Commit | Line | Data |
---|---|---|
b257a10b MD |
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 | * |
af02d47e MD |
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 | |
54843abc PM |
22 | * |
23 | * IBM's contributions to this file may be relicensed under LGPLv2 or later. | |
b257a10b MD |
24 | */ |
25 | ||
fdf01eed | 26 | #define _BSD_SOURCE |
c1d2c60b | 27 | #define _GNU_SOURCE |
71c811bf | 28 | #define _LGPL_SOURCE |
27b012e2 MD |
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> |
e8043c1b | 37 | #include <poll.h> |
27b012e2 | 38 | |
d73fb81f | 39 | #include "urcu/wfcqueue.h" |
57760d44 | 40 | #include "urcu/map/urcu.h" |
af7c2dbe | 41 | #include "urcu/static/urcu.h" |
618b2595 | 42 | #include "urcu-pointer.h" |
bd252a04 | 43 | #include "urcu/tls-compat.h" |
71c811bf | 44 | |
4a6d7378 | 45 | #include "urcu-die.h" |
5bffdd5d | 46 | #include "urcu-wait.h" |
4a6d7378 | 47 | |
121a5d44 | 48 | /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */ |
71c811bf | 49 | #undef _LGPL_SOURCE |
27b012e2 | 50 | #include "urcu.h" |
71c811bf | 51 | #define _LGPL_SOURCE |
27b012e2 | 52 | |
3a71751e PB |
53 | /* |
54 | * If a reader is really non-cooperative and refuses to commit its | |
55 | * rcu_active_readers count to memory (there is no barrier in the reader | |
56 | * per-se), kick it after a few loops waiting for it. | |
57 | */ | |
58 | #define KICK_READER_LOOPS 10000 | |
59 | ||
60 | /* | |
61 | * Active attempts to check for reader Q.S. before calling futex(). | |
62 | */ | |
63 | #define RCU_QS_ACTIVE_ATTEMPTS 100 | |
64 | ||
fdf01eed | 65 | #ifdef RCU_MEMBARRIER |
834a45ba | 66 | static int init_done; |
1de4df4b | 67 | int rcu_has_sys_membarrier; |
834a45ba | 68 | |
02be5561 | 69 | void __attribute__((constructor)) rcu_init(void); |
fdf01eed MD |
70 | #endif |
71 | ||
72 | #ifdef RCU_MB | |
02be5561 | 73 | void rcu_init(void) |
e90a6e9c MD |
74 | { |
75 | } | |
76 | #endif | |
8a5fb4c9 | 77 | |
fdf01eed MD |
78 | #ifdef RCU_SIGNAL |
79 | static int init_done; | |
80 | ||
81 | void __attribute__((constructor)) rcu_init(void); | |
82 | void __attribute__((destructor)) rcu_exit(void); | |
83 | #endif | |
84 | ||
6abb4bd5 | 85 | static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER; |
ed1b099e | 86 | struct urcu_gp rcu_gp = { .ctr = RCU_GP_COUNT }; |
27b012e2 | 87 | |
b0d5e790 MD |
88 | /* |
89 | * Written to only by each individual reader. Read by both the reader and the | |
90 | * writers. | |
91 | */ | |
bd252a04 | 92 | DEFINE_URCU_TLS(struct rcu_reader, rcu_reader); |
27b012e2 | 93 | |
cf380c2f | 94 | #ifdef DEBUG_YIELD |
1de4df4b MD |
95 | unsigned int rcu_yield_active; |
96 | DEFINE_URCU_TLS(unsigned int, rcu_rand_yield); | |
cf380c2f MD |
97 | #endif |
98 | ||
16aa9ee8 | 99 | static CDS_LIST_HEAD(registry); |
27b012e2 | 100 | |
5bffdd5d MD |
101 | /* |
102 | * Queue keeping threads awaiting to wait for a grace period. Contains | |
103 | * struct gp_waiters_thread objects. | |
104 | */ | |
105 | static DEFINE_URCU_WAIT_QUEUE(gp_waiters); | |
106 | ||
6abb4bd5 | 107 | static void mutex_lock(pthread_mutex_t *mutex) |
41718ff9 MD |
108 | { |
109 | int ret; | |
09a9f986 PM |
