liburcu: Use membarrier private expedited when available
[urcu.git] / src / urcu.c
CommitLineData
b257a10b
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1/*
2 * urcu.c
3 *
4 * Userspace RCU library
5 *
6982d6d7 6 * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
af02d47e 7 * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
b257a10b 8 *
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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
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22 *
23 * IBM's contributions to this file may be relicensed under LGPLv2 or later.
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24 */
25
fdf01eed 26#define _BSD_SOURCE
71c811bf 27#define _LGPL_SOURCE
82d50e1a 28#define _DEFAULT_SOURCE
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29#include <stdio.h>
30#include <pthread.h>
31#include <signal.h>
32#include <assert.h>
f69f195a 33#include <stdlib.h>
6d841bc2 34#include <stdint.h>
f69f195a 35#include <string.h>
09a9f986 36#include <errno.h>
c0bb9f69 37#include <stdbool.h>
e8043c1b 38#include <poll.h>
27b012e2 39
999991c6 40#include "urcu/arch.h"
d73fb81f 41#include "urcu/wfcqueue.h"
57760d44 42#include "urcu/map/urcu.h"
af7c2dbe 43#include "urcu/static/urcu.h"
618b2595 44#include "urcu-pointer.h"
bd252a04 45#include "urcu/tls-compat.h"
71c811bf 46
4a6d7378 47#include "urcu-die.h"
5bffdd5d 48#include "urcu-wait.h"
4a6d7378 49
121a5d44 50/* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
71c811bf 51#undef _LGPL_SOURCE
27b012e2 52#include "urcu.h"
71c811bf 53#define _LGPL_SOURCE
27b012e2 54
3a71751e
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55/*
56 * If a reader is really non-cooperative and refuses to commit its
57 * rcu_active_readers count to memory (there is no barrier in the reader
9340c38d 58 * per-se), kick it after 10 loops waiting for it.
3a71751e 59 */
9340c38d 60#define KICK_READER_LOOPS 10
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61
62/*
63 * Active attempts to check for reader Q.S. before calling futex().
64 */
65#define RCU_QS_ACTIVE_ATTEMPTS 100
66
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67/* If the headers do not support membarrier system call, fall back on RCU_MB */
68#ifdef __NR_membarrier
69# define membarrier(...) syscall(__NR_membarrier, __VA_ARGS__)
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70#else
71# define membarrier(...) -ENOSYS
72#endif
73
64f469e6 74enum membarrier_cmd {
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75 MEMBARRIER_CMD_QUERY = 0,
76 MEMBARRIER_CMD_SHARED = (1 << 0),
77 /* reserved for MEMBARRIER_CMD_SHARED_EXPEDITED (1 << 1) */
78 /* reserved for MEMBARRIER_CMD_PRIVATE (1 << 2) */
79 MEMBARRIER_CMD_PRIVATE_EXPEDITED = (1 << 3),
80 MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED = (1 << 4),
64f469e6 81};
553b7eb9 82
fdf01eed 83#ifdef RCU_MEMBARRIER
834a45ba 84static int init_done;
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85static int has_sys_membarrier_private_expedited;
86
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87#ifndef CONFIG_RCU_FORCE_SYS_MEMBARRIER
88int rcu_has_sys_membarrier_memb;
89#endif
834a45ba 90
02be5561 91void __attribute__((constructor)) rcu_init(void);
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92#endif
93
94#ifdef RCU_MB
02be5561 95void rcu_init(void)
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96{
97}
98#endif
8a5fb4c9 99
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100#ifdef RCU_SIGNAL
101static int init_done;
102
103void __attribute__((constructor)) rcu_init(void);
104void __attribute__((destructor)) rcu_exit(void);
105#endif
106
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107/*
108 * rcu_gp_lock ensures mutual exclusion between threads calling
109 * synchronize_rcu().
110 */
6abb4bd5 111static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER;
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112/*
113 * rcu_registry_lock ensures mutual exclusion between threads
114 * registering and unregistering themselves to/from the registry, and
115 * with threads reading that registry from synchronize_rcu(). However,
116 * this lock is not held all the way through the completion of awaiting
117 * for the grace period. It is sporadically released between iterations
118 * on the registry.
119 * rcu_registry_lock may nest inside rcu_gp_lock.
