| 1 | /* |
| 2 | * urcu-bp.c |
| 3 | * |
| 4 | * Userspace RCU library, "bulletproof" version. |
| 5 | * |
| 6 | * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 7 | * Copyright (c) 2009 Paul E. McKenney, IBM Corporation. |
| 8 | * |
| 9 | * This library is free software; you can redistribute it and/or |
| 10 | * modify it under the terms of the GNU Lesser General Public |
| 11 | * License as published by the Free Software Foundation; either |
| 12 | * version 2.1 of the License, or (at your option) any later version. |
| 13 | * |
| 14 | * This library is distributed in the hope that it will be useful, |
| 15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 17 | * Lesser General Public License for more details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU Lesser General Public |
| 20 | * License along with this library; if not, write to the Free Software |
| 21 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 22 | * |
| 23 | * IBM's contributions to this file may be relicensed under LGPLv2 or later. |
| 24 | */ |
| 25 | |
| 26 | #define _GNU_SOURCE |
| 27 | #define _LGPL_SOURCE |
| 28 | #include <stdio.h> |
| 29 | #include <pthread.h> |
| 30 | #include <signal.h> |
| 31 | #include <assert.h> |
| 32 | #include <stdlib.h> |
| 33 | #include <string.h> |
| 34 | #include <errno.h> |
| 35 | #include <poll.h> |
| 36 | #include <unistd.h> |
| 37 | #include <sys/mman.h> |
| 38 | |
| 39 | #include "urcu/wfqueue.h" |
| 40 | #include "urcu/map/urcu-bp.h" |
| 41 | #include "urcu/static/urcu-bp.h" |
| 42 | #include "urcu-pointer.h" |
| 43 | #include "urcu/tls-compat.h" |
| 44 | |
| 45 | #include "urcu-die.h" |
| 46 | |
| 47 | /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */ |
| 48 | #undef _LGPL_SOURCE |
| 49 | #include "urcu-bp.h" |
| 50 | #define _LGPL_SOURCE |
| 51 | |
| 52 | #ifndef MAP_ANONYMOUS |
| 53 | #define MAP_ANONYMOUS MAP_ANON |
| 54 | #endif |
| 55 | |
| 56 | #ifdef __linux__ |
| 57 | static |
| 58 | void *mremap_wrapper(void *old_address, size_t old_size, |
| 59 | size_t new_size, int flags) |
| 60 | { |
| 61 | return mremap(old_address, old_size, new_size, flags); |
| 62 | } |
| 63 | #else |
| 64 | |
| 65 | #define MREMAP_MAYMOVE 1 |
| 66 | #define MREMAP_FIXED 2 |
| 67 | |
| 68 | /* |
| 69 | * mremap wrapper for non-Linux systems not allowing MAYMOVE. |
| 70 | * This is not generic. |
| 71 | */ |
| 72 | static |
| 73 | void *mremap_wrapper(void *old_address, size_t old_size, |
| 74 | size_t new_size, int flags) |
| 75 | { |
| 76 | assert(!(flags & MREMAP_MAYMOVE)); |
| 77 | |
| 78 | return MAP_FAILED; |
| 79 | } |
| 80 | #endif |
| 81 | |
| 82 | /* Sleep delay in us */ |
| 83 | #define RCU_SLEEP_DELAY 1000 |
| 84 | #define INIT_NR_THREADS 8 |
| 85 | #define ARENA_INIT_ALLOC \ |
| 86 | sizeof(struct registry_chunk) \ |
| 87 | + INIT_NR_THREADS * sizeof(struct rcu_reader) |
| 88 | |
| 89 | /* |
| 90 | * Active attempts to check for reader Q.S. before calling sleep(). |
