Commit | Line | Data |
---|---|---|
9f1621ca | 1 | /* |
7ac06cef | 2 | * urcu-qsbr.c |
9f1621ca | 3 | * |
7ac06cef | 4 | * Userspace RCU QSBR library |
9f1621ca | 5 | * |
6982d6d7 | 6 | * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
9f1621ca MD |
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 | ||
c1d2c60b | 26 | #define _GNU_SOURCE |
71c811bf | 27 | #define _LGPL_SOURCE |
9f1621ca MD |
28 | #include <stdio.h> |
29 | #include <pthread.h> | |
30 | #include <signal.h> | |
31 | #include <assert.h> | |
32 | #include <stdlib.h> | |
6d841bc2 | 33 | #include <stdint.h> |
9f1621ca MD |
34 | #include <string.h> |
35 | #include <errno.h> | |
36 | #include <poll.h> | |
37 | ||
d73fb81f | 38 | #include "urcu/wfcqueue.h" |
6362f68f | 39 | #include "urcu/wfstack.h" |
57760d44 | 40 | #include "urcu/map/urcu-qsbr.h" |
727f819d | 41 | #define BUILD_QSBR_LIB |
af7c2dbe | 42 | #include "urcu/static/urcu-qsbr.h" |
618b2595 | 43 | #include "urcu-pointer.h" |
bd252a04 | 44 | #include "urcu/tls-compat.h" |
71c811bf | 45 | |
4a6d7378 MD |
46 | #include "urcu-die.h" |
47 | ||
9f1621ca | 48 | /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */ |
71c811bf | 49 | #undef _LGPL_SOURCE |
7ac06cef | 50 | #include "urcu-qsbr.h" |
71c811bf | 51 | #define _LGPL_SOURCE |
9f1621ca | 52 | |
f6d18c64 MD |
53 | void __attribute__((destructor)) rcu_exit(void); |
54 | ||
6abb4bd5 | 55 | static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER; |
9f1621ca | 56 | |
1de4df4b | 57 | int32_t rcu_gp_futex; |
bc6c15bb | 58 | |
9f1621ca MD |
59 | /* |
60 | * Global grace period counter. | |
61 | */ | |
02be5561 | 62 | unsigned long rcu_gp_ctr = RCU_GP_ONLINE; |
9f1621ca | 63 | |
408f6d92 PB |
64 | /* |
65 | * Active attempts to check for reader Q.S. before calling futex(). | |
66 | */ | |
67 | #define RCU_QS_ACTIVE_ATTEMPTS 100 | |
68 | ||
9f1621ca MD |
69 | /* |
70 | * Written to only by each individual reader. Read by both the reader and the | |
71 | * writers. | |
72 | */ | |
bd252a04 | 73 | DEFINE_URCU_TLS(struct rcu_reader, rcu_reader); |
9f1621ca MD |
74 | |
75 | #ifdef DEBUG_YIELD | |
1de4df4b MD |
76 | unsigned int rcu_yield_active; |
77 | DEFINE_URCU_TLS(unsigned int, rcu_rand_yield); | |
9f1621ca MD |
78 | #endif |
79 | ||
16aa9ee8 | 80 | static CDS_LIST_HEAD(registry); |
9f1621ca | 81 | |
6362f68f MD |
82 | /* |
83 | * Number of busy-loop attempts before waiting on futex for grace period | |
84 | * batching. | |
85 | */ | |
86 | #define RCU_AWAKE_ATTEMPTS 1000 | |
87 | ||
88 | enum adapt_wakeup_state { | |
89 | /* AWAKE_WAITING is compared directly (futex compares it). */ | |
90 | AWAKE_WAITING = 0, | |
91 | /* non-zero are used as masks. */ | |
92 | AWAKE_WAKEUP = (1 << 0), | |
93 | AWAKE_AWAKENED = (1 << 1), | |
94 | AWAKE_TEARDOWN = (1 << 2), | |
95 | }; | |
96 | ||
97 | struct gp_waiters_thread { | |
98 | struct cds_wfs_node node; | |
99 | int32_t wait_futex; | |
100 | }; | |
101 | ||
102 | /* | |
103 | * Stack keeping threads awaiting to wait for a grace period. Contains | |
104 | * struct gp_waiters_thread objects. | |
105 | */ | |
106 | static struct cds_wfs_stack gp_waiters = { | |
107 | .head = CDS_WFS_END, | |
108 | .lock = PTHREAD_MUTEX_INITIALIZER, | |
109 | }; | |
110 | ||
6abb4bd5 | 111 | static void mutex_lock(pthread_mutex_t *mutex) |
9f1621ca MD |
112 | { |
113 | int ret; | |
114 | ||
