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" |
6b6204e4 | 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; | |
6b6204e4 | 124 | static long cpus_array_len; |
b57aee66 | 125 | |
6b6204e4 | 126 | static void cpus_array_len_reset(void) |
60af049d | 127 | { |
6b6204e4 | 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 | ||
6b6204e4 | 138 | if (cpus_array_len != 0) |
b57aee66 | 139 | return; |
6b6204e4 MJ |
140 | cpus_array_len = get_possible_cpus_array_len(); |
141 | if (cpus_array_len <= 0) { | |
b57aee66 PM |
142 | return; |
143 | } | |
6b6204e4 | 144 | p = malloc(cpus_array_len * sizeof(*per_cpu_call_rcu_data)); |
b57aee66 | 145 | if (p != NULL) { |
6b6204e4 | 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; | |
6b6204e4 | 164 | static const long cpus_array_len = -1; |
b57aee66 | 165 | |
6b6204e4 | 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 | */ | |
2388c075 | 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); | |
8e3690db | 219 | ret = sched_setaffinity(0, sizeof(mask), &mask); |
0614a2e6 | 220 | |
8e3690db MD |
221 | /* |
222 | * EINVAL is fine: can be caused by hotunplugged CPUs, or by | |
223 | * cpuset(7). This is why we should always retry if we detect | |
224 | * migration. | |
225 | */ | |
226 | if (ret && errno == EINVAL) { | |
227 | ret = 0; | |
228 | errno = 0; | |
229 | } | |
230 | return ret; | |
c1d2c60b MD |
231 | } |
232 | #else | |
233 | static | |
a142df4e | 234 | int set_thread_cpu_affinity(struct call_rcu_data *crdp __attribute__((unused))) |
c1d2c60b MD |
235 | { |
236 | return 0; | |
237 | } | |
238 | #endif | |
239 | ||
03fe58b3 MD |
240 | static void call_rcu_wait(struct call_rcu_data *crdp) |
241 | { | |
242 | /* Read call_rcu list before read futex */ | |
243 | cmm_smp_mb(); | |
4b783ba2 MD |
244 | while (uatomic_read(&crdp->futex) == -1) { |
245 | if (!futex_async(&crdp->futex, FUTEX_WAIT, -1, NULL, NULL, 0)) { | |
246 | /* | |
247 | * Prior queued wakeups queued by unrelated code | |
248 | * using the same address can cause futex wait to | |
249 | * return 0 even through the futex value is still | |
250 | * -1 (spurious wakeups). Check the value again | |
251 | * in user-space to validate whether it really | |
252 | * differs from -1. | |
253 | */ | |
254 | continue; | |
255 | } | |
b0a841b4 | 256 | switch (errno) { |
4b783ba2 | 257 | case EAGAIN: |
b0a841b4 MD |
258 | /* Value already changed. */ |
259 | return; | |
260 | case EINTR: | |
261 | /* Retry if interrupted by signal. */ | |
4b783ba2 | 262 | break; /* Get out of switch. Check again. */ |
b0a841b4 MD |
263 | default: |
264 | /* Unexpected error. */ | |
265 | urcu_die(errno); | |
266 | } | |
267 | } | |
03fe58b3 MD |
268 | } |
269 | ||
270 | static void call_rcu_wake_up(struct call_rcu_data *crdp) | |
271 | { | |
272 | /* Write to call_rcu list before reading/writing futex */ | |
273 | cmm_smp_mb(); | |
a0b7f7ea | 274 | if (caa_unlikely(uatomic_read(&crdp->futex) == -1)) { |
03fe58b3 | 275 | uatomic_set(&crdp->futex, 0); |
b0a841b4 MD |
276 | if (futex_async(&crdp->futex, FUTEX_WAKE, 1, |
277 | NULL, NULL, 0) < 0) | |
278 | urcu_die(errno); | |
03fe58b3 MD |
279 | } |
280 | } | |
281 | ||
b7f721d9 MD |
282 | static void call_rcu_completion_wait(struct call_rcu_completion *completion) |
283 | { | |
284 | /* Read completion barrier count before read futex */ | |
285 | cmm_smp_mb(); | |
4b783ba2 MD |
286 | while (uatomic_read(&completion->futex) == -1) { |
287 | if (!futex_async(&completion->futex, FUTEX_WAIT, -1, NULL, NULL, 0)) { | |
288 | /* | |
289 | * Prior queued wakeups queued by unrelated code | |
290 | * using the same address can cause futex wait to | |
291 | * return 0 even through the futex value is still | |
292 | * -1 (spurious wakeups). Check the value again | |
293 | * in user-space to validate whether it really | |
294 | * differs from -1. | |
295 | */ | |
296 | continue; | |
297 | } | |
b0a841b4 | 298 | switch (errno) { |
4b783ba2 | 299 | case EAGAIN: |
b0a841b4 MD |
300 | /* Value already changed. */ |
301 | return; | |
302 | case EINTR: | |
303 | /* Retry if interrupted by signal. */ | |
