fix: warnings on non-Linux platforms
[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/config.h>
41 #include <urcu/arch.h>
42 #include <urcu/wfcqueue.h>
43 #include <urcu/map/urcu-bp.h>
44 #include <urcu/static/urcu-bp.h>
45 #include <urcu/pointer.h>
46 #include <urcu/tls-compat.h>
47
48 #include "urcu-die.h"
49 #include "urcu-utils.h"
50
51 #define URCU_API_MAP
52 /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
53 #undef _LGPL_SOURCE
54 #include <urcu/urcu-bp.h>
55 #define _LGPL_SOURCE
56
57 #ifndef MAP_ANONYMOUS
58 #define MAP_ANONYMOUS MAP_ANON
59 #endif
60
61 #ifdef __linux__
62 static
63 void *mremap_wrapper(void *old_address, size_t old_size,
64 size_t new_size, int flags)
65 {
66 return mremap(old_address, old_size, new_size, flags);
67 }
68 #else
69
70 #define MREMAP_MAYMOVE 1
71 #define MREMAP_FIXED 2
72
73 /*
74 * mremap wrapper for non-Linux systems not allowing MAYMOVE.
75 * This is not generic.
76 */
77 static
78 void *mremap_wrapper(void *old_address __attribute__((unused)),
79 size_t old_size __attribute__((unused)),
80 size_t new_size __attribute__((unused)),
81 int flags)
82 {
83 assert(!(flags & MREMAP_MAYMOVE));
84
85 return MAP_FAILED;
86 }
87 #endif
88
89 /* Sleep delay in ms */
90 #define RCU_SLEEP_DELAY_MS 10
91 #define INIT_NR_THREADS 8
92 #define ARENA_INIT_ALLOC \
93 sizeof(struct registry_chunk) \
94 + INIT_NR_THREADS * sizeof(struct urcu_bp_reader)
95
96 /*
97 * Active attempts to check for reader Q.S. before calling sleep().
98 */
99 #define RCU_QS_ACTIVE_ATTEMPTS 100
100
101 static
102 int urcu_bp_refcount;
103
104 /* If the headers do not support membarrier system call, fall back smp_mb. */
105 #ifdef __NR_membarrier
106 # define membarrier(...) syscall(__NR_membarrier, __VA_ARGS__)
107 #else
108 # define membarrier(...) -ENOSYS
109 #endif
110
111 enum membarrier_cmd {
112 MEMBARRIER_CMD_QUERY = 0,
113 MEMBARRIER_CMD_SHARED = (1 << 0),
114 /* reserved for MEMBARRIER_CMD_SHARED_EXPEDITED (1 << 1) */
115 /* reserved for MEMBARRIER_CMD_PRIVATE (1 << 2) */
116 MEMBARRIER_CMD_PRIVATE_EXPEDITED = (1 << 3),
117 MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED = (1 << 4),
118 };
119
120 static
121 void __attribute__((constructor)) _urcu_bp_init(void);
122 static
123 void __attribute__((destructor)) urcu_bp_exit(void);
124
125 #ifndef CONFIG_RCU_FORCE_SYS_MEMBARRIER
126 int urcu_bp_has_sys_membarrier;
127 #endif
128
129 /*
130 * rcu_gp_lock ensures mutual exclusion between threads calling
131 * synchronize_rcu().
132 */
133 static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER;
134 /*
135 * rcu_registry_lock ensures mutual exclusion between threads
136 * registering and unregistering themselves to/from the registry, and
137 * with threads reading that registry from synchronize_rcu(). However,
138 * this lock is not held all the way through the completion of awaiting
139 * for the grace period. It is sporadically released between iterations
140 * on the registry.
141 * rcu_registry_lock may nest inside rcu_gp_lock.
142 */
143 static pthread_mutex_t rcu_registry_lock = PTHREAD_MUTEX_INITIALIZER;
144
145 static pthread_mutex_t init_lock = PTHREAD_MUTEX_INITIALIZER;
146 static int initialized;
147
148 static pthread_key_t urcu_bp_key;
149
150 struct urcu_bp_gp urcu_bp_gp = { .ctr = URCU_BP_GP_COUNT };
151 URCU_ATTR_ALIAS("urcu_bp_gp") extern struct urcu_bp_gp rcu_gp_bp;
152
153 /*
154 * Pointer to registry elements. Written to only by each individual reader. Read
155 * by both the reader and the writers.