115 | #ifndef DISTRUST_SIGNALS_EXTREME | |
6abb4bd5 | 116 | ret = pthread_mutex_lock(mutex); |
4a6d7378 MD |
117 | if (ret) |
118 | urcu_die(ret); | |
9f1621ca | 119 | #else /* #ifndef DISTRUST_SIGNALS_EXTREME */ |
6abb4bd5 | 120 | while ((ret = pthread_mutex_trylock(mutex)) != 0) { |
4a6d7378 MD |
121 | if (ret != EBUSY && ret != EINTR) |
122 | urcu_die(ret); | |
9f1621ca MD |
123 | poll(NULL,0,10); |
124 | } | |
125 | #endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */ | |
126 | } | |
127 | ||
6abb4bd5 | 128 | static void mutex_unlock(pthread_mutex_t *mutex) |
9f1621ca MD |
129 | { |
130 | int ret; | |
131 | ||
6abb4bd5 | 132 | ret = pthread_mutex_unlock(mutex); |
4a6d7378 MD |
133 | if (ret) |
134 | urcu_die(ret); | |
9f1621ca MD |
135 | } |
136 | ||
bc6c15bb MD |
137 | /* |
138 | * synchronize_rcu() waiting. Single thread. | |
139 | */ | |
4d703340 | 140 | static void wait_gp(void) |
bc6c15bb | 141 | { |
4d703340 | 142 | /* Read reader_gp before read futex */ |
5481ddb3 | 143 | cmm_smp_rmb(); |
1de4df4b MD |
144 | if (uatomic_read(&rcu_gp_futex) == -1) |
145 | futex_noasync(&rcu_gp_futex, FUTEX_WAIT, -1, | |
4d703340 | 146 | NULL, NULL, 0); |
bc6c15bb MD |
147 | } |
148 | ||
6362f68f MD |
149 | /* |
150 | * Note: urcu_adaptative_wake_up needs "value" to stay allocated | |
151 | * throughout its execution. In this scheme, the waiter owns the futex | |
152 | * memory, and we only allow it to free this memory when it receives the | |
153 | * AWAKE_TEARDOWN flag. | |
154 | */ | |
155 | static void urcu_adaptative_wake_up(int32_t *value) | |
156 | { | |
157 | cmm_smp_mb(); | |
158 | assert(uatomic_read(value) == AWAKE_WAITING); | |
159 | uatomic_set(value, AWAKE_WAKEUP); | |
160 | if (!(uatomic_read(value) & AWAKE_AWAKENED)) | |
161 | futex_noasync(value, FUTEX_WAKE, 1, NULL, NULL, 0); | |
162 | /* Allow teardown of "value" memory. */ | |
163 | uatomic_or(value, AWAKE_TEARDOWN); | |
164 | } | |
165 | ||
166 | /* | |
167 | * Caller must initialize "value" to AWAKE_WAITING before passing its | |
168 | * memory to waker thread. | |
169 | */ | |
170 | static void urcu_adaptative_busy_wait(int32_t *value) | |
171 | { | |
172 | unsigned int i; | |
173 | ||
174 | /* Load and test condition before read futex */ | |
175 | cmm_smp_rmb(); | |
176 | for (i = 0; i < RCU_AWAKE_ATTEMPTS; i++) { | |
177 | if (uatomic_read(value) != AWAKE_WAITING) | |
178 | goto skip_futex_wait; | |
179 | caa_cpu_relax(); | |
180 | } | |
181 | futex_noasync(value, FUTEX_WAIT, AWAKE_WAITING, NULL, NULL, 0); | |
182 | skip_futex_wait: | |
183 | ||
184 | /* Tell waker thread than we are awakened. */ | |
185 | uatomic_or(value, AWAKE_AWAKENED); | |
186 | ||
187 | /* | |
188 | * Wait until waker thread lets us know it's ok to tear down | |
189 | * memory allocated for value. | |
190 | */ | |
191 | for (i = 0; i < RCU_AWAKE_ATTEMPTS; i++) { | |
192 | if (uatomic_read(value) & AWAKE_TEARDOWN) | |
193 | break; | |
194 | caa_cpu_relax(); | |
195 | } | |
196 | while (!(uatomic_read(value) & AWAKE_TEARDOWN)) | |
197 | poll(NULL, 0, 10); | |
198 | assert(uatomic_read(value) & AWAKE_TEARDOWN); | |
199 | } | |
200 | ||
708d89f0 MD |
201 | static void wait_for_readers(struct cds_list_head *input_readers, |
202 | struct cds_list_head *cur_snap_readers, | |
203 | struct cds_list_head *qsreaders) | |
9f1621ca | 204 | { |
