int copy_parents,
 837                            struct rcu_rbtree_node *stop)
 838 {
 839         dbg_printf("transplant %p\n", v->begin);
 840
 841         lock_test_mutex();
 842         if (rcu_rbtree_is_nil(rbtree, get_parent(u)))
 843                 rbtree->root = v;
 844         else if (u == get_parent(u)->_left)
 845                 get_parent(u)->_left = v;
 846         else
 847                 get_parent(u)->_right = v;
 848         set_parent(v, get_parent(u), get_pos(u));
 849         unlock_test_mutex();
 850 }
 851
 852 #endif
 853
 854 static void rcu_rbtree_remove_fixup(struct rcu_rbtree *rbtree,
 855                                     struct rcu_rbtree_node *x)
 856 {
 857         dbg_printf("remove fixup %p\n", x->begin);
 858
 859         while (x != rbtree->root && x->color == COLOR_BLACK) {
 860                 assert(!is_decay(get_parent(x)));
 861                 assert(!is_decay(get_parent(x)->_left));
 862                 if (x == get_parent(x)->_left) {
 863                         struct rcu_rbtree_node *w;
 864
 865                         w = get_parent(x)->_right;
 866
 867                         if (w->color == COLOR_RED) {
 868                                 w->color = COLOR_BLACK;
 869                                 get_parent(x)->color = COLOR_RED;
 870                                 left_rotate(rbtree, get_parent(x));
 871                                 x = get_decay(x);
 872                                 assert(!is_decay(rbtree->root));
 873                                 w = get_parent(x)->_right;
 874                         }
 875                         if (w->_left->color == COLOR_BLACK
 876                             && w->_right->color == COLOR_BLACK) {
 877                                 w->color = COLOR_RED;
 878                                 x = get_parent(x);
 879                                 assert(!is_decay(rbtree->root));
 880                                 assert(!is_decay(x));
 881                         } else {
 882                                 if (w->_right->color == COLOR_BLACK) {
 883                                         w->_left->color = COLOR_BLACK;
 884                                         w->color = COLOR_RED;
 885                                         right_rotate(rbtree, w);
 886                                         assert(!is_decay(rbtree->root));
 887                                         x = get_decay(x);
 888                                         w = get_parent(x)->_right;
 889                                 }
 890                                 w->color = get_parent(x)->color;
 891                                 get_parent(x)->color = COLOR_BLACK;
 892                                 w->_right->color = COLOR_BLACK;
 893                                 left_rotate(rbtree, get_parent(x));
 894                                 assert(!is_decay(rbtree->root));
 895                                 x = rbtree->root;
 896                         }
 897                 } else {
 898                         struct rcu_rbtree_node *w;
 899
 900                         w = get_parent(x)->_left;
 901
 902                         if (w->color == COLOR_RED) {
 903                                 w->color = COLOR_BLACK;
 904                                 get_parent(x)->color = COLOR_RED;
 905                                 right_rotate(rbtree, get_parent(x));
 906                                 assert(!is_decay(rbtree->root));
 907                                 x = get_decay(x);
 908                                 w = get_parent(x)->_left;
 909                         }
 910                         if (w->_right->color == COLOR_BLACK
 911                             && w->_left->color == COLOR_BLACK) {
 912                                 w->color = COLOR_RED;
 913                                 x = get_parent(x);
 914                                 assert(!is_decay(rbtree->root));
 915                                 assert(!is_decay(x));
 916                         } else {
 917                                 if (w->_left->color == COLOR_BLACK) {
 918                                         w->_right->color = COLOR_BLACK;
 919                                         w->color = COLOR_RED;
 920                                         left_rotate(rbtree, w);
 921                                         assert(!is_decay(rbtree->root));
 922                                         x = get_decay(x);
 923                                         w = get_parent(x)->_left;
 924                                 }
 925                                 w->color = get_parent(x)->color;
 926                                 get_parent(x)->color = COLOR_BLACK;
 927                                 w->_left->color = COLOR_BLACK;
 928                                 right_rotate(rbtree, get_parent(x));
 929                                 assert(!is_decay(rbtree->root));
 930                                 x = rbtree->root;
 931                         }
 932                 }
 933         }
 934         x->color = COLOR_BLACK;
 935 }
 936
 937 /*
 938  * Delete z. All non-copied children left/right positions are unchanged.