110 | |
111 | #ifndef DISTRUST_SIGNALS_EXTREME | |
6abb4bd5 | 112 | ret = pthread_mutex_lock(mutex); |
4a6d7378 MD |
113 | if (ret) |
114 | urcu_die(ret); | |
09a9f986 | 115 | #else /* #ifndef DISTRUST_SIGNALS_EXTREME */ |
6abb4bd5 | 116 | while ((ret = pthread_mutex_trylock(mutex)) != 0) { |
4a6d7378 MD |
117 | if (ret != EBUSY && ret != EINTR) |
118 | urcu_die(ret); | |
bd252a04 | 119 | if (CMM_LOAD_SHARED(URCU_TLS(rcu_reader).need_mb)) { |
5481ddb3 | 120 | cmm_smp_mb(); |
bd252a04 | 121 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).need_mb, 0); |
5481ddb3 | 122 | cmm_smp_mb(); |
09a9f986 PM |
123 | } |
124 | poll(NULL,0,10); | |
125 | } | |
126 | #endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */ | |
41718ff9 MD |
127 | } |
128 | ||
6abb4bd5 | 129 | static void mutex_unlock(pthread_mutex_t *mutex) |
41718ff9 MD |
130 | { |
131 | int ret; | |
132 | ||
6abb4bd5 | 133 | ret = pthread_mutex_unlock(mutex); |
4a6d7378 MD |
134 | if (ret) |
135 | urcu_die(ret); | |
41718ff9 MD |
136 | } |
137 | ||
fdf01eed | 138 | #ifdef RCU_MEMBARRIER |
25cc6d18 | 139 | static void smp_mb_master(int group) |
fdf01eed | 140 | { |
1de4df4b | 141 | if (caa_likely(rcu_has_sys_membarrier)) |
f0708810 | 142 | membarrier(MEMBARRIER_EXPEDITED); |
fdf01eed | 143 | else |
5481ddb3 | 144 | cmm_smp_mb(); |
fdf01eed MD |
145 | } |
146 | #endif | |
147 | ||
02be5561 | 148 | #ifdef RCU_MB |
25cc6d18 | 149 | static void smp_mb_master(int group) |
40e140c9 | 150 | { |
5481ddb3 | 151 | cmm_smp_mb(); |
40e140c9 | 152 | } |
fdf01eed MD |
153 | #endif |
154 | ||
155 | #ifdef RCU_SIGNAL | |
78ff9419 | 156 | static void force_mb_all_readers(void) |
27b012e2 | 157 | { |
02be5561 | 158 | struct rcu_reader *index; |
e3b0cef0 | 159 | |
27b012e2 | 160 | /* |
5481ddb3 | 161 | * Ask for each threads to execute a cmm_smp_mb() so we can consider the |
27b012e2 MD |
162 | * compiler barriers around rcu read lock as real memory barriers. |
163 | */ | |
16aa9ee8 | 164 | if (cds_list_empty(®istry)) |
27b012e2 | 165 | return; |
3a86deba | 166 | /* |
5481ddb3 | 167 | * pthread_kill has a cmm_smp_mb(). But beware, we assume it performs |
157dca95 | 168 | * a cache flush on architectures with non-coherent cache. Let's play |
5481ddb3 | 169 | * safe and don't assume anything : we use cmm_smp_mc() to make sure the |
157dca95 | 170 | * cache flush is enforced. |
3a86deba | 171 | */ |
16aa9ee8 | 172 | cds_list_for_each_entry(index, ®istry, node) { |
6cf3827c | 173 | CMM_STORE_SHARED(index->need_mb, 1); |
02be5561 | 174 | pthread_kill(index->tid, SIGRCU); |
09a9f986 | 175 | } |
27b012e2 MD |
176 | /* |
177 | * Wait for sighandler (and thus mb()) to execute on every thread. | |
09a9f986 PM |
178 | * |
179 | * Note that the pthread_kill() will never be executed on systems | |
180 | * that correctly deliver signals in a timely manner. However, it | |
181 | * is not uncommon for kernels to have bugs that can result in | |
182 | * lost or unduly delayed signals. | |
183 | * | |
184 | * If you are seeing the below pthread_kill() executing much at | |
185 | * all, we suggest testing the underlying kernel and filing the | |