156 */
157 DEFINE_URCU_TLS(struct urcu_bp_reader *, urcu_bp_reader);
158 DEFINE_URCU_TLS_ALIAS(struct urcu_bp_reader *, urcu_bp_reader, rcu_reader_bp);
159
160 static CDS_LIST_HEAD(registry);
161
162 struct registry_chunk {
163 size_t data_len; /* data length */
164 size_t used; /* amount of data used */
165 struct cds_list_head node; /* chunk_list node */
166 char data[];
167 };
168
169 struct registry_arena {
170 struct cds_list_head chunk_list;
171 };
172
173 static struct registry_arena registry_arena = {
174 .chunk_list = CDS_LIST_HEAD_INIT(registry_arena.chunk_list),
175 };
176
177 /* Saved fork signal mask, protected by rcu_gp_lock */
178 static sigset_t saved_fork_signal_mask;
179
180 static void mutex_lock(pthread_mutex_t *mutex)
181 {
182 int ret;
183
184 #ifndef DISTRUST_SIGNALS_EXTREME
185 ret = pthread_mutex_lock(mutex);
186 if (ret)
187 urcu_die(ret);
188 #else /* #ifndef DISTRUST_SIGNALS_EXTREME */
189 while ((ret = pthread_mutex_trylock(mutex)) != 0) {
190 if (ret != EBUSY && ret != EINTR)
191 urcu_die(ret);
192 poll(NULL,0,10);
193 }
194 #endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */
195 }
196
197 static void mutex_unlock(pthread_mutex_t *mutex)
198 {
199 int ret;
200
201 ret = pthread_mutex_unlock(mutex);
202 if (ret)
203 urcu_die(ret);
204 }
205
206 static void smp_mb_master(void)
207 {
208 if (caa_likely(urcu_bp_has_sys_membarrier)) {
209 if (membarrier(MEMBARRIER_CMD_PRIVATE_EXPEDITED, 0))
210 urcu_die(errno);
211 } else {
212 cmm_smp_mb();
213 }
214 }
215
216 /*
217 * Always called with rcu_registry lock held. Releases this lock between
218 * iterations and grabs it again. Holds the lock when it returns.
219 */
220 static void wait_for_readers(struct cds_list_head *input_readers,
221 struct cds_list_head *cur_snap_readers,
222 struct cds_list_head *qsreaders)
223 {
224 unsigned int wait_loops = 0;
225 struct urcu_bp_reader *index, *tmp;
226
227 /*
228 * Wait for each thread URCU_TLS(urcu_bp_reader).ctr to either
229 * indicate quiescence (not nested), or observe the current
230 * rcu_gp.ctr value.
231 */
232 for (;;) {
233 if (wait_loops < RCU_QS_ACTIVE_ATTEMPTS)
234 wait_loops++;
235
236 cds_list_for_each_entry_safe(index, tmp, input_readers, node) {
237 switch (urcu_bp_reader_state(&index->ctr)) {
238 case URCU_BP_READER_ACTIVE_CURRENT:
239 if (cur_snap_readers) {
240 cds_list_move(&index->node,
241 cur_snap_readers);
242 break;
243 }
244 /* Fall-through */
245 case URCU_BP_READER_INACTIVE:
246 cds_list_move(&index->node, qsreaders);
247 break;
248 case URCU_BP_READER_ACTIVE_OLD:
249 /*
250 * Old snapshot. Leaving node in
251 * input_readers will make us busy-loop
252 * until the snapshot becomes current or
253 * the reader becomes inactive.
254 */
255 break;
256 }
257 }
258
259 if (cds_list_empty(input_readers)) {
260 break;
261 } else {
262 /* Temporarily unlock the registry lock. */
263 mutex_unlock(&rcu_registry_lock);
264 if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS)
265 (void) poll(NULL, 0, RCU_SLEEP_DELAY_MS);
266 else
267 caa_cpu_relax();
268 /* Re-lock the registry lock before the next loop. */
269 mutex_lock(&rcu_registry_lock);
270 }
271 }
272 }
273
274 void urcu_bp_synchronize_rcu(void)
275 {
276 CDS_LIST_HEAD(cur_snap_readers);
277 CDS_LIST_HEAD(qsreaders);
278 sigset_t newmask, oldmask;
279 int ret;
280
281 ret = sigfillset(&newmask);
282 assert(!ret);
283 ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask);
284 assert(!ret);
285
286 mutex_lock(&rcu_gp_lock);
287
288 mutex_lock(&rcu_registry_lock);
289
290 if (cds_list_empty(&registry))
291 goto out;
292
293 /* All threads should read qparity before accessing data structure
294 * where new ptr points to. */
295 /* Write new ptr before changing the qparity */
296 smp_mb_master();
297
298 /*
299 * Wait for readers to observe original parity or be quiescent.