4d703340 | 205 | int wait_loops = 0; |
02be5561 | 206 | struct rcu_reader *index, *tmp; |
9f1621ca | 207 | |
9f1621ca | 208 | /* |
f6b42f9c MD |
209 | * Wait for each thread URCU_TLS(rcu_reader).ctr to either |
210 | * indicate quiescence (offline), or for them to observe the | |
211 | * current rcu_gp_ctr value. | |
9f1621ca | 212 | */ |
4d703340 MD |
213 | for (;;) { |
214 | wait_loops++; | |
83a2c421 | 215 | if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) { |
1de4df4b | 216 | uatomic_set(&rcu_gp_futex, -1); |
83a2c421 PB |
217 | /* |
218 | * Write futex before write waiting (the other side | |
219 | * reads them in the opposite order). | |
220 | */ | |
221 | cmm_smp_wmb(); | |
708d89f0 | 222 | cds_list_for_each_entry(index, input_readers, node) { |
83a2c421 PB |
223 | _CMM_STORE_SHARED(index->waiting, 1); |
224 | } | |
4d703340 | 225 | /* Write futex before read reader_gp */ |
5481ddb3 | 226 | cmm_smp_mb(); |
4d703340 | 227 | } |
708d89f0 MD |
228 | cds_list_for_each_entry_safe(index, tmp, input_readers, node) { |
229 | switch (rcu_reader_state(&index->ctr)) { | |
230 | case RCU_READER_ACTIVE_CURRENT: | |
231 | if (cur_snap_readers) { | |
232 | cds_list_move(&index->node, | |
233 | cur_snap_readers); | |
234 | break; | |
235 | } | |
236 | /* Fall-through */ | |
237 | case RCU_READER_INACTIVE: | |
238 | cds_list_move(&index->node, qsreaders); | |
239 | break; | |
240 | case RCU_READER_ACTIVE_OLD: | |
241 | /* | |
242 | * Old snapshot. Leaving node in | |
243 | * input_readers will make us busy-loop | |
244 | * until the snapshot becomes current or | |
245 | * the reader becomes inactive. | |
246 | */ | |
247 | break; | |
248 | } | |
4d703340 | 249 | } |
bc6c15bb | 250 | |
708d89f0 | 251 | if (cds_list_empty(input_readers)) { |
83a2c421 | 252 | if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) { |
4d703340 | 253 | /* Read reader_gp before write futex */ |
5481ddb3 | 254 | cmm_smp_mb(); |
1de4df4b | 255 | uatomic_set(&rcu_gp_futex, 0); |
4d703340 MD |
256 | } |
257 | break; | |
258 | } else { | |
83a2c421 | 259 | if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) { |
4d703340 | 260 | wait_gp(); |
bc6c15bb | 261 | } else { |
9f1621ca | 262 | #ifndef HAS_INCOHERENT_CACHES |
06f22bdb | 263 | caa_cpu_relax(); |
9f1621ca | 264 | #else /* #ifndef HAS_INCOHERENT_CACHES */ |
5481ddb3 | 265 | cmm_smp_mb(); |
9f1621ca | 266 | #endif /* #else #ifndef HAS_INCOHERENT_CACHES */ |
bc6c15bb MD |
267 | } |
268 | } | |
9f1621ca MD |
269 | } |
270 | } | |
271 | ||
47d2f29e MD |
272 | /* |
273 | * Using a two-subphases algorithm for architectures with smaller than 64-bit | |
274 | * long-size to ensure we do not encounter an overflow bug. | |
275 | */ | |
276 | ||
b39e1761 | 277 | #if (CAA_BITS_PER_LONG < 64) |
47d2f29e MD |
278 | void synchronize_rcu(void) |
279 | { | |
708d89f0 MD |
280 | CDS_LIST_HEAD(cur_snap_readers); |
281 | CDS_LIST_HEAD(qsreaders); | |
bc49c323 | 282 | unsigned long was_online; |
6362f68f MD |
283 | struct gp_waiters_thread gp_waiters_thread; |
284 | struct cds_wfs_head *gp_waiters_head; | |
285 | struct cds_wfs_node *waiters_iter, *waiters_iter_n; | |
bc49c323 | 286 | |
bd252a04 | 287 | was_online = URCU_TLS(rcu_reader).ctr; |
bc49c323 | 288 | |
47d2f29e | 289 | /* All threads should read qparity before accessing data structure |
27b940e7 PB |
290 | * where new ptr points to. In the "then" case, rcu_thread_offline |