| 91 | */ |
| 92 | #define RCU_QS_ACTIVE_ATTEMPTS 100 |
| 93 | |
| 94 | static |
| 95 | int rcu_bp_refcount; |
| 96 | |
| 97 | static |
| 98 | void __attribute__((constructor)) rcu_bp_init(void); |
| 99 | static |
| 100 | void __attribute__((destructor)) rcu_bp_exit(void); |
| 101 | |
| 102 | static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER; |
| 103 | |
| 104 | static pthread_mutex_t init_lock = PTHREAD_MUTEX_INITIALIZER; |
| 105 | static int initialized; |
| 106 | |
| 107 | static pthread_key_t urcu_bp_key; |
| 108 | |
| 109 | #ifdef DEBUG_YIELD |
| 110 | unsigned int yield_active; |
| 111 | __DEFINE_URCU_TLS_GLOBAL(unsigned int, rand_yield); |
| 112 | #endif |
| 113 | |
| 114 | /* |
| 115 | * Global grace period counter. |
| 116 | * Contains the current RCU_GP_CTR_PHASE. |
| 117 | * Also has a RCU_GP_COUNT of 1, to accelerate the reader fast path. |
| 118 | * Written to only by writer with mutex taken. Read by both writer and readers. |
| 119 | */ |
| 120 | long rcu_gp_ctr = RCU_GP_COUNT; |
| 121 | |
| 122 | /* |
| 123 | * Pointer to registry elements. Written to only by each individual reader. Read |
| 124 | * by both the reader and the writers. |
| 125 | */ |
| 126 | __DEFINE_URCU_TLS_GLOBAL(struct rcu_reader *, rcu_reader); |
| 127 | |
| 128 | static CDS_LIST_HEAD(registry); |
| 129 | |
| 130 | struct registry_chunk { |
| 131 | size_t data_len; /* data length */ |
| 132 | size_t used; /* amount of data used */ |
| 133 | struct cds_list_head node; /* chunk_list node */ |
| 134 | char data[]; |
| 135 | }; |
| 136 | |
| 137 | struct registry_arena { |
| 138 | struct cds_list_head chunk_list; |
| 139 | }; |
| 140 | |
| 141 | static struct registry_arena registry_arena = { |
| 142 | .chunk_list = CDS_LIST_HEAD_INIT(registry_arena.chunk_list), |
| 143 | }; |
| 144 | |
| 145 | /* Saved fork signal mask, protected by rcu_gp_lock */ |
| 146 | static sigset_t saved_fork_signal_mask; |
| 147 | |
| 148 | static void mutex_lock(pthread_mutex_t *mutex) |
| 149 | { |
| 150 | int ret; |
| 151 | |
| 152 | #ifndef DISTRUST_SIGNALS_EXTREME |
| 153 | ret = pthread_mutex_lock(mutex); |
| 154 | if (ret) |
| 155 | urcu_die(ret); |
| 156 | #else /* #ifndef DISTRUST_SIGNALS_EXTREME */ |
| 157 | while ((ret = pthread_mutex_trylock(mutex)) != 0) { |
| 158 | if (ret != EBUSY && ret != EINTR) |
| 159 | urcu_die(ret); |
| 160 | poll(NULL,0,10); |
| 161 | } |
| 162 | #endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */ |
| 163 | } |
| 164 | |
| 165 | static void mutex_unlock(pthread_mutex_t *mutex) |
| 166 | { |
| 167 | int ret; |
| 168 | |
| 169 | ret = pthread_mutex_unlock(mutex); |
| 170 | if (ret) |
| 171 | urcu_die(ret); |
| 172 | } |
| 173 | |
| 174 | void update_counter_and_wait(void) |
| 175 | { |
| 176 | CDS_LIST_HEAD(qsreaders); |
| 177 | int wait_loops = 0; |
| 178 | struct rcu_reader *index, *tmp; |
| 179 | |
| 180 | /* Switch parity: 0 -> 1, 1 -> 0 */ |