4b783ba2 | 304 | break; /* Get out of switch. Check again. */ |
b0a841b4 MD |
305 | default: |
306 | /* Unexpected error. */ | |
307 | urcu_die(errno); | |
308 | } | |
309 | } | |
b7f721d9 MD |
310 | } |
311 | ||
312 | static void call_rcu_completion_wake_up(struct call_rcu_completion *completion) | |
313 | { | |
314 | /* Write to completion barrier count before reading/writing futex */ | |
315 | cmm_smp_mb(); | |
316 | if (caa_unlikely(uatomic_read(&completion->futex) == -1)) { | |
317 | uatomic_set(&completion->futex, 0); | |
b0a841b4 MD |
318 | if (futex_async(&completion->futex, FUTEX_WAKE, 1, |
319 | NULL, NULL, 0) < 0) | |
320 | urcu_die(errno); | |
b7f721d9 MD |
321 | } |
322 | } | |
323 | ||
b57aee66 PM |
324 | /* This is the code run by each call_rcu thread. */ |
325 | ||
326 | static void *call_rcu_thread(void *arg) | |
327 | { | |
328 | unsigned long cbcount; | |
5161f31e | 329 | struct call_rcu_data *crdp = (struct call_rcu_data *) arg; |
2870aa1e | 330 | int rt = !!(uatomic_read(&crdp->flags) & URCU_CALL_RCU_RT); |
b57aee66 | 331 | |
8e3690db | 332 | if (set_thread_cpu_affinity(crdp)) |
4a6d7378 | 333 | urcu_die(errno); |
c1d2c60b | 334 | |
765f3ead MD |
335 | /* |
336 | * If callbacks take a read-side lock, we need to be registered. | |
337 | */ | |
338 | rcu_register_thread(); | |
339 | ||
bd252a04 | 340 | URCU_TLS(thread_call_rcu_data) = crdp; |
bc94ca9b MD |
341 | if (!rt) { |
342 | uatomic_dec(&crdp->futex); | |
343 | /* Decrement futex before reading call_rcu list */ | |
344 | cmm_smp_mb(); | |
345 | } | |
b57aee66 | 346 | for (;;) { |
5161f31e MD |
347 | struct cds_wfcq_head cbs_tmp_head; |
348 | struct cds_wfcq_tail cbs_tmp_tail; | |
349 | struct cds_wfcq_node *cbs, *cbs_tmp_n; | |
ae25b7e2 | 350 | enum cds_wfcq_ret splice_ret; |
5161f31e | 351 | |
8e3690db MD |
352 | if (set_thread_cpu_affinity(crdp)) |
353 | urcu_die(errno); | |
354 | ||
e85451a1 MD |
355 | if (uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSE) { |
356 | /* | |
357 | * Pause requested. Become quiescent: remove | |
358 | * ourself from all global lists, and don't | |
359 | * process any callback. The callback lists may | |
360 | * still be non-empty though. | |
361 | */ | |
362 | rcu_unregister_thread(); | |
363 | cmm_smp_mb__before_uatomic_or(); | |
364 | uatomic_or(&crdp->flags, URCU_CALL_RCU_PAUSED); | |
365 | while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSE) != 0) | |
109105b7 | 366 | (void) poll(NULL, 0, 1); |
fc236e5e KF |
367 | uatomic_and(&crdp->flags, ~URCU_CALL_RCU_PAUSED); |
368 | cmm_smp_mb__after_uatomic_and(); | |
e85451a1 MD |
369 | rcu_register_thread(); |
370 | } | |
371 | ||
5161f31e | 372 | cds_wfcq_init(&cbs_tmp_head, &cbs_tmp_tail); |
ae25b7e2 MD |
373 | splice_ret = __cds_wfcq_splice_blocking(&cbs_tmp_head, |
374 | &cbs_tmp_tail, &crdp->cbs_head, &crdp->cbs_tail); | |
375 | assert(splice_ret != CDS_WFCQ_RET_WOULDBLOCK); | |
376 | assert(splice_ret != CDS_WFCQ_RET_DEST_NON_EMPTY); | |
377 | if (splice_ret != CDS_WFCQ_RET_SRC_EMPTY) { | |
b57aee66 PM |
378 | synchronize_rcu(); |
379 | cbcount = 0; | |
5161f31e MD |
380 | __cds_wfcq_for_each_blocking_safe(&cbs_tmp_head, |
381 | &cbs_tmp_tail, cbs, cbs_tmp_n) { | |
382 | struct rcu_head *rhp; | |
383 | ||
384 | rhp = caa_container_of(cbs, | |
385 | struct rcu_head, next); | |
b57aee66 PM |
386 | rhp->func(rhp); |
387 | cbcount++; | |
5161f31e | 388 | } |
b57aee66 PM |
389 | uatomic_sub(&crdp->qlen, cbcount); |
390 | } | |
bc94ca9b MD |
391 | if (uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOP) |
392 | break; | |
765f3ead | 393 | rcu_thread_offline(); |
bc94ca9b | 394 | if (!rt) { |
5161f31e MD |
395 | if (cds_wfcq_empty(&crdp->cbs_head, |
396 | &crdp->cbs_tail)) { | |
bc94ca9b | 397 | call_rcu_wait(crdp); |
109105b7 | 398 | (void) poll(NULL, 0, 10); |
bc94ca9b | 399 | uatomic_dec(&crdp->futex); |
c768e45e | 400 | /* |
bc94ca9b MD |
401 | * Decrement futex before reading |
402 | * call_rcu list. | |
c768e45e MD |
403 | */ |
404 | cmm_smp_mb(); | |
ccbac24d | 405 | } else { |
109105b7 | 406 | (void) poll(NULL, 0, 10); |
