test: fork handling
[urcu.git] / urcu-call-rcu-impl.h
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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
c1d2c60b 23#define _GNU_SOURCE
5161f31e 24#define _LGPL_SOURCE
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25#include <stdio.h>
26#include <pthread.h>
27#include <signal.h>
28#include <assert.h>
29#include <stdlib.h>
6d841bc2 30#include <stdint.h>
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31#include <string.h>
32#include <errno.h>
33#include <poll.h>
34#include <sys/time.h>
b57aee66 35#include <unistd.h>
c1d2c60b 36#include <sched.h>
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37
38#include "config.h"
5161f31e 39#include "urcu/wfcqueue.h"
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40#include "urcu-call-rcu.h"
41#include "urcu-pointer.h"
3c24913f 42#include "urcu/list.h"
41849996 43#include "urcu/futex.h"
bd252a04 44#include "urcu/tls-compat.h"
4a6d7378 45#include "urcu-die.h"
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46
47/* Data structure that identifies a call_rcu thread. */
48
49struct call_rcu_data {
5161f31e 50 /*
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51 * We do not align head on a different cache-line than tail
52 * mainly because call_rcu callback-invocation threads use
53 * batching ("splice") to get an entire list of callbacks, which
54 * effectively empties the queue, and requires to touch the tail
55 * anyway.
5161f31e 56 */
b9f893b6 57 struct cds_wfcq_tail cbs_tail;
0b8ab7df 58 struct cds_wfcq_head cbs_head;
b57aee66 59 unsigned long flags;
6d841bc2 60 int32_t futex;
73987721 61 unsigned long qlen; /* maintained for debugging. */
b57aee66 62 pthread_t tid;
c1d2c60b 63 int cpu_affinity;
3c24913f 64 struct cds_list_head list;
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65} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
66
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67/*
68 * List of all call_rcu_data structures to keep valgrind happy.
69 * Protected by call_rcu_mutex.
70 */
71
bab44e28 72static CDS_LIST_HEAD(call_rcu_data_list);
3c24913f 73
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74/* Link a thread using call_rcu() to its call_rcu thread. */
75
bd252a04 76static DEFINE_URCU_TLS(struct call_rcu_data *, thread_call_rcu_data);
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77
78/* Guard call_rcu thread creation. */
79
80static pthread_mutex_t call_rcu_mutex = PTHREAD_MUTEX_INITIALIZER;
81
82/* If a given thread does not have its own call_rcu thread, this is default. */
83
84static struct call_rcu_data *default_call_rcu_data;
85
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86/*
87 * If the sched_getcpu() and sysconf(_SC_NPROCESSORS_CONF) calls are
88 * available, then we can have call_rcu threads assigned to individual
89 * CPUs rather than only to specific threads.
90 */
91
92#if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF)
93
94/*
95 * Pointer to array of pointers to per-CPU call_rcu_data structures
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96 * and # CPUs. per_cpu_call_rcu_data is a RCU-protected pointer to an
97 * array of RCU-protected pointers to call_rcu_data. call_rcu acts as a
98 * RCU read-side and reads per_cpu_call_rcu_data and the per-cpu pointer
99 * without mutex. The call_rcu_mutex protects updates.
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100 */
101
102static struct call_rcu_data **per_cpu_call_rcu_data;
103static long maxcpus;
104
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105static void maxcpus_reset(void)
106{
107 maxcpus = 0;
108}
109
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110/* Allocate the array if it has not already been allocated. */
111
112static void alloc_cpu_call_rcu_data(void)
113{
114 struct call_rcu_data **p;
115 static int warned = 0;
116
117 if (maxcpus != 0)
118 return;
119 maxcpus = sysconf(_SC_NPROCESSORS_CONF);
120 if (maxcpus <= 0) {
121 return;
122 }
123 p = malloc(maxcpus * sizeof(*per_cpu_call_rcu_data));
124 if (p != NULL) {
125 memset(p, '\0', maxcpus * sizeof(*per_cpu_call_rcu_data));
618b2595 126 rcu_set_pointer(&per_cpu_call_rcu_data, p);
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127 } else {
128 if (!warned) {
129 fprintf(stderr, "[error] liburcu: unable to allocate per-CPU pointer array\n");
130 }
131 warned = 1;
132 }
133}
134
135#else /* #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) */
136
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137/*
138 * per_cpu_call_rcu_data should be constant, but some functions below, used both
139 * for cases where cpu number is available and not available, assume it it not
140 * constant.