291 | * includes a memory barrier. | |
292 | * | |
bc49c323 | 293 | * Mark the writer thread offline to make sure we don't wait for |
5e77fc1f PM |
294 | * our own quiescent state. This allows using synchronize_rcu() |
295 | * in threads registered as readers. | |
bc49c323 | 296 | */ |
27b940e7 PB |
297 | if (was_online) |
298 | rcu_thread_offline(); | |
299 | else | |
300 | cmm_smp_mb(); | |
bc49c323 | 301 | |
6362f68f MD |
302 | /* |
303 | * Add ourself to gp_waiters stack of threads awaiting to wait | |
304 | * for a grace period. Proceed to perform the grace period only | |
305 | * if we are the first thread added into the stack. | |
306 | */ | |
307 | cds_wfs_node_init(&gp_waiters_thread.node); | |
308 | gp_waiters_thread.wait_futex = AWAKE_WAITING; | |
309 | if (cds_wfs_push(&gp_waiters, &gp_waiters_node) != 0) { | |
310 | /* Not first in stack: will be awakened by another thread. */ | |
311 | urcu_adaptative_busy_wait(&gp_waiters_thread.wait_futex); | |
312 | goto gp_end; | |
313 | } | |
314 | ||
6abb4bd5 | 315 | mutex_lock(&rcu_gp_lock); |
47d2f29e | 316 | |
6362f68f MD |
317 | /* |
318 | * Pop all waiters into our local stack head. | |
319 | */ | |
320 | gp_waiters_head = __cds_wfs_pop_all(&gp_waiters); | |
321 | ||
16aa9ee8 | 322 | if (cds_list_empty(®istry)) |
2dfb8b5e | 323 | goto out; |
47d2f29e MD |
324 | |
325 | /* | |
f6b42f9c | 326 | * Wait for readers to observe original parity or be quiescent. |
47d2f29e | 327 | */ |
708d89f0 | 328 | wait_for_readers(®istry, &cur_snap_readers, &qsreaders); |
47d2f29e MD |
329 | |
330 | /* | |
f6b42f9c MD |
331 | * Must finish waiting for quiescent state for original parity |
332 | * before committing next rcu_gp_ctr update to memory. Failure | |
333 | * to do so could result in the writer waiting forever while new | |
5e77fc1f | 334 | * readers are always accessing data (no progress). Enforce |
f6b42f9c MD |
335 | * compiler-order of load URCU_TLS(rcu_reader).ctr before store |
336 | * to rcu_gp_ctr. | |
47d2f29e | 337 | */ |
5481ddb3 | 338 | cmm_barrier(); |
47d2f29e | 339 | |
47d2f29e | 340 | /* |
5481ddb3 | 341 | * Adding a cmm_smp_mb() which is _not_ formally required, but makes the |
2dfb8b5e MD |
342 | * model easier to understand. It does not have a big performance impact |
343 | * anyway, given this is the write-side. | |
47d2f29e | 344 | */ |
5481ddb3 | 345 | cmm_smp_mb(); |
47d2f29e | 346 | |
f6b42f9c MD |
347 | /* Switch parity: 0 -> 1, 1 -> 0 */ |
348 | CMM_STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR); | |
349 | ||
47d2f29e | 350 | /* |
f6b42f9c MD |
351 | * Must commit rcu_gp_ctr update to memory before waiting for |
352 | * quiescent state. Failure to do so could result in the writer | |
353 | * waiting forever while new readers are always accessing data | |
354 | * (no progress). Enforce compiler-order of store to rcu_gp_ctr | |
355 | * before load URCU_TLS(rcu_reader).ctr. | |
47d2f29e | 356 | */ |
f6b42f9c MD |
357 | cmm_barrier(); |
358 | ||
359 | /* | |
360 | * Adding a cmm_smp_mb() which is _not_ formally required, but makes the | |
361 | * model easier to understand. It does not have a big performance impact | |
362 | * anyway, given this is the write-side. | |
363 | */ | |
364 | cmm_smp_mb(); | |
365 | ||
366 | /* | |
367 | * Wait for readers to observe new parity or be quiescent. | |