300 * wait_for_readers() can release and grab again rcu_registry_lock
301 * interally.
302 */
303 wait_for_readers(&registry, &cur_snap_readers, &qsreaders);
304
305 /*
306 * Adding a cmm_smp_mb() which is _not_ formally required, but makes the
307 * model easier to understand. It does not have a big performance impact
308 * anyway, given this is the write-side.
309 */
310 cmm_smp_mb();
311
312 /* Switch parity: 0 -> 1, 1 -> 0 */
313 CMM_STORE_SHARED(rcu_gp.ctr, rcu_gp.ctr ^ URCU_BP_GP_CTR_PHASE);
314
315 /*
316 * Must commit qparity update to memory before waiting for other parity
317 * quiescent state. Failure to do so could result in the writer waiting
318 * forever while new readers are always accessing data (no progress).
319 * Ensured by CMM_STORE_SHARED and CMM_LOAD_SHARED.
320 */
321
322 /*
323 * Adding a cmm_smp_mb() which is _not_ formally required, but makes the
324 * model easier to understand. It does not have a big performance impact
325 * anyway, given this is the write-side.
326 */
327 cmm_smp_mb();
328
329 /*
330 * Wait for readers to observe new parity or be quiescent.
331 * wait_for_readers() can release and grab again rcu_registry_lock
332 * interally.
333 */
334 wait_for_readers(&cur_snap_readers, NULL, &qsreaders);
335
336 /*
337 * Put quiescent reader list back into registry.
338 */
339 cds_list_splice(&qsreaders, &registry);
340
341 /*
342 * Finish waiting for reader threads before letting the old ptr being
343 * freed.
344 */
345 smp_mb_master();
346 out:
347 mutex_unlock(&rcu_registry_lock);
348 mutex_unlock(&rcu_gp_lock);
349 ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
350 assert(!ret);
351 }
352 URCU_ATTR_ALIAS("urcu_bp_synchronize_rcu") void synchronize_rcu_bp();
353
354 /*
355 * library wrappers to be used by non-LGPL compatible source code.
356 */
357
358 void urcu_bp_read_lock(void)
359 {
360 _urcu_bp_read_lock();
361 }
362 URCU_ATTR_ALIAS("urcu_bp_read_lock") void rcu_read_lock_bp();
363
364 void urcu_bp_read_unlock(void)
365 {
366 _urcu_bp_read_unlock();
367 }
368 URCU_ATTR_ALIAS("urcu_bp_read_unlock") void rcu_read_unlock_bp();
369
370 int urcu_bp_read_ongoing(void)
371 {
372 return _urcu_bp_read_ongoing();
373 }
374 URCU_ATTR_ALIAS("urcu_bp_read_ongoing") int rcu_read_ongoing_bp();
375
376 /*
377 * Only grow for now. If empty, allocate a ARENA_INIT_ALLOC sized chunk.
378 * Else, try expanding the last chunk. If this fails, allocate a new
379 * chunk twice as big as the last chunk.
380 * Memory used by chunks _never_ moves. A chunk could theoretically be
381 * freed when all "used" slots are released, but we don't do it at this
382 * point.
