urcu-bp: perform thread registration on urcu_bp_register_thread
[urcu.git] / src / urcu-bp.c
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 URCU_NO_COMPAT_IDENTIFIERS
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 <stdbool.h>
38 #include <sys/mman.h>
39
40 #include <urcu/arch.h>
41 #include <urcu/wfcqueue.h>
42 #include <urcu/map/urcu-bp.h>
43 #include <urcu/static/urcu-bp.h>
44 #include <urcu/pointer.h>
45 #include <urcu/tls-compat.h>
46
47 #include "urcu-die.h"
48 #include "urcu-utils.h"
49
50 #define URCU_API_MAP
51 /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
52 #undef _LGPL_SOURCE
53 #include <urcu/urcu-bp.h>
54 #define _LGPL_SOURCE
55
56 #ifndef MAP_ANONYMOUS
57 #define MAP_ANONYMOUS MAP_ANON
58 #endif
59
60 #ifdef __linux__
61 static
62 void *mremap_wrapper(void *old_address, size_t old_size,
63 size_t new_size, int flags)
64 {
65 return mremap(old_address, old_size, new_size, flags);
66 }
67 #else
68
69 #define MREMAP_MAYMOVE 1
70 #define MREMAP_FIXED 2
71
72 /*
73 * mremap wrapper for non-Linux systems not allowing MAYMOVE.
74 * This is not generic.
75 */
76 static
77 void *mremap_wrapper(void *old_address, size_t old_size,
78 size_t new_size, int flags)
79 {
80 assert(!(flags & MREMAP_MAYMOVE));
81
82 return MAP_FAILED;
83 }
84 #endif
85
86 /* Sleep delay in ms */
87 #define RCU_SLEEP_DELAY_MS 10
88 #define INIT_NR_THREADS 8
89 #define ARENA_INIT_ALLOC \
90 sizeof(struct registry_chunk) \
91 + INIT_NR_THREADS * sizeof(struct urcu_bp_reader)
92
93 /*
94 * Active attempts to check for reader Q.S. before calling sleep().
95 */
96 #define RCU_QS_ACTIVE_ATTEMPTS 100
97
98 static
99 int urcu_bp_refcount;
100
101 /* If the headers do not support membarrier system call, fall back smp_mb. */
102 #ifdef __NR_membarrier
103 # define membarrier(...) syscall(__NR_membarrier, __VA_ARGS__)
104 #else
105 # define membarrier(...) -ENOSYS
106 #endif
107
108 enum membarrier_cmd {
109 MEMBARRIER_CMD_QUERY = 0,
110 MEMBARRIER_CMD_SHARED = (1 << 0),
111 /* reserved for MEMBARRIER_CMD_SHARED_EXPEDITED (1 << 1) */
112 /* reserved for MEMBARRIER_CMD_PRIVATE (1 << 2) */
113 MEMBARRIER_CMD_PRIVATE_EXPEDITED = (1 << 3),
114 MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED = (1 << 4),
115 };
116
117 static
118 void __attribute__((constructor)) _urcu_bp_init(void);
119 static
120 void __attribute__((destructor)) urcu_bp_exit(void);
121
122 #ifndef CONFIG_RCU_FORCE_SYS_MEMBARRIER
123 int urcu_bp_has_sys_membarrier;
124 #endif
125
126 /*
127 * rcu_gp_lock ensures mutual exclusion between threads calling
128 * synchronize_rcu().
129 */
130 static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER;
131 /*
132 * rcu_registry_lock ensures mutual exclusion between threads
133 * registering and unregistering themselves to/from the registry, and
134 * with threads reading that registry from synchronize_rcu(). However,
135 * this lock is not held all the way through the completion of awaiting
136 * for the grace period. It is sporadically released between iterations
137 * on the registry.
138 * rcu_registry_lock may nest inside rcu_gp_lock.
139 */
140 static pthread_mutex_t rcu_registry_lock = PTHREAD_MUTEX_INITIALIZER;
141
142 static pthread_mutex_t init_lock = PTHREAD_MUTEX_INITIALIZER;
143 static int initialized;
144
145 static pthread_key_t urcu_bp_key;
146
147 struct urcu_bp_gp urcu_bp_gp = { .ctr = URCU_BP_GP_COUNT };
148 URCU_ATTR_ALIAS("urcu_bp_gp") extern struct urcu_bp_gp rcu_gp_bp;
149
150 /*
151 * Pointer to registry elements. Written to only by each individual reader. Read
152 * by both the reader and the writers.
