Commit | Line | Data |
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b57aee66 PM |
1 | /* |
2 | * urcu-call-rcu.c | |
3 | * | |
4 | * Userspace RCU library - batch memory reclamation with kernel API | |
5 | * | |
6 | * Copyright (c) 2010 Paul E. McKenney <paulmck@linux.vnet.ibm.com> | |
7 | * | |
8 | * This library is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU Lesser General Public | |
10 | * License as published by the Free Software Foundation; either | |
11 | * version 2.1 of the License, or (at your option) any later version. | |
12 | * | |
13 | * This library is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | * Lesser General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU Lesser General Public | |
19 | * License along with this library; if not, write to the Free Software | |
20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
21 | */ | |
22 | ||
5161f31e | 23 | #define _LGPL_SOURCE |
b57aee66 PM |
24 | #include <stdio.h> |
25 | #include <pthread.h> | |
26 | #include <signal.h> | |
27 | #include <assert.h> | |
28 | #include <stdlib.h> | |
6d841bc2 | 29 | #include <stdint.h> |
b57aee66 PM |
30 | #include <string.h> |
31 | #include <errno.h> | |
32 | #include <poll.h> | |
33 | #include <sys/time.h> | |
b57aee66 | 34 | #include <unistd.h> |
c1d2c60b | 35 | #include <sched.h> |
b57aee66 | 36 | |
a47dd11c | 37 | #include "compat-getcpu.h" |
4477a870 MD |
38 | #include <urcu/wfcqueue.h> |
39 | #include <urcu/call-rcu.h> | |
40 | #include <urcu/pointer.h> | |
41 | #include <urcu/list.h> | |
42 | #include <urcu/futex.h> | |
43 | #include <urcu/tls-compat.h> | |
44 | #include <urcu/ref.h> | |
4a6d7378 | 45 | #include "urcu-die.h" |
4477a870 | 46 | #include "urcu-utils.h" |
01730852 | 47 | #include "compat-smp.h" |
b57aee66 | 48 | |
8e3690db MD |
49 | #define SET_AFFINITY_CHECK_PERIOD (1U << 8) /* 256 */ |
50 | #define SET_AFFINITY_CHECK_PERIOD_MASK (SET_AFFINITY_CHECK_PERIOD - 1) | |
51 | ||
b57aee66 PM |
52 | /* Data structure that identifies a call_rcu thread. */ |
53 | ||
54 | struct call_rcu_data { | |
5161f31e | 55 | /* |
0b8ab7df MD |
56 | * We do not align head on a different cache-line than tail |
57 | * mainly because call_rcu callback-invocation threads use | |
58 | * batching ("splice") to get an entire list of callbacks, which | |
59 | * effectively empties the queue, and requires to touch the tail | |
60 | * anyway. | |
5161f31e | 61 | */ |
b9f893b6 | 62 | struct cds_wfcq_tail cbs_tail; |
0b8ab7df | 63 | struct cds_wfcq_head cbs_head; |
b57aee66 | 64 | unsigned long flags; |
6d841bc2 | 65 | int32_t futex; |
73987721 | 66 | unsigned long qlen; /* maintained for debugging. */ |
b57aee66 | 67 | pthread_t tid; |
c1d2c60b | 68 | int cpu_affinity; |
8e3690db | 69 | unsigned long gp_count; |
3c24913f | 70 | struct cds_list_head list; |
b57aee66 PM |
71 | } __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
72 | ||
b7f721d9 MD |
73 | struct call_rcu_completion { |
74 | int barrier_count; | |
75 | int32_t futex; | |
81dd9134 | 76 | struct urcu_ref ref; |
b7f721d9 MD |
77 | }; |
78 | ||
79 | struct call_rcu_completion_work { | |
80 | struct rcu_head head; | |
81 | struct call_rcu_completion *completion; | |
82 | }; | |
83 | ||
3c24913f PM |
84 | /* |
85 | * List of all call_rcu_data structures to keep valgrind happy. | |
86 | * Protected by call_rcu_mutex. | |
87 | */ | |
88 | ||
bab44e28 | 89 | static CDS_LIST_HEAD(call_rcu_data_list); |
3c24913f | 90 | |
b57aee66 PM |
91 | /* Link a thread using call_rcu() to its call_rcu thread. */ |
92 | ||
2f661865 | 93 | static DEFINE_URCU_TLS(struct call_rcu_data *, thread_call_rcu_data); |
b57aee66 | 94 | |
e85451a1 MD |
95 | /* |
96 | * Guard call_rcu thread creation and atfork handlers. | |
97 | */ | |
b57aee66 PM |
98 | static pthread_mutex_t call_rcu_mutex = PTHREAD_MUTEX_INITIALIZER; |
99 | ||
100 | /* If a given thread does not have its own call_rcu thread, this is default. */ | |
101 | ||
102 | static struct call_rcu_data *default_call_rcu_data; | |
103 | ||
d0ec0ed2 MD |
104 | static struct urcu_atfork *registered_rculfhash_atfork; |
105 | static unsigned long registered_rculfhash_atfork_refcount; | |
106 | ||
b57aee66 PM |
107 | /* |
108 | * If the sched_getcpu() and sysconf(_SC_NPROCESSORS_CONF) calls are | |
109 | * available, then we can have call_rcu threads assigned to individual | |
110 | * CPUs rather than only to specific threads. | |
111 | */ | |
112 | ||
a47dd11c | 113 | #if defined(HAVE_SYSCONF) && (defined(HAVE_SCHED_GETCPU) || defined(HAVE_GETCPUID)) |
b57aee66 PM |
114 | |
115 | /* | |
116 | * Pointer to array of pointers to per-CPU call_rcu_data structures | |
618b2595 MD |
117 | * and # CPUs. per_cpu_call_rcu_data is a RCU-protected pointer to an |
118 | * array of RCU-protected pointers to call_rcu_data. call_rcu acts as a | |
119 | * RCU read-side and reads per_cpu_call_rcu_data and the per-cpu pointer | |
120 | * without mutex. The call_rcu_mutex protects updates. | |
b57aee66 PM |
121 | */ |
122 | ||
123 | static struct call_rcu_data **per_cpu_call_rcu_data; | |
01730852 | 124 | static long cpus_array_len; |
b57aee66 | 125 | |
01730852 | 126 | static void cpus_array_len_reset(void) |
60af049d | 127 | { |
01730852 | 128 | cpus_array_len = 0; |
60af049d LJ |
129 | } |
130 | ||
b57aee66 PM |
131 | /* Allocate the array if it has not already been allocated. */ |
132 | ||
133 | static void alloc_cpu_call_rcu_data(void) | |
134 | { | |
135 | struct call_rcu_data **p; | |