| 181 | CMM_STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE); |
| 182 | |
| 183 | /* |
| 184 | * Must commit qparity update to memory before waiting for other parity |
| 185 | * quiescent state. Failure to do so could result in the writer waiting |
| 186 | * forever while new readers are always accessing data (no progress). |
| 187 | * Ensured by CMM_STORE_SHARED and CMM_LOAD_SHARED. |
| 188 | */ |
| 189 | |
| 190 | /* |
| 191 | * Adding a cmm_smp_mb() which is _not_ formally required, but makes the |
| 192 | * model easier to understand. It does not have a big performance impact |
| 193 | * anyway, given this is the write-side. |
| 194 | */ |
| 195 | cmm_smp_mb(); |
| 196 | |
| 197 | /* |
| 198 | * Wait for each thread rcu_reader.ctr count to become 0. |
| 199 | */ |
| 200 | for (;;) { |
| 201 | wait_loops++; |
| 202 | cds_list_for_each_entry_safe(index, tmp, ®istry, node) { |
| 203 | if (!rcu_old_gp_ongoing(&index->ctr)) |
| 204 | cds_list_move(&index->node, &qsreaders); |
| 205 | } |
| 206 | |
| 207 | if (cds_list_empty(®istry)) { |
| 208 | break; |
| 209 | } else { |
| 210 | if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) |
| 211 | usleep(RCU_SLEEP_DELAY); |
| 212 | else |
| 213 | caa_cpu_relax(); |
| 214 | } |
| 215 | } |
| 216 | /* put back the reader list in the registry */ |
| 217 | cds_list_splice(&qsreaders, ®istry); |
| 218 | } |
| 219 | |
| 220 | void synchronize_rcu(void) |
| 221 | { |
| 222 | sigset_t newmask, oldmask; |
| 223 | int ret; |
| 224 | |
| 225 | ret = sigfillset(&newmask); |
| 226 | assert(!ret); |
| 227 | ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask); |
| 228 | assert(!ret); |
| 229 | |
| 230 | mutex_lock(&rcu_gp_lock); |
| 231 | |
| 232 | if (cds_list_empty(®istry)) |
| 233 | goto out; |
| 234 | |
| 235 | /* All threads should read qparity before accessing data structure |
| 236 | * where new ptr points to. */ |
| 237 | /* Write new ptr before changing the qparity */ |
| 238 | cmm_smp_mb(); |
| 239 | |
| 240 | /* |
| 241 | * Wait for previous parity to be empty of readers. |
| 242 | */ |
| 243 | update_counter_and_wait(); /* 0 -> 1, wait readers in parity 0 */ |
| 244 | |
| 245 | /* |
| 246 | * Adding a cmm_smp_mb() which is _not_ formally required, but makes the |
| 247 | * model easier to understand. It does not have a big performance impact |
| 248 | * anyway, given this is the write-side. |
| 249 | */ |
| 250 | cmm_smp_mb(); |
| 251 | |
| 252 | /* |
| 253 | * Wait for previous parity to be empty of readers. |
| 254 | */ |
| 255 | update_counter_and_wait(); /* 1 -> 0, wait readers in parity 1 */ |
| 256 | |
| 257 | /* |
| 258 | * Finish waiting for reader threads before letting the old ptr being |
| 259 | * freed. |
| 260 | */ |
| 261 | cmm_smp_mb(); |
| 262 | out: |
| 263 | mutex_unlock(&rcu_gp_lock); |
| 264 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); |
| 265 | assert(!ret); |
| 266 | } |