 939  */
 940 static
 941 void rcu_rbtree_remove_nonil(struct rcu_rbtree *rbtree,
 942                              struct rcu_rbtree_node *z,
 943                              struct rcu_rbtree_node *y)
 944 {
 945         struct rcu_rbtree_node *x;
 946
 947         dbg_printf("remove nonil %p\n", z->begin);
 948         show_tree(rbtree);
 949
 950         assert(!is_decay(z));
 951         assert(!is_decay(y));
 952         assert(!is_decay(y->_right));
 953         assert(!is_decay(get_parent(y)));
 954         x = y->_right;
 955         assert(!is_decay(x));
 956         if (get_parent(y) == z) {
 957                 y = dup_decay_node(rbtree, y);
 958                 set_parent(x, y, get_pos(x));   /* parent for nil */
 959                 /* y is z's right node: set left will just update y */
 960                 set_left(rbtree, y, z->_left);
 961                 rcu_rbtree_transplant(rbtree, z, y, 1, NULL);
 962         } else {
 963                 struct rcu_rbtree_node *oy_right, *z_right;
 964
 965                 /*
 966                  * Need to make sure y is always visible by readers.
 967                  */
 968                 y = rcu_rbtree_min_dup_decay(rbtree, z->_right, &z_right);
 969                 assert(!is_decay(y));
 970                 assert(!is_decay(z));
 971                 oy_right = y->_right;
 972
 973                 /*
 974                  * The max child begin of z_right does not change, because
 975                  * we're only changing its left children.
 976                  */
 977                 y->_right = z_right;
 978                 set_parent(y->_right, y, IS_RIGHT);
 979                 assert(!is_decay(z->_left));
 980                 y->_left = z->_left;
 981                 assert(!is_decay(oy_right));
 982                 /*
 983                  * Transplant of oy_right to old y's location will only
 984                  * trigger a "end" value update of the already copied branch
 985                  * (which is not visible yet). We are transplanting
 986                  * oy_right as a left child of old y's parent, so the
 987                  * min values update propagated upward necessarily stops
 988                  * at z_right.
 989                  */
 990                 rcu_rbtree_transplant(rbtree, y, oy_right, 0, y);
 991                 rcu_rbtree_transplant(rbtree, z, y, 1, NULL);
 992                 /* Update children */
 993                 (void) rcu_rbtree_min_update_decay(rbtree, y->_right);
 994         }
 995         y = get_decay(y);
 996         assert(!is_decay(z));
 997         assert(!is_decay(z->_left));
 998         y->color = z->color;
 999         set_parent(y->_left, y, IS_LEFT);
1000         set_parent(y->_right, get_decay(get_parent(y->_right)), IS_RIGHT);
1001         assert(!is_decay(y->_left));
1002         assert(!is_decay(y->_right));
1003 }
1004
1005 int rcu_rbtree_remove(struct rcu_rbtree *rbtree,
1006                       struct rcu_rbtree_node *z)
1007 {
1008         struct rcu_rbtree_node *x, *y;
1009         unsigned int y_original_color;
1010
1011         assert(!is_decay(rbtree->root));
1012         dbg_printf("remove %p\n", z->begin);
1013         show_tree(rbtree);
1014
1015         assert(!is_decay(z));
1016         y = z;
1017         y_original_color = y->color;
1018
1019         if (rcu_rbtree_is_nil(rbtree, z->_left)) {
1020                 rcu_rbtree_transplant(rbtree, z, z->_right, 1, NULL);
1021                 assert(!is_decay(z));
1022                 x = get_decay(z->_right);
1023                 show_tree(rbtree);
1024         } else if (rcu_rbtree_is_nil(rbtree, z->_right)) {
1025                 rcu_rbtree_transplant(rbtree, z, z->_left, 1, NULL);
1026                 assert(!is_decay(z));
1027                 x = get_decay(z->_left);
1028                 show_tree(rbtree);
1029         } else {
1030                 y = rcu_rbtree_min(rbtree, z->_right);
1031                 assert(!is_decay(y));
1032                 y_original_color = y->color;
1033                 x = y->_right;
1034                 rcu_rbtree_remove_nonil(rbtree, z, y);
1035                 x = get_decay(x);
1036                 show_tree(rbtree);
1037         }
1038         if (y_original_color == COLOR_BLACK)
1039                 rcu_rbtree_remove_fixup(rbtree, x);
1040         show_tree(rbtree);
1041         /*
1042          * Commit all _CMM_STORE_SHARED().
1043          */
1044         cmm_smp_wmc();
1045
1046         return 0;
1047 }