136 | static int warned = 0; | |
137 | ||
01730852 | 138 | if (cpus_array_len != 0) |
b57aee66 | 139 | return; |
01730852 MJ |
140 | cpus_array_len = get_possible_cpus_array_len(); |
141 | if (cpus_array_len <= 0) { | |
b57aee66 PM |
142 | return; |
143 | } | |
01730852 | 144 | p = malloc(cpus_array_len * sizeof(*per_cpu_call_rcu_data)); |
b57aee66 | 145 | if (p != NULL) { |
01730852 | 146 | memset(p, '\0', cpus_array_len * sizeof(*per_cpu_call_rcu_data)); |
618b2595 | 147 | rcu_set_pointer(&per_cpu_call_rcu_data, p); |
b57aee66 PM |
148 | } else { |
149 | if (!warned) { | |
150 | fprintf(stderr, "[error] liburcu: unable to allocate per-CPU pointer array\n"); | |
151 | } | |
152 | warned = 1; | |
153 | } | |
154 | } | |
155 | ||
63b495d8 | 156 | #else /* #if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU) */ |
b57aee66 | 157 | |
f9437098 MD |
158 | /* |
159 | * per_cpu_call_rcu_data should be constant, but some functions below, used both | |
160 | * for cases where cpu number is available and not available, assume it it not | |
161 | * constant. | |
162 | */ | |
163 | static struct call_rcu_data **per_cpu_call_rcu_data = NULL; | |
01730852 | 164 | static const long cpus_array_len = -1; |
b57aee66 | 165 | |
01730852 | 166 | static void cpus_array_len_reset(void) |
60af049d LJ |
167 | { |
168 | } | |
169 | ||
b57aee66 PM |
170 | static void alloc_cpu_call_rcu_data(void) |
171 | { | |
172 | } | |
173 | ||
63b495d8 | 174 | #endif /* #else #if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU) */ |
b57aee66 PM |
175 | |
176 | /* Acquire the specified pthread mutex. */ | |
177 | ||
178 | static void call_rcu_lock(pthread_mutex_t *pmp) | |
179 | { | |
4a6d7378 MD |
180 | int ret; |
181 | ||
182 | ret = pthread_mutex_lock(pmp); | |
183 | if (ret) | |
184 | urcu_die(ret); | |
b57aee66 PM |
185 | } |
186 | ||
187 | /* Release the specified pthread mutex. */ | |
188 | ||
189 | static void call_rcu_unlock(pthread_mutex_t *pmp) | |
190 | { | |
4a6d7378 MD |
191 | int ret; |
192 | ||
193 | ret = pthread_mutex_unlock(pmp); | |
194 | if (ret) | |
195 | urcu_die(ret); | |
b57aee66 PM |
196 | } |
197 | ||
8e3690db MD |
198 | /* |
199 | * Periodically retry setting CPU affinity if we migrate. | |
200 | * Losing affinity can be caused by CPU hotunplug/hotplug, or by | |
201 | * cpuset(7). | |
202 | */ | |
a9e31859 | 203 | #ifdef HAVE_SCHED_SETAFFINITY |
c1d2c60b MD |
204 | static |
205 | int set_thread_cpu_affinity(struct call_rcu_data *crdp) | |
206 | { | |
207 | cpu_set_t mask; | |
8e3690db | 208 | int ret; |
c1d2c60b MD |
209 | |
210 | if (crdp->cpu_affinity < 0) | |
211 | return 0; | |
8e3690db MD |
212 | if (++crdp->gp_count & SET_AFFINITY_CHECK_PERIOD_MASK) |
213 | return 0; | |
214 | if (urcu_sched_getcpu() == crdp->cpu_affinity) | |
215 | return 0; | |
c1d2c60b MD |
216 | |
217 | CPU_ZERO(&mask); | |
218 | CPU_SET(crdp->cpu_affinity, &mask); | |
219 | #if SCHED_SETAFFINITY_ARGS == 2 | |
8e3690db | 220 | ret = sched_setaffinity(0, &mask); |
c1d2c60b | 221 | #else |
8e3690db | 222 | ret = sched_setaffinity(0, sizeof(mask), &mask); |
c1d2c60b | 223 | #endif |
8e3690db MD |
224 | /* |
225 | * EINVAL is fine: can be caused by hotunplugged CPUs, or by | |
226 | * cpuset(7). This is why we should always retry if we detect | |
227 | * migration. | |
228 | */ | |
229 | if (ret && errno == EINVAL) { | |
230 | ret = 0; | |
231 | errno = 0; | |
232 | } | |
233 | return ret; | |
c1d2c60b MD |
234 | } |
235 | #else | |
236 | static | |
0d657320 | 237 | int set_thread_cpu_affinity(struct call_rcu_data *crdp __attribute__((unused))) |
c1d2c60b MD |
238 | { |
239 | return 0; | |
240 | } | |
241 | #endif | |
242 | ||
03fe58b3 MD |
243 | static void call_rcu_wait(struct call_rcu_data *crdp) |
244 | { | |
245 | /* Read call_rcu list before read futex */ | |
246 | cmm_smp_mb(); | |
d60603e8 MD |
247 | while (uatomic_read(&crdp->futex) == -1) { |
248 | if (!futex_async(&crdp->futex, FUTEX_WAIT, -1, NULL, NULL, 0)) { | |
249 | /* | |
250 | * Prior queued wakeups queued by unrelated code | |
251 | * using the same address can cause futex wait to | |
252 | * return 0 even through the futex value is still | |
253 | * -1 (spurious wakeups). Check the value again | |
254 | * in user-space to validate whether it really | |
255 | * differs from -1. | |
256 | */ | |
257 | continue; | |
258 | } | |
b0a841b4 | 259 | switch (errno) { |
d60603e8 | 260 | case EAGAIN: |
b0a841b4 MD |
261 | /* Value already changed. */ |
262 | return; | |
263 | case EINTR: | |
264 | /* Retry if interrupted by signal. */ | |
d60603e8 | 265 | break; /* Get out of switch. Check again. */ |
b0a841b4 MD |
266 | default: |
267 | /* Unexpected error. */ | |
268 | urcu_die(errno); | |
269 | } | |
270 | } | |
03fe58b3 MD |
271 | } |
272 | ||
273 | static void call_rcu_wake_up(struct call_rcu_data *crdp) | |
274 | { | |
275 | /* Write to call_rcu list before reading/writing futex */ | |
276 | cmm_smp_mb(); | |
a0b7f7ea | 277 | if (caa_unlikely(uatomic_read(&crdp->futex) == -1)) { |
03fe58b3 | 278 | uatomic_set(&crdp->futex, 0); |
b0a841b4 MD |
279 | if (futex_async(&crdp->futex, FUTEX_WAKE, 1, |
280 | NULL, NULL, 0) < 0) | |
281 | urcu_die(errno); | |
03fe58b3 MD |
282 | } |
283 | } | |
284 | ||
b7f721d9 MD |
285 | static void call_rcu_completion_wait(struct call_rcu_completion *completion) |
286 | { | |
287 | /* Read completion barrier count before read futex */ | |
288 | cmm_smp_mb(); | |
d60603e8 MD |
289 | while (uatomic_read(&completion->futex) == -1) { |