c768e45e | 407 | } |
bc94ca9b | 408 | } else { |
109105b7 | 409 | (void) poll(NULL, 0, 10); |
b57aee66 | 410 | } |
765f3ead | 411 | rcu_thread_online(); |
bc94ca9b MD |
412 | } |
413 | if (!rt) { | |
414 | /* | |
415 | * Read call_rcu list before write futex. | |
416 | */ | |
417 | cmm_smp_mb(); | |
418 | uatomic_set(&crdp->futex, 0); | |
b57aee66 | 419 | } |
2870aa1e | 420 | uatomic_or(&crdp->flags, URCU_CALL_RCU_STOPPED); |
765f3ead | 421 | rcu_unregister_thread(); |
7106ddf8 | 422 | return NULL; |
b57aee66 PM |
423 | } |
424 | ||
425 | /* | |
426 | * Create both a call_rcu thread and the corresponding call_rcu_data | |
3c24913f PM |
427 | * structure, linking the structure in as specified. Caller must hold |
428 | * call_rcu_mutex. | |
b57aee66 PM |
429 | */ |
430 | ||
3c24913f | 431 | static void call_rcu_data_init(struct call_rcu_data **crdpp, |
c1d2c60b MD |
432 | unsigned long flags, |
433 | int cpu_affinity) | |
b57aee66 PM |
434 | { |
435 | struct call_rcu_data *crdp; | |
4a6d7378 | 436 | int ret; |
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; | |
4a6d7378 MD |
451 | ret = pthread_create(&crdp->tid, NULL, call_rcu_thread, crdp); |
452 | if (ret) | |
453 | urcu_die(ret); | |
b57aee66 PM |
454 | } |
455 | ||
456 | /* | |
457 | * Return a pointer to the call_rcu_data structure for the specified | |
458 | * CPU, returning NULL if there is none. We cannot automatically | |
459 | * created it because the platform we are running on might not define | |
63b495d8 | 460 | * urcu_sched_getcpu(). |
618b2595 MD |
461 | * |
462 | * The call to this function and use of the returned call_rcu_data | |
463 | * should be protected by RCU read-side lock. | |
b57aee66 PM |
464 | */ |
465 | ||
466 | struct call_rcu_data *get_cpu_call_rcu_data(int cpu) | |
467 | { | |
468 | static int warned = 0; | |
618b2595 | 469 | struct call_rcu_data **pcpu_crdp; |
b57aee66 | 470 | |
618b2595 MD |
471 | pcpu_crdp = rcu_dereference(per_cpu_call_rcu_data); |
472 | if (pcpu_crdp == NULL) | |
b57aee66 | 473 | return NULL; |
6b6204e4 | 474 | if (!warned && cpus_array_len > 0 && (cpu < 0 || cpus_array_len <= cpu)) { |
b57aee66 PM |
475 | fprintf(stderr, "[error] liburcu: get CPU # out of range\n"); |
476 | warned = 1; | |
477 | } | |
6b6204e4 | 478 | if (cpu < 0 || cpus_array_len <= cpu) |
b57aee66 | 479 | return NULL; |
618b2595 | 480 | return rcu_dereference(pcpu_crdp[cpu]); |
b57aee66 PM |
481 | } |
482 | ||
483 | /* | |
484 | * Return the tid corresponding to the call_rcu thread whose | |
485 | * call_rcu_data structure is specified. | |
486 | */ | |
487 | ||
488 | pthread_t get_call_rcu_thread(struct call_rcu_data *crdp) | |
489 | { | |
490 | return crdp->tid; | |
491 | } | |
492 | ||
493 | /* | |
494 | * Create a call_rcu_data structure (with thread) and return a pointer. | |
495 | */ | |
496 | ||
c1d2c60b MD |
497 | static struct call_rcu_data *__create_call_rcu_data(unsigned long flags, |
498 | int cpu_affinity) | |
b57aee66 PM |
499 | { |
500 | struct call_rcu_data *crdp; | |
501 | ||
c1d2c60b | 502 | call_rcu_data_init(&crdp, flags, cpu_affinity); |
b57aee66 PM |
503 | return crdp; |
504 | } | |
505 | ||
c1d2c60b MD |
506 | struct call_rcu_data *create_call_rcu_data(unsigned long flags, |
507 | int cpu_affinity) | |
3c24913f PM |
508 | { |
509 | struct call_rcu_data *crdp; | |
510 | ||
511 | call_rcu_lock(&call_rcu_mutex); | |
c1d2c60b | 512 | crdp = __create_call_rcu_data(flags, cpu_affinity); |
3c24913f PM |
513 | call_rcu_unlock(&call_rcu_mutex); |
514 | return crdp; | |
515 | } | |
516 | ||
b57aee66 PM |
517 | /* |
518 | * Set the specified CPU to use the specified call_rcu_data structure. | |
7106ddf8 PM |
519 | * |
520 | * Use NULL to remove a CPU's call_rcu_data structure, but it is | |
521 | * the caller's responsibility to dispose of the removed structure. | |
522 | * Use get_cpu_call_rcu_data() to obtain a pointer to the old structure | |
523 | * (prior to NULLing it out, of course). | |
f9da0936 MD |
524 | * |
525 | * The caller must wait for a grace-period to pass between return from | |