153 */
154 DEFINE_URCU_TLS(struct urcu_bp_reader *, urcu_bp_reader);
155 DEFINE_URCU_TLS_ALIAS(struct urcu_bp_reader *, urcu_bp_reader, rcu_reader_bp);
156
157 static CDS_LIST_HEAD(registry);
158
159 struct registry_chunk {
160 size_t data_len; /* data length */
161 size_t used; /* amount of data used */
162 struct cds_list_head node; /* chunk_list node */
163 char data[];
164 };
165
166 struct registry_arena {
167 struct cds_list_head chunk_list;
168 };
169
170 static struct registry_arena registry_arena = {
171 .chunk_list = CDS_LIST_HEAD_INIT(registry_arena.chunk_list),
172 };
173
174 /* Saved fork signal mask, protected by rcu_gp_lock */
175 static sigset_t saved_fork_signal_mask;
176
177 static void mutex_lock(pthread_mutex_t *mutex)
178 {
179 int ret;
180
181 #ifndef DISTRUST_SIGNALS_EXTREME
182 ret = pthread_mutex_lock(mutex);
183 if (ret)
184 urcu_die(ret);
185 #else /* #ifndef DISTRUST_SIGNALS_EXTREME */
186 while ((ret = pthread_mutex_trylock(mutex)) != 0) {
187 if (ret != EBUSY && ret != EINTR)
188 urcu_die(ret);
189 poll(NULL,0,10);
190 }
191 #endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */
192 }
193
194 static void mutex_unlock(pthread_mutex_t *mutex)
195 {
196 int ret;
197
198 ret = pthread_mutex_unlock(mutex);
199 if (ret)
200 urcu_die(ret);
201 }
202
203 static void smp_mb_master(void)
204 {
205 if (caa_likely(urcu_bp_has_sys_membarrier)) {
206 if (membarrier(MEMBARRIER_CMD_PRIVATE_EXPEDITED, 0))
207 urcu_die(errno);
208 } else {
209 cmm_smp_mb();
210 }
211 }
212
213 /*
214 * Always called with rcu_registry lock held. Releases this lock between
215 * iterations and grabs it again. Holds the lock when it returns.
216 */
217 static void wait_for_readers(struct cds_list_head *input_readers,
218 struct cds_list_head *cur_snap_readers,
219 struct cds_list_head *qsreaders)
220 {
221 unsigned int wait_loops = 0;
222 struct urcu_bp_reader *index, *tmp;
223
224 /*
225 * Wait for each thread URCU_TLS(urcu_bp_reader).ctr to either
226 * indicate quiescence (not nested), or observe the current
227 * rcu_gp.ctr value.
228 */
229 for (;;) {
230 if (wait_loops < RCU_QS_ACTIVE_ATTEMPTS)
231 wait_loops++;
232
233 cds_list_for_each_entry_safe(index, tmp, input_readers, node) {
234 switch (urcu_bp_reader_state(&index->ctr)) {
235 case URCU_BP_READER_ACTIVE_CURRENT:
236 if (cur_snap_readers) {
237 cds_list_move(&index->node,
238 cur_snap_readers);
239 break;
240 }
241 /* Fall-through */
242 case URCU_BP_READER_INACTIVE:
243 cds_list_move(&index->node, qsreaders);
244 break;
245 case URCU_BP_READER_ACTIVE_OLD:
246 /*
247 * Old snapshot. Leaving node in
248 * input_readers will make us busy-loop
249 * until the snapshot becomes current or
250 * the reader becomes inactive.
251 */
252 break;
253 }
254 }
255
256 if (cds_list_empty(input_readers)) {
257 break;
258 } else {
259 /* Temporarily unlock the registry lock. */
260 mutex_unlock(&rcu_registry_lock);
261 if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS)
262 (void) poll(NULL, 0, RCU_SLEEP_DELAY_MS);
263 else
264 caa_cpu_relax();
265 /* Re-lock the registry lock before the next loop. */
266 mutex_lock(&rcu_registry_lock);
267 }
268 }
269 }
270
271 void urcu_bp_synchronize_rcu(void)
272 {
273 CDS_LIST_HEAD(cur_snap_readers);
274 CDS_LIST_HEAD(qsreaders);
275 sigset_t newmask, oldmask;
276 int ret;
277
278 ret = sigfillset(&newmask);
279 assert(!ret);
280 ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask);
281 assert(!ret);
282
283 mutex_lock(&rcu_gp_lock);
284
285 mutex_lock(&rcu_registry_lock);
286
287 if (cds_list_empty(&registry))
288 goto out;
289
290 /* All threads should read qparity before accessing data structure
291 * where new ptr points to. */
292 /* Write new ptr before changing the qparity */
293 smp_mb_master();
294
295 /*
296 * Wait for readers to observe original parity or be quiescent.