290 | if (!futex_async(&completion->futex, FUTEX_WAIT, -1, NULL, NULL, 0)) { | |
291 | /* | |
292 | * Prior queued wakeups queued by unrelated code | |
293 | * using the same address can cause futex wait to | |
294 | * return 0 even through the futex value is still | |
295 | * -1 (spurious wakeups). Check the value again | |
296 | * in user-space to validate whether it really | |
297 | * differs from -1. | |
298 | */ | |
299 | continue; | |
300 | } | |
b0a841b4 | 301 | switch (errno) { |
d60603e8 | 302 | case EAGAIN: |
b0a841b4 MD |
303 | /* Value already changed. */ |
304 | return; | |
305 | case EINTR: | |
306 | /* Retry if interrupted by signal. */ | |
d60603e8 | 307 | break; /* Get out of switch. Check again. */ |
b0a841b4 MD |
308 | default: |
309 | /* Unexpected error. */ | |
310 | urcu_die(errno); | |
311 | } | |
312 | } | |
b7f721d9 MD |
313 | } |
314 | ||
315 | static void call_rcu_completion_wake_up(struct call_rcu_completion *completion) | |
316 | { | |
317 | /* Write to completion barrier count before reading/writing futex */ | |
318 | cmm_smp_mb(); | |
319 | if (caa_unlikely(uatomic_read(&completion->futex) == -1)) { | |
320 | uatomic_set(&completion->futex, 0); | |
b0a841b4 MD |
321 | if (futex_async(&completion->futex, FUTEX_WAKE, 1, |
322 | NULL, NULL, 0) < 0) | |
323 | urcu_die(errno); | |
b7f721d9 MD |
324 | } |
325 | } | |
326 | ||
b57aee66 PM |
327 | /* This is the code run by each call_rcu thread. */ |
328 | ||
329 | static void *call_rcu_thread(void *arg) | |
330 | { | |
331 | unsigned long cbcount; | |
5161f31e | 332 | struct call_rcu_data *crdp = (struct call_rcu_data *) arg; |
2870aa1e | 333 | int rt = !!(uatomic_read(&crdp->flags) & URCU_CALL_RCU_RT); |
b57aee66 | 334 | |
8e3690db | 335 | if (set_thread_cpu_affinity(crdp)) |
4a6d7378 | 336 | urcu_die(errno); |
c1d2c60b | 337 | |
765f3ead MD |
338 | /* |
339 | * If callbacks take a read-side lock, we need to be registered. | |
340 | */ | |
341 | rcu_register_thread(); | |
342 | ||
bd252a04 | 343 | URCU_TLS(thread_call_rcu_data) = crdp; |
bc94ca9b MD |
344 | if (!rt) { |
345 | uatomic_dec(&crdp->futex); | |
346 | /* Decrement futex before reading call_rcu list */ | |
347 | cmm_smp_mb(); | |
348 | } | |
b57aee66 | 349 | for (;;) { |
5161f31e MD |
350 | struct cds_wfcq_head cbs_tmp_head; |
351 | struct cds_wfcq_tail cbs_tmp_tail; | |
352 | struct cds_wfcq_node *cbs, *cbs_tmp_n; | |
ae25b7e2 | 353 | enum cds_wfcq_ret splice_ret; |
5161f31e | 354 | |
8e3690db MD |
355 | if (set_thread_cpu_affinity(crdp)) |
356 | urcu_die(errno); | |
357 | ||
e85451a1 MD |
358 | if (uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSE) { |
359 | /* | |
360 | * Pause requested. Become quiescent: remove | |
361 | * ourself from all global lists, and don't | |
362 | * process any callback. The callback lists may | |
363 | * still be non-empty though. | |
364 | */ | |
365 | rcu_unregister_thread(); | |
366 | cmm_smp_mb__before_uatomic_or(); | |
367 | uatomic_or(&crdp->flags, URCU_CALL_RCU_PAUSED); | |
368 | while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSE) != 0) | |
109105b7 | 369 | (void) poll(NULL, 0, 1); |
fc236e5e KF |
370 | uatomic_and(&crdp->flags, ~URCU_CALL_RCU_PAUSED); |
371 | cmm_smp_mb__after_uatomic_and(); | |
e85451a1 MD |
372 | rcu_register_thread(); |
373 | } | |
374 | ||
5161f31e | 375 | cds_wfcq_init(&cbs_tmp_head, &cbs_tmp_tail); |
ae25b7e2 MD |
376 | splice_ret = __cds_wfcq_splice_blocking(&cbs_tmp_head, |
377 | &cbs_tmp_tail, &crdp->cbs_head, &crdp->cbs_tail); | |
378 | assert(splice_ret != CDS_WFCQ_RET_WOULDBLOCK); | |
379 | assert(splice_ret != CDS_WFCQ_RET_DEST_NON_EMPTY); | |
380 | if (splice_ret != CDS_WFCQ_RET_SRC_EMPTY) { | |
b57aee66 PM |
381 | synchronize_rcu(); |
382 | cbcount = 0; | |
5161f31e MD |
383 | __cds_wfcq_for_each_blocking_safe(&cbs_tmp_head, |
384 | &cbs_tmp_tail, cbs, cbs_tmp_n) { | |
385 | struct rcu_head *rhp; | |
386 | ||
387 | rhp = caa_container_of(cbs, | |
388 | struct rcu_head, next); | |
b57aee66 PM |
389 | rhp->func(rhp); |
390 | cbcount++; | |
5161f31e | 391 | } |
b57aee66 PM |
392 | uatomic_sub(&crdp->qlen, cbcount); |
393 | } | |
bc94ca9b MD |
394 | if (uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOP) |
395 | break; | |
765f3ead | 396 | rcu_thread_offline(); |
bc94ca9b | 397 | if (!rt) { |
5161f31e MD |
398 | if (cds_wfcq_empty(&crdp->cbs_head, |
399 | &crdp->cbs_tail)) { | |
bc94ca9b | 400 | call_rcu_wait(crdp); |
109105b7 | 401 | (void) poll(NULL, 0, 10); |
bc94ca9b | 402 | uatomic_dec(&crdp->futex); |
c768e45e | 403 | /* |
bc94ca9b MD |
404 | * Decrement futex before reading |
405 | * call_rcu list. | |
c768e45e MD |
406 | */ |
407 | cmm_smp_mb(); | |
ccbac24d | 408 | } else { |
109105b7 | 409 | (void) poll(NULL, 0, 10); |
c768e45e | 410 | } |
bc94ca9b | 411 | } else { |
109105b7 | 412 | (void) poll(NULL, 0, 10); |
b57aee66 | 413 | } |
765f3ead | 414 | rcu_thread_online(); |
bc94ca9b MD |
415 | } |
416 | if (!rt) { | |
417 | /* | |
418 | * Read call_rcu list before write futex. | |
419 | */ | |
420 | cmm_smp_mb(); | |
421 | uatomic_set(&crdp->futex, 0); | |
b57aee66 | 422 | } |
2870aa1e | 423 | uatomic_or(&crdp->flags, URCU_CALL_RCU_STOPPED); |
765f3ead | 424 | rcu_unregister_thread(); |
7106ddf8 | 425 | return NULL; |
b57aee66 PM |
426 | } |
427 | ||
428 | /* | |
429 | * Create both a call_rcu thread and the corresponding call_rcu_data | |
3c24913f PM |
430 | * structure, linking the structure in as specified. Caller must hold |
431 | * call_rcu_mutex. | |