141 */
142static struct call_rcu_data **per_cpu_call_rcu_data = NULL;
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143static const long maxcpus = -1;
144
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145static void maxcpus_reset(void)
146{
147}
148
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149static void alloc_cpu_call_rcu_data(void)
150{
151}
152
153static int sched_getcpu(void)
154{
155 return -1;
156}
157
158#endif /* #else #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) */
159
160/* Acquire the specified pthread mutex. */
161
162static void call_rcu_lock(pthread_mutex_t *pmp)
163{
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164 int ret;
165
166 ret = pthread_mutex_lock(pmp);
167 if (ret)
168 urcu_die(ret);
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169}
170
171/* Release the specified pthread mutex. */
172
173static void call_rcu_unlock(pthread_mutex_t *pmp)
174{
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175 int ret;
176
177 ret = pthread_mutex_unlock(pmp);
178 if (ret)
179 urcu_die(ret);
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180}
181
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182#if HAVE_SCHED_SETAFFINITY
183static
184int set_thread_cpu_affinity(struct call_rcu_data *crdp)
185{
186 cpu_set_t mask;
187
188 if (crdp->cpu_affinity < 0)
189 return 0;
190
191 CPU_ZERO(&mask);
192 CPU_SET(crdp->cpu_affinity, &mask);
193#if SCHED_SETAFFINITY_ARGS == 2
194 return sched_setaffinity(0, &mask);
195#else
196 return sched_setaffinity(0, sizeof(mask), &mask);
197#endif
198}
199#else
200static
201int set_thread_cpu_affinity(struct call_rcu_data *crdp)
202{
203 return 0;
204}
205#endif
206
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207static void call_rcu_wait(struct call_rcu_data *crdp)
208{
209 /* Read call_rcu list before read futex */
210 cmm_smp_mb();
211 if (uatomic_read(&crdp->futex) == -1)
212 futex_async(&crdp->futex, FUTEX_WAIT, -1,
213 NULL, NULL, 0);
214}
215
216static void call_rcu_wake_up(struct call_rcu_data *crdp)
217{
218 /* Write to call_rcu list before reading/writing futex */
219 cmm_smp_mb();
a0b7f7ea 220 if (caa_unlikely(uatomic_read(&crdp->futex) == -1)) {
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221 uatomic_set(&crdp->futex, 0);
222 futex_async(&crdp->futex, FUTEX_WAKE, 1,
223 NULL, NULL, 0);
224 }
225}
226
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227/* This is the code run by each call_rcu thread. */
228
229static void *call_rcu_thread(void *arg)
230{
231 unsigned long cbcount;
5161f31e 232 struct call_rcu_data *crdp = (struct call_rcu_data *) arg;
2870aa1e 233 int rt = !!(uatomic_read(&crdp->flags) & URCU_CALL_RCU_RT);
4a6d7378 234 int ret;
b57aee66 235
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236 ret = set_thread_cpu_affinity(crdp);
237 if (ret)
238 urcu_die(errno);
c1d2c60b 239
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240 /*
241 * If callbacks take a read-side lock, we need to be registered.