297 * wait_for_readers() can release and grab again rcu_registry_lock
298 * interally.
299 */
300 wait_for_readers(&registry, &cur_snap_readers, &qsreaders);
301
302 /*
303 * Adding a cmm_smp_mb() which is _not_ formally required, but makes the
304 * model easier to understand. It does not have a big performance impact
305 * anyway, given this is the write-side.
306 */
307 cmm_smp_mb();
308
309 /* Switch parity: 0 -> 1, 1 -> 0 */
310 CMM_STORE_SHARED(rcu_gp.ctr, rcu_gp.ctr ^ URCU_BP_GP_CTR_PHASE);
311
312 /*
313 * Must commit qparity update to memory before waiting for other parity
314 * quiescent state. Failure to do so could result in the writer waiting
315 * forever while new readers are always accessing data (no progress).
316 * Ensured by CMM_STORE_SHARED and CMM_LOAD_SHARED.
317 */
318
319 /*
320 * Adding a cmm_smp_mb() which is _not_ formally required, but makes the
321 * model easier to understand. It does not have a big performance impact
322 * anyway, given this is the write-side.
323 */
324 cmm_smp_mb();
325
326 /*
327 * Wait for readers to observe new parity or be quiescent.
328 * wait_for_readers() can release and grab again rcu_registry_lock
329 * interally.
330 */
331 wait_for_readers(&cur_snap_readers, NULL, &qsreaders);
332
333 /*
334 * Put quiescent reader list back into registry.
335 */
336 cds_list_splice(&qsreaders, &registry);
337
338 /*
339 * Finish waiting for reader threads before letting the old ptr being
340 * freed.
341 */
342 smp_mb_master();
343 out:
344 mutex_unlock(&rcu_registry_lock);
345 mutex_unlock(&rcu_gp_lock);
346 ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
347 assert(!ret);
348 }
349 URCU_ATTR_ALIAS("urcu_bp_synchronize_rcu") void synchronize_rcu_bp();
350
351 /*
352 * library wrappers to be used by non-LGPL compatible source code.
353 */
354
355 void urcu_bp_read_lock(void)
356 {
357 _urcu_bp_read_lock();
358 }
359 URCU_ATTR_ALIAS("urcu_bp_read_lock") void rcu_read_lock_bp();
360
361 void urcu_bp_read_unlock(void)
362 {
363 _urcu_bp_read_unlock();
364 }
365 URCU_ATTR_ALIAS("urcu_bp_read_unlock") void rcu_read_unlock_bp();
366
367 int urcu_bp_read_ongoing(void)
368 {
369 return _urcu_bp_read_ongoing();
370 }
371 URCU_ATTR_ALIAS("urcu_bp_read_ongoing") int rcu_read_ongoing_bp();
372
373 /*
374 * Only grow for now. If empty, allocate a ARENA_INIT_ALLOC sized chunk.
375 * Else, try expanding the last chunk. If this fails, allocate a new
376 * chunk twice as big as the last chunk.
377 * Memory used by chunks _never_ moves. A chunk could theoretically be
378 * freed when all "used" slots are released, but we don't do it at this
379 * point.