b57aee66 PM |
432 | */ |
433 | ||
3c24913f | 434 | static void call_rcu_data_init(struct call_rcu_data **crdpp, |
c1d2c60b MD |
435 | unsigned long flags, |
436 | int cpu_affinity) | |
b57aee66 PM |
437 | { |
438 | struct call_rcu_data *crdp; | |
4a6d7378 | 439 | int ret; |
b57aee66 PM |
440 | |
441 | crdp = malloc(sizeof(*crdp)); | |
4a6d7378 MD |
442 | if (crdp == NULL) |
443 | urcu_die(errno); | |
b57aee66 | 444 | memset(crdp, '\0', sizeof(*crdp)); |
5161f31e | 445 | cds_wfcq_init(&crdp->cbs_head, &crdp->cbs_tail); |
b57aee66 | 446 | crdp->qlen = 0; |
263e3cf9 MD |
447 | crdp->futex = 0; |
448 | crdp->flags = flags; | |
3c24913f | 449 | cds_list_add(&crdp->list, &call_rcu_data_list); |
c1d2c60b | 450 | crdp->cpu_affinity = cpu_affinity; |
8e3690db | 451 | crdp->gp_count = 0; |
b57aee66 PM |
452 | cmm_smp_mb(); /* Structure initialized before pointer is planted. */ |
453 | *crdpp = crdp; | |
4a6d7378 MD |
454 | ret = pthread_create(&crdp->tid, NULL, call_rcu_thread, crdp); |
455 | if (ret) | |
456 | urcu_die(ret); | |
b57aee66 PM |
457 | } |
458 | ||
459 | /* | |
460 | * Return a pointer to the call_rcu_data structure for the specified | |
461 | * CPU, returning NULL if there is none. We cannot automatically | |
462 | * created it because the platform we are running on might not define | |
63b495d8 | 463 | * urcu_sched_getcpu(). |
618b2595 MD |
464 | * |
465 | * The call to this function and use of the returned call_rcu_data | |
466 | * should be protected by RCU read-side lock. | |
b57aee66 PM |
467 | */ |
468 | ||
469 | struct call_rcu_data *get_cpu_call_rcu_data(int cpu) | |
470 | { | |
471 | static int warned = 0; | |
618b2595 | 472 | struct call_rcu_data **pcpu_crdp; |
b57aee66 | 473 | |
618b2595 MD |
474 | pcpu_crdp = rcu_dereference(per_cpu_call_rcu_data); |
475 | if (pcpu_crdp == NULL) | |
b57aee66 | 476 | return NULL; |
01730852 | 477 | if (!warned && cpus_array_len > 0 && (cpu < 0 || cpus_array_len <= cpu)) { |
b57aee66 PM |
478 | fprintf(stderr, "[error] liburcu: get CPU # out of range\n"); |
479 | warned = 1; | |
480 | } | |
01730852 | 481 | if (cpu < 0 || cpus_array_len <= cpu) |
b57aee66 | 482 | return NULL; |
618b2595 | 483 | return rcu_dereference(pcpu_crdp[cpu]); |
b57aee66 | 484 | } |
ce28e67a | 485 | URCU_ATTR_ALIAS(urcu_stringify(get_cpu_call_rcu_data)) |
4477a870 | 486 | struct call_rcu_data *alias_get_cpu_call_rcu_data(); |
b57aee66 PM |
487 | |
488 | /* | |
489 | * Return the tid corresponding to the call_rcu thread whose | |
490 | * call_rcu_data structure is specified. | |
491 | */ | |
492 | ||
493 | pthread_t get_call_rcu_thread(struct call_rcu_data *crdp) | |
494 | { | |
495 | return crdp->tid; | |
496 | } | |
ce28e67a | 497 | URCU_ATTR_ALIAS(urcu_stringify(get_call_rcu_thread)) |
4477a870 | 498 | pthread_t alias_get_call_rcu_thread(); |
b57aee66 PM |
499 | |
500 | /* | |
501 | * Create a call_rcu_data structure (with thread) and return a pointer. | |
502 | */ | |
503 | ||
c1d2c60b MD |
504 | static struct call_rcu_data *__create_call_rcu_data(unsigned long flags, |
505 | int cpu_affinity) | |
b57aee66 PM |
506 | { |
507 | struct call_rcu_data *crdp; | |
508 | ||
c1d2c60b | 509 | call_rcu_data_init(&crdp, flags, cpu_affinity); |
b57aee66 PM |
510 | return crdp; |
511 | } | |
512 | ||
ce28e67a | 513 | URCU_ATTR_ALIAS(urcu_stringify(create_call_rcu_data)) |
4477a870 | 514 | struct call_rcu_data *alias_create_call_rcu_data(); |
c1d2c60b MD |
515 | struct call_rcu_data *create_call_rcu_data(unsigned long flags, |
516 | int cpu_affinity) | |
3c24913f PM |
517 | { |
518 | struct call_rcu_data *crdp; | |
519 | ||
520 | call_rcu_lock(&call_rcu_mutex); | |
c1d2c60b | 521 | crdp = __create_call_rcu_data(flags, cpu_affinity); |
3c24913f PM |
522 | call_rcu_unlock(&call_rcu_mutex); |
523 | return crdp; | |
524 | } | |
525 | ||
b57aee66 PM |
526 | /* |
527 | * Set the specified CPU to use the specified call_rcu_data structure. | |
7106ddf8 PM |
528 | * |
529 | * Use NULL to remove a CPU's call_rcu_data structure, but it is | |
530 | * the caller's responsibility to dispose of the removed structure. | |
531 | * Use get_cpu_call_rcu_data() to obtain a pointer to the old structure | |
532 | * (prior to NULLing it out, of course). | |
f9da0936 MD |
533 | * |
534 | * The caller must wait for a grace-period to pass between return from | |
535 | * set_cpu_call_rcu_data() and call to call_rcu_data_free() passing the | |
536 | * previous call rcu data as argument. | |
b57aee66 PM |
537 | */ |
538 | ||
539 | int set_cpu_call_rcu_data(int cpu, struct call_rcu_data *crdp) | |
540 | { | |
dcfc8165 | 541 | static int warned = 0; |
b57aee66 PM |
542 | |
543 | call_rcu_lock(&call_rcu_mutex); | |
f3776786 | 544 | alloc_cpu_call_rcu_data(); |
01730852 | 545 | if (cpu < 0 || cpus_array_len <= cpu) { |
b57aee66 PM |
546 | if (!warned) { |
547 | fprintf(stderr, "[error] liburcu: set CPU # out of range\n"); | |
548 | warned = 1; | |
549 | } | |
550 | call_rcu_unlock(&call_rcu_mutex); | |
551 | errno = EINVAL; | |
552 | return -EINVAL; | |
553 | } | |
53a55535 | 554 | |
b57aee66 | 555 | if (per_cpu_call_rcu_data == NULL) { |
3670fef2 | 556 | call_rcu_unlock(&call_rcu_mutex); |
b57aee66 PM |
557 | errno = ENOMEM; |
558 | return -ENOMEM; | |
559 | } | |
53a55535 LJ |
560 | |
561 | if (per_cpu_call_rcu_data[cpu] != NULL && crdp != NULL) { | |
562 | call_rcu_unlock(&call_rcu_mutex); | |
563 | errno = EEXIST; | |
564 | return -EEXIST; | |
565 | } | |
566 | ||