| 267 | |
| 268 | /* |
| 269 | * library wrappers to be used by non-LGPL compatible source code. |
| 270 | */ |
| 271 | |
| 272 | void rcu_read_lock(void) |
| 273 | { |
| 274 | _rcu_read_lock(); |
| 275 | } |
| 276 | |
| 277 | void rcu_read_unlock(void) |
| 278 | { |
| 279 | _rcu_read_unlock(); |
| 280 | } |
| 281 | |
| 282 | /* |
| 283 | * Only grow for now. If empty, allocate a ARENA_INIT_ALLOC sized chunk. |
| 284 | * Else, try expanding the last chunk. If this fails, allocate a new |
| 285 | * chunk twice as big as the last chunk. |
| 286 | * Memory used by chunks _never_ moves. A chunk could theoretically be |
| 287 | * freed when all "used" slots are released, but we don't do it at this |
| 288 | * point. |
| 289 | */ |
| 290 | static |
| 291 | void expand_arena(struct registry_arena *arena) |
| 292 | { |
| 293 | struct registry_chunk *new_chunk, *last_chunk; |
| 294 | size_t old_chunk_len, new_chunk_len; |
| 295 | |
| 296 | /* No chunk. */ |
| 297 | if (cds_list_empty(&arena->chunk_list)) { |
| 298 | assert(ARENA_INIT_ALLOC >= |
| 299 | sizeof(struct registry_chunk) |
| 300 | + sizeof(struct rcu_reader)); |
| 301 | new_chunk_len = ARENA_INIT_ALLOC; |
| 302 | new_chunk = mmap(NULL, new_chunk_len, |
| 303 | PROT_READ | PROT_WRITE, |
| 304 | MAP_ANONYMOUS | MAP_PRIVATE, |
| 305 | -1, 0); |
| 306 | if (new_chunk == MAP_FAILED) |
| 307 | abort(); |
| 308 | bzero(new_chunk, new_chunk_len); |
| 309 | new_chunk->data_len = |
| 310 | new_chunk_len - sizeof(struct registry_chunk); |
| 311 | cds_list_add_tail(&new_chunk->node, &arena->chunk_list); |
| 312 | return; /* We're done. */ |
| 313 | } |
| 314 | |
| 315 | /* Try expanding last chunk. */ |
| 316 | last_chunk = cds_list_entry(arena->chunk_list.prev, |
| 317 | struct registry_chunk, node); |
| 318 | old_chunk_len = |
| 319 | last_chunk->data_len + sizeof(struct registry_chunk); |
| 320 | new_chunk_len = old_chunk_len << 1; |
| 321 | |
| 322 | /* Don't allow memory mapping to move, just expand. */ |
| 323 | new_chunk = mremap_wrapper(last_chunk, old_chunk_len, |
| 324 | new_chunk_len, 0); |
| 325 | if (new_chunk != MAP_FAILED) { |
| 326 | /* Should not have moved. */ |
| 327 | assert(new_chunk == last_chunk); |
| 328 | bzero((char *) last_chunk + old_chunk_len, |
| 329 | new_chunk_len - old_chunk_len); |
| 330 | last_chunk->data_len = |
| 331 | new_chunk_len - sizeof(struct registry_chunk); |
| 332 | return; /* We're done. */ |
| 333 | } |
| 334 | |
| 335 | /* Remap did not succeed, we need to add a new chunk. */ |
| 336 | new_chunk = mmap(NULL, new_chunk_len, |
| 337 | PROT_READ | PROT_WRITE, |
| 338 | MAP_ANONYMOUS | MAP_PRIVATE, |
| 339 | -1, 0); |
| 340 | if (new_chunk == MAP_FAILED) |
| 341 | abort(); |
| 342 | bzero(new_chunk, new_chunk_len); |
| 343 | new_chunk->data_len = |
| 344 | new_chunk_len - sizeof(struct registry_chunk); |
| 345 | cds_list_add_tail(&new_chunk->node, &arena->chunk_list); |
| 346 | } |
| 347 | |
