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> | |
b57aee66 | 27 | #include <stdlib.h> |
6d841bc2 | 28 | #include <stdint.h> |
b57aee66 PM |
29 | #include <string.h> |
30 | #include <errno.h> | |
31 | #include <poll.h> | |
32 | #include <sys/time.h> | |
b57aee66 | 33 | #include <unistd.h> |
c1d2c60b | 34 | #include <sched.h> |
b57aee66 | 35 | |
a47dd11c | 36 | #include "compat-getcpu.h" |
01477510 | 37 | #include <urcu/assert.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" |
5cfe81b7 | 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 | 104 | static struct urcu_atfork *registered_rculfhash_atfork; |
d0ec0ed2 | 105 | |
b57aee66 PM |
106 | /* |
107 | * If the sched_getcpu() and sysconf(_SC_NPROCESSORS_CONF) calls are | |
108 | * available, then we can have call_rcu threads assigned to individual | |
109 | * CPUs rather than only to specific threads. | |
110 | */ | |
111 | ||
a47dd11c | 112 | #if defined(HAVE_SYSCONF) && (defined(HAVE_SCHED_GETCPU) || defined(HAVE_GETCPUID)) |
b57aee66 PM |
113 | |
114 | /* | |
115 | * Pointer to array of pointers to per-CPU call_rcu_data structures | |
618b2595 MD |
116 | * and # CPUs. per_cpu_call_rcu_data is a RCU-protected pointer to an |
117 | * array of RCU-protected pointers to call_rcu_data. call_rcu acts as a | |
118 | * RCU read-side and reads per_cpu_call_rcu_data and the per-cpu pointer | |
119 | * without mutex. The call_rcu_mutex protects updates. | |
b57aee66 PM |
120 | */ |
121 | ||
122 | static struct call_rcu_data **per_cpu_call_rcu_data; | |
5cfe81b7 | 123 | static long cpus_array_len; |
b57aee66 | 124 | |
5cfe81b7 | 125 | static void cpus_array_len_reset(void) |
60af049d | 126 | { |
5cfe81b7 | 127 | cpus_array_len = 0; |
60af049d LJ |
128 | } |
129 | ||
b57aee66 PM |
130 | /* Allocate the array if it has not already been allocated. */ |
131 | ||
132 | static void alloc_cpu_call_rcu_data(void) | |
133 | { | |
134 | struct call_rcu_data **p; | |
135 | static int warned = 0; | |
136 | ||
5cfe81b7 | 137 | if (cpus_array_len != 0) |
b57aee66 | 138 | return; |
5cfe81b7 MJ |
139 | cpus_array_len = get_possible_cpus_array_len(); |
140 | if (cpus_array_len <= 0) { | |
b57aee66 PM |
141 | return; |
142 | } | |
5cfe81b7 | 143 | p = malloc(cpus_array_len * sizeof(*per_cpu_call_rcu_data)); |
b57aee66 | 144 | if (p != NULL) { |
5cfe81b7 | 145 | memset(p, '\0', cpus_array_len * sizeof(*per_cpu_call_rcu_data)); |
618b2595 | 146 | rcu_set_pointer(&per_cpu_call_rcu_data, p); |
b57aee66 PM |
147 | } else { |
148 | if (!warned) { | |
149 | fprintf(stderr, "[error] liburcu: unable to allocate per-CPU pointer array\n"); | |
150 | } | |
151 | warned = 1; | |
152 | } | |
153 | } | |
154 | ||
63b495d8 | 155 | #else /* #if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU) */ |
b57aee66 | 156 | |
f9437098 MD |
157 | /* |
158 | * per_cpu_call_rcu_data should be constant, but some functions below, used both | |
159 | * for cases where cpu number is available and not available, assume it it not | |
160 | * constant. | |
161 | */ | |
162 | static struct call_rcu_data **per_cpu_call_rcu_data = NULL; | |
5cfe81b7 | 163 | static const long cpus_array_len = -1; |
b57aee66 | 164 | |
5cfe81b7 | 165 | static void cpus_array_len_reset(void) |
60af049d LJ |
166 | { |
167 | } | |
168 | ||
b57aee66 PM |
169 | static void alloc_cpu_call_rcu_data(void) |
170 | { | |
171 | } | |
172 | ||
63b495d8 | 173 | #endif /* #else #if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU) */ |
b57aee66 PM |
174 | |
175 | /* Acquire the specified pthread mutex. */ | |
176 | ||
177 | static void call_rcu_lock(pthread_mutex_t *pmp) | |
178 | { | |
4a6d7378 MD |
179 | int ret; |
180 | ||
181 | ret = pthread_mutex_lock(pmp); | |
182 | if (ret) | |
183 | urcu_die(ret); | |
b57aee66 PM |
184 | } |
185 | ||
186 | /* Release the specified pthread mutex. */ | |
187 | ||
188 | static void call_rcu_unlock(pthread_mutex_t *pmp) | |
189 | { | |
4a6d7378 MD |
190 | int ret; |
191 | ||
192 | ret = pthread_mutex_unlock(pmp); | |
193 | if (ret) | |
194 | urcu_die(ret); | |
b57aee66 PM |
195 | } |
196 | ||
8e3690db MD |
197 | /* |
198 | * Periodically retry setting CPU affinity if we migrate. | |
199 | * Losing affinity can be caused by CPU hotunplug/hotplug, or by | |
200 | * cpuset(7). | |
201 | */ | |
2388c075 | 202 | #ifdef HAVE_SCHED_SETAFFINITY |
c1d2c60b MD |
203 | static |
204 | int set_thread_cpu_affinity(struct call_rcu_data *crdp) | |
205 | { | |
206 | cpu_set_t mask; | |