368 | */ | |
708d89f0 MD |
369 | wait_for_readers(&cur_snap_readers, NULL, &qsreaders); |
370 | ||
371 | /* | |
372 | * Put quiescent reader list back into registry. | |
373 | */ | |
374 | cds_list_splice(&qsreaders, ®istry); | |
2dfb8b5e | 375 | out: |
6abb4bd5 | 376 | mutex_unlock(&rcu_gp_lock); |
47d2f29e | 377 | |
6362f68f MD |
378 | /* Wake all waiters in our stack head, excluding ourself. */ |
379 | cds_wfs_for_each_blocking_safe(gp_waiters_head, waiters_iter, | |
380 | waiters_iter_n) { | |
381 | struct gp_waiters_thread *wt; | |
382 | ||
383 | wt = caa_container_of(waiters_iter, | |
384 | struct gp_waiters_thread, node); | |
385 | if (wt == &gp_waiters_thread) | |
386 | continue; | |
387 | urcu_adaptative_wake_up(&wt->wait_futex); | |
388 | } | |
389 | ||
390 | gp_end: | |
bc49c323 MD |
391 | /* |
392 | * Finish waiting for reader threads before letting the old ptr being | |
47d2f29e MD |
393 | * freed. |
394 | */ | |
bc49c323 | 395 | if (was_online) |
27b940e7 PB |
396 | rcu_thread_online(); |
397 | else | |
398 | cmm_smp_mb(); | |
47d2f29e | 399 | } |
b39e1761 | 400 | #else /* !(CAA_BITS_PER_LONG < 64) */ |
9f1621ca MD |
401 | void synchronize_rcu(void) |
402 | { | |
708d89f0 | 403 | CDS_LIST_HEAD(qsreaders); |
f0f7dbdd | 404 | unsigned long was_online; |
6362f68f MD |
405 | struct gp_waiters_thread gp_waiters_thread; |
406 | struct cds_wfs_head *gp_waiters_head; | |
407 | struct cds_wfs_node *waiters_iter, *waiters_iter_n; | |
ff2f67a0 | 408 | |
bd252a04 | 409 | was_online = URCU_TLS(rcu_reader).ctr; |
ff2f67a0 MD |
410 | |
411 | /* | |
412 | * Mark the writer thread offline to make sure we don't wait for | |
5e77fc1f PM |
413 | * our own quiescent state. This allows using synchronize_rcu() |
414 | * in threads registered as readers. | |
ff2f67a0 | 415 | */ |
27b940e7 PB |
416 | if (was_online) |
417 | rcu_thread_offline(); | |
418 | else | |
419 | cmm_smp_mb(); | |
ff2f67a0 | 420 | |
6362f68f MD |
421 | /* |
422 | * Add ourself to gp_waiters stack of threads awaiting to wait | |
423 | * for a grace period. Proceed to perform the grace period only | |
424 | * if we are the first thread added into the stack. | |
425 | */ | |
426 | cds_wfs_node_init(&gp_waiters_thread.node); | |
427 | gp_waiters_thread.wait_futex = AWAKE_WAITING; | |
428 | if (cds_wfs_push(&gp_waiters, &gp_waiters_thread.node) != 0) { | |
429 | /* Not first in stack: will be awakened by another thread. */ | |
430 | urcu_adaptative_busy_wait(&gp_waiters_thread.wait_futex); | |
431 | goto gp_end; | |
432 | } | |
433 | ||
6abb4bd5 | 434 | mutex_lock(&rcu_gp_lock); |
6362f68f MD |
435 | |
436 | /* | |
437 | * Pop all waiters into our local stack head. | |
438 | */ | |
439 | gp_waiters_head = __cds_wfs_pop_all(&gp_waiters); | |
440 | ||
16aa9ee8 | 441 | if (cds_list_empty(®istry)) |
2dfb8b5e | 442 | goto out; |
f6b42f9c MD |
443 | |
444 | /* Increment current G.P. */ | |
445 | CMM_STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr + RCU_GP_CTR); | |
446 | ||
447 | /* | |
448 | * Must commit rcu_gp_ctr update to memory before waiting for | |
449 | * quiescent state. Failure to do so could result in the writer | |
450 | * waiting forever while new readers are always accessing data | |
451 | * (no progress). Enforce compiler-order of store to rcu_gp_ctr | |
452 | * before load URCU_TLS(rcu_reader).ctr. | |