120 */
121static pthread_mutex_t rcu_registry_lock = PTHREAD_MUTEX_INITIALIZER;
4de0cd31 122struct rcu_gp rcu_gp = { .ctr = RCU_GP_COUNT };
27b012e2 123
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124/*
125 * Written to only by each individual reader. Read by both the reader and the
126 * writers.
127 */
2f661865 128DEFINE_URCU_TLS(struct rcu_reader, rcu_reader);
27b012e2 129
16aa9ee8 130static CDS_LIST_HEAD(registry);
27b012e2 131
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132/*
133 * Queue keeping threads awaiting to wait for a grace period. Contains
134 * struct gp_waiters_thread objects.
135 */
136static DEFINE_URCU_WAIT_QUEUE(gp_waiters);
137
6abb4bd5 138static void mutex_lock(pthread_mutex_t *mutex)
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139{
140 int ret;
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141
142#ifndef DISTRUST_SIGNALS_EXTREME
6abb4bd5 143 ret = pthread_mutex_lock(mutex);
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144 if (ret)
145 urcu_die(ret);
09a9f986 146#else /* #ifndef DISTRUST_SIGNALS_EXTREME */
6abb4bd5 147 while ((ret = pthread_mutex_trylock(mutex)) != 0) {
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148 if (ret != EBUSY && ret != EINTR)
149 urcu_die(ret);
bd252a04 150 if (CMM_LOAD_SHARED(URCU_TLS(rcu_reader).need_mb)) {
5481ddb3 151 cmm_smp_mb();
bd252a04 152 _CMM_STORE_SHARED(URCU_TLS(rcu_reader).need_mb, 0);
5481ddb3 153 cmm_smp_mb();
09a9f986 154 }
8999a9ee 155 (void) poll(NULL, 0, 10);
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156 }
157#endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */
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158}
159
6abb4bd5 160static void mutex_unlock(pthread_mutex_t *mutex)
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161{
162 int ret;
163
6abb4bd5 164 ret = pthread_mutex_unlock(mutex);
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165 if (ret)
166 urcu_die(ret);
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167}
168
fdf01eed 169#ifdef RCU_MEMBARRIER
a4922ed9 170static void smp_mb_master(void)
fdf01eed 171{
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172 if (caa_likely(rcu_has_sys_membarrier_memb)) {
173 if (membarrier(has_sys_membarrier_private_expedited ?
174 MEMBARRIER_CMD_PRIVATE_EXPEDITED :
175 MEMBARRIER_CMD_SHARED, 0))
176 urcu_die(errno);
177 } else {
5481ddb3 178 cmm_smp_mb();
c0bb9f69 179 }
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180}
181#endif
182
02be5561 183#ifdef RCU_MB
a4922ed9 184static void smp_mb_master(void)
40e140c9 185{
5481ddb3 186 cmm_smp_mb();
40e140c9 187}
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188#endif
189
190#ifdef RCU_SIGNAL
78ff9419 191static void force_mb_all_readers(void)
27b012e2 192{
02be5561 193 struct rcu_reader *index;
e3b0cef0 194
27b012e2 195 /*
5481ddb3 196 * Ask for each threads to execute a cmm_smp_mb() so we can consider the
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197 * compiler barriers around rcu read lock as real memory barriers.
198 */
16aa9ee8 199 if (cds_list_empty(&registry))
27b012e2 200 return;
3a86deba 201 /*
5481ddb3 202 * pthread_kill has a cmm_smp_mb(). But beware, we assume it performs
157dca95 203 * a cache flush on architectures with non-coherent cache. Let's play
5481ddb3 204 * safe and don't assume anything : we use cmm_smp_mc() to make sure the
157dca95 205 * cache flush is enforced.
3a86deba 206 */
16aa9ee8 207 cds_list_for_each_entry(index, &registry, node) {
6cf3827c 208 CMM_STORE_SHARED(index->need_mb, 1);
02be5561 209 pthread_kill(index->tid, SIGRCU);
09a9f986 210 }
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211 /*
212 * Wait for sighandler (and thus mb()) to execute on every thread.
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213 *
214 * Note that the pthread_kill() will never be executed on systems
215 * that correctly deliver signals in a timely manner. However, it
216 * is not uncommon for kernels to have bugs that can result in
217 * lost or unduly delayed signals.