242 */
243 rcu_register_thread();
244
bd252a04 245 URCU_TLS(thread_call_rcu_data) = crdp;
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246 if (!rt) {
247 uatomic_dec(&crdp->futex);
248 /* Decrement futex before reading call_rcu list */
249 cmm_smp_mb();
250 }
b57aee66 251 for (;;) {
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252 struct cds_wfcq_head cbs_tmp_head;
253 struct cds_wfcq_tail cbs_tmp_tail;
254 struct cds_wfcq_node *cbs, *cbs_tmp_n;
ae25b7e2 255 enum cds_wfcq_ret splice_ret;
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256
257 cds_wfcq_init(&cbs_tmp_head, &cbs_tmp_tail);
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258 splice_ret = __cds_wfcq_splice_blocking(&cbs_tmp_head,
259 &cbs_tmp_tail, &crdp->cbs_head, &crdp->cbs_tail);
260 assert(splice_ret != CDS_WFCQ_RET_WOULDBLOCK);
261 assert(splice_ret != CDS_WFCQ_RET_DEST_NON_EMPTY);
262 if (splice_ret != CDS_WFCQ_RET_SRC_EMPTY) {
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263 synchronize_rcu();
264 cbcount = 0;
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265 __cds_wfcq_for_each_blocking_safe(&cbs_tmp_head,
266 &cbs_tmp_tail, cbs, cbs_tmp_n) {
267 struct rcu_head *rhp;
268
269 rhp = caa_container_of(cbs,
270 struct rcu_head, next);
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271 rhp->func(rhp);
272 cbcount++;
5161f31e 273 }
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274 uatomic_sub(&crdp->qlen, cbcount);
275 }
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276 if (uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOP)
277 break;
765f3ead 278 rcu_thread_offline();
bc94ca9b 279 if (!rt) {
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280 if (cds_wfcq_empty(&crdp->cbs_head,
281 &crdp->cbs_tail)) {
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282 call_rcu_wait(crdp);
283 poll(NULL, 0, 10);
284 uatomic_dec(&crdp->futex);
c768e45e 285 /*
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286 * Decrement futex before reading
287 * call_rcu list.
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288 */
289 cmm_smp_mb();
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290 } else {
291 poll(NULL, 0, 10);
c768e45e 292 }
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293 } else {
294 poll(NULL, 0, 10);
b57aee66 295 }
765f3ead 296 rcu_thread_online();
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297 }
298 if (!rt) {
299 /*
300 * Read call_rcu list before write futex.
301 */
302 cmm_smp_mb();
303 uatomic_set(&crdp->futex, 0);
b57aee66 304 }
2870aa1e 305 uatomic_or(&crdp->flags, URCU_CALL_RCU_STOPPED);
765f3ead 306 rcu_unregister_thread();
7106ddf8 307 return NULL;
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308}
309
310/*
311 * Create both a call_rcu thread and the corresponding call_rcu_data
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312 * structure, linking the structure in as specified. Caller must hold
313 * call_rcu_mutex.
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314 */
315
3c24913f 316static void call_rcu_data_init(struct call_rcu_data **crdpp,
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317 unsigned long flags,
318 int cpu_affinity)
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319{
320 struct call_rcu_data *crdp;
4a6d7378 321 int ret;
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322
323 crdp = malloc(sizeof(*crdp));
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324 if (crdp == NULL)
325 urcu_die(errno);
b57aee66 326 memset(crdp, '\0', sizeof(*crdp));
5161f31e 327 cds_wfcq_init(&crdp->cbs_head, &crdp->cbs_tail);
b57aee66 328 crdp->qlen = 0;
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329 crdp->futex = 0;
330 crdp->flags = flags;
3c24913f 331 cds_list_add(&crdp->list, &call_rcu_data_list);
c1d2c60b 332 crdp->cpu_affinity = cpu_affinity;
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333 cmm_smp_mb(); /* Structure initialized before pointer is planted. */
334 *crdpp = crdp;
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335 ret = pthread_create(&crdp->tid, NULL, call_rcu_thread, crdp);
336 if (ret)
337 urcu_die(ret);
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338}
339
340/*
341 * Return a pointer to the call_rcu_data structure for the specified
342 * CPU, returning NULL if there is none. We cannot automatically
343 * created it because the platform we are running on might not define
344 * sched_getcpu().
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345 *
346 * The call to this function and use of the returned call_rcu_data
347 * should be protected by RCU read-side lock.