380 */
381 static
382 void expand_arena(struct registry_arena *arena)
383 {
384 struct registry_chunk *new_chunk, *last_chunk;
385 size_t old_chunk_len, new_chunk_len;
386
387 /* No chunk. */
388 if (cds_list_empty(&arena->chunk_list)) {
389 assert(ARENA_INIT_ALLOC >=
390 sizeof(struct registry_chunk)
391 + sizeof(struct rcu_reader));
392 new_chunk_len = ARENA_INIT_ALLOC;
393 new_chunk = (struct registry_chunk *) mmap(NULL,
394 new_chunk_len,
395 PROT_READ | PROT_WRITE,
396 MAP_ANONYMOUS | MAP_PRIVATE,
397 -1, 0);
398 if (new_chunk == MAP_FAILED)
399 abort();
400 memset(new_chunk, 0, new_chunk_len);
401 new_chunk->data_len =
402 new_chunk_len - sizeof(struct registry_chunk);
403 cds_list_add_tail(&new_chunk->node, &arena->chunk_list);
404 return; /* We're done. */
405 }
406
407 /* Try expanding last chunk. */
408 last_chunk = cds_list_entry(arena->chunk_list.prev,
409 struct registry_chunk, node);
410 old_chunk_len =
411 last_chunk->data_len + sizeof(struct registry_chunk);
412 new_chunk_len = old_chunk_len << 1;
413
414 /* Don't allow memory mapping to move, just expand. */
415 new_chunk = mremap_wrapper(last_chunk, old_chunk_len,
416 new_chunk_len, 0);
417 if (new_chunk != MAP_FAILED) {
418 /* Should not have moved. */
419 assert(new_chunk == last_chunk);
420 memset((char *) last_chunk + old_chunk_len, 0,
421 new_chunk_len - old_chunk_len);
422 last_chunk->data_len =
423 new_chunk_len - sizeof(struct registry_chunk);
424 return; /* We're done. */
425 }
426
427 /* Remap did not succeed, we need to add a new chunk. */
428 new_chunk = (struct registry_chunk *) mmap(NULL,
429 new_chunk_len,
430 PROT_READ | PROT_WRITE,
431 MAP_ANONYMOUS | MAP_PRIVATE,
432 -1, 0);
433 if (new_chunk == MAP_FAILED)
434 abort();
435 memset(new_chunk, 0, new_chunk_len);
436 new_chunk->data_len =
437 new_chunk_len - sizeof(struct registry_chunk);
438 cds_list_add_tail(&new_chunk->node, &arena->chunk_list);
439 }
440
441 static
442 struct rcu_reader *arena_alloc(struct registry_arena *arena)
443 {
444 struct registry_chunk *chunk;
445 struct rcu_reader *rcu_reader_reg;
446 int expand_done = 0; /* Only allow to expand once per alloc */
447 size_t len = sizeof(struct rcu_reader);
448
449 retry:
450 cds_list_for_each_entry(chunk, &arena->chunk_list, node) {
451 if (chunk->data_len - chunk->used < len)
452 continue;
453 /* Find spot */
454 for (rcu_reader_reg = (struct rcu_reader *) &chunk->data[0];
455 rcu_reader_reg < (struct rcu_reader *) &chunk->data[chunk->data_len];
456 rcu_reader_reg++) {
457 if (!rcu_reader_reg->alloc) {
458 rcu_reader_reg->alloc = 1;
459 chunk->used += len;
460 return rcu_reader_reg;
461 }
462 }
463 }
464
465 if (!expand_done) {
466 expand_arena(arena);
467 expand_done = 1;
468 goto retry;
469 }
470
471 return NULL;
472 }
473
474 /* Called with signals off and mutex locked */
475 static
476 void add_thread(void)
477 {
478 struct rcu_reader *rcu_reader_reg;
479 int ret;
480
481 rcu_reader_reg = arena_alloc(&registry_arena);
482 if (!rcu_reader_reg)
483 abort();
484 ret = pthread_setspecific(urcu_bp_key, rcu_reader_reg);
485 if (ret)
486 abort();
487
488 /* Add to registry */
489 rcu_reader_reg->tid = pthread_self();
490 assert(rcu_reader_reg->ctr == 0);
491 cds_list_add(&rcu_reader_reg->node, &registry);
492 /*
493 * Reader threads are pointing to the reader registry. This is
494 * why its memory should never be relocated.