218 *
219 * If you are seeing the below pthread_kill() executing much at
220 * all, we suggest testing the underlying kernel and filing the
221 * relevant bug report. For Linux kernels, we recommend getting
222 * the Linux Test Project (LTP).
27b012e2 223 */
16aa9ee8 224 cds_list_for_each_entry(index, &registry, node) {
6cf3827c 225 while (CMM_LOAD_SHARED(index->need_mb)) {
02be5561 226 pthread_kill(index->tid, SIGRCU);
8999a9ee 227 (void) poll(NULL, 0, 1);
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228 }
229 }
5481ddb3 230 cmm_smp_mb(); /* read ->need_mb before ending the barrier */
27b012e2 231}
9d7e3f89 232
a4922ed9 233static void smp_mb_master(void)
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234{
235 force_mb_all_readers();
236}
fdf01eed 237#endif /* #ifdef RCU_SIGNAL */
27b012e2 238
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239/*
240 * synchronize_rcu() waiting. Single thread.
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241 * Always called with rcu_registry lock held. Releases this lock and
242 * grabs it again. Holds the lock when it returns.
bc6c15bb 243 */
cfe78e25 244static void wait_gp(void)
bc6c15bb 245{
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246 /*
247 * Read reader_gp before read futex. smp_mb_master() needs to
248 * be called with the rcu registry lock held in RCU_SIGNAL
249 * flavor.
250 */
a4922ed9 251 smp_mb_master();
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252 /* Temporarily unlock the registry lock. */
253 mutex_unlock(&rcu_registry_lock);
b0a841b4 254 if (uatomic_read(&rcu_gp.futex) != -1)
fca9fb96 255 goto end;
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256 while (futex_async(&rcu_gp.futex, FUTEX_WAIT, -1,
257 NULL, NULL, 0)) {
258 switch (errno) {
259 case EWOULDBLOCK:
260 /* Value already changed. */
fca9fb96 261 goto end;
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262 case EINTR:
263 /* Retry if interrupted by signal. */
264 break; /* Get out of switch. */
265 default:
266 /* Unexpected error. */
267 urcu_die(errno);
268 }
269 }
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270end:
271 /*
272 * Re-lock the registry lock before the next loop.
273 */
274 mutex_lock(&rcu_registry_lock);
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275}
276
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277/*
278 * Always called with rcu_registry lock held. Releases this lock between
279 * iterations and grabs it again. Holds the lock when it returns.
280 */
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281static void wait_for_readers(struct cds_list_head *input_readers,
282 struct cds_list_head *cur_snap_readers,
283 struct cds_list_head *qsreaders)
27b012e2 284{
9340c38d 285 unsigned int wait_loops = 0;
02be5561 286 struct rcu_reader *index, *tmp;
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287#ifdef HAS_INCOHERENT_CACHES
288 unsigned int wait_gp_loops = 0;
289#endif /* HAS_INCOHERENT_CACHES */
27b012e2 290
40e140c9 291 /*
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292 * Wait for each thread URCU_TLS(rcu_reader).ctr to either
293 * indicate quiescence (not nested), or observe the current
ed1b099e 294 * rcu_gp.ctr value.
27b012e2 295 */
cfe78e25 296 for (;;) {
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297 if (wait_loops < RCU_QS_ACTIVE_ATTEMPTS)
298 wait_loops++;
9340c38d 299 if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
ed1b099e 300 uatomic_dec(&rcu_gp.futex);
cfe78e25 301 /* Write futex before read reader_gp */
a4922ed9 302 smp_mb_master();
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303 }
304
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305 cds_list_for_each_entry_safe(index, tmp, input_readers, node) {
306 switch (rcu_reader_state(&index->ctr)) {
307 case RCU_READER_ACTIVE_CURRENT:
308 if (cur_snap_readers) {
309 cds_list_move(&index->node,
310 cur_snap_readers);
311 break;
312 }
313 /* Fall-through */
314 case RCU_READER_INACTIVE:
315 cds_list_move(&index->node, qsreaders);
316 break;
317 case RCU_READER_ACTIVE_OLD:
318 /*
319 * Old snapshot. Leaving node in
320 * input_readers will make us busy-loop
321 * until the snapshot becomes current or
322 * the reader becomes inactive.