526 | * set_cpu_call_rcu_data() and call to call_rcu_data_free() passing the | |
527 | * previous call rcu data as argument. | |
b57aee66 PM |
528 | */ |
529 | ||
530 | int set_cpu_call_rcu_data(int cpu, struct call_rcu_data *crdp) | |
531 | { | |
dcfc8165 | 532 | static int warned = 0; |
b57aee66 PM |
533 | |
534 | call_rcu_lock(&call_rcu_mutex); | |
f3776786 | 535 | alloc_cpu_call_rcu_data(); |
6b6204e4 | 536 | if (cpu < 0 || cpus_array_len <= cpu) { |
b57aee66 PM |
537 | if (!warned) { |
538 | fprintf(stderr, "[error] liburcu: set CPU # out of range\n"); | |
539 | warned = 1; | |
540 | } | |
541 | call_rcu_unlock(&call_rcu_mutex); | |
542 | errno = EINVAL; | |
543 | return -EINVAL; | |
544 | } | |
53a55535 | 545 | |
b57aee66 | 546 | if (per_cpu_call_rcu_data == NULL) { |
3670fef2 | 547 | call_rcu_unlock(&call_rcu_mutex); |
b57aee66 PM |
548 | errno = ENOMEM; |
549 | return -ENOMEM; | |
550 | } | |
53a55535 LJ |
551 | |
552 | if (per_cpu_call_rcu_data[cpu] != NULL && crdp != NULL) { | |
553 | call_rcu_unlock(&call_rcu_mutex); | |
554 | errno = EEXIST; | |
555 | return -EEXIST; | |
556 | } | |
557 | ||
618b2595 | 558 | rcu_set_pointer(&per_cpu_call_rcu_data[cpu], crdp); |
3670fef2 | 559 | call_rcu_unlock(&call_rcu_mutex); |
b57aee66 PM |
560 | return 0; |
561 | } | |
562 | ||
563 | /* | |
564 | * Return a pointer to the default call_rcu_data structure, creating | |
565 | * one if need be. Because we never free call_rcu_data structures, | |
566 | * we don't need to be in an RCU read-side critical section. | |
567 | */ | |
568 | ||
569 | struct call_rcu_data *get_default_call_rcu_data(void) | |
570 | { | |
571 | if (default_call_rcu_data != NULL) | |
572 | return rcu_dereference(default_call_rcu_data); | |
573 | call_rcu_lock(&call_rcu_mutex); | |
574 | if (default_call_rcu_data != NULL) { | |
575 | call_rcu_unlock(&call_rcu_mutex); | |
576 | return default_call_rcu_data; | |
577 | } | |
c1d2c60b | 578 | call_rcu_data_init(&default_call_rcu_data, 0, -1); |
b57aee66 PM |
579 | call_rcu_unlock(&call_rcu_mutex); |
580 | return default_call_rcu_data; | |
581 | } | |
582 | ||
583 | /* | |
584 | * Return the call_rcu_data structure that applies to the currently | |
585 | * running thread. Any call_rcu_data structure assigned specifically | |
586 | * to this thread has first priority, followed by any call_rcu_data | |
587 | * structure assigned to the CPU on which the thread is running, | |
588 | * followed by the default call_rcu_data structure. If there is not | |
589 | * yet a default call_rcu_data structure, one will be created. | |
618b2595 MD |
590 | * |
591 | * Calls to this function and use of the returned call_rcu_data should | |
592 | * be protected by RCU read-side lock. | |
b57aee66 PM |
593 | */ |
594 | struct call_rcu_data *get_call_rcu_data(void) | |
595 | { | |
9744f3bb | 596 | struct call_rcu_data *crd; |
b57aee66 | 597 | |
bd252a04 MD |
598 | if (URCU_TLS(thread_call_rcu_data) != NULL) |
599 | return URCU_TLS(thread_call_rcu_data); | |
9744f3bb | 600 | |
6b6204e4 | 601 | if (cpus_array_len > 0) { |
63b495d8 | 602 | crd = get_cpu_call_rcu_data(urcu_sched_getcpu()); |
9744f3bb LJ |
603 | if (crd) |
604 | return crd; | |
b57aee66 | 605 | } |
9744f3bb | 606 | |
b57aee66 PM |
607 | return get_default_call_rcu_data(); |
608 | } | |
609 | ||
610 | /* | |
611 | * Return a pointer to this task's call_rcu_data if there is one. | |
612 | */ | |
613 | ||
614 | struct call_rcu_data *get_thread_call_rcu_data(void) | |
615 | { | |
bd252a04 | 616 | return URCU_TLS(thread_call_rcu_data); |
b57aee66 PM |
617 | } |
618 | ||
619 | /* | |
620 | * Set this task's call_rcu_data structure as specified, regardless | |
621 | * of whether or not this task already had one. (This allows switching | |
622 | * to and from real-time call_rcu threads, for example.) | |
7106ddf8 PM |
623 | * |
624 | * Use NULL to remove a thread's call_rcu_data structure, but it is | |
625 | * the caller's responsibility to dispose of the removed structure. | |
626 | * Use get_thread_call_rcu_data() to obtain a pointer to the old structure | |
627 | * (prior to NULLing it out, of course). | |