495 */
496 URCU_TLS(urcu_bp_reader) = rcu_reader_reg;
497 }
498
499 /* Called with mutex locked */
500 static
501 void cleanup_thread(struct registry_chunk *chunk,
502 struct rcu_reader *rcu_reader_reg)
503 {
504 rcu_reader_reg->ctr = 0;
505 cds_list_del(&rcu_reader_reg->node);
506 rcu_reader_reg->tid = 0;
507 rcu_reader_reg->alloc = 0;
508 chunk->used -= sizeof(struct rcu_reader);
509 }
510
511 static
512 struct registry_chunk *find_chunk(struct rcu_reader *rcu_reader_reg)
513 {
514 struct registry_chunk *chunk;
515
516 cds_list_for_each_entry(chunk, &registry_arena.chunk_list, node) {
517 if (rcu_reader_reg < (struct rcu_reader *) &chunk->data[0])
518 continue;
519 if (rcu_reader_reg >= (struct rcu_reader *) &chunk->data[chunk->data_len])
520 continue;
521 return chunk;
522 }
523 return NULL;
524 }
525
526 /* Called with signals off and mutex locked */
527 static
528 void remove_thread(struct rcu_reader *rcu_reader_reg)
529 {
530 cleanup_thread(find_chunk(rcu_reader_reg), rcu_reader_reg);
531 URCU_TLS(urcu_bp_reader) = NULL;
532 }
533
534 /* Disable signals, take mutex, add to registry */
535 void urcu_bp_register(void)
536 {
537 sigset_t newmask, oldmask;
538 int ret;
539
540 ret = sigfillset(&newmask);
541 if (ret)
542 abort();
543 ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask);
544 if (ret)
545 abort();
546
547 /*
548 * Check if a signal concurrently registered our thread since
549 * the check in rcu_read_lock().
550 */
551 if (URCU_TLS(urcu_bp_reader))
552 goto end;
553
554 /*
555 * Take care of early registration before urcu_bp constructor.
556 */
557 _urcu_bp_init();
558
559 mutex_lock(&rcu_registry_lock);
560 add_thread();
561 mutex_unlock(&rcu_registry_lock);
562 end:
563 ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
564 if (ret)
565 abort();
566 }
567 URCU_ATTR_ALIAS("urcu_bp_register") void rcu_bp_register();
568
569 void urcu_bp_register_thread(void)
570 {
571 if (caa_unlikely(!URCU_TLS(urcu_bp_reader)))
572 urcu_bp_register(); /* If not yet registered. */
573 }
574
575 /* Disable signals, take mutex, remove from registry */
576 static
577 void urcu_bp_unregister(struct rcu_reader *rcu_reader_reg)
578 {
579 sigset_t newmask, oldmask;
580 int ret;
581
582 ret = sigfillset(&newmask);
583 if (ret)
584 abort();
585 ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask);
586 if (ret)
587 abort();
588
589 mutex_lock(&rcu_registry_lock);
590 remove_thread(rcu_reader_reg);
591 mutex_unlock(&rcu_registry_lock);
592 ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
593 if (ret)
594 abort();
595 urcu_bp_exit();
596 }
597
598 /*
599 * Remove thread from the registry when it exits, and flag it as
600 * destroyed so garbage collection can take care of it.
601 */
602 static
603 void urcu_bp_thread_exit_notifier(void *rcu_key)
604 {
605 urcu_bp_unregister(rcu_key);
606 }
607
608 #ifdef CONFIG_RCU_FORCE_SYS_MEMBARRIER
609 static
610 void urcu_bp_sys_membarrier_status(bool available)
611 {
612 if (!available)
613 abort();
614 }
615 #else
616 static
617 void urcu_bp_sys_membarrier_status(bool available)
618 {
619 if (!available)
620 return;
621 urcu_bp_has_sys_membarrier = 1;
622 }
623 #endif
624
625 static
626 void urcu_bp_sys_membarrier_init(void)
627 {
628 bool available = false;
629 int mask;
630
631 mask = membarrier(MEMBARRIER_CMD_QUERY, 0);
632 if (mask >= 0) {
633 if (mask & MEMBARRIER_CMD_PRIVATE_EXPEDITED) {
634 if (membarrier(MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED, 0))
635 urcu_die(errno);
636 available = true;
637 }
638 }
639 urcu_bp_sys_membarrier_status(available);
640 }
641
642 static
643 void _urcu_bp_init(void)
644 {
645 mutex_lock(&init_lock);
646 if (!urcu_bp_refcount++) {
647 int ret;
648
649 ret = pthread_key_create(&urcu_bp_key,
650 urcu_bp_thread_exit_notifier);
651 if (ret)
652 abort();
653 urcu_bp_sys_membarrier_init();
654 initialized = 1;
655 }
656 mutex_unlock(&init_lock);
657 }
658
659 static
660 void urcu_bp_exit(void)
661 {
662 mutex_lock(&init_lock);
663 if (!--urcu_bp_refcount) {
664 struct registry_chunk *chunk, *tmp;
665 int ret;
666
667 cds_list_for_each_entry_safe(chunk, tmp,
668 &registry_arena.chunk_list, node) {
669 munmap((void *) chunk, chunk->data_len
670 + sizeof(struct registry_chunk));
671 }
672 CDS_INIT_LIST_HEAD(&registry_arena.chunk_list);
673 ret = pthread_key_delete(urcu_bp_key);
674 if (ret)
675 abort();
676 }
677 mutex_unlock(&init_lock);
678 }
679
680 /*
681 * Holding the rcu_gp_lock and rcu_registry_lock across fork will make
682 * sure we fork() don't race with a concurrent thread executing with
683 * any of those locks held. This ensures that the registry and data
684 * protected by rcu_gp_lock are in a coherent state in the child.