186 | * relevant bug report. For Linux kernels, we recommend getting | |
187 | * the Linux Test Project (LTP). | |
27b012e2 | 188 | */ |
16aa9ee8 | 189 | cds_list_for_each_entry(index, ®istry, node) { |
6cf3827c | 190 | while (CMM_LOAD_SHARED(index->need_mb)) { |
02be5561 | 191 | pthread_kill(index->tid, SIGRCU); |
09a9f986 PM |
192 | poll(NULL, 0, 1); |
193 | } | |
194 | } | |
5481ddb3 | 195 | cmm_smp_mb(); /* read ->need_mb before ending the barrier */ |
27b012e2 | 196 | } |
9d7e3f89 | 197 | |
25cc6d18 | 198 | static void smp_mb_master(int group) |
9d7e3f89 MD |
199 | { |
200 | force_mb_all_readers(); | |
201 | } | |
fdf01eed | 202 | #endif /* #ifdef RCU_SIGNAL */ |
27b012e2 | 203 | |
bc6c15bb MD |
204 | /* |
205 | * synchronize_rcu() waiting. Single thread. | |
206 | */ | |
cfe78e25 | 207 | static void wait_gp(void) |
bc6c15bb | 208 | { |
cfe78e25 | 209 | /* Read reader_gp before read futex */ |
25cc6d18 | 210 | smp_mb_master(RCU_MB_GROUP); |
ed1b099e LJ |
211 | if (uatomic_read(&rcu_gp.futex) == -1) |
212 | futex_async(&rcu_gp.futex, FUTEX_WAIT, -1, | |
cfe78e25 | 213 | NULL, NULL, 0); |
bc6c15bb MD |
214 | } |
215 | ||
fd189fa5 MD |
216 | static void wait_for_readers(struct cds_list_head *input_readers, |
217 | struct cds_list_head *cur_snap_readers, | |
218 | struct cds_list_head *qsreaders) | |
27b012e2 | 219 | { |
cfe78e25 | 220 | int wait_loops = 0; |
02be5561 | 221 | struct rcu_reader *index, *tmp; |
27b012e2 | 222 | |
40e140c9 | 223 | /* |
c9488684 MD |
224 | * Wait for each thread URCU_TLS(rcu_reader).ctr to either |
225 | * indicate quiescence (not nested), or observe the current | |
ed1b099e | 226 | * rcu_gp.ctr value. |
27b012e2 | 227 | */ |
cfe78e25 MD |
228 | for (;;) { |
229 | wait_loops++; | |
230 | if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) { | |
ed1b099e | 231 | uatomic_dec(&rcu_gp.futex); |
cfe78e25 | 232 | /* Write futex before read reader_gp */ |
25cc6d18 | 233 | smp_mb_master(RCU_MB_GROUP); |
cfe78e25 MD |
234 | } |
235 | ||
fd189fa5 MD |
236 | cds_list_for_each_entry_safe(index, tmp, input_readers, node) { |
237 | switch (rcu_reader_state(&index->ctr)) { | |
238 | case RCU_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 RCU_READER_INACTIVE: | |
246 | cds_list_move(&index->node, qsreaders); | |
247 | break; | |
248 | case RCU_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 | } | |
cfe78e25 MD |
257 | } |
258 | ||
e8043c1b | 259 | #ifndef HAS_INCOHERENT_CACHES |
fd189fa5 | 260 | if (cds_list_empty(input_readers)) { |
cfe78e25 MD |
261 | if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) { |
262 | /* Read reader_gp before write futex */ | |
25cc6d18 | 263 | smp_mb_master(RCU_MB_GROUP); |
ed1b099e | 264 | uatomic_set(&rcu_gp.futex, 0); |
bc6c15bb | 265 | } |
cfe78e25 MD |
266 | break; |
267 | } else { | |
268 | if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) | |
269 | wait_gp(); | |
270 | else | |
06f22bdb | 271 | caa_cpu_relax(); |
bc6c15bb | 272 | } |
e8043c1b | 273 | #else /* #ifndef HAS_INCOHERENT_CACHES */ |
27b012e2 | 274 | /* |
40e140c9 | 275 | * BUSY-LOOP. Force the reader thread to commit its |
bd252a04 MD |
276 | * URCU_TLS(rcu_reader).ctr update to memory if we wait |