b57aee66 PM |
628 | */ |
629 | ||
630 | void set_thread_call_rcu_data(struct call_rcu_data *crdp) | |
631 | { | |
bd252a04 | 632 | URCU_TLS(thread_call_rcu_data) = crdp; |
b57aee66 PM |
633 | } |
634 | ||
635 | /* | |
636 | * Create a separate call_rcu thread for each CPU. This does not | |
637 | * replace a pre-existing call_rcu thread -- use the set_cpu_call_rcu_data() | |
0938c541 MD |
638 | * function if you want that behavior. Should be paired with |
639 | * free_all_cpu_call_rcu_data() to teardown these call_rcu worker | |
640 | * threads. | |
b57aee66 PM |
641 | */ |
642 | ||
643 | int create_all_cpu_call_rcu_data(unsigned long flags) | |
644 | { | |
645 | int i; | |
646 | struct call_rcu_data *crdp; | |
647 | int ret; | |
648 | ||
649 | call_rcu_lock(&call_rcu_mutex); | |
650 | alloc_cpu_call_rcu_data(); | |
651 | call_rcu_unlock(&call_rcu_mutex); | |
6b6204e4 | 652 | if (cpus_array_len <= 0) { |
b57aee66 PM |
653 | errno = EINVAL; |
654 | return -EINVAL; | |
655 | } | |
656 | if (per_cpu_call_rcu_data == NULL) { | |
657 | errno = ENOMEM; | |
658 | return -ENOMEM; | |
659 | } | |
6b6204e4 | 660 | for (i = 0; i < cpus_array_len; i++) { |
b57aee66 PM |
661 | call_rcu_lock(&call_rcu_mutex); |
662 | if (get_cpu_call_rcu_data(i)) { | |
663 | call_rcu_unlock(&call_rcu_mutex); | |
664 | continue; | |
665 | } | |
c1d2c60b | 666 | crdp = __create_call_rcu_data(flags, i); |
b57aee66 PM |
667 | if (crdp == NULL) { |
668 | call_rcu_unlock(&call_rcu_mutex); | |
669 | errno = ENOMEM; | |
670 | return -ENOMEM; | |
671 | } | |
672 | call_rcu_unlock(&call_rcu_mutex); | |
673 | if ((ret = set_cpu_call_rcu_data(i, crdp)) != 0) { | |
356c8794 LJ |
674 | call_rcu_data_free(crdp); |
675 | ||
676 | /* it has been created by other thread */ | |
677 | if (ret == -EEXIST) | |
678 | continue; | |
679 | ||
680 | return ret; | |
b57aee66 PM |
681 | } |
682 | } | |
683 | return 0; | |
684 | } | |
685 | ||
7106ddf8 PM |
686 | /* |
687 | * Wake up the call_rcu thread corresponding to the specified | |
688 | * call_rcu_data structure. | |
689 | */ | |
690 | static void wake_call_rcu_thread(struct call_rcu_data *crdp) | |
691 | { | |
263e3cf9 MD |
692 | if (!(_CMM_LOAD_SHARED(crdp->flags) & URCU_CALL_RCU_RT)) |
693 | call_rcu_wake_up(crdp); | |
7106ddf8 PM |
694 | } |
695 | ||
b7f721d9 MD |
696 | static void _call_rcu(struct rcu_head *head, |
697 | void (*func)(struct rcu_head *head), | |
698 | struct call_rcu_data *crdp) | |
699 | { | |
700 | cds_wfcq_node_init(&head->next); | |
701 | head->func = func; | |
702 | cds_wfcq_enqueue(&crdp->cbs_head, &crdp->cbs_tail, &head->next); | |
703 | uatomic_inc(&crdp->qlen); | |
704 | wake_call_rcu_thread(crdp); | |
705 | } | |
706 | ||
b57aee66 PM |
707 | /* |
708 | * Schedule a function to be invoked after a following grace period. | |
709 | * This is the only function that must be called -- the others are | |
710 | * only present to allow applications to tune their use of RCU for | |
711 | * maximum performance. | |
712 | * | |
713 | * Note that unless a call_rcu thread has not already been created, | |
714 | * the first invocation of call_rcu() will create one. So, if you | |
715 | * need the first invocation of call_rcu() to be fast, make sure | |
716 | * to create a call_rcu thread first. One way to accomplish this is | |
717 | * "get_call_rcu_data();", and another is create_all_cpu_call_rcu_data(). | |
618b2595 MD |
718 | * |
719 | * call_rcu must be called by registered RCU read-side threads. | |
b57aee66 | 720 | */ |
b57aee66 PM |
721 | void call_rcu(struct rcu_head *head, |
722 | void (*func)(struct rcu_head *head)) | |
723 | { | |
724 | struct call_rcu_data *crdp; | |
725 | ||
618b2595 | 726 | /* Holding rcu read-side lock across use of per-cpu crdp */ |
ffb4aaa7 | 727 | _rcu_read_lock(); |
b57aee66 | 728 | crdp = get_call_rcu_data(); |
b7f721d9 | 729 | _call_rcu(head, func, crdp); |
ffb4aaa7 | 730 | _rcu_read_unlock(); |
7106ddf8 PM |
731 | } |
732 | ||
733 | /* | |
734 | * Free up the specified call_rcu_data structure, terminating the | |
735 | * associated call_rcu thread. The caller must have previously | |