323 */
324 break;
325 }
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326 }
327
e8043c1b 328#ifndef HAS_INCOHERENT_CACHES
fd189fa5 329 if (cds_list_empty(input_readers)) {
9340c38d 330 if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
cfe78e25 331 /* Read reader_gp before write futex */
a4922ed9 332 smp_mb_master();
ed1b099e 333 uatomic_set(&rcu_gp.futex, 0);
bc6c15bb 334 }
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335 break;
336 } else {
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337 if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
338 /* wait_gp unlocks/locks registry lock. */
cfe78e25 339 wait_gp();
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340 } else {
341 /* Temporarily unlock the registry lock. */
342 mutex_unlock(&rcu_registry_lock);
06f22bdb 343 caa_cpu_relax();
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344 /*
345 * Re-lock the registry lock before the
346 * next loop.
347 */
348 mutex_lock(&rcu_registry_lock);
349 }
bc6c15bb 350 }
e8043c1b 351#else /* #ifndef HAS_INCOHERENT_CACHES */
27b012e2 352 /*
40e140c9 353 * BUSY-LOOP. Force the reader thread to commit its
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354 * URCU_TLS(rcu_reader).ctr update to memory if we wait
355 * for too long.
27b012e2 356 */
fd189fa5 357 if (cds_list_empty(input_readers)) {
9340c38d 358 if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
cfe78e25 359 /* Read reader_gp before write futex */
a4922ed9 360 smp_mb_master();
ed1b099e 361 uatomic_set(&rcu_gp.futex, 0);
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362 }
363 break;
364 } else {
9340c38d 365 if (wait_gp_loops == KICK_READER_LOOPS) {
a4922ed9 366 smp_mb_master();
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367 wait_gp_loops = 0;
368 }
369 if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
fca9fb96 370 /* wait_gp unlocks/locks registry lock. */
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371 wait_gp();
372 wait_gp_loops++;
373 } else {
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374 /* Temporarily unlock the registry lock. */
375 mutex_unlock(&rcu_registry_lock);
06f22bdb 376 caa_cpu_relax();
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377 /*
378 * Re-lock the registry lock before the
379 * next loop.
380 */
381 mutex_lock(&rcu_registry_lock);
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382 }
383 }
e8043c1b 384#endif /* #else #ifndef HAS_INCOHERENT_CACHES */
27b012e2 385 }
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386}
387
9598a481 388void synchronize_rcu(void)
2bc59bd7 389{
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390 CDS_LIST_HEAD(cur_snap_readers);
391 CDS_LIST_HEAD(qsreaders);
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392 DEFINE_URCU_WAIT_NODE(wait, URCU_WAIT_WAITING);
393 struct urcu_waiters waiters;
394
395 /*
396 * Add ourself to gp_waiters queue of threads awaiting to wait
397 * for a grace period. Proceed to perform the grace period only
398 * if we are the first thread added into the queue.
399 * The implicit memory barrier before urcu_wait_add()
400 * orders prior memory accesses of threads put into the wait
401 * queue before their insertion into the wait queue.
402 */
403 if (urcu_wait_add(&gp_waiters, &wait) != 0) {
404 /* Not first in queue: will be awakened by another thread. */
405 urcu_adaptative_busy_wait(&wait);
406 /* Order following memory accesses after grace period. */
407 cmm_smp_mb();
408 return;
409 }
410 /* We won't need to wake ourself up */
411 urcu_wait_set_state(&wait, URCU_WAIT_RUNNING);
fd189fa5 412
6abb4bd5 413 mutex_lock(&rcu_gp_lock);
135530fd 414
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415 /*
416 * Move all waiters into our local queue.
417 */
418 urcu_move_waiters(&waiters, &gp_waiters);
419
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420 mutex_lock(&rcu_registry_lock);
421
16aa9ee8 422 if (cds_list_empty(&registry))
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423 goto out;
424
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425 /*
426 * All threads should read qparity before accessing data structure
427 * where new ptr points to. Must be done within rcu_registry_lock
428 * because it iterates on reader threads.