277 | * for too long. | |
27b012e2 | 278 | */ |
fd189fa5 | 279 | if (cds_list_empty(input_readers)) { |
cfe78e25 MD |
280 | if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) { |
281 | /* Read reader_gp before write futex */ | |
25cc6d18 | 282 | smp_mb_master(RCU_MB_GROUP); |
ed1b099e | 283 | uatomic_set(&rcu_gp.futex, 0); |
cfe78e25 MD |
284 | } |
285 | break; | |
286 | } else { | |
287 | switch (wait_loops) { | |
bc6c15bb | 288 | case RCU_QS_ACTIVE_ATTEMPTS: |
cfe78e25 MD |
289 | wait_gp(); |
290 | break; /* only escape switch */ | |
bc6c15bb | 291 | case KICK_READER_LOOPS: |
25cc6d18 | 292 | smp_mb_master(RCU_MB_GROUP); |
40e140c9 | 293 | wait_loops = 0; |
cfe78e25 | 294 | break; /* only escape switch */ |
bc6c15bb | 295 | default: |
06f22bdb | 296 | caa_cpu_relax(); |
40e140c9 MD |
297 | } |
298 | } | |
e8043c1b | 299 | #endif /* #else #ifndef HAS_INCOHERENT_CACHES */ |
27b012e2 | 300 | } |
27b012e2 MD |
301 | } |
302 | ||
9598a481 | 303 | void synchronize_rcu(void) |
2bc59bd7 | 304 | { |
fd189fa5 MD |
305 | CDS_LIST_HEAD(cur_snap_readers); |
306 | CDS_LIST_HEAD(qsreaders); | |
5bffdd5d MD |
307 | DEFINE_URCU_WAIT_NODE(wait, URCU_WAIT_WAITING); |
308 | struct urcu_waiters waiters; | |
309 | ||
310 | /* | |
311 | * Add ourself to gp_waiters queue of threads awaiting to wait | |
312 | * for a grace period. Proceed to perform the grace period only | |
313 | * if we are the first thread added into the queue. | |
314 | * The implicit memory barrier before urcu_wait_add() | |
315 | * orders prior memory accesses of threads put into the wait | |
316 | * queue before their insertion into the wait queue. | |
317 | */ | |
318 | if (urcu_wait_add(&gp_waiters, &wait) != 0) { | |
319 | /* Not first in queue: will be awakened by another thread. */ | |
320 | urcu_adaptative_busy_wait(&wait); | |
321 | /* Order following memory accesses after grace period. */ | |
322 | cmm_smp_mb(); | |
323 | return; | |
324 | } | |
325 | /* We won't need to wake ourself up */ | |
326 | urcu_wait_set_state(&wait, URCU_WAIT_RUNNING); | |
fd189fa5 | 327 | |
6abb4bd5 | 328 | mutex_lock(&rcu_gp_lock); |
135530fd | 329 | |
5bffdd5d MD |
330 | /* |
331 | * Move all waiters into our local queue. | |
332 | */ | |
333 | urcu_move_waiters(&waiters, &gp_waiters); | |
334 | ||
16aa9ee8 | 335 | if (cds_list_empty(®istry)) |
2dfb8b5e MD |
336 | goto out; |
337 | ||
9598a481 | 338 | /* All threads should read qparity before accessing data structure |
6abb4bd5 MD |
339 | * where new ptr points to. Must be done within rcu_gp_lock because it |
340 | * iterates on reader threads.*/ | |
9598a481 | 341 | /* Write new ptr before changing the qparity */ |
25cc6d18 | 342 | smp_mb_master(RCU_MB_GROUP); |
9598a481 | 343 | |
9598a481 | 344 | /* |
c9488684 | 345 | * Wait for readers to observe original parity or be quiescent. |
9598a481 | 346 | */ |
fd189fa5 | 347 | wait_for_readers(®istry, &cur_snap_readers, &qsreaders); |
9598a481 MD |
348 | |
349 | /* | |
c9488684 | 350 | * Must finish waiting for quiescent state for original parity before |
ed1b099e | 351 | * committing next rcu_gp.ctr update to memory. Failure to do so could |