618b2595 | 567 | rcu_set_pointer(&per_cpu_call_rcu_data[cpu], crdp); |
3670fef2 | 568 | call_rcu_unlock(&call_rcu_mutex); |
b57aee66 PM |
569 | return 0; |
570 | } | |
ce28e67a | 571 | URCU_ATTR_ALIAS(urcu_stringify(set_cpu_call_rcu_data)) |
4477a870 | 572 | int alias_set_cpu_call_rcu_data(); |
b57aee66 PM |
573 | |
574 | /* | |
575 | * Return a pointer to the default call_rcu_data structure, creating | |
576 | * one if need be. Because we never free call_rcu_data structures, | |
577 | * we don't need to be in an RCU read-side critical section. | |
578 | */ | |
579 | ||
580 | struct call_rcu_data *get_default_call_rcu_data(void) | |
581 | { | |
582 | if (default_call_rcu_data != NULL) | |
583 | return rcu_dereference(default_call_rcu_data); | |
584 | call_rcu_lock(&call_rcu_mutex); | |
585 | if (default_call_rcu_data != NULL) { | |
586 | call_rcu_unlock(&call_rcu_mutex); | |
587 | return default_call_rcu_data; | |
588 | } | |
c1d2c60b | 589 | call_rcu_data_init(&default_call_rcu_data, 0, -1); |
b57aee66 PM |
590 | call_rcu_unlock(&call_rcu_mutex); |
591 | return default_call_rcu_data; | |
592 | } | |
ce28e67a | 593 | URCU_ATTR_ALIAS(urcu_stringify(get_default_call_rcu_data)) |
4477a870 | 594 | struct call_rcu_data *alias_get_default_call_rcu_data(); |
b57aee66 PM |
595 | |
596 | /* | |
597 | * Return the call_rcu_data structure that applies to the currently | |
598 | * running thread. Any call_rcu_data structure assigned specifically | |
599 | * to this thread has first priority, followed by any call_rcu_data | |
600 | * structure assigned to the CPU on which the thread is running, | |
601 | * followed by the default call_rcu_data structure. If there is not | |
602 | * yet a default call_rcu_data structure, one will be created. | |
618b2595 MD |
603 | * |
604 | * Calls to this function and use of the returned call_rcu_data should | |
605 | * be protected by RCU read-side lock. | |
b57aee66 PM |
606 | */ |
607 | struct call_rcu_data *get_call_rcu_data(void) | |
608 | { | |
9744f3bb | 609 | struct call_rcu_data *crd; |
b57aee66 | 610 | |
bd252a04 MD |
611 | if (URCU_TLS(thread_call_rcu_data) != NULL) |
612 | return URCU_TLS(thread_call_rcu_data); | |
9744f3bb | 613 | |
01730852 | 614 | if (cpus_array_len > 0) { |
63b495d8 | 615 | crd = get_cpu_call_rcu_data(urcu_sched_getcpu()); |
9744f3bb LJ |
616 | if (crd) |
617 | return crd; | |
b57aee66 | 618 | } |
9744f3bb | 619 | |
b57aee66 PM |
620 | return get_default_call_rcu_data(); |
621 | } | |
ce28e67a | 622 | URCU_ATTR_ALIAS(urcu_stringify(get_call_rcu_data)) |
4477a870 | 623 | struct call_rcu_data *alias_get_call_rcu_data(); |
b57aee66 PM |
624 | |
625 | /* | |
626 | * Return a pointer to this task's call_rcu_data if there is one. | |
627 | */ | |
628 | ||
629 | struct call_rcu_data *get_thread_call_rcu_data(void) | |
630 | { | |
bd252a04 | 631 | return URCU_TLS(thread_call_rcu_data); |
b57aee66 | 632 | } |
ce28e67a | 633 | URCU_ATTR_ALIAS(urcu_stringify(get_thread_call_rcu_data)) |
4477a870 | 634 | struct call_rcu_data *alias_get_thread_call_rcu_data(); |
b57aee66 PM |
635 | |
636 | /* | |
637 | * Set this task's call_rcu_data structure as specified, regardless | |
638 | * of whether or not this task already had one. (This allows switching | |
639 | * to and from real-time call_rcu threads, for example.) | |
7106ddf8 PM |
640 | * |
641 | * Use NULL to remove a thread's call_rcu_data structure, but it is | |
642 | * the caller's responsibility to dispose of the removed structure. | |
643 | * Use get_thread_call_rcu_data() to obtain a pointer to the old structure | |
644 | * (prior to NULLing it out, of course). | |
b57aee66 PM |
645 | */ |
646 | ||
647 | void set_thread_call_rcu_data(struct call_rcu_data *crdp) | |
648 | { | |
bd252a04 | 649 | URCU_TLS(thread_call_rcu_data) = crdp; |
b57aee66 | 650 | } |
ce28e67a | 651 | URCU_ATTR_ALIAS(urcu_stringify(set_thread_call_rcu_data)) |
4477a870 | 652 | void alias_set_thread_call_rcu_data(); |
b57aee66 PM |
653 | |
654 | /* | |
655 | * Create a separate call_rcu thread for each CPU. This does not | |
656 | * replace a pre-existing call_rcu thread -- use the set_cpu_call_rcu_data() | |
0938c541 MD |
657 | * function if you want that behavior. Should be paired with |
658 | * free_all_cpu_call_rcu_data() to teardown these call_rcu worker | |
659 | * threads. | |
b57aee66 PM |
660 | */ |
661 | ||
662 | int create_all_cpu_call_rcu_data(unsigned long flags) | |
663 | { | |
664 | int i; | |
665 | struct call_rcu_data *crdp; | |
666 | int ret; | |
667 | ||
668 | call_rcu_lock(&call_rcu_mutex); | |
669 | alloc_cpu_call_rcu_data(); | |
670 | call_rcu_unlock(&call_rcu_mutex); | |
01730852 | 671 | if (cpus_array_len <= 0) { |
b57aee66 PM |
672 | errno = EINVAL; |
673 | return -EINVAL; | |
674 | } | |
675 | if (per_cpu_call_rcu_data == NULL) { | |
676 | errno = ENOMEM; | |
677 | return -ENOMEM; | |
678 | } | |
01730852 | 679 | for (i = 0; i < cpus_array_len; i++) { |
b57aee66 PM |
680 | call_rcu_lock(&call_rcu_mutex); |
681 | if (get_cpu_call_rcu_data(i)) { | |
682 | call_rcu_unlock(&call_rcu_mutex); | |
683 | continue; | |
684 | } | |
c1d2c60b | 685 | crdp = __create_call_rcu_data(flags, i); |
b57aee66 PM |
686 | if (crdp == NULL) { |
687 | call_rcu_unlock(&call_rcu_mutex); | |
688 | errno = ENOMEM; | |
689 | return -ENOMEM; | |
690 | } | |
691 | call_rcu_unlock(&call_rcu_mutex); | |
692 | if ((ret = set_cpu_call_rcu_data(i, crdp)) != 0) { | |
356c8794 LJ |
693 | call_rcu_data_free(crdp); |
694 | ||
695 | /* it has been created by other thread */ | |