736 | * removed the call_rcu_data structure from per-thread or per-CPU | |
737 | * usage. For example, set_cpu_call_rcu_data(cpu, NULL) for per-CPU | |
738 | * call_rcu_data structures or set_thread_call_rcu_data(NULL) for | |
739 | * per-thread call_rcu_data structures. | |
740 | * | |
741 | * We silently refuse to free up the default call_rcu_data structure | |
742 | * because that is where we put any leftover callbacks. Note that | |
743 | * the possibility of self-spawning callbacks makes it impossible | |
744 | * to execute all the callbacks in finite time without putting any | |
745 | * newly spawned callbacks somewhere else. The "somewhere else" of | |
746 | * last resort is the default call_rcu_data structure. | |
747 | * | |
748 | * We also silently refuse to free NULL pointers. This simplifies | |
749 | * the calling code. | |
f9da0936 MD |
750 | * |
751 | * The caller must wait for a grace-period to pass between return from | |
752 | * set_cpu_call_rcu_data() and call to call_rcu_data_free() passing the | |
753 | * previous call rcu data as argument. | |
03e5118f MD |
754 | * |
755 | * Note: introducing __cds_wfcq_splice_blocking() in this function fixed | |
756 | * a list corruption bug in the 0.7.x series. The equivalent fix | |
757 | * appeared in 0.6.8 for the stable-0.6 branch. | |
7106ddf8 PM |
758 | */ |
759 | void call_rcu_data_free(struct call_rcu_data *crdp) | |
760 | { | |
7106ddf8 PM |
761 | if (crdp == NULL || crdp == default_call_rcu_data) { |
762 | return; | |
763 | } | |
2870aa1e PB |
764 | if ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOPPED) == 0) { |
765 | uatomic_or(&crdp->flags, URCU_CALL_RCU_STOP); | |
7106ddf8 | 766 | wake_call_rcu_thread(crdp); |
2870aa1e | 767 | while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOPPED) == 0) |
109105b7 | 768 | (void) poll(NULL, 0, 1); |
7106ddf8 | 769 | } |
51b98c3c | 770 | call_rcu_lock(&call_rcu_mutex); |
5161f31e | 771 | if (!cds_wfcq_empty(&crdp->cbs_head, &crdp->cbs_tail)) { |
51b98c3c PM |
772 | call_rcu_unlock(&call_rcu_mutex); |
773 | /* Create default call rcu data if need be. */ | |
774 | /* CBs queued here will be handed to the default list. */ | |
698d0778 | 775 | (void) get_default_call_rcu_data(); |
51b98c3c | 776 | call_rcu_lock(&call_rcu_mutex); |
5161f31e MD |
777 | __cds_wfcq_splice_blocking(&default_call_rcu_data->cbs_head, |
778 | &default_call_rcu_data->cbs_tail, | |
779 | &crdp->cbs_head, &crdp->cbs_tail); | |
7106ddf8 PM |
780 | uatomic_add(&default_call_rcu_data->qlen, |
781 | uatomic_read(&crdp->qlen)); | |
1e92aa15 | 782 | wake_call_rcu_thread(default_call_rcu_data); |
7106ddf8 | 783 | } |
59dc9e9d LJ |
784 | |
785 | cds_list_del(&crdp->list); | |
b75dffe6 LJ |
786 | call_rcu_unlock(&call_rcu_mutex); |
787 | ||
59dc9e9d | 788 | free(crdp); |
7106ddf8 PM |
789 | } |
790 | ||
791 | /* | |
792 | * Clean up all the per-CPU call_rcu threads. | |
793 | */ | |
794 | void free_all_cpu_call_rcu_data(void) | |
795 | { | |
796 | int cpu; | |
618b2595 MD |
797 | struct call_rcu_data **crdp; |
798 | static int warned = 0; | |
7106ddf8 | 799 | |
6b6204e4 | 800 | if (cpus_array_len <= 0) |
7106ddf8 | 801 | return; |
618b2595 | 802 | |
6b6204e4 | 803 | crdp = malloc(sizeof(*crdp) * cpus_array_len); |
618b2595 MD |
804 | if (!crdp) { |
805 | if (!warned) { | |
806 | fprintf(stderr, "[error] liburcu: unable to allocate per-CPU pointer array\n"); | |
807 | } | |
808 | warned = 1; | |
d31150b4 | 809 | return; |
618b2595 MD |
810 | } |
811 | ||
6b6204e4 | 812 | for (cpu = 0; cpu < cpus_array_len; cpu++) { |
618b2595 MD |
813 | crdp[cpu] = get_cpu_call_rcu_data(cpu); |
814 | if (crdp[cpu] == NULL) | |
7106ddf8 PM |
815 | continue; |
816 | set_cpu_call_rcu_data(cpu, NULL); | |
7106ddf8 | 817 | } |
618b2595 MD |
818 | /* |
819 | * Wait for call_rcu sites acting as RCU readers of the | |
820 | * call_rcu_data to become quiescent. | |
821 | */ | |
822 | synchronize_rcu(); | |
6b6204e4 | 823 | for (cpu = 0; cpu < cpus_array_len; cpu++) { |
618b2595 MD |
824 | if (crdp[cpu] == NULL) |
825 | continue; | |