d40fde2c MD |
352 | * result in the writer waiting forever while new readers are always |
353 | * accessing data (no progress). Enforce compiler-order of load | |
ed1b099e | 354 | * URCU_TLS(rcu_reader).ctr before store to rcu_gp.ctr. |
9598a481 | 355 | */ |
5481ddb3 | 356 | cmm_barrier(); |
9598a481 | 357 | |
5dba80f9 | 358 | /* |
5481ddb3 | 359 | * Adding a cmm_smp_mb() which is _not_ formally required, but makes the |
5dba80f9 MD |
360 | * model easier to understand. It does not have a big performance impact |
361 | * anyway, given this is the write-side. | |
362 | */ | |
5481ddb3 | 363 | cmm_smp_mb(); |
67c2d80b | 364 | |
c9488684 | 365 | /* Switch parity: 0 -> 1, 1 -> 0 */ |
ed1b099e | 366 | CMM_STORE_SHARED(rcu_gp.ctr, rcu_gp.ctr ^ RCU_GP_CTR_PHASE); |
c9488684 MD |
367 | |
368 | /* | |
ed1b099e | 369 | * Must commit rcu_gp.ctr update to memory before waiting for quiescent |
c9488684 MD |
370 | * state. Failure to do so could result in the writer waiting forever |
371 | * while new readers are always accessing data (no progress). Enforce | |
ed1b099e | 372 | * compiler-order of store to rcu_gp.ctr before load rcu_reader ctr. |
c9488684 MD |
373 | */ |
374 | cmm_barrier(); | |
375 | ||
376 | /* | |
377 | * | |
378 | * Adding a cmm_smp_mb() which is _not_ formally required, but makes the | |
379 | * model easier to understand. It does not have a big performance impact | |
380 | * anyway, given this is the write-side. | |
381 | */ | |
382 | cmm_smp_mb(); | |
383 | ||
9598a481 | 384 | /* |
c9488684 | 385 | * Wait for readers to observe new parity or be quiescent. |
9598a481 | 386 | */ |
fd189fa5 MD |
387 | wait_for_readers(&cur_snap_readers, NULL, &qsreaders); |
388 | ||
389 | /* | |
390 | * Put quiescent reader list back into registry. | |
391 | */ | |
392 | cds_list_splice(&qsreaders, ®istry); | |
9598a481 | 393 | |
9598a481 | 394 | /* Finish waiting for reader threads before letting the old ptr being |
6abb4bd5 MD |
395 | * freed. Must be done within rcu_gp_lock because it iterates on reader |
396 | * threads. */ | |
25cc6d18 | 397 | smp_mb_master(RCU_MB_GROUP); |
2dfb8b5e | 398 | out: |
6abb4bd5 | 399 | mutex_unlock(&rcu_gp_lock); |
5bffdd5d MD |
400 | |
401 | /* | |
402 | * Wakeup waiters only after we have completed the grace period | |
403 | * and have ensured the memory barriers at the end of the grace | |
404 | * period have been issued. | |
405 | */ | |
406 | urcu_wake_all_waiters(&waiters); | |
2bc59bd7 PM |
407 | } |
408 | ||
121a5d44 MD |
409 | /* |
410 | * library wrappers to be used by non-LGPL compatible source code. | |
411 | */ | |
412 | ||
413 | void rcu_read_lock(void) | |
414 | { | |
415 | _rcu_read_lock(); | |
416 | } | |
417 | ||
418 | void rcu_read_unlock(void) | |
419 | { | |
420 | _rcu_read_unlock(); | |
421 | } | |
422 | ||
882f3357 MD |
423 | int rcu_read_ongoing(void) |
424 | { | |
425 | return _rcu_read_ongoing(); | |
426 | } | |
427 | ||
121a5d44 | 428 | void rcu_register_thread(void) |
27b012e2 | 429 | { |
bd252a04 MD |
430 | URCU_TLS(rcu_reader).tid = pthread_self(); |
431 | assert(URCU_TLS(rcu_reader).need_mb == 0); | |
432 | assert(!(URCU_TLS(rcu_reader).ctr & RCU_GP_CTR_NEST_MASK)); | |