8e3690db | 207 | int ret; |
c1d2c60b MD |
208 | |
209 | if (crdp->cpu_affinity < 0) | |
210 | return 0; | |
8e3690db MD |
211 | if (++crdp->gp_count & SET_AFFINITY_CHECK_PERIOD_MASK) |
212 | return 0; | |
213 | if (urcu_sched_getcpu() == crdp->cpu_affinity) | |
214 | return 0; | |
c1d2c60b MD |
215 | |
216 | CPU_ZERO(&mask); | |
217 | CPU_SET(crdp->cpu_affinity, &mask); | |
8e3690db | 218 | ret = sched_setaffinity(0, sizeof(mask), &mask); |
0614a2e6 | 219 | |
8e3690db MD |
220 | /* |
221 | * EINVAL is fine: can be caused by hotunplugged CPUs, or by | |
222 | * cpuset(7). This is why we should always retry if we detect | |
223 | * migration. | |
224 | */ | |
225 | if (ret && errno == EINVAL) { | |
226 | ret = 0; | |
227 | errno = 0; | |
228 | } | |
229 | return ret; | |
c1d2c60b MD |
230 | } |
231 | #else | |
232 | static | |
a142df4e | 233 | int set_thread_cpu_affinity(struct call_rcu_data *crdp __attribute__((unused))) |
c1d2c60b MD |
234 | { |
235 | return 0; | |
236 | } | |
237 | #endif | |
238 | ||
03fe58b3 MD |
239 | static void call_rcu_wait(struct call_rcu_data *crdp) |
240 | { | |
241 | /* Read call_rcu list before read futex */ | |
242 | cmm_smp_mb(); | |
98d705dd MD |
243 | while (uatomic_read(&crdp->futex) == -1) { |
244 | if (!futex_async(&crdp->futex, FUTEX_WAIT, -1, NULL, NULL, 0)) { | |
245 | /* | |
246 | * Prior queued wakeups queued by unrelated code | |
247 | * using the same address can cause futex wait to | |
248 | * return 0 even through the futex value is still | |
249 | * -1 (spurious wakeups). Check the value again | |
250 | * in user-space to validate whether it really | |
251 | * differs from -1. | |
252 | */ | |
253 | continue; | |
254 | } | |
b0a841b4 | 255 | switch (errno) { |
98d705dd | 256 | case EAGAIN: |
b0a841b4 MD |
257 | /* Value already changed. */ |
258 | return; | |
259 | case EINTR: | |
260 | /* Retry if interrupted by signal. */ | |
98d705dd | 261 | break; /* Get out of switch. Check again. */ |
b0a841b4 MD |
262 | default: |
263 | /* Unexpected error. */ | |
264 | urcu_die(errno); | |
265 | } | |
266 | } | |
03fe58b3 MD |
267 | } |
268 | ||
269 | static void call_rcu_wake_up(struct call_rcu_data *crdp) | |
270 | { | |
271 | /* Write to call_rcu list before reading/writing futex */ | |
272 | cmm_smp_mb(); | |
a0b7f7ea | 273 | if (caa_unlikely(uatomic_read(&crdp->futex) == -1)) { |
03fe58b3 | 274 | uatomic_set(&crdp->futex, 0); |
b0a841b4 MD |
275 | if (futex_async(&crdp->futex, FUTEX_WAKE, 1, |
276 | NULL, NULL, 0) < 0) | |
277 | urcu_die(errno); | |
03fe58b3 MD |
278 | } |
279 | } | |
280 | ||
b7f721d9 MD |
281 | static void call_rcu_completion_wait(struct call_rcu_completion *completion) |
282 | { | |
283 | /* Read completion barrier count before read futex */ | |
284 | cmm_smp_mb(); | |
98d705dd MD |
285 | while (uatomic_read(&completion->futex) == -1) { |
286 | if (!futex_async(&completion->futex, FUTEX_WAIT, -1, NULL, NULL, 0)) { | |
287 | /* | |
288 | * Prior queued wakeups queued by unrelated code | |
289 | * using the same address can cause futex wait to | |
290 | * return 0 even through the futex value is still | |
291 | * -1 (spurious wakeups). Check the value again | |
292 | * in user-space to validate whether it really | |
293 | * differs from -1. | |
294 | */ | |
295 | continue; | |
296 | } | |
b0a841b4 | 297 | switch (errno) { |
98d705dd | 298 | case EAGAIN: |
b0a841b4 MD |
299 | /* Value already changed. */ |
300 | return; | |
301 | case EINTR: | |
302 | /* Retry if interrupted by signal. */ | |
98d705dd | 303 | break; /* Get out of switch. Check again. */ |
b0a841b4 MD |
304 | default: |
305 | /* Unexpected error. */ | |
306 | urcu_die(errno); | |
307 | } | |
308 | } | |
b7f721d9 MD |
309 | } |
310 | ||
311 | static void call_rcu_completion_wake_up(struct call_rcu_completion *completion) | |
312 | { | |
313 | /* Write to completion barrier count before reading/writing futex */ | |
314 | cmm_smp_mb(); | |
315 | if (caa_unlikely(uatomic_read(&completion->futex) == -1)) { | |
316 | uatomic_set(&completion->futex, 0); | |
b0a841b4 MD |
317 | if (futex_async(&completion->futex, FUTEX_WAKE, 1, |
318 | NULL, NULL, 0) < 0) | |
319 | urcu_die(errno); | |
b7f721d9 MD |
320 | } |
321 | } | |
322 | ||
b57aee66 PM |
323 | /* This is the code run by each call_rcu thread. */ |
324 | ||
325 | static void *call_rcu_thread(void *arg) | |
326 | { | |
327 | unsigned long cbcount; | |
5161f31e | 328 | struct call_rcu_data *crdp = (struct call_rcu_data *) arg; |