383 */
384 static
385 void expand_arena(struct registry_arena *arena)
386 {
387 struct registry_chunk *new_chunk, *last_chunk;
388 size_t old_chunk_len, new_chunk_len;
389
390 /* No chunk. */
391 if (cds_list_empty(&arena->chunk_list)) {
392 assert(ARENA_INIT_ALLOC >=
393 sizeof(struct registry_chunk)
394 + sizeof(struct rcu_reader));
395 new_chunk_len = ARENA_INIT_ALLOC;
396 new_chunk = (struct registry_chunk *) mmap(NULL,
397 new_chunk_len,
398 PROT_READ | PROT_WRITE,
399 MAP_ANONYMOUS | MAP_PRIVATE,
400 -1, 0);
401 if (new_chunk == MAP_FAILED)
402 abort();
403 memset(new_chunk, 0, new_chunk_len);
404 new_chunk->data_len =
405 new_chunk_len - sizeof(struct registry_chunk);
406 cds_list_add_tail(&new_chunk->node, &arena->chunk_list);
407 return; /* We're done. */
408 }
409
410 /* Try expanding last chunk. */
411 last_chunk = cds_list_entry(arena->chunk_list.prev,
412 struct registry_chunk, node);
413 old_chunk_len =
414 last_chunk->data_len + sizeof(struct registry_chunk);
415 new_chunk_len = old_chunk_len << 1;
416
417 /* Don't allow memory mapping to move, just expand. */
418 new_chunk = mremap_wrapper(last_chunk, old_chunk_len,
419 new_chunk_len, 0);
420 if (new_chunk != MAP_FAILED) {
421 /* Should not have moved. */
422 assert(new_chunk == last_chunk);
423 memset((char *) last_chunk + old_chunk_len, 0,
424 new_chunk_len - old_chunk_len);
425 last_chunk->data_len =
426 new_chunk_len - sizeof(struct registry_chunk);
427 return; /* We're done. */
428 }
429
430 /* Remap did not succeed, we need to add a new chunk. */
431 new_chunk = (struct registry_chunk *) mmap(NULL,
432 new_chunk_len,
433 PROT_READ | PROT_WRITE,
434 MAP_ANONYMOUS | MAP_PRIVATE,
435 -1, 0);
436 if (new_chunk == MAP_FAILED)
437 abort();
438 memset(new_chunk, 0, new_chunk_len);
439 new_chunk->data_len =
440 new_chunk_len - sizeof(struct registry_chunk);
441 cds_list_add_tail(&new_chunk->node, &arena->chunk_list);
442 }
443
444 static
445 struct rcu_reader *arena_alloc(struct registry_arena *arena)
446 {
447 struct registry_chunk *chunk;
448 struct rcu_reader *rcu_reader_reg;
449 int expand_done = 0; /* Only allow to expand once per alloc */
450 size_t len = sizeof(struct rcu_reader);
451
452 retry:
453 cds_list_for_each_entry(chunk, &arena->chunk_list, node) {
454 if (chunk->data_len - chunk->used < len)
455 continue;
456 /* Find spot */
457 for (rcu_reader_reg = (struct rcu_reader *) &chunk->data[0];
458 rcu_reader_reg < (struct rcu_reader *) &chunk->data[chunk->data_len];
459 rcu_reader_reg++) {
460 if (!rcu_reader_reg->alloc) {
461 rcu_reader_reg->alloc = 1;
462 chunk->used += len;
463 return rcu_reader_reg;
464 }
465 }
466 }
467
468 if (!expand_done) {
469 expand_arena(arena);
470 expand_done = 1;
471 goto retry;
472 }
473
474 return NULL;
475 }
476
477 /* Called with signals off and mutex locked */
478 static
479 void add_thread(void)
480 {
481 struct rcu_reader *rcu_reader_reg;
482 int ret;
483
484 rcu_reader_reg = arena_alloc(&registry_arena);
485 if (!rcu_reader_reg)
486 abort();
487 ret = pthread_setspecific(urcu_bp_key, rcu_reader_reg);
488 if (ret)
489 abort();
490
491 /* Add to registry */
492 rcu_reader_reg->tid = pthread_self();
493 assert(rcu_reader_reg->ctr == 0);
494 cds_list_add(&rcu_reader_reg->node, &registry);
495 /*
496 * Reader threads are pointing to the reader registry. This is
497 * why its memory should never be relocated.
498 */
499 URCU_TLS(urcu_bp_reader) = rcu_reader_reg;
500 }
501
502 /* Called with mutex locked */
503 static
504 void cleanup_thread(struct registry_chunk *chunk,
505 struct rcu_reader *rcu_reader_reg)
506 {
507 rcu_reader_reg->ctr = 0;
508 cds_list_del(&rcu_reader_reg->node);
509 rcu_reader_reg->tid = 0;
510 rcu_reader_reg->alloc = 0;
511 chunk->used -= sizeof(struct rcu_reader);
512 }
513
514 static
515 struct registry_chunk *find_chunk(struct rcu_reader *rcu_reader_reg)
516 {
517 struct registry_chunk *chunk;
518
519 cds_list_for_each_entry(chunk, &registry_arena.chunk_list, node) {
520 if (rcu_reader_reg < (struct rcu_reader *) &chunk->data[0])
521 continue;
522 if (rcu_reader_reg >= (struct rcu_reader *) &chunk->data[chunk->data_len])
523 continue;
524 return chunk;
525 }
526 return NULL;
527 }
528
529 /* Called with signals off and mutex locked */
530 static
531 void remove_thread(struct rcu_reader *rcu_reader_reg)
532 {
533 cleanup_thread(find_chunk(rcu_reader_reg), rcu_reader_reg);
534 URCU_TLS(urcu_bp_reader) = NULL;
535 }
536
537 /* Disable signals, take mutex, add to registry */
538 void urcu_bp_register(void)
539 {
540 sigset_t newmask, oldmask;
541 int ret;
542
543 ret = sigfillset(&newmask);
544 if (ret)
545 abort();
546 ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask);
547 if (ret)
548 abort();
549
550 /*
551 * Check if a signal concurrently registered our thread since
552 * the check in rcu_read_lock().