| 348 | static |
| 349 | struct rcu_reader *arena_alloc(struct registry_arena *arena) |
| 350 | { |
| 351 | struct registry_chunk *chunk; |
| 352 | struct rcu_reader *rcu_reader_reg; |
| 353 | int expand_done = 0; /* Only allow to expand once per alloc */ |
| 354 | size_t len = sizeof(struct rcu_reader); |
| 355 | |
| 356 | retry: |
| 357 | cds_list_for_each_entry(chunk, &arena->chunk_list, node) { |
| 358 | if (chunk->data_len - chunk->used < len) |
| 359 | continue; |
| 360 | /* Find spot */ |
| 361 | for (rcu_reader_reg = (struct rcu_reader *) &chunk->data[0]; |
| 362 | rcu_reader_reg < (struct rcu_reader *) &chunk->data[chunk->data_len]; |
| 363 | rcu_reader_reg++) { |
| 364 | if (!rcu_reader_reg->alloc) { |
| 365 | rcu_reader_reg->alloc = 1; |
| 366 | chunk->used += len; |
| 367 | return rcu_reader_reg; |
| 368 | } |
| 369 | } |
| 370 | } |
| 371 | |
| 372 | if (!expand_done) { |
| 373 | expand_arena(arena); |
| 374 | expand_done = 1; |
| 375 | goto retry; |
| 376 | } |
| 377 | |
| 378 | return NULL; |
| 379 | } |
| 380 | |
| 381 | /* Called with signals off and mutex locked */ |
| 382 | static |
| 383 | void add_thread(void) |
| 384 | { |
| 385 | struct rcu_reader *rcu_reader_reg; |
| 386 | int ret; |
| 387 | |
| 388 | rcu_reader_reg = arena_alloc(®istry_arena); |
| 389 | if (!rcu_reader_reg) |
| 390 | abort(); |
| 391 | ret = pthread_setspecific(urcu_bp_key, rcu_reader_reg); |
| 392 | if (ret) |
| 393 | abort(); |
| 394 | |
| 395 | /* Add to registry */ |
| 396 | rcu_reader_reg->tid = pthread_self(); |
| 397 | assert(rcu_reader_reg->ctr == 0); |
| 398 | cds_list_add(&rcu_reader_reg->node, ®istry); |
| 399 | /* |
| 400 | * Reader threads are pointing to the reader registry. This is |
| 401 | * why its memory should never be relocated. |
| 402 | */ |
| 403 | URCU_TLS(rcu_reader) = rcu_reader_reg; |
| 404 | } |
| 405 | |
| 406 | /* Called with mutex locked */ |
| 407 | static |
| 408 | void cleanup_thread(struct registry_chunk *chunk, |
| 409 | struct rcu_reader *rcu_reader_reg) |
| 410 | { |
| 411 | rcu_reader_reg->ctr = 0; |
| 412 | cds_list_del(&rcu_reader_reg->node); |
| 413 | rcu_reader_reg->tid = 0; |
| 414 | rcu_reader_reg->alloc = 0; |
| 415 | chunk->used -= sizeof(struct rcu_reader); |
| 416 | } |
| 417 | |
| 418 | static |
| 419 | struct registry_chunk *find_chunk(struct rcu_reader *rcu_reader_reg) |
| 420 | { |
| 421 | struct registry_chunk *chunk; |
| 422 | |
| 423 | cds_list_for_each_entry(chunk, ®istry_arena.chunk_list, node) { |
| 424 | if (rcu_reader_reg < (struct rcu_reader *) &chunk->data[0]) |
| 425 | continue; |
| 426 | if (rcu_reader_reg >= (struct rcu_reader *) &chunk->data[chunk->data_len]) |
| 427 | continue; |
| 428 | return chunk; |
| 429 | } |
| 430 | return NULL; |
| 431 | } |
| 432 | |
| 433 | /* Called with signals off and mutex locked */ |
| 434 | static |
| 435 | void remove_thread(struct rcu_reader *rcu_reader_reg) |
| 436 | { |