2870aa1e | 329 | int rt = !!(uatomic_read(&crdp->flags) & URCU_CALL_RCU_RT); |
b57aee66 | 330 | |
8e3690db | 331 | if (set_thread_cpu_affinity(crdp)) |
4a6d7378 | 332 | urcu_die(errno); |
c1d2c60b | 333 | |
765f3ead MD |
334 | /* |
335 | * If callbacks take a read-side lock, we need to be registered. | |
336 | */ | |
337 | rcu_register_thread(); | |
338 | ||
bd252a04 | 339 | URCU_TLS(thread_call_rcu_data) = crdp; |
bc94ca9b MD |
340 | if (!rt) { |
341 | uatomic_dec(&crdp->futex); | |
342 | /* Decrement futex before reading call_rcu list */ | |
343 | cmm_smp_mb(); | |
344 | } | |
b57aee66 | 345 | for (;;) { |
5161f31e MD |
346 | struct cds_wfcq_head cbs_tmp_head; |
347 | struct cds_wfcq_tail cbs_tmp_tail; | |
348 | struct cds_wfcq_node *cbs, *cbs_tmp_n; | |
ae25b7e2 | 349 | enum cds_wfcq_ret splice_ret; |
5161f31e | 350 | |
8e3690db MD |
351 | if (set_thread_cpu_affinity(crdp)) |
352 | urcu_die(errno); | |
353 | ||
e85451a1 MD |
354 | if (uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSE) { |
355 | /* | |
356 | * Pause requested. Become quiescent: remove | |
357 | * ourself from all global lists, and don't | |
358 | * process any callback. The callback lists may | |
359 | * still be non-empty though. | |
360 | */ | |
361 | rcu_unregister_thread(); | |
362 | cmm_smp_mb__before_uatomic_or(); | |
363 | uatomic_or(&crdp->flags, URCU_CALL_RCU_PAUSED); | |
364 | while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSE) != 0) | |
109105b7 | 365 | (void) poll(NULL, 0, 1); |
fc236e5e KF |
366 | uatomic_and(&crdp->flags, ~URCU_CALL_RCU_PAUSED); |
367 | cmm_smp_mb__after_uatomic_and(); | |
e85451a1 MD |
368 | rcu_register_thread(); |
369 | } | |
370 | ||
5161f31e | 371 | cds_wfcq_init(&cbs_tmp_head, &cbs_tmp_tail); |
ae25b7e2 MD |
372 | splice_ret = __cds_wfcq_splice_blocking(&cbs_tmp_head, |
373 | &cbs_tmp_tail, &crdp->cbs_head, &crdp->cbs_tail); | |
01477510 FD |
374 | urcu_posix_assert(splice_ret != CDS_WFCQ_RET_WOULDBLOCK); |
375 | urcu_posix_assert(splice_ret != CDS_WFCQ_RET_DEST_NON_EMPTY); | |
ae25b7e2 | 376 | if (splice_ret != CDS_WFCQ_RET_SRC_EMPTY) { |
b57aee66 PM |
377 | synchronize_rcu(); |
378 | cbcount = 0; | |
5161f31e MD |
379 | __cds_wfcq_for_each_blocking_safe(&cbs_tmp_head, |
380 | &cbs_tmp_tail, cbs, cbs_tmp_n) { | |
381 | struct rcu_head *rhp; | |
382 | ||
383 | rhp = caa_container_of(cbs, | |
384 | struct rcu_head, next); | |
b57aee66 PM |
385 | rhp->func(rhp); |
386 | cbcount++; | |
5161f31e | 387 | } |
b57aee66 PM |
388 | uatomic_sub(&crdp->qlen, cbcount); |
389 | } | |
bc94ca9b MD |
390 | if (uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOP) |
391 | break; | |
765f3ead | 392 | rcu_thread_offline(); |
bc94ca9b | 393 | if (!rt) { |
5161f31e MD |
394 | if (cds_wfcq_empty(&crdp->cbs_head, |
395 | &crdp->cbs_tail)) { | |
bc94ca9b | 396 | call_rcu_wait(crdp); |
109105b7 | 397 | (void) poll(NULL, 0, 10); |
bc94ca9b | 398 | uatomic_dec(&crdp->futex); |
c768e45e | 399 | /* |
bc94ca9b MD |
400 | * Decrement futex before reading |
401 | * call_rcu list. | |
c768e45e MD |
402 | */ |
403 | cmm_smp_mb(); | |
ccbac24d | 404 | } else { |
109105b7 | 405 | (void) poll(NULL, 0, 10); |
c768e45e | 406 | } |
bc94ca9b | 407 | } else { |
109105b7 | 408 | (void) poll(NULL, 0, 10); |
b57aee66 | 409 | } |
765f3ead | 410 | rcu_thread_online(); |
bc94ca9b MD |
411 | } |
412 | if (!rt) { | |
413 | /* | |
414 | * Read call_rcu list before write futex. | |
415 | */ | |
416 | cmm_smp_mb(); | |
417 | uatomic_set(&crdp->futex, 0); | |
b57aee66 | 418 | } |
2870aa1e | 419 | uatomic_or(&crdp->flags, URCU_CALL_RCU_STOPPED); |
765f3ead | 420 | rcu_unregister_thread(); |
7106ddf8 | 421 | return NULL; |
b57aee66 PM |
422 | } |
423 | ||
424 | /* | |
425 | * Create both a call_rcu thread and the corresponding call_rcu_data | |
3c24913f PM |
426 | * structure, linking the structure in as specified. Caller must hold |
427 | * call_rcu_mutex. | |
b57aee66 PM |
428 | */ |
429 | ||
3c24913f | 430 | static void call_rcu_data_init(struct call_rcu_data **crdpp, |
c1d2c60b MD |
431 | unsigned long flags, |
432 | int cpu_affinity) | |
b57aee66 PM |
433 | { |
434 | struct call_rcu_data *crdp; | |
4a6d7378 | 435 | int ret; |
ea3a28a3 | 436 | sigset_t newmask, oldmask; |
b57aee66 PM |
437 | |
438 | crdp = malloc(sizeof(*crdp)); | |
4a6d7378 MD |
439 | if (crdp == NULL) |
440 | urcu_die(errno); | |
b57aee66 | 441 | memset(crdp, '\0', sizeof(*crdp)); |