553 */
554 if (URCU_TLS(urcu_bp_reader))
555 goto end;
556
557 /*
558 * Take care of early registration before urcu_bp constructor.
559 */
560 _urcu_bp_init();
561
562 mutex_lock(&rcu_registry_lock);
563 add_thread();
564 mutex_unlock(&rcu_registry_lock);
565 end:
566 ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
567 if (ret)
568 abort();
569 }
570 URCU_ATTR_ALIAS("urcu_bp_register") void rcu_bp_register();
571
572 void urcu_bp_register_thread(void)
573 {
574 if (caa_unlikely(!URCU_TLS(urcu_bp_reader)))
575 urcu_bp_register(); /* If not yet registered. */
576 }
577
578 /* Disable signals, take mutex, remove from registry */
579 static
580 void urcu_bp_unregister(struct rcu_reader *rcu_reader_reg)
581 {
582 sigset_t newmask, oldmask;
583 int ret;
584
585 ret = sigfillset(&newmask);
586 if (ret)
587 abort();
588 ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask);
589 if (ret)
590 abort();
591
592 mutex_lock(&rcu_registry_lock);
593 remove_thread(rcu_reader_reg);
594 mutex_unlock(&rcu_registry_lock);
595 ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
596 if (ret)
597 abort();
598 urcu_bp_exit();
599 }
600
601 /*
602 * Remove thread from the registry when it exits, and flag it as
603 * destroyed so garbage collection can take care of it.
604 */
605 static
606 void urcu_bp_thread_exit_notifier(void *rcu_key)
607 {
608 urcu_bp_unregister(rcu_key);
609 }
610
611 #ifdef CONFIG_RCU_FORCE_SYS_MEMBARRIER
612 static
613 void urcu_bp_sys_membarrier_status(bool available)
614 {
615 if (!available)
616 abort();
617 }
618 #else
619 static
620 void urcu_bp_sys_membarrier_status(bool available)
621 {
622 if (!available)
623 return;
624 urcu_bp_has_sys_membarrier = 1;
625 }
626 #endif
627
628 static
629 void urcu_bp_sys_membarrier_init(void)
630 {
631 bool available = false;
632 int mask;
633
634 mask = membarrier(MEMBARRIER_CMD_QUERY, 0);
635 if (mask >= 0) {
636 if (mask & MEMBARRIER_CMD_PRIVATE_EXPEDITED) {
637 if (membarrier(MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED, 0))
638 urcu_die(errno);
639 available = true;
640 }
641 }
642 urcu_bp_sys_membarrier_status(available);
643 }
644
645 static
646 void _urcu_bp_init(void)
647 {
648 mutex_lock(&init_lock);
649 if (!urcu_bp_refcount++) {
650 int ret;
651
652 ret = pthread_key_create(&urcu_bp_key,
653 urcu_bp_thread_exit_notifier);
654 if (ret)
655 abort();
656 urcu_bp_sys_membarrier_init();
657 initialized = 1;
658 }
659 mutex_unlock(&init_lock);
660 }
661
662 static
663 void urcu_bp_exit(void)
664 {
665 mutex_lock(&init_lock);
666 if (!--urcu_bp_refcount) {
667 struct registry_chunk *chunk, *tmp;
668 int ret;
669
670 cds_list_for_each_entry_safe(chunk, tmp,
671 &registry_arena.chunk_list, node) {
672 munmap((void *) chunk, chunk->data_len
673 + sizeof(struct registry_chunk));
674 }
675 CDS_INIT_LIST_HEAD(&registry_arena.chunk_list);
676 ret = pthread_key_delete(urcu_bp_key);
677 if (ret)
678 abort();
679 }
680 mutex_unlock(&init_lock);
681 }
682
683 /*
684 * Holding the rcu_gp_lock and rcu_registry_lock across fork will make
685 * sure we fork() don't race with a concurrent thread executing with
686 * any of those locks held. This ensures that the registry and data
687 * protected by rcu_gp_lock are in a coherent state in the child.