429 */
9598a481 430 /* Write new ptr before changing the qparity */
a4922ed9 431 smp_mb_master();
9598a481 432
9598a481 433 /*
c9488684 434 * Wait for readers to observe original parity or be quiescent.
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435 * wait_for_readers() can release and grab again rcu_registry_lock
436 * interally.
9598a481 437 */
fd189fa5 438 wait_for_readers(&registry, &cur_snap_readers, &qsreaders);
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439
440 /*
c9488684 441 * Must finish waiting for quiescent state for original parity before
ed1b099e 442 * committing next rcu_gp.ctr update to memory. Failure to do so could
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443 * result in the writer waiting forever while new readers are always
444 * accessing data (no progress). Enforce compiler-order of load
ed1b099e 445 * URCU_TLS(rcu_reader).ctr before store to rcu_gp.ctr.
9598a481 446 */
5481ddb3 447 cmm_barrier();
9598a481 448
5dba80f9 449 /*
5481ddb3 450 * Adding a cmm_smp_mb() which is _not_ formally required, but makes the
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451 * model easier to understand. It does not have a big performance impact
452 * anyway, given this is the write-side.
453 */
5481ddb3 454 cmm_smp_mb();
67c2d80b 455
c9488684 456 /* Switch parity: 0 -> 1, 1 -> 0 */
ed1b099e 457 CMM_STORE_SHARED(rcu_gp.ctr, rcu_gp.ctr ^ RCU_GP_CTR_PHASE);
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458
459 /*
ed1b099e 460 * Must commit rcu_gp.ctr update to memory before waiting for quiescent
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461 * state. Failure to do so could result in the writer waiting forever
462 * while new readers are always accessing data (no progress). Enforce
ed1b099e 463 * compiler-order of store to rcu_gp.ctr before load rcu_reader ctr.
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464 */
465 cmm_barrier();
466
467 /*
468 *
469 * Adding a cmm_smp_mb() which is _not_ formally required, but makes the
470 * model easier to understand. It does not have a big performance impact
471 * anyway, given this is the write-side.
472 */
473 cmm_smp_mb();
474
9598a481 475 /*
c9488684 476 * Wait for readers to observe new parity or be quiescent.
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477 * wait_for_readers() can release and grab again rcu_registry_lock
478 * interally.
9598a481 479 */
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480 wait_for_readers(&cur_snap_readers, NULL, &qsreaders);
481
482 /*
483 * Put quiescent reader list back into registry.
484 */
485 cds_list_splice(&qsreaders, &registry);
9598a481 486
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487 /*
488 * Finish waiting for reader threads before letting the old ptr
489 * being freed. Must be done within rcu_registry_lock because it
490 * iterates on reader threads.
491 */
a4922ed9 492 smp_mb_master();
2dfb8b5e 493out:
731ccb96 494 mutex_unlock(&rcu_registry_lock);
6abb4bd5 495 mutex_unlock(&rcu_gp_lock);
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496
497 /*
498 * Wakeup waiters only after we have completed the grace period
499 * and have ensured the memory barriers at the end of the grace
500 * period have been issued.
501 */
502 urcu_wake_all_waiters(&waiters);
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503}
504
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505/*
506 * library wrappers to be used by non-LGPL compatible source code.