5161f31e | 442 | cds_wfcq_init(&crdp->cbs_head, &crdp->cbs_tail); |
b57aee66 | 443 | crdp->qlen = 0; |
263e3cf9 MD |
444 | crdp->futex = 0; |
445 | crdp->flags = flags; | |
3c24913f | 446 | cds_list_add(&crdp->list, &call_rcu_data_list); |
c1d2c60b | 447 | crdp->cpu_affinity = cpu_affinity; |
8e3690db | 448 | crdp->gp_count = 0; |
b57aee66 PM |
449 | cmm_smp_mb(); /* Structure initialized before pointer is planted. */ |
450 | *crdpp = crdp; | |
ea3a28a3 MD |
451 | |
452 | ret = sigfillset(&newmask); | |
453 | urcu_posix_assert(!ret); | |
454 | ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask); | |
455 | urcu_posix_assert(!ret); | |
456 | ||
4a6d7378 MD |
457 | ret = pthread_create(&crdp->tid, NULL, call_rcu_thread, crdp); |
458 | if (ret) | |
459 | urcu_die(ret); | |
ea3a28a3 MD |
460 | |
461 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); | |
462 | urcu_posix_assert(!ret); | |
b57aee66 PM |
463 | } |
464 | ||
465 | /* | |
466 | * Return a pointer to the call_rcu_data structure for the specified | |
467 | * CPU, returning NULL if there is none. We cannot automatically | |
468 | * created it because the platform we are running on might not define | |
63b495d8 | 469 | * urcu_sched_getcpu(). |
618b2595 MD |
470 | * |
471 | * The call to this function and use of the returned call_rcu_data | |
472 | * should be protected by RCU read-side lock. | |
b57aee66 PM |
473 | */ |
474 | ||
475 | struct call_rcu_data *get_cpu_call_rcu_data(int cpu) | |
476 | { | |
477 | static int warned = 0; | |
618b2595 | 478 | struct call_rcu_data **pcpu_crdp; |
b57aee66 | 479 | |
618b2595 MD |
480 | pcpu_crdp = rcu_dereference(per_cpu_call_rcu_data); |
481 | if (pcpu_crdp == NULL) | |
b57aee66 | 482 | return NULL; |
5cfe81b7 | 483 | if (!warned && cpus_array_len > 0 && (cpu < 0 || cpus_array_len <= cpu)) { |
b57aee66 PM |
484 | fprintf(stderr, "[error] liburcu: get CPU # out of range\n"); |
485 | warned = 1; | |
486 | } | |
5cfe81b7 | 487 | if (cpu < 0 || cpus_array_len <= cpu) |
b57aee66 | 488 | return NULL; |
618b2595 | 489 | return rcu_dereference(pcpu_crdp[cpu]); |
b57aee66 PM |
490 | } |
491 | ||
492 | /* | |
493 | * Return the tid corresponding to the call_rcu thread whose | |
494 | * call_rcu_data structure is specified. | |
495 | */ | |
496 | ||
497 | pthread_t get_call_rcu_thread(struct call_rcu_data *crdp) | |
498 | { | |
499 | return crdp->tid; | |
500 | } | |
501 | ||
502 | /* | |
503 | * Create a call_rcu_data structure (with thread) and return a pointer. | |
504 | */ | |
505 | ||
c1d2c60b MD |
506 | static struct call_rcu_data *__create_call_rcu_data(unsigned long flags, |
507 | int cpu_affinity) | |
b57aee66 PM |
508 | { |
509 | struct call_rcu_data *crdp; | |
510 | ||
c1d2c60b | 511 | call_rcu_data_init(&crdp, flags, cpu_affinity); |
b57aee66 PM |
512 | return crdp; |
513 | } | |
514 | ||
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(); |
5cfe81b7 | 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 | } | |
571 | ||
572 | /* | |
573 | * Return a pointer to the default call_rcu_data structure, creating | |
574 | * one if need be. Because we never free call_rcu_data structures, | |
575 | * we don't need to be in an RCU read-side critical section. | |
576 | */ | |
577 | ||
578 | struct call_rcu_data *get_default_call_rcu_data(void) | |
579 | { | |
580 | if (default_call_rcu_data != NULL) | |
581 | return rcu_dereference(default_call_rcu_data); | |
582 | call_rcu_lock(&call_rcu_mutex); | |
583 | if (default_call_rcu_data != NULL) { | |
584 | call_rcu_unlock(&call_rcu_mutex); | |
585 | return default_call_rcu_data; | |
586 | } | |
c1d2c60b | 587 | call_rcu_data_init(&default_call_rcu_data, 0, -1); |
b57aee66 PM |
588 | call_rcu_unlock(&call_rcu_mutex); |
589 | return default_call_rcu_data; | |
590 | } | |
591 | ||
592 | /* | |
593 | * Return the call_rcu_data structure that applies to the currently | |
594 | * running thread. Any call_rcu_data structure assigned specifically | |
595 | * to this thread has first priority, followed by any call_rcu_data | |
596 | * structure assigned to the CPU on which the thread is running, | |
597 | * followed by the default call_rcu_data structure. If there is not | |
598 | * yet a default call_rcu_data structure, one will be created. | |
618b2595 MD |
599 | * |
600 | * Calls to this function and use of the returned call_rcu_data should | |
601 | * be protected by RCU read-side lock. | |
b57aee66 PM |
602 | */ |