| 437 | cleanup_thread(find_chunk(rcu_reader_reg), rcu_reader_reg); |
| 438 | URCU_TLS(rcu_reader) = NULL; |
| 439 | } |
| 440 | |
| 441 | /* Disable signals, take mutex, add to registry */ |
| 442 | void rcu_bp_register(void) |
| 443 | { |
| 444 | sigset_t newmask, oldmask; |
| 445 | int ret; |
| 446 | |
| 447 | ret = sigfillset(&newmask); |
| 448 | if (ret) |
| 449 | abort(); |
| 450 | ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask); |
| 451 | if (ret) |
| 452 | abort(); |
| 453 | |
| 454 | /* |
| 455 | * Check if a signal concurrently registered our thread since |
| 456 | * the check in rcu_read_lock(). |
| 457 | */ |
| 458 | if (URCU_TLS(rcu_reader)) |
| 459 | goto end; |
| 460 | |
| 461 | /* |
| 462 | * Take care of early registration before urcu_bp constructor. |
| 463 | */ |
| 464 | rcu_bp_init(); |
| 465 | |
| 466 | mutex_lock(&rcu_gp_lock); |
| 467 | add_thread(); |
| 468 | mutex_unlock(&rcu_gp_lock); |
| 469 | end: |
| 470 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); |
| 471 | if (ret) |
| 472 | abort(); |
| 473 | } |
| 474 | |
| 475 | /* Disable signals, take mutex, remove from registry */ |
| 476 | static |
| 477 | void rcu_bp_unregister(struct rcu_reader *rcu_reader_reg) |
| 478 | { |
| 479 | sigset_t newmask, oldmask; |
| 480 | int ret; |
| 481 | |
| 482 | ret = sigfillset(&newmask); |
| 483 | if (ret) |
| 484 | abort(); |
| 485 | ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask); |
| 486 | if (ret) |
| 487 | abort(); |
| 488 | |
| 489 | mutex_lock(&rcu_gp_lock); |
| 490 | remove_thread(rcu_reader_reg); |
| 491 | mutex_unlock(&rcu_gp_lock); |
| 492 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); |
| 493 | if (ret) |
| 494 | abort(); |
| 495 | rcu_bp_exit(); |
| 496 | } |
| 497 | |
| 498 | /* |
| 499 | * Remove thread from the registry when it exits, and flag it as |
| 500 | * destroyed so garbage collection can take care of it. |
| 501 | */ |
| 502 | static |
| 503 | void urcu_bp_thread_exit_notifier(void *rcu_key) |
| 504 | { |
| 505 | rcu_bp_unregister(rcu_key); |
| 506 | } |
| 507 | |
| 508 | static |
| 509 | void rcu_bp_init(void) |
| 510 | { |
| 511 | mutex_lock(&init_lock); |
| 512 | if (!rcu_bp_refcount++) { |
| 513 | int ret; |
| 514 | |
| 515 | ret = pthread_key_create(&urcu_bp_key, |
| 516 | urcu_bp_thread_exit_notifier); |
| 517 | if (ret) |
| 518 | abort(); |
| 519 | initialized = 1; |
| 520 | } |
| 521 | mutex_unlock(&init_lock); |
| 522 | } |
| 523 | |
| 524 | static |
| 525 | void rcu_bp_exit(void) |
| 526 | { |
| 527 | mutex_lock(&init_lock); |
| 528 | if (!--rcu_bp_refcount) { |
| 529 | struct registry_chunk *chunk, *tmp; |
| 530 | int ret; |
| 531 | |
| 532 | cds_list_for_each_entry_safe(chunk, tmp, |
| 533 | ®istry_arena.chunk_list, node) { |
| 534 | munmap(chunk, chunk->data_len |
| 535 | + sizeof(struct registry_chunk)); |
| 536 | } |
| 537 | ret = pthread_key_delete(urcu_bp_key); |
| 538 | if (ret) |