826 | call_rcu_data_free(crdp[cpu]); | |
827 | } | |
828 | free(crdp); | |
7106ddf8 PM |
829 | } |
830 | ||
81dd9134 KF |
831 | static |
832 | void free_completion(struct urcu_ref *ref) | |
833 | { | |
834 | struct call_rcu_completion *completion; | |
835 | ||
836 | completion = caa_container_of(ref, struct call_rcu_completion, ref); | |
837 | free(completion); | |
838 | } | |
839 | ||
b7f721d9 MD |
840 | static |
841 | void _rcu_barrier_complete(struct rcu_head *head) | |
842 | { | |
843 | struct call_rcu_completion_work *work; | |
844 | struct call_rcu_completion *completion; | |
845 | ||
846 | work = caa_container_of(head, struct call_rcu_completion_work, head); | |
847 | completion = work->completion; | |
81dd9134 KF |
848 | if (!uatomic_sub_return(&completion->barrier_count, 1)) |
849 | call_rcu_completion_wake_up(completion); | |
850 | urcu_ref_put(&completion->ref, free_completion); | |
b7f721d9 MD |
851 | free(work); |
852 | } | |
853 | ||
854 | /* | |
855 | * Wait for all in-flight call_rcu callbacks to complete execution. | |
856 | */ | |
857 | void rcu_barrier(void) | |
858 | { | |
859 | struct call_rcu_data *crdp; | |
81dd9134 | 860 | struct call_rcu_completion *completion; |
63f0fc6d | 861 | int count = 0; |
b7f721d9 MD |
862 | int was_online; |
863 | ||
864 | /* Put in offline state in QSBR. */ | |
ffb4aaa7 | 865 | was_online = _rcu_read_ongoing(); |
b7f721d9 MD |
866 | if (was_online) |
867 | rcu_thread_offline(); | |
868 | /* | |
869 | * Calling a rcu_barrier() within a RCU read-side critical | |
870 | * section is an error. | |
871 | */ | |
ffb4aaa7 | 872 | if (_rcu_read_ongoing()) { |
b7f721d9 MD |
873 | static int warned = 0; |
874 | ||
875 | if (!warned) { | |
876 | fprintf(stderr, "[error] liburcu: rcu_barrier() called from within RCU read-side critical section.\n"); | |
877 | } | |
878 | warned = 1; | |
879 | goto online; | |
880 | } | |
881 | ||
81dd9134 KF |
882 | completion = calloc(sizeof(*completion), 1); |
883 | if (!completion) | |
884 | urcu_die(errno); | |
885 | ||
b7f721d9 MD |
886 | call_rcu_lock(&call_rcu_mutex); |
887 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) | |
888 | count++; | |
889 | ||
81dd9134 KF |
890 | /* Referenced by rcu_barrier() and each call_rcu thread. */ |
891 | urcu_ref_set(&completion->ref, count + 1); | |
892 | completion->barrier_count = count; | |
b7f721d9 MD |
893 | |
894 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) { | |
895 | struct call_rcu_completion_work *work; | |
896 | ||
897 | work = calloc(sizeof(*work), 1); | |
63f0fc6d MD |
898 | if (!work) |
899 | urcu_die(errno); | |
81dd9134 | 900 | work->completion = completion; |
b7f721d9 | 901 | _call_rcu(&work->head, _rcu_barrier_complete, crdp); |
b7f721d9 MD |
902 | } |
903 | call_rcu_unlock(&call_rcu_mutex); | |
904 | ||
b7f721d9 MD |
905 | /* Wait for them */ |
906 | for (;;) { | |
81dd9134 | 907 | uatomic_dec(&completion->futex); |
b7f721d9 MD |
908 | /* Decrement futex before reading barrier_count */ |
909 | cmm_smp_mb(); | |
81dd9134 | 910 | if (!uatomic_read(&completion->barrier_count)) |
b7f721d9 | 911 | break; |
81dd9134 | 912 | call_rcu_completion_wait(completion); |
b7f721d9 | 913 | } |
81dd9134 KF |
914 | |
915 | urcu_ref_put(&completion->ref, free_completion); | |
916 | ||
b7f721d9 MD |
917 | online: |
918 | if (was_online) | |
919 | rcu_thread_online(); | |
920 | } | |
921 | ||
81ad2e19 PM |
922 | /* |
923 | * Acquire the call_rcu_mutex in order to ensure that the child sees | |
e85451a1 MD |
924 | * all of the call_rcu() data structures in a consistent state. Ensure |
925 | * that all call_rcu threads are in a quiescent state across fork. | |
81ad2e19 PM |
926 | * Suitable for pthread_atfork() and friends. |
927 | */ | |
928 | void call_rcu_before_fork(void) | |
929 | { | |
e85451a1 | 930 | struct call_rcu_data *crdp; |
d0ec0ed2 | 931 | struct urcu_atfork *atfork; |
e85451a1 | 932 | |
81ad2e19 | 933 | call_rcu_lock(&call_rcu_mutex); |
e85451a1 | 934 | |
d0ec0ed2 MD |
935 | atfork = registered_rculfhash_atfork; |
936 | if (atfork) | |
937 | atfork->before_fork(atfork->priv); | |
938 | ||