603 | struct call_rcu_data *get_call_rcu_data(void) | |
604 | { | |
9744f3bb | 605 | struct call_rcu_data *crd; |
b57aee66 | 606 | |
bd252a04 MD |
607 | if (URCU_TLS(thread_call_rcu_data) != NULL) |
608 | return URCU_TLS(thread_call_rcu_data); | |
9744f3bb | 609 | |
5cfe81b7 | 610 | if (cpus_array_len > 0) { |
63b495d8 | 611 | crd = get_cpu_call_rcu_data(urcu_sched_getcpu()); |
9744f3bb LJ |
612 | if (crd) |
613 | return crd; | |
b57aee66 | 614 | } |
9744f3bb | 615 | |
b57aee66 PM |
616 | return get_default_call_rcu_data(); |
617 | } | |
618 | ||
619 | /* | |
620 | * Return a pointer to this task's call_rcu_data if there is one. | |
621 | */ | |
622 | ||
623 | struct call_rcu_data *get_thread_call_rcu_data(void) | |
624 | { | |
bd252a04 | 625 | return URCU_TLS(thread_call_rcu_data); |
b57aee66 PM |
626 | } |
627 | ||
628 | /* | |
629 | * Set this task's call_rcu_data structure as specified, regardless | |
630 | * of whether or not this task already had one. (This allows switching | |
631 | * to and from real-time call_rcu threads, for example.) | |
7106ddf8 PM |
632 | * |
633 | * Use NULL to remove a thread's call_rcu_data structure, but it is | |
634 | * the caller's responsibility to dispose of the removed structure. | |
635 | * Use get_thread_call_rcu_data() to obtain a pointer to the old structure | |
636 | * (prior to NULLing it out, of course). | |
b57aee66 PM |
637 | */ |
638 | ||
639 | void set_thread_call_rcu_data(struct call_rcu_data *crdp) | |
640 | { | |
bd252a04 | 641 | URCU_TLS(thread_call_rcu_data) = crdp; |
b57aee66 PM |
642 | } |
643 | ||
644 | /* | |
645 | * Create a separate call_rcu thread for each CPU. This does not | |
646 | * replace a pre-existing call_rcu thread -- use the set_cpu_call_rcu_data() | |
0938c541 MD |
647 | * function if you want that behavior. Should be paired with |
648 | * free_all_cpu_call_rcu_data() to teardown these call_rcu worker | |
649 | * threads. | |
b57aee66 PM |
650 | */ |
651 | ||
652 | int create_all_cpu_call_rcu_data(unsigned long flags) | |
653 | { | |
654 | int i; | |
655 | struct call_rcu_data *crdp; | |
656 | int ret; | |
657 | ||
658 | call_rcu_lock(&call_rcu_mutex); | |
659 | alloc_cpu_call_rcu_data(); | |
660 | call_rcu_unlock(&call_rcu_mutex); | |
5cfe81b7 | 661 | if (cpus_array_len <= 0) { |
b57aee66 PM |
662 | errno = EINVAL; |
663 | return -EINVAL; | |
664 | } | |
665 | if (per_cpu_call_rcu_data == NULL) { | |
666 | errno = ENOMEM; | |
667 | return -ENOMEM; | |
668 | } | |
5cfe81b7 | 669 | for (i = 0; i < cpus_array_len; i++) { |
b57aee66 PM |
670 | call_rcu_lock(&call_rcu_mutex); |
671 | if (get_cpu_call_rcu_data(i)) { | |
672 | call_rcu_unlock(&call_rcu_mutex); | |
673 | continue; | |
674 | } | |
c1d2c60b | 675 | crdp = __create_call_rcu_data(flags, i); |
b57aee66 PM |
676 | if (crdp == NULL) { |
677 | call_rcu_unlock(&call_rcu_mutex); | |
678 | errno = ENOMEM; | |
679 | return -ENOMEM; | |
680 | } | |
681 | call_rcu_unlock(&call_rcu_mutex); | |
682 | if ((ret = set_cpu_call_rcu_data(i, crdp)) != 0) { | |
356c8794 LJ |
683 | call_rcu_data_free(crdp); |
684 | ||
685 | /* it has been created by other thread */ | |
686 | if (ret == -EEXIST) | |
687 | continue; | |
688 | ||
689 | return ret; | |
b57aee66 PM |
690 | } |
691 | } | |
692 | return 0; | |
693 | } | |
694 | ||
7106ddf8 PM |
695 | /* |
696 | * Wake up the call_rcu thread corresponding to the specified | |
697 | * call_rcu_data structure. | |
698 | */ | |
699 | static void wake_call_rcu_thread(struct call_rcu_data *crdp) | |
700 | { | |
263e3cf9 MD |
701 | if (!(_CMM_LOAD_SHARED(crdp->flags) & URCU_CALL_RCU_RT)) |
702 | call_rcu_wake_up(crdp); | |
7106ddf8 PM |
703 | } |
704 | ||
b7f721d9 MD |
705 | static void _call_rcu(struct rcu_head *head, |
706 | void (*func)(struct rcu_head *head), | |
707 | struct call_rcu_data *crdp) | |
708 | { | |
709 | cds_wfcq_node_init(&head->next); | |
710 | head->func = func; | |
711 | cds_wfcq_enqueue(&crdp->cbs_head, &crdp->cbs_tail, &head->next); | |
712 | uatomic_inc(&crdp->qlen); | |
713 | wake_call_rcu_thread(crdp); | |
714 | } | |
715 | ||
b57aee66 PM |
716 | /* |
717 | * Schedule a function to be invoked after a following grace period. | |
718 | * This is the only function that must be called -- the others are | |
719 | * only present to allow applications to tune their use of RCU for | |
720 | * maximum performance. | |
721 | * | |
722 | * Note that unless a call_rcu thread has not already been created, | |