685 */
686 void urcu_bp_before_fork(void)
687 {
688 sigset_t newmask, oldmask;
689 int ret;
690
691 ret = sigfillset(&newmask);
692 assert(!ret);
693 ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask);
694 assert(!ret);
695 mutex_lock(&rcu_gp_lock);
696 mutex_lock(&rcu_registry_lock);
697 saved_fork_signal_mask = oldmask;
698 }
699 URCU_ATTR_ALIAS("urcu_bp_before_fork") void rcu_bp_before_fork();
700
701 void urcu_bp_after_fork_parent(void)
702 {
703 sigset_t oldmask;
704 int ret;
705
706 oldmask = saved_fork_signal_mask;
707 mutex_unlock(&rcu_registry_lock);
708 mutex_unlock(&rcu_gp_lock);
709 ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
710 assert(!ret);
711 }
712 URCU_ATTR_ALIAS("urcu_bp_after_fork_parent")
713 void rcu_bp_after_fork_parent(void);
714
715 /*
716 * Prune all entries from registry except our own thread. Fits the Linux
717 * fork behavior. Called with rcu_gp_lock and rcu_registry_lock held.
718 */
719 static
720 void urcu_bp_prune_registry(void)
721 {
722 struct registry_chunk *chunk;
723 struct urcu_bp_reader *rcu_reader_reg;
724
725 cds_list_for_each_entry(chunk, &registry_arena.chunk_list, node) {
726 for (rcu_reader_reg = (struct urcu_bp_reader *) &chunk->data[0];
727 rcu_reader_reg < (struct urcu_bp_reader *) &chunk->data[chunk->data_len];
728 rcu_reader_reg++) {
729 if (!rcu_reader_reg->alloc)
730 continue;
731 if (rcu_reader_reg->tid == pthread_self())
732 continue;
733 cleanup_thread(chunk, rcu_reader_reg);
734 }
735 }
736 }
737
738 void urcu_bp_after_fork_child(void)
739 {
740 sigset_t oldmask;
741 int ret;
742
743 urcu_bp_prune_registry();
744 oldmask = saved_fork_signal_mask;
745 mutex_unlock(&rcu_registry_lock);
746 mutex_unlock(&rcu_gp_lock);
747 ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
748 assert(!ret);
749 }
750 URCU_ATTR_ALIAS("urcu_bp_after_fork_child")
751 void rcu_bp_after_fork_child(void);
752
753 void *urcu_bp_dereference_sym(void *p)
754 {
755 return _rcu_dereference(p);
756 }
757 URCU_ATTR_ALIAS("urcu_bp_dereference_sym")
758 void *rcu_dereference_sym_bp();
759
760 void *urcu_bp_set_pointer_sym(void **p, void *v)
761 {
762 cmm_wmb();
763 uatomic_set(p, v);
764 return v;
765 }
766 URCU_ATTR_ALIAS("urcu_bp_set_pointer_sym")
767 void *rcu_set_pointer_sym_bp();
768
769 void *urcu_bp_xchg_pointer_sym(void **p, void *v)
770 {
771 cmm_wmb();
772 return uatomic_xchg(p, v);
773 }
774 URCU_ATTR_ALIAS("urcu_bp_xchg_pointer_sym")
775 void *rcu_xchg_pointer_sym_bp();
776
777 void *urcu_bp_cmpxchg_pointer_sym(void **p, void *old, void *_new)
778 {
779 cmm_wmb();
780 return uatomic_cmpxchg(p, old, _new);
781 }
782 URCU_ATTR_ALIAS("urcu_bp_cmpxchg_pointer_sym")
783 void *rcu_cmpxchg_pointer_sym_bp();
784
785 DEFINE_RCU_FLAVOR(rcu_flavor);
786 DEFINE_RCU_FLAVOR_ALIAS(rcu_flavor, alias_rcu_flavor);
787
788 #include "urcu-call-rcu-impl.h"
789 #include "urcu-defer-impl.h"
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