696 | if (ret == -EEXIST) | |
697 | continue; | |
698 | ||
699 | return ret; | |
b57aee66 PM |
700 | } |
701 | } | |
702 | return 0; | |
703 | } | |
ce28e67a | 704 | URCU_ATTR_ALIAS(urcu_stringify(create_all_cpu_call_rcu_data)) |
4477a870 | 705 | int alias_create_all_cpu_call_rcu_data(); |
b57aee66 | 706 | |
7106ddf8 PM |
707 | /* |
708 | * Wake up the call_rcu thread corresponding to the specified | |
709 | * call_rcu_data structure. | |
710 | */ | |
711 | static void wake_call_rcu_thread(struct call_rcu_data *crdp) | |
712 | { | |
263e3cf9 MD |
713 | if (!(_CMM_LOAD_SHARED(crdp->flags) & URCU_CALL_RCU_RT)) |
714 | call_rcu_wake_up(crdp); | |
7106ddf8 PM |
715 | } |
716 | ||
b7f721d9 MD |
717 | static void _call_rcu(struct rcu_head *head, |
718 | void (*func)(struct rcu_head *head), | |
719 | struct call_rcu_data *crdp) | |
720 | { | |
721 | cds_wfcq_node_init(&head->next); | |
722 | head->func = func; | |
723 | cds_wfcq_enqueue(&crdp->cbs_head, &crdp->cbs_tail, &head->next); | |
724 | uatomic_inc(&crdp->qlen); | |
725 | wake_call_rcu_thread(crdp); | |
726 | } | |
727 | ||
b57aee66 PM |
728 | /* |
729 | * Schedule a function to be invoked after a following grace period. | |
730 | * This is the only function that must be called -- the others are | |
731 | * only present to allow applications to tune their use of RCU for | |
732 | * maximum performance. | |
733 | * | |
734 | * Note that unless a call_rcu thread has not already been created, | |
735 | * the first invocation of call_rcu() will create one. So, if you | |
736 | * need the first invocation of call_rcu() to be fast, make sure | |
737 | * to create a call_rcu thread first. One way to accomplish this is | |
738 | * "get_call_rcu_data();", and another is create_all_cpu_call_rcu_data(). | |
618b2595 MD |
739 | * |
740 | * call_rcu must be called by registered RCU read-side threads. | |
b57aee66 | 741 | */ |
b57aee66 PM |
742 | void call_rcu(struct rcu_head *head, |
743 | void (*func)(struct rcu_head *head)) | |
744 | { | |
745 | struct call_rcu_data *crdp; | |
746 | ||
618b2595 | 747 | /* Holding rcu read-side lock across use of per-cpu crdp */ |
ffb4aaa7 | 748 | _rcu_read_lock(); |
b57aee66 | 749 | crdp = get_call_rcu_data(); |
b7f721d9 | 750 | _call_rcu(head, func, crdp); |
ffb4aaa7 | 751 | _rcu_read_unlock(); |
7106ddf8 | 752 | } |
ce28e67a | 753 | URCU_ATTR_ALIAS(urcu_stringify(call_rcu)) void alias_call_rcu(); |
7106ddf8 PM |
754 | |
755 | /* | |
756 | * Free up the specified call_rcu_data structure, terminating the | |
757 | * associated call_rcu thread. The caller must have previously | |
758 | * removed the call_rcu_data structure from per-thread or per-CPU | |
759 | * usage. For example, set_cpu_call_rcu_data(cpu, NULL) for per-CPU | |
760 | * call_rcu_data structures or set_thread_call_rcu_data(NULL) for | |
761 | * per-thread call_rcu_data structures. | |
762 | * | |
763 | * We silently refuse to free up the default call_rcu_data structure | |
764 | * because that is where we put any leftover callbacks. Note that | |
765 | * the possibility of self-spawning callbacks makes it impossible | |
766 | * to execute all the callbacks in finite time without putting any | |
767 | * newly spawned callbacks somewhere else. The "somewhere else" of | |
768 | * last resort is the default call_rcu_data structure. | |
769 | * | |
770 | * We also silently refuse to free NULL pointers. This simplifies | |
771 | * the calling code. | |
f9da0936 MD |
772 | * |
773 | * The caller must wait for a grace-period to pass between return from | |
774 | * set_cpu_call_rcu_data() and call to call_rcu_data_free() passing the | |
775 | * previous call rcu data as argument. | |
03e5118f MD |
776 | * |
777 | * Note: introducing __cds_wfcq_splice_blocking() in this function fixed | |
778 | * a list corruption bug in the 0.7.x series. The equivalent fix | |
779 | * appeared in 0.6.8 for the stable-0.6 branch. | |
7106ddf8 PM |
780 | */ |
781 | void call_rcu_data_free(struct call_rcu_data *crdp) | |
782 | { | |
7106ddf8 PM |
783 | if (crdp == NULL || crdp == default_call_rcu_data) { |
784 | return; | |
785 | } | |
2870aa1e PB |
786 | if ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOPPED) == 0) { |
787 | uatomic_or(&crdp->flags, URCU_CALL_RCU_STOP); | |
7106ddf8 | 788 | wake_call_rcu_thread(crdp); |
2870aa1e | 789 | while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOPPED) == 0) |
109105b7 | 790 | (void) poll(NULL, 0, 1); |
7106ddf8 | 791 | } |
9049d56a | 792 | call_rcu_lock(&call_rcu_mutex); |
5161f31e | 793 | if (!cds_wfcq_empty(&crdp->cbs_head, &crdp->cbs_tail)) { |
9049d56a PM |
794 | call_rcu_unlock(&call_rcu_mutex); |
795 | /* Create default call rcu data if need be. */ | |
796 | /* CBs queued here will be handed to the default list. */ | |
698d0778 | 797 | (void) get_default_call_rcu_data(); |
9049d56a | 798 | call_rcu_lock(&call_rcu_mutex); |
5161f31e MD |
799 | __cds_wfcq_splice_blocking(&default_call_rcu_data->cbs_head, |
800 | &default_call_rcu_data->cbs_tail, | |
801 | &crdp->cbs_head, &crdp->cbs_tail); | |
7106ddf8 PM |
802 | uatomic_add(&default_call_rcu_data->qlen, |
803 | uatomic_read(&crdp->qlen)); | |
1e92aa15 | 804 | wake_call_rcu_thread(default_call_rcu_data); |
7106ddf8 | 805 | } |
59dc9e9d LJ |
806 | |
807 | cds_list_del(&crdp->list); | |
b75dffe6 LJ |
808 | call_rcu_unlock(&call_rcu_mutex); |
809 | ||
59dc9e9d | 810 | free(crdp); |
7106ddf8 | 811 | } |
ce28e67a | 812 | URCU_ATTR_ALIAS(urcu_stringify(call_rcu_data_free)) |