507 */
508
509void rcu_read_lock(void)
510{
511 _rcu_read_lock();
512}
513
514void rcu_read_unlock(void)
515{
516 _rcu_read_unlock();
517}
518
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519int rcu_read_ongoing(void)
520{
521 return _rcu_read_ongoing();
522}
523
121a5d44 524void rcu_register_thread(void)
27b012e2 525{
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526 URCU_TLS(rcu_reader).tid = pthread_self();
527 assert(URCU_TLS(rcu_reader).need_mb == 0);
528 assert(!(URCU_TLS(rcu_reader).ctr & RCU_GP_CTR_NEST_MASK));
02be5561 529
731ccb96 530 mutex_lock(&rcu_registry_lock);
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531 assert(!URCU_TLS(rcu_reader).registered);
532 URCU_TLS(rcu_reader).registered = 1;
02be5561 533 rcu_init(); /* In case gcc does not support constructor attribute */
bd252a04 534 cds_list_add(&URCU_TLS(rcu_reader).node, &registry);
731ccb96 535 mutex_unlock(&rcu_registry_lock);
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536}
537
121a5d44 538void rcu_unregister_thread(void)
27b012e2 539{
731ccb96 540 mutex_lock(&rcu_registry_lock);
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541 assert(URCU_TLS(rcu_reader).registered);
542 URCU_TLS(rcu_reader).registered = 0;
bd252a04 543 cds_list_del(&URCU_TLS(rcu_reader).node);
731ccb96 544 mutex_unlock(&rcu_registry_lock);
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545}
546
fdf01eed 547#ifdef RCU_MEMBARRIER
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548
549#ifdef CONFIG_RCU_FORCE_SYS_MEMBARRIER
550static
c0bb9f69 551void rcu_sys_membarrier_status(bool available)
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552{
553 if (!available)
554 abort();
555}
556#else
557static
c0bb9f69 558void rcu_sys_membarrier_status(bool available)
d8d9a340 559{
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560 if (!available)
561 return;
562 rcu_has_sys_membarrier_memb = 1;
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563}
564#endif
565
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566static
567void rcu_sys_membarrier_init(void)
fdf01eed 568{
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569 bool available = false;
570 int mask;
571
572 mask = membarrier(MEMBARRIER_CMD_QUERY, 0);
573 if (mask >= 0) {
574 if (mask & MEMBARRIER_CMD_PRIVATE_EXPEDITED) {
575 if (membarrier(MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED, 0))
576 urcu_die(errno);
577 has_sys_membarrier_private_expedited = 1;
578 available = true;
579 } else if (mask & MEMBARRIER_CMD_SHARED) {
580 available = true;
581 }
582 }
583 rcu_sys_membarrier_status(available);
584}
64f469e6 585
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586void rcu_init(void)
587{
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588 if (init_done)
589 return;
590 init_done = 1;
c0bb9f69 591 rcu_sys_membarrier_init();
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592}
593#endif
594
595#ifdef RCU_SIGNAL
02be5561 596static void sigrcu_handler(int signo, siginfo_t *siginfo, void *context)
27b012e2 597{
40e140c9 598 /*
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599 * Executing this cmm_smp_mb() is the only purpose of this signal handler.
600 * It punctually promotes cmm_barrier() into cmm_smp_mb() on every thread it is
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601 * executed on.
602 */
5481ddb3 603 cmm_smp_mb();
bd252a04 604 _CMM_STORE_SHARED(URCU_TLS(rcu_reader).need_mb, 0);
5481ddb3 605 cmm_smp_mb();
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606}
607
8a5fb4c9 608/*
02be5561 609 * rcu_init constructor. Called when the library is linked, but also when
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610 * reader threads are calling rcu_register_thread().
611 * Should only be called by a single thread at a given time. This is ensured by
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612 * holing the rcu_registry_lock from rcu_register_thread() or by running
613 * at library load time, which should not be executed by multiple
614 * threads nor concurrently with rcu_register_thread() anyway.
8a5fb4c9 615 */
02be5561 616void rcu_init(void)
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617{
618 struct sigaction act;
619 int ret;
620
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621 if (init_done)
622 return;
623 init_done = 1;
624
02be5561 625 act.sa_sigaction = sigrcu_handler;
dd052bd3 626 act.sa_flags = SA_SIGINFO | SA_RESTART;
c297c21c 627 sigemptyset(&act.sa_mask);
02be5561 628 ret = sigaction(SIGRCU, &act, NULL);
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629 if (ret)
630 urcu_die(errno);
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631}
632
02be5561 633void rcu_exit(void)
27b012e2 634{
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635 /*
636 * Don't unregister the SIGRCU signal handler anymore, because
637 * call_rcu threads could still be using it shortly before the
638 * application exits.
639 * Assertion disabled because call_rcu threads are now rcu
640 * readers, and left running at exit.
641 * assert(cds_list_empty(&registry));
642 */
27b012e2 643}
5e77fc1f 644
fdf01eed 645#endif /* #ifdef RCU_SIGNAL */
5e77fc1f 646
5e6b23a6 647DEFINE_RCU_FLAVOR(rcu_flavor);
541d828d 648
5e77fc1f 649#include "urcu-call-rcu-impl.h"
0376e7b2 650#include "urcu-defer-impl.h"
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