| 539 | abort(); |
| 540 | } |
| 541 | mutex_unlock(&init_lock); |
| 542 | } |
| 543 | |
| 544 | /* |
| 545 | * Holding the rcu_gp_lock across fork will make sure we fork() don't race with |
| 546 | * a concurrent thread executing with this same lock held. This ensures that the |
| 547 | * registry is in a coherent state in the child. |
| 548 | */ |
| 549 | void rcu_bp_before_fork(void) |
| 550 | { |
| 551 | sigset_t newmask, oldmask; |
| 552 | int ret; |
| 553 | |
| 554 | ret = sigfillset(&newmask); |
| 555 | assert(!ret); |
| 556 | ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask); |
| 557 | assert(!ret); |
| 558 | mutex_lock(&rcu_gp_lock); |
| 559 | saved_fork_signal_mask = oldmask; |
| 560 | } |
| 561 | |
| 562 | void rcu_bp_after_fork_parent(void) |
| 563 | { |
| 564 | sigset_t oldmask; |
| 565 | int ret; |
| 566 | |
| 567 | oldmask = saved_fork_signal_mask; |
| 568 | mutex_unlock(&rcu_gp_lock); |
| 569 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); |
| 570 | assert(!ret); |
| 571 | } |
| 572 | |
| 573 | /* |
| 574 | * Prune all entries from registry except our own thread. Fits the Linux |
| 575 | * fork behavior. Called with rcu_gp_lock held. |
| 576 | */ |
| 577 | static |
| 578 | void urcu_bp_prune_registry(void) |
| 579 | { |
| 580 | struct registry_chunk *chunk; |
| 581 | struct rcu_reader *rcu_reader_reg; |
| 582 | |
| 583 | cds_list_for_each_entry(chunk, ®istry_arena.chunk_list, node) { |
| 584 | for (rcu_reader_reg = (struct rcu_reader *) &chunk->data[0]; |
| 585 | rcu_reader_reg < (struct rcu_reader *) &chunk->data[chunk->data_len]; |
| 586 | rcu_reader_reg++) { |
| 587 | if (!rcu_reader_reg->alloc) |
| 588 | continue; |
| 589 | if (rcu_reader_reg->tid == pthread_self()) |
| 590 | continue; |
| 591 | cleanup_thread(chunk, rcu_reader_reg); |
| 592 | } |
| 593 | } |
| 594 | } |
| 595 | |
| 596 | void rcu_bp_after_fork_child(void) |
| 597 | { |
| 598 | sigset_t oldmask; |
| 599 | int ret; |
| 600 | |
| 601 | urcu_bp_prune_registry(); |
| 602 | oldmask = saved_fork_signal_mask; |
| 603 | mutex_unlock(&rcu_gp_lock); |
| 604 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); |
| 605 | assert(!ret); |
| 606 | } |
| 607 | |
| 608 | void *rcu_dereference_sym_bp(void *p) |
| 609 | { |
| 610 | return _rcu_dereference(p); |
| 611 | } |
| 612 | |
| 613 | void *rcu_set_pointer_sym_bp(void **p, void *v) |
| 614 | { |
| 615 | cmm_wmb(); |
| 616 | uatomic_set(p, v); |
| 617 | return v; |
| 618 | } |
| 619 | |
| 620 | void *rcu_xchg_pointer_sym_bp(void **p, void *v) |
| 621 | { |
| 622 | cmm_wmb(); |
| 623 | return uatomic_xchg(p, v); |
| 624 | } |
| 625 | |
| 626 | void *rcu_cmpxchg_pointer_sym_bp(void **p, void *old, void *_new) |
| 627 | { |
| 628 | cmm_wmb(); |
| 629 | return uatomic_cmpxchg(p, old, _new); |
| 630 | } |
| 631 | |
| 632 | DEFINE_RCU_FLAVOR(rcu_flavor); |
| 633 | |
| 634 | #include "urcu-call-rcu-impl.h" |
| 635 | #include "urcu-defer-impl.h" |