723 | * the first invocation of call_rcu() will create one. So, if you | |
724 | * need the first invocation of call_rcu() to be fast, make sure | |
725 | * to create a call_rcu thread first. One way to accomplish this is | |
726 | * "get_call_rcu_data();", and another is create_all_cpu_call_rcu_data(). | |
618b2595 MD |
727 | * |
728 | * call_rcu must be called by registered RCU read-side threads. | |
b57aee66 | 729 | */ |
b57aee66 PM |
730 | void call_rcu(struct rcu_head *head, |
731 | void (*func)(struct rcu_head *head)) | |
732 | { | |
733 | struct call_rcu_data *crdp; | |
734 | ||
618b2595 | 735 | /* Holding rcu read-side lock across use of per-cpu crdp */ |
ffb4aaa7 | 736 | _rcu_read_lock(); |
b57aee66 | 737 | crdp = get_call_rcu_data(); |
b7f721d9 | 738 | _call_rcu(head, func, crdp); |
ffb4aaa7 | 739 | _rcu_read_unlock(); |
7106ddf8 PM |
740 | } |
741 | ||
742 | /* | |
743 | * Free up the specified call_rcu_data structure, terminating the | |
744 | * associated call_rcu thread. The caller must have previously | |
745 | * removed the call_rcu_data structure from per-thread or per-CPU | |
746 | * usage. For example, set_cpu_call_rcu_data(cpu, NULL) for per-CPU | |
747 | * call_rcu_data structures or set_thread_call_rcu_data(NULL) for | |
748 | * per-thread call_rcu_data structures. | |
749 | * | |
750 | * We silently refuse to free up the default call_rcu_data structure | |
751 | * because that is where we put any leftover callbacks. Note that | |
752 | * the possibility of self-spawning callbacks makes it impossible | |
753 | * to execute all the callbacks in finite time without putting any | |
754 | * newly spawned callbacks somewhere else. The "somewhere else" of | |
755 | * last resort is the default call_rcu_data structure. | |
756 | * | |
757 | * We also silently refuse to free NULL pointers. This simplifies | |
758 | * the calling code. | |
f9da0936 MD |
759 | * |
760 | * The caller must wait for a grace-period to pass between return from | |
761 | * set_cpu_call_rcu_data() and call to call_rcu_data_free() passing the | |
762 | * previous call rcu data as argument. | |
03e5118f MD |
763 | * |
764 | * Note: introducing __cds_wfcq_splice_blocking() in this function fixed | |
765 | * a list corruption bug in the 0.7.x series. The equivalent fix | |
766 | * appeared in 0.6.8 for the stable-0.6 branch. | |
7106ddf8 PM |
767 | */ |
768 | void call_rcu_data_free(struct call_rcu_data *crdp) | |
769 | { | |
7106ddf8 PM |
770 | if (crdp == NULL || crdp == default_call_rcu_data) { |
771 | return; | |
772 | } | |
2870aa1e PB |
773 | if ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOPPED) == 0) { |
774 | uatomic_or(&crdp->flags, URCU_CALL_RCU_STOP); | |
7106ddf8 | 775 | wake_call_rcu_thread(crdp); |
2870aa1e | 776 | while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOPPED) == 0) |
109105b7 | 777 | (void) poll(NULL, 0, 1); |
7106ddf8 | 778 | } |
51b98c3c | 779 | call_rcu_lock(&call_rcu_mutex); |
5161f31e | 780 | if (!cds_wfcq_empty(&crdp->cbs_head, &crdp->cbs_tail)) { |
51b98c3c PM |
781 | call_rcu_unlock(&call_rcu_mutex); |
782 | /* Create default call rcu data if need be. */ | |
783 | /* CBs queued here will be handed to the default list. */ | |
698d0778 | 784 | (void) get_default_call_rcu_data(); |
51b98c3c | 785 | call_rcu_lock(&call_rcu_mutex); |
5161f31e MD |
786 | __cds_wfcq_splice_blocking(&default_call_rcu_data->cbs_head, |
787 | &default_call_rcu_data->cbs_tail, | |
788 | &crdp->cbs_head, &crdp->cbs_tail); | |
7106ddf8 PM |
789 | uatomic_add(&default_call_rcu_data->qlen, |
790 | uatomic_read(&crdp->qlen)); | |
1e92aa15 | 791 | wake_call_rcu_thread(default_call_rcu_data); |
7106ddf8 | 792 | } |
59dc9e9d LJ |
793 | |
794 | cds_list_del(&crdp->list); | |
b75dffe6 LJ |
795 | call_rcu_unlock(&call_rcu_mutex); |
796 | ||
59dc9e9d | 797 | free(crdp); |
7106ddf8 PM |
798 | } |
799 | ||
800 | /* | |
801 | * Clean up all the per-CPU call_rcu threads. | |
802 | */ | |
803 | void free_all_cpu_call_rcu_data(void) | |
804 | { | |
805 | int cpu; | |
618b2595 MD |
806 | struct call_rcu_data **crdp; |
807 | static int warned = 0; | |
7106ddf8 | 808 | |
5cfe81b7 | 809 | if (cpus_array_len <= 0) |
7106ddf8 | 810 | return; |
618b2595 | 811 | |
5cfe81b7 | 812 | crdp = malloc(sizeof(*crdp) * cpus_array_len); |
618b2595 MD |
813 | if (!crdp) { |
814 | if (!warned) { | |
815 | fprintf(stderr, "[error] liburcu: unable to allocate per-CPU pointer array\n"); | |
816 | } | |
817 | warned = 1; | |