e85451a1 MD |
939 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) { |
940 | uatomic_or(&crdp->flags, URCU_CALL_RCU_PAUSE); | |
941 | cmm_smp_mb__after_uatomic_or(); | |
942 | wake_call_rcu_thread(crdp); | |
943 | } | |
944 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) { | |
945 | while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSED) == 0) | |
109105b7 | 946 | (void) poll(NULL, 0, 1); |
e85451a1 | 947 | } |
81ad2e19 PM |
948 | } |
949 | ||
950 | /* | |
951 | * Clean up call_rcu data structures in the parent of a successful fork() | |
952 | * that is not followed by exec() in the child. Suitable for | |
953 | * pthread_atfork() and friends. | |
954 | */ | |
955 | void call_rcu_after_fork_parent(void) | |
956 | { | |
e85451a1 | 957 | struct call_rcu_data *crdp; |
d0ec0ed2 | 958 | struct urcu_atfork *atfork; |
e85451a1 MD |
959 | |
960 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) | |
961 | uatomic_and(&crdp->flags, ~URCU_CALL_RCU_PAUSE); | |
fc236e5e KF |
962 | cds_list_for_each_entry(crdp, &call_rcu_data_list, list) { |
963 | while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSED) != 0) | |
109105b7 | 964 | (void) poll(NULL, 0, 1); |
fc236e5e | 965 | } |
d0ec0ed2 MD |
966 | atfork = registered_rculfhash_atfork; |
967 | if (atfork) | |
968 | atfork->after_fork_parent(atfork->priv); | |
81ad2e19 PM |
969 | call_rcu_unlock(&call_rcu_mutex); |
970 | } | |
971 | ||
7106ddf8 PM |
972 | /* |
973 | * Clean up call_rcu data structures in the child of a successful fork() | |
81ad2e19 PM |
974 | * that is not followed by exec(). Suitable for pthread_atfork() and |
975 | * friends. | |
7106ddf8 PM |
976 | */ |
977 | void call_rcu_after_fork_child(void) | |
978 | { | |
077ff173 | 979 | struct call_rcu_data *crdp, *next; |
d0ec0ed2 | 980 | struct urcu_atfork *atfork; |
7106ddf8 | 981 | |
81ad2e19 PM |
982 | /* Release the mutex. */ |
983 | call_rcu_unlock(&call_rcu_mutex); | |
984 | ||
d0ec0ed2 MD |
985 | atfork = registered_rculfhash_atfork; |
986 | if (atfork) | |
987 | atfork->after_fork_child(atfork->priv); | |
988 | ||
ad1b9909 LJ |
989 | /* Do nothing when call_rcu() has not been used */ |
990 | if (cds_list_empty(&call_rcu_data_list)) | |
991 | return; | |
992 | ||
7106ddf8 PM |
993 | /* |
994 | * Allocate a new default call_rcu_data structure in order | |
995 | * to get a working call_rcu thread to go with it. | |
996 | */ | |
997 | default_call_rcu_data = NULL; | |
998 | (void)get_default_call_rcu_data(); | |
999 | ||
60af049d | 1000 | /* Cleanup call_rcu_data pointers before use */ |
6b6204e4 | 1001 | cpus_array_len_reset(); |
60af049d | 1002 | free(per_cpu_call_rcu_data); |
618b2595 | 1003 | rcu_set_pointer(&per_cpu_call_rcu_data, NULL); |
bd252a04 | 1004 | URCU_TLS(thread_call_rcu_data) = NULL; |
60af049d | 1005 | |
e85451a1 MD |
1006 | /* |
1007 | * Dispose of all of the rest of the call_rcu_data structures. | |
1008 | * Leftover call_rcu callbacks will be merged into the new | |
1009 | * default call_rcu thread queue. | |
1010 | */ | |
077ff173 | 1011 | cds_list_for_each_entry_safe(crdp, next, &call_rcu_data_list, list) { |
7106ddf8 | 1012 | if (crdp == default_call_rcu_data) |
077ff173 | 1013 | continue; |
2870aa1e | 1014 | uatomic_set(&crdp->flags, URCU_CALL_RCU_STOPPED); |
7106ddf8 | 1015 | call_rcu_data_free(crdp); |
b57aee66 PM |
1016 | } |
1017 | } | |
d0ec0ed2 MD |
1018 | |
1019 | void urcu_register_rculfhash_atfork(struct urcu_atfork *atfork) | |
1020 | { | |
1021 | call_rcu_lock(&call_rcu_mutex); | |
1022 | if (registered_rculfhash_atfork_refcount++) | |
1023 | goto end; | |
1024 | registered_rculfhash_atfork = atfork; | |
1025 | end: | |
1026 | call_rcu_unlock(&call_rcu_mutex); | |
1027 | } | |
1028 | ||
70469b43 | 1029 | void urcu_unregister_rculfhash_atfork(struct urcu_atfork *atfork __attribute__((unused))) |
d0ec0ed2 MD |
1030 | { |
1031 | call_rcu_lock(&call_rcu_mutex); | |
1032 | if (--registered_rculfhash_atfork_refcount) | |
1033 | goto end; | |
1034 | registered_rculfhash_atfork = NULL; | |
1035 | end: | |
1036 | call_rcu_unlock(&call_rcu_mutex); | |
1037 | } |