688 */
689 void urcu_bp_before_fork(void)
690 {
691 sigset_t newmask, oldmask;
692 int ret;
693
694 ret = sigfillset(&newmask);
695 assert(!ret);
696 ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask);
697 assert(!ret);
698 mutex_lock(&rcu_gp_lock);
699 mutex_lock(&rcu_registry_lock);
700 saved_fork_signal_mask = oldmask;
701 }
702 URCU_ATTR_ALIAS("urcu_bp_before_fork") void rcu_bp_before_fork();
703
704 void urcu_bp_after_fork_parent(void)
705 {
706 sigset_t oldmask;
707 int ret;
708
709 oldmask = saved_fork_signal_mask;
710 mutex_unlock(&rcu_registry_lock);
711 mutex_unlock(&rcu_gp_lock);
712 ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
713 assert(!ret);
714 }
715 URCU_ATTR_ALIAS("urcu_bp_after_fork_parent")
716 void rcu_bp_after_fork_parent(void);
717
718 /*
719 * Prune all entries from registry except our own thread. Fits the Linux
720 * fork behavior. Called with rcu_gp_lock and rcu_registry_lock held.
721 */
722 static
723 void urcu_bp_prune_registry(void)
724 {
725 struct registry_chunk *chunk;
726 struct urcu_bp_reader *rcu_reader_reg;
727
728 cds_list_for_each_entry(chunk, &registry_arena.chunk_list, node) {
729 for (rcu_reader_reg = (struct urcu_bp_reader *) &chunk->data[0];
730 rcu_reader_reg < (struct urcu_bp_reader *) &chunk->data[chunk->data_len];
731 rcu_reader_reg++) {
732 if (!rcu_reader_reg->alloc)
733 continue;
734 if (rcu_reader_reg->tid == pthread_self())
735 continue;
736 cleanup_thread(chunk, rcu_reader_reg);
737 }
738 }
739 }
740
741 void urcu_bp_after_fork_child(void)
742 {
743 sigset_t oldmask;
744 int ret;
745
746 urcu_bp_prune_registry();
747 oldmask = saved_fork_signal_mask;
748 mutex_unlock(&rcu_registry_lock);
749 mutex_unlock(&rcu_gp_lock);
750 ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
751 assert(!ret);
752 }
753 URCU_ATTR_ALIAS("urcu_bp_after_fork_child")
754 void rcu_bp_after_fork_child(void);
755
756 void *urcu_bp_dereference_sym(void *p)
757 {
758 return _rcu_dereference(p);
759 }
760 URCU_ATTR_ALIAS("urcu_bp_dereference_sym")
761 void *rcu_dereference_sym_bp();
762
763 void *urcu_bp_set_pointer_sym(void **p, void *v)
764 {
765 cmm_wmb();
766 uatomic_set(p, v);
767 return v;
768 }
769 URCU_ATTR_ALIAS("urcu_bp_set_pointer_sym")
770 void *rcu_set_pointer_sym_bp();
771
772 void *urcu_bp_xchg_pointer_sym(void **p, void *v)
773 {
774 cmm_wmb();
775 return uatomic_xchg(p, v);
776 }
777 URCU_ATTR_ALIAS("urcu_bp_xchg_pointer_sym")
778 void *rcu_xchg_pointer_sym_bp();
779
780 void *urcu_bp_cmpxchg_pointer_sym(void **p, void *old, void *_new)
781 {
782 cmm_wmb();
783 return uatomic_cmpxchg(p, old, _new);
784 }
785 URCU_ATTR_ALIAS("urcu_bp_cmpxchg_pointer_sym")
786 void *rcu_cmpxchg_pointer_sym_bp();
787
788 DEFINE_RCU_FLAVOR(rcu_flavor);
789 DEFINE_RCU_FLAVOR_ALIAS(rcu_flavor, alias_rcu_flavor);
790
791 #include "urcu-call-rcu-impl.h"
792 #include "urcu-defer-impl.h"
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