4477a870 | 813 | void alias_call_rcu_data_free(); |
7106ddf8 PM |
814 | |
815 | /* | |
816 | * Clean up all the per-CPU call_rcu threads. | |
817 | */ | |
818 | void free_all_cpu_call_rcu_data(void) | |
819 | { | |
820 | int cpu; | |
618b2595 MD |
821 | struct call_rcu_data **crdp; |
822 | static int warned = 0; | |
7106ddf8 | 823 | |
01730852 | 824 | if (cpus_array_len <= 0) |
7106ddf8 | 825 | return; |
618b2595 | 826 | |
01730852 | 827 | crdp = malloc(sizeof(*crdp) * cpus_array_len); |
618b2595 MD |
828 | if (!crdp) { |
829 | if (!warned) { | |
830 | fprintf(stderr, "[error] liburcu: unable to allocate per-CPU pointer array\n"); | |
831 | } | |
832 | warned = 1; | |
d31150b4 | 833 | return; |
618b2595 MD |
834 | } |
835 | ||
01730852 | 836 | for (cpu = 0; cpu < cpus_array_len; cpu++) { |
618b2595 MD |
837 | crdp[cpu] = get_cpu_call_rcu_data(cpu); |
838 | if (crdp[cpu] == NULL) | |
7106ddf8 PM |
839 | continue; |
840 | set_cpu_call_rcu_data(cpu, NULL); | |
7106ddf8 | 841 | } |
618b2595 MD |
842 | /* |
843 | * Wait for call_rcu sites acting as RCU readers of the | |
844 | * call_rcu_data to become quiescent. | |
845 | */ | |
846 | synchronize_rcu(); | |
01730852 | 847 | for (cpu = 0; cpu < cpus_array_len; cpu++) { |
618b2595 MD |
848 | if (crdp[cpu] == NULL) |
849 | continue; | |
850 | call_rcu_data_free(crdp[cpu]); | |
851 | } | |
852 | free(crdp); | |
7106ddf8 | 853 | } |
4477a870 MD |
854 | #ifdef RCU_QSBR |
855 | /* ABI6 has a non-namespaced free_all_cpu_call_rcu_data for qsbr */ | |
856 | #undef free_all_cpu_call_rcu_data | |
ce28e67a | 857 | URCU_ATTR_ALIAS("urcu_qsbr_free_all_cpu_call_rcu_data") |
4477a870 MD |
858 | void free_all_cpu_call_rcu_data(); |
859 | #define free_all_cpu_call_rcu_data urcu_qsbr_free_all_cpu_call_rcu_data | |
860 | #else | |
ce28e67a | 861 | URCU_ATTR_ALIAS(urcu_stringify(free_all_cpu_call_rcu_data)) |
4477a870 MD |
862 | void alias_free_all_cpu_call_rcu_data(); |
863 | #endif | |
7106ddf8 | 864 | |
81dd9134 KF |
865 | static |
866 | void free_completion(struct urcu_ref *ref) | |
867 | { | |
868 | struct call_rcu_completion *completion; | |
869 | ||
870 | completion = caa_container_of(ref, struct call_rcu_completion, ref); | |
871 | free(completion); | |
872 | } | |
873 | ||
b7f721d9 MD |
874 | static |
875 | void _rcu_barrier_complete(struct rcu_head *head) | |
876 | { | |
877 | struct call_rcu_completion_work *work; | |
878 | struct call_rcu_completion *completion; | |
879 | ||
880 | work = caa_container_of(head, struct call_rcu_completion_work, head); | |
881 | completion = work->completion; | |
81dd9134 KF |
882 | if (!uatomic_sub_return(&completion->barrier_count, 1)) |
883 | call_rcu_completion_wake_up(completion); | |
884 | urcu_ref_put(&completion->ref, free_completion); | |
b7f721d9 MD |
885 | free(work); |
886 | } | |
887 | ||
888 | /* | |
889 | * Wait for all in-flight call_rcu callbacks to complete execution. | |
890 | */ | |
891 | void rcu_barrier(void) | |
892 | { | |
893 | struct call_rcu_data *crdp; | |
81dd9134 | 894 | struct call_rcu_completion *completion; |
63f0fc6d | 895 | int count = 0; |
b7f721d9 MD |
896 | int was_online; |
897 | ||
898 | /* Put in offline state in QSBR. */ | |
ffb4aaa7 | 899 | was_online = _rcu_read_ongoing(); |
b7f721d9 MD |
900 | if (was_online) |
901 | rcu_thread_offline(); | |
902 | /* | |
903 | * Calling a rcu_barrier() within a RCU read-side critical | |
904 | * section is an error. | |
905 | */ | |
ffb4aaa7 | 906 | if (_rcu_read_ongoing()) { |
b7f721d9 MD |
907 | static int warned = 0; |
908 | ||
909 | if (!warned) { | |
910 | fprintf(stderr, "[error] liburcu: rcu_barrier() called from within RCU read-side critical section.\n"); | |
911 | } | |
912 | warned = 1; | |
913 | goto online; | |
914 | } | |
915 | ||
81dd9134 KF |
916 | completion = calloc(sizeof(*completion), 1); |
917 | if (!completion) | |
918 | urcu_die(errno); | |
919 | ||
b7f721d9 MD |
920 | call_rcu_lock(&call_rcu_mutex); |
921 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) | |
922 | count++; | |
923 | ||
81dd9134 KF |
924 | /* Referenced by rcu_barrier() and each call_rcu thread. */ |
925 | urcu_ref_set(&completion->ref, count + 1); | |
926 | completion->barrier_count = count; | |
b7f721d9 MD |
927 | |
928 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) { | |
929 | struct call_rcu_completion_work *work; | |
930 | ||
931 | work = calloc(sizeof(*work), 1); | |
63f0fc6d MD |
932 | if (!work) |
933 | urcu_die(errno); | |
81dd9134 | 934 | work->completion = completion; |
b7f721d9 | 935 | _call_rcu(&work->head, _rcu_barrier_complete, crdp); |
b7f721d9 MD |
936 | } |
937 | call_rcu_unlock(&call_rcu_mutex); | |
938 | ||
b7f721d9 MD |
939 | /* Wait for them */ |
940 | for (;;) { | |
81dd9134 | 941 | uatomic_dec(&completion->futex); |
b7f721d9 MD |
942 | /* Decrement futex before reading barrier_count */ |
943 | cmm_smp_mb(); | |
81dd9134 | 944 | if (!uatomic_read(&completion->barrier_count)) |
b7f721d9 | 945 | break; |
81dd9134 | 946 | call_rcu_completion_wait(completion); |
b7f721d9 | 947 | } |
81dd9134 KF |
948 | |
949 | urcu_ref_put(&completion->ref, free_completion); | |
950 | ||
b7f721d9 MD |
951 | online: |
952 | if (was_online) | |
953 | rcu_thread_online(); | |
954 | } | |
ce28e67a | 955 | URCU_ATTR_ALIAS(urcu_stringify(rcu_barrier)) |
4477a870 | 956 | void alias_rcu_barrier(); |
b7f721d9 | 957 | |
81ad2e19 PM |
958 | /* |
959 | * Acquire the call_rcu_mutex in order to ensure that the child sees | |