02be5561 | 433 | |
6abb4bd5 | 434 | mutex_lock(&rcu_gp_lock); |
02be5561 | 435 | rcu_init(); /* In case gcc does not support constructor attribute */ |
bd252a04 | 436 | cds_list_add(&URCU_TLS(rcu_reader).node, ®istry); |
6abb4bd5 | 437 | mutex_unlock(&rcu_gp_lock); |
27b012e2 MD |
438 | } |
439 | ||
121a5d44 | 440 | void rcu_unregister_thread(void) |
27b012e2 | 441 | { |
6abb4bd5 | 442 | mutex_lock(&rcu_gp_lock); |
bd252a04 | 443 | cds_list_del(&URCU_TLS(rcu_reader).node); |
6abb4bd5 | 444 | mutex_unlock(&rcu_gp_lock); |
27b012e2 MD |
445 | } |
446 | ||
fdf01eed MD |
447 | #ifdef RCU_MEMBARRIER |
448 | void rcu_init(void) | |
449 | { | |
450 | if (init_done) | |
451 | return; | |
452 | init_done = 1; | |
cf5271ee | 453 | if (!membarrier(MEMBARRIER_EXPEDITED | MEMBARRIER_QUERY)) |
1de4df4b | 454 | rcu_has_sys_membarrier = 1; |
fdf01eed MD |
455 | } |
456 | #endif | |
457 | ||
458 | #ifdef RCU_SIGNAL | |
02be5561 | 459 | static void sigrcu_handler(int signo, siginfo_t *siginfo, void *context) |
27b012e2 | 460 | { |
40e140c9 | 461 | /* |
5481ddb3 DG |
462 | * Executing this cmm_smp_mb() is the only purpose of this signal handler. |
463 | * It punctually promotes cmm_barrier() into cmm_smp_mb() on every thread it is | |
40e140c9 MD |
464 | * executed on. |
465 | */ | |
5481ddb3 | 466 | cmm_smp_mb(); |
bd252a04 | 467 | _CMM_STORE_SHARED(URCU_TLS(rcu_reader).need_mb, 0); |
5481ddb3 | 468 | cmm_smp_mb(); |
27b012e2 MD |
469 | } |
470 | ||
8a5fb4c9 | 471 | /* |
02be5561 | 472 | * rcu_init constructor. Called when the library is linked, but also when |
8a5fb4c9 MD |
473 | * reader threads are calling rcu_register_thread(). |
474 | * Should only be called by a single thread at a given time. This is ensured by | |
6abb4bd5 MD |
475 | * holing the rcu_gp_lock from rcu_register_thread() or by running at library |
476 | * load time, which should not be executed by multiple threads nor concurrently | |
477 | * with rcu_register_thread() anyway. | |
8a5fb4c9 | 478 | */ |
02be5561 | 479 | void rcu_init(void) |
27b012e2 MD |
480 | { |
481 | struct sigaction act; | |
482 | int ret; | |
483 | ||
8a5fb4c9 MD |
484 | if (init_done) |
485 | return; | |
486 | init_done = 1; | |
487 | ||
02be5561 | 488 | act.sa_sigaction = sigrcu_handler; |
dd052bd3 | 489 | act.sa_flags = SA_SIGINFO | SA_RESTART; |
c297c21c | 490 | sigemptyset(&act.sa_mask); |
02be5561 | 491 | ret = sigaction(SIGRCU, &act, NULL); |
4a6d7378 MD |
492 | if (ret) |
493 | urcu_die(errno); | |
27b012e2 MD |
494 | } |
495 | ||
02be5561 | 496 | void rcu_exit(void) |
27b012e2 MD |
497 | { |
498 | struct sigaction act; | |
499 | int ret; | |
500 | ||
02be5561 | 501 | ret = sigaction(SIGRCU, NULL, &act); |
4a6d7378 MD |
502 | if (ret) |
503 | urcu_die(errno); | |
02be5561 | 504 | assert(act.sa_sigaction == sigrcu_handler); |
16aa9ee8 | 505 | assert(cds_list_empty(®istry)); |
27b012e2 | 506 | } |
5e77fc1f | 507 | |
fdf01eed | 508 | #endif /* #ifdef RCU_SIGNAL */ |
5e77fc1f | 509 | |
5e6b23a6 | 510 | DEFINE_RCU_FLAVOR(rcu_flavor); |
541d828d | 511 | |
5e77fc1f | 512 | #include "urcu-call-rcu-impl.h" |
0376e7b2 | 513 | #include "urcu-defer-impl.h" |