d31150b4 | 818 | return; |
618b2595 MD |
819 | } |
820 | ||
5cfe81b7 | 821 | for (cpu = 0; cpu < cpus_array_len; cpu++) { |
618b2595 MD |
822 | crdp[cpu] = get_cpu_call_rcu_data(cpu); |
823 | if (crdp[cpu] == NULL) | |
7106ddf8 PM |
824 | continue; |
825 | set_cpu_call_rcu_data(cpu, NULL); | |
7106ddf8 | 826 | } |
618b2595 MD |
827 | /* |
828 | * Wait for call_rcu sites acting as RCU readers of the | |
829 | * call_rcu_data to become quiescent. | |
830 | */ | |
831 | synchronize_rcu(); | |
5cfe81b7 | 832 | for (cpu = 0; cpu < cpus_array_len; cpu++) { |
618b2595 MD |
833 | if (crdp[cpu] == NULL) |
834 | continue; | |
835 | call_rcu_data_free(crdp[cpu]); | |
836 | } | |
837 | free(crdp); | |
7106ddf8 PM |
838 | } |
839 | ||
81dd9134 KF |
840 | static |
841 | void free_completion(struct urcu_ref *ref) | |
842 | { | |
843 | struct call_rcu_completion *completion; | |
844 | ||
845 | completion = caa_container_of(ref, struct call_rcu_completion, ref); | |
846 | free(completion); | |
847 | } | |
848 | ||
b7f721d9 MD |
849 | static |
850 | void _rcu_barrier_complete(struct rcu_head *head) | |
851 | { | |
852 | struct call_rcu_completion_work *work; | |
853 | struct call_rcu_completion *completion; | |
854 | ||
855 | work = caa_container_of(head, struct call_rcu_completion_work, head); | |
856 | completion = work->completion; | |
81dd9134 KF |
857 | if (!uatomic_sub_return(&completion->barrier_count, 1)) |
858 | call_rcu_completion_wake_up(completion); | |
859 | urcu_ref_put(&completion->ref, free_completion); | |
b7f721d9 MD |
860 | free(work); |
861 | } | |
862 | ||
863 | /* | |
864 | * Wait for all in-flight call_rcu callbacks to complete execution. | |
865 | */ | |
866 | void rcu_barrier(void) | |
867 | { | |
868 | struct call_rcu_data *crdp; | |
81dd9134 | 869 | struct call_rcu_completion *completion; |
63f0fc6d | 870 | int count = 0; |
b7f721d9 MD |
871 | int was_online; |
872 | ||
873 | /* Put in offline state in QSBR. */ | |
ffb4aaa7 | 874 | was_online = _rcu_read_ongoing(); |
b7f721d9 MD |
875 | if (was_online) |
876 | rcu_thread_offline(); | |
877 | /* | |
878 | * Calling a rcu_barrier() within a RCU read-side critical | |
879 | * section is an error. | |
880 | */ | |
ffb4aaa7 | 881 | if (_rcu_read_ongoing()) { |
b7f721d9 MD |
882 | static int warned = 0; |
883 | ||
884 | if (!warned) { | |
885 | fprintf(stderr, "[error] liburcu: rcu_barrier() called from within RCU read-side critical section.\n"); | |
886 | } | |
887 | warned = 1; | |
888 | goto online; | |
889 | } | |
890 | ||
81dd9134 KF |
891 | completion = calloc(sizeof(*completion), 1); |
892 | if (!completion) | |
893 | urcu_die(errno); | |
894 | ||
b7f721d9 MD |
895 | call_rcu_lock(&call_rcu_mutex); |
896 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) | |
897 | count++; | |
898 | ||
81dd9134 KF |
899 | /* Referenced by rcu_barrier() and each call_rcu thread. */ |
900 | urcu_ref_set(&completion->ref, count + 1); | |
901 | completion->barrier_count = count; | |
b7f721d9 MD |
902 | |
903 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) { | |
904 | struct call_rcu_completion_work *work; | |
905 | ||
906 | work = calloc(sizeof(*work), 1); | |
63f0fc6d MD |
907 | if (!work) |
908 | urcu_die(errno); | |
81dd9134 | 909 | work->completion = completion; |
b7f721d9 | 910 | _call_rcu(&work->head, _rcu_barrier_complete, crdp); |
b7f721d9 MD |
911 | } |
912 | call_rcu_unlock(&call_rcu_mutex); | |
913 | ||
b7f721d9 MD |
914 | /* Wait for them */ |
915 | for (;;) { | |
81dd9134 | 916 | uatomic_dec(&completion->futex); |
b7f721d9 MD |
917 | /* Decrement futex before reading barrier_count */ |
918 | cmm_smp_mb(); | |
81dd9134 | 919 | if (!uatomic_read(&completion->barrier_count)) |
b7f721d9 | 920 | break; |
81dd9134 | 921 | call_rcu_completion_wait(completion); |
b7f721d9 | 922 | } |
81dd9134 KF |
923 | |
924 | urcu_ref_put(&completion->ref, free_completion); | |
925 | ||
b7f721d9 MD |
926 | online: |
927 | if (was_online) | |
928 | rcu_thread_online(); | |
929 | } | |
930 | ||
81ad2e19 PM |
931 | /* |
932 | * Acquire the call_rcu_mutex in order to ensure that the child sees | |
e85451a1 MD |
933 | * all of the call_rcu() data structures in a consistent state. Ensure |
934 | * that all call_rcu threads are in a quiescent state across fork. | |
81ad2e19 PM |
935 | * Suitable for pthread_atfork() and friends. |
936 | */ | |
937 | void call_rcu_before_fork(void) | |
938 | { | |
e85451a1 | 939 | struct call_rcu_data *crdp; |