e85451a1 MD |
960 | * all of the call_rcu() data structures in a consistent state. Ensure |
961 | * that all call_rcu threads are in a quiescent state across fork. | |
81ad2e19 PM |
962 | * Suitable for pthread_atfork() and friends. |
963 | */ | |
964 | void call_rcu_before_fork(void) | |
965 | { | |
e85451a1 | 966 | struct call_rcu_data *crdp; |
d0ec0ed2 | 967 | struct urcu_atfork *atfork; |
e85451a1 | 968 | |
81ad2e19 | 969 | call_rcu_lock(&call_rcu_mutex); |
e85451a1 | 970 | |
d0ec0ed2 MD |
971 | atfork = registered_rculfhash_atfork; |
972 | if (atfork) | |
973 | atfork->before_fork(atfork->priv); | |
974 | ||
e85451a1 MD |
975 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) { |
976 | uatomic_or(&crdp->flags, URCU_CALL_RCU_PAUSE); | |
977 | cmm_smp_mb__after_uatomic_or(); | |
978 | wake_call_rcu_thread(crdp); | |
979 | } | |
980 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) { | |
981 | while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSED) == 0) | |
109105b7 | 982 | (void) poll(NULL, 0, 1); |
e85451a1 | 983 | } |
81ad2e19 | 984 | } |
ce28e67a | 985 | URCU_ATTR_ALIAS(urcu_stringify(call_rcu_before_fork)) |
4477a870 | 986 | void alias_call_rcu_before_fork(); |
81ad2e19 PM |
987 | |
988 | /* | |
989 | * Clean up call_rcu data structures in the parent of a successful fork() | |
990 | * that is not followed by exec() in the child. Suitable for | |
991 | * pthread_atfork() and friends. | |
992 | */ | |
993 | void call_rcu_after_fork_parent(void) | |
994 | { | |
e85451a1 | 995 | struct call_rcu_data *crdp; |
d0ec0ed2 | 996 | struct urcu_atfork *atfork; |
e85451a1 MD |
997 | |
998 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) | |
999 | uatomic_and(&crdp->flags, ~URCU_CALL_RCU_PAUSE); | |
fc236e5e KF |
1000 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) { |
1001 | while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSED) != 0) | |
109105b7 | 1002 | (void) poll(NULL, 0, 1); |
fc236e5e | 1003 | } |
d0ec0ed2 MD |
1004 | atfork = registered_rculfhash_atfork; |
1005 | if (atfork) | |
1006 | atfork->after_fork_parent(atfork->priv); | |
81ad2e19 PM |
1007 | call_rcu_unlock(&call_rcu_mutex); |
1008 | } | |
ce28e67a | 1009 | URCU_ATTR_ALIAS(urcu_stringify(call_rcu_after_fork_parent)) |
4477a870 | 1010 | void alias_call_rcu_after_fork_parent(); |
81ad2e19 | 1011 | |
7106ddf8 PM |
1012 | /* |
1013 | * Clean up call_rcu data structures in the child of a successful fork() | |
81ad2e19 PM |
1014 | * that is not followed by exec(). Suitable for pthread_atfork() and |
1015 | * friends. | |
7106ddf8 PM |
1016 | */ |
1017 | void call_rcu_after_fork_child(void) | |
1018 | { | |
077ff173 | 1019 | struct call_rcu_data *crdp, *next; |
d0ec0ed2 | 1020 | struct urcu_atfork *atfork; |
7106ddf8 | 1021 | |
81ad2e19 PM |
1022 | /* Release the mutex. */ |
1023 | call_rcu_unlock(&call_rcu_mutex); | |
1024 | ||
d0ec0ed2 MD |
1025 | atfork = registered_rculfhash_atfork; |
1026 | if (atfork) | |
1027 | atfork->after_fork_child(atfork->priv); | |
1028 | ||
ad1b9909 LJ |
1029 | /* Do nothing when call_rcu() has not been used */ |
1030 | if (cds_list_empty(&call_rcu_data_list)) | |
1031 | return; | |
1032 | ||
7106ddf8 PM |
1033 | /* |
1034 | * Allocate a new default call_rcu_data structure in order | |
1035 | * to get a working call_rcu thread to go with it. | |
1036 | */ | |
1037 | default_call_rcu_data = NULL; | |
1038 | (void)get_default_call_rcu_data(); | |
1039 | ||
60af049d | 1040 | /* Cleanup call_rcu_data pointers before use */ |
01730852 | 1041 | cpus_array_len_reset(); |
60af049d | 1042 | free(per_cpu_call_rcu_data); |
618b2595 | 1043 | rcu_set_pointer(&per_cpu_call_rcu_data, NULL); |
bd252a04 | 1044 | URCU_TLS(thread_call_rcu_data) = NULL; |
60af049d | 1045 | |
e85451a1 MD |
1046 | /* |
1047 | * Dispose of all of the rest of the call_rcu_data structures. | |
1048 | * Leftover call_rcu callbacks will be merged into the new | |
1049 | * default call_rcu thread queue. | |
1050 | */ | |
077ff173 | 1051 | cds_list_for_each_entry_safe(crdp, next, &call_rcu_data_list, list) { |
7106ddf8 | 1052 | if (crdp == default_call_rcu_data) |
077ff173 | 1053 | continue; |
2870aa1e | 1054 | uatomic_set(&crdp->flags, URCU_CALL_RCU_STOPPED); |
7106ddf8 | 1055 | call_rcu_data_free(crdp); |
b57aee66 PM |
1056 | } |
1057 | } | |
ce28e67a | 1058 | URCU_ATTR_ALIAS(urcu_stringify(call_rcu_after_fork_child)) |
4477a870 | 1059 | void alias_call_rcu_after_fork_child(); |
d0ec0ed2 MD |
1060 | |
1061 | void urcu_register_rculfhash_atfork(struct urcu_atfork *atfork) | |
1062 | { | |
1063 | call_rcu_lock(&call_rcu_mutex); | |
1064 | if (registered_rculfhash_atfork_refcount++) | |
1065 | goto end; | |
1066 | registered_rculfhash_atfork = atfork; | |
1067 | end: | |
1068 | call_rcu_unlock(&call_rcu_mutex); | |
1069 | } | |
ce28e67a | 1070 | URCU_ATTR_ALIAS(urcu_stringify(urcu_register_rculfhash_atfork)) |
4477a870 | 1071 | void alias_urcu_register_rculfhash_atfork(); |
d0ec0ed2 | 1072 | |
17a8f206 | 1073 | void urcu_unregister_rculfhash_atfork(struct urcu_atfork *atfork __attribute__((unused))) |
d0ec0ed2 MD |
1074 | { |
1075 | call_rcu_lock(&call_rcu_mutex); | |
1076 | if (--registered_rculfhash_atfork_refcount) | |
1077 | goto end; | |
1078 | registered_rculfhash_atfork = NULL; | |
1079 | end: | |
1080 | call_rcu_unlock(&call_rcu_mutex); | |
1081 | } | |
ce28e67a | 1082 | URCU_ATTR_ALIAS(urcu_stringify(urcu_unregister_rculfhash_atfork)) |
4477a870 | 1083 | void alias_urcu_unregister_rculfhash_atfork(); |