453 | */ | |
454 | cmm_barrier(); | |
455 | ||
456 | /* | |
457 | * Adding a cmm_smp_mb() which is _not_ formally required, but makes the | |
458 | * model easier to understand. It does not have a big performance impact | |
459 | * anyway, given this is the write-side. | |
460 | */ | |
461 | cmm_smp_mb(); | |
462 | ||
463 | /* | |
464 | * Wait for readers to observe new count of be quiescent. | |
465 | */ | |
708d89f0 MD |
466 | wait_for_readers(®istry, NULL, &qsreaders); |
467 | ||
468 | /* | |
469 | * Put quiescent reader list back into registry. | |
470 | */ | |
471 | cds_list_splice(&qsreaders, ®istry); | |
2dfb8b5e | 472 | out: |
6abb4bd5 | 473 | mutex_unlock(&rcu_gp_lock); |
ff2f67a0 | 474 | |
6362f68f MD |
475 | /* Wake all waiters in our stack head, excluding ourself. */ |
476 | cds_wfs_for_each_blocking_safe(gp_waiters_head, waiters_iter, | |
477 | waiters_iter_n) { | |
478 | struct gp_waiters_thread *wt; | |
479 | ||
480 | wt = caa_container_of(waiters_iter, | |
481 | struct gp_waiters_thread, node); | |
482 | if (wt == &gp_waiters_thread) | |
483 | continue; | |
484 | urcu_adaptative_wake_up(&wt->wait_futex); | |
485 | } | |
486 | ||
487 | gp_end: | |
ff2f67a0 | 488 | if (was_online) |
27b940e7 PB |
489 | rcu_thread_online(); |
490 | else | |
491 | cmm_smp_mb(); | |
9f1621ca | 492 | } |
b39e1761 | 493 | #endif /* !(CAA_BITS_PER_LONG < 64) */ |
9f1621ca MD |
494 | |
495 | /* | |
496 | * library wrappers to be used by non-LGPL compatible source code. | |
497 | */ | |
498 | ||
499 | void rcu_read_lock(void) | |
500 | { | |
501 | _rcu_read_lock(); | |
502 | } | |
503 | ||
504 | void rcu_read_unlock(void) | |
505 | { | |
506 | _rcu_read_unlock(); | |
507 | } | |
508 | ||
7ac06cef MD |
509 | void rcu_quiescent_state(void) |
510 | { | |
511 | _rcu_quiescent_state(); | |
512 | } | |
513 | ||
514 | void rcu_thread_offline(void) | |
515 | { | |
516 | _rcu_thread_offline(); | |
517 | } | |
518 | ||
519 | void rcu_thread_online(void) | |
520 | { | |
521 | _rcu_thread_online(); | |
522 | } | |
523 | ||
9f1621ca MD |
524 | void rcu_register_thread(void) |
525 | { | |
bd252a04 MD |
526 | URCU_TLS(rcu_reader).tid = pthread_self(); |
527 | assert(URCU_TLS(rcu_reader).ctr == 0); | |
4f8e3380 | 528 | |
6abb4bd5 | 529 | mutex_lock(&rcu_gp_lock); |
bd252a04 | 530 | cds_list_add(&URCU_TLS(rcu_reader).node, ®istry); |
6abb4bd5 | 531 | mutex_unlock(&rcu_gp_lock); |
5f373c84 | 532 | _rcu_thread_online(); |
9f1621ca MD |
533 | } |
534 | ||
535 | void rcu_unregister_thread(void) | |
536 | { | |
76f3022f MD |
537 | /* |
538 | * We have to make the thread offline otherwise we end up dealocking | |
539 | * with a waiting writer. | |
540 | */ | |
541 | _rcu_thread_offline(); | |
6abb4bd5 | 542 | mutex_lock(&rcu_gp_lock); |
bd252a04 | 543 | cds_list_del(&URCU_TLS(rcu_reader).node); |
6abb4bd5 | 544 | mutex_unlock(&rcu_gp_lock); |
9f1621ca | 545 | } |
f6d18c64 MD |
546 | |
547 | void rcu_exit(void) | |
548 | { | |
01cadde4 MD |
549 | /* |
550 | * Assertion disabled because call_rcu threads are now rcu | |
551 | * readers, and left running at exit. | |
552 | * assert(cds_list_empty(®istry)); | |
553 | */ | |
f6d18c64 | 554 | } |
5e77fc1f | 555 | |
5e6b23a6 | 556 | DEFINE_RCU_FLAVOR(rcu_flavor); |
541d828d | 557 | |
5e77fc1f | 558 | #include "urcu-call-rcu-impl.h" |
0376e7b2 | 559 | #include "urcu-defer-impl.h" |