d0ec0ed2 | 940 | struct urcu_atfork *atfork; |
e85451a1 | 941 | |
81ad2e19 | 942 | call_rcu_lock(&call_rcu_mutex); |
e85451a1 | 943 | |
d0ec0ed2 MD |
944 | atfork = registered_rculfhash_atfork; |
945 | if (atfork) | |
946 | atfork->before_fork(atfork->priv); | |
947 | ||
e85451a1 MD |
948 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) { |
949 | uatomic_or(&crdp->flags, URCU_CALL_RCU_PAUSE); | |
950 | cmm_smp_mb__after_uatomic_or(); | |
951 | wake_call_rcu_thread(crdp); | |
952 | } | |
953 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) { | |
954 | while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSED) == 0) | |
109105b7 | 955 | (void) poll(NULL, 0, 1); |
e85451a1 | 956 | } |
81ad2e19 PM |
957 | } |
958 | ||
959 | /* | |
960 | * Clean up call_rcu data structures in the parent of a successful fork() | |
961 | * that is not followed by exec() in the child. Suitable for | |
962 | * pthread_atfork() and friends. | |
963 | */ | |
964 | void call_rcu_after_fork_parent(void) | |
965 | { | |
e85451a1 | 966 | struct call_rcu_data *crdp; |
d0ec0ed2 | 967 | struct urcu_atfork *atfork; |
e85451a1 MD |
968 | |
969 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) | |
970 | uatomic_and(&crdp->flags, ~URCU_CALL_RCU_PAUSE); | |
fc236e5e KF |
971 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) { |
972 | while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSED) != 0) | |
109105b7 | 973 | (void) poll(NULL, 0, 1); |
fc236e5e | 974 | } |
d0ec0ed2 MD |
975 | atfork = registered_rculfhash_atfork; |
976 | if (atfork) | |
977 | atfork->after_fork_parent(atfork->priv); | |
81ad2e19 PM |
978 | call_rcu_unlock(&call_rcu_mutex); |
979 | } | |
980 | ||
7106ddf8 PM |
981 | /* |
982 | * Clean up call_rcu data structures in the child of a successful fork() | |
81ad2e19 PM |
983 | * that is not followed by exec(). Suitable for pthread_atfork() and |
984 | * friends. | |
7106ddf8 PM |
985 | */ |
986 | void call_rcu_after_fork_child(void) | |
987 | { | |
077ff173 | 988 | struct call_rcu_data *crdp, *next; |
d0ec0ed2 | 989 | struct urcu_atfork *atfork; |
7106ddf8 | 990 | |
81ad2e19 PM |
991 | /* Release the mutex. */ |
992 | call_rcu_unlock(&call_rcu_mutex); | |
993 | ||
d0ec0ed2 MD |
994 | atfork = registered_rculfhash_atfork; |
995 | if (atfork) | |
996 | atfork->after_fork_child(atfork->priv); | |
997 | ||
ad1b9909 LJ |
998 | /* Do nothing when call_rcu() has not been used */ |
999 | if (cds_list_empty(&call_rcu_data_list)) | |
1000 | return; | |
1001 | ||
7106ddf8 PM |
1002 | /* |
1003 | * Allocate a new default call_rcu_data structure in order | |
1004 | * to get a working call_rcu thread to go with it. | |
1005 | */ | |
1006 | default_call_rcu_data = NULL; | |
1007 | (void)get_default_call_rcu_data(); | |
1008 | ||
60af049d | 1009 | /* Cleanup call_rcu_data pointers before use */ |
5cfe81b7 | 1010 | cpus_array_len_reset(); |
60af049d | 1011 | free(per_cpu_call_rcu_data); |
618b2595 | 1012 | rcu_set_pointer(&per_cpu_call_rcu_data, NULL); |
bd252a04 | 1013 | URCU_TLS(thread_call_rcu_data) = NULL; |
60af049d | 1014 | |
e85451a1 MD |
1015 | /* |
1016 | * Dispose of all of the rest of the call_rcu_data structures. | |
1017 | * Leftover call_rcu callbacks will be merged into the new | |
1018 | * default call_rcu thread queue. | |
1019 | */ | |
077ff173 | 1020 | cds_list_for_each_entry_safe(crdp, next, &call_rcu_data_list, list) { |
7106ddf8 | 1021 | if (crdp == default_call_rcu_data) |
077ff173 | 1022 | continue; |
2870aa1e | 1023 | uatomic_set(&crdp->flags, URCU_CALL_RCU_STOPPED); |
7106ddf8 | 1024 | call_rcu_data_free(crdp); |
b57aee66 PM |
1025 | } |
1026 | } | |
d0ec0ed2 MD |
1027 | |
1028 | void urcu_register_rculfhash_atfork(struct urcu_atfork *atfork) | |
1029 | { | |
b047e7a7 MD |
1030 | if (CMM_LOAD_SHARED(registered_rculfhash_atfork)) |
1031 | return; | |
d0ec0ed2 | 1032 | call_rcu_lock(&call_rcu_mutex); |
b047e7a7 MD |
1033 | if (!registered_rculfhash_atfork) |
1034 | registered_rculfhash_atfork = atfork; | |
d0ec0ed2 MD |
1035 | call_rcu_unlock(&call_rcu_mutex); |
1036 | } | |
1037 | ||
b047e7a7 MD |
1038 | /* |
1039 | * This unregistration function is deprecated, meant only for internal | |
1040 | * use by rculfhash. | |
1041 | */ | |
1042 | __attribute__((noreturn)) | |
70469b43 | 1043 | void urcu_unregister_rculfhash_atfork(struct urcu_atfork *atfork __attribute__((unused))) |
d0ec0ed2 | 1044 | { |
b047e7a7 | 1045 | urcu_die(EPERM); |
d0ec0ed2 | 1046 | } |