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348 */
349
350struct call_rcu_data *get_cpu_call_rcu_data(int cpu)
351{
352 static int warned = 0;
618b2595 353 struct call_rcu_data **pcpu_crdp;
b57aee66 354
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355 pcpu_crdp = rcu_dereference(per_cpu_call_rcu_data);
356 if (pcpu_crdp == NULL)
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357 return NULL;
358 if (!warned && maxcpus > 0 && (cpu < 0 || maxcpus <= cpu)) {
359 fprintf(stderr, "[error] liburcu: get CPU # out of range\n");
360 warned = 1;
361 }
362 if (cpu < 0 || maxcpus <= cpu)
363 return NULL;
618b2595 364 return rcu_dereference(pcpu_crdp[cpu]);
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365}
366
367/*
368 * Return the tid corresponding to the call_rcu thread whose
369 * call_rcu_data structure is specified.
370 */
371
372pthread_t get_call_rcu_thread(struct call_rcu_data *crdp)
373{
374 return crdp->tid;
375}
376
377/*
378 * Create a call_rcu_data structure (with thread) and return a pointer.
379 */
380
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381static struct call_rcu_data *__create_call_rcu_data(unsigned long flags,
382 int cpu_affinity)
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383{
384 struct call_rcu_data *crdp;
385
c1d2c60b 386 call_rcu_data_init(&crdp, flags, cpu_affinity);
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387 return crdp;
388}
389
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390struct call_rcu_data *create_call_rcu_data(unsigned long flags,
391 int cpu_affinity)
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392{
393 struct call_rcu_data *crdp;
394
395 call_rcu_lock(&call_rcu_mutex);
c1d2c60b 396 crdp = __create_call_rcu_data(flags, cpu_affinity);
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397 call_rcu_unlock(&call_rcu_mutex);
398 return crdp;
399}
400
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401/*
402 * Set the specified CPU to use the specified call_rcu_data structure.
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403 *
404 * Use NULL to remove a CPU's call_rcu_data structure, but it is
405 * the caller's responsibility to dispose of the removed structure.
406 * Use get_cpu_call_rcu_data() to obtain a pointer to the old structure
407 * (prior to NULLing it out, of course).
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408 *
409 * The caller must wait for a grace-period to pass between return from
410 * set_cpu_call_rcu_data() and call to call_rcu_data_free() passing the
411 * previous call rcu data as argument.
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412 */
413
414int set_cpu_call_rcu_data(int cpu, struct call_rcu_data *crdp)
415{
dcfc8165 416 static int warned = 0;
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417
418 call_rcu_lock(&call_rcu_mutex);
f3776786 419 alloc_cpu_call_rcu_data();
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420 if (cpu < 0 || maxcpus <= cpu) {
421 if (!warned) {
422 fprintf(stderr, "[error] liburcu: set CPU # out of range\n");
423 warned = 1;
424 }
425 call_rcu_unlock(&call_rcu_mutex);
426 errno = EINVAL;
427 return -EINVAL;
428 }
53a55535 429
b57aee66 430 if (per_cpu_call_rcu_data == NULL) {
3670fef2 431 call_rcu_unlock(&call_rcu_mutex);
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432 errno = ENOMEM;
433 return -ENOMEM;
434 }
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435
436 if (per_cpu_call_rcu_data[cpu] != NULL && crdp != NULL) {
437 call_rcu_unlock(&call_rcu_mutex);
438 errno = EEXIST;
439 return -EEXIST;
440 }
441
618b2595 442 rcu_set_pointer(&per_cpu_call_rcu_data[cpu], crdp);
3670fef2 443 call_rcu_unlock(&call_rcu_mutex);
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444 return 0;
445}
446
447/*
448 * Return a pointer to the default call_rcu_data structure, creating
449 * one if need be. Because we never free call_rcu_data structures,
450 * we don't need to be in an RCU read-side critical section.
451 */
452
453struct call_rcu_data *get_default_call_rcu_data(void)
454{
455 if (default_call_rcu_data != NULL)
456 return rcu_dereference(default_call_rcu_data);
457 call_rcu_lock(&call_rcu_mutex);
458 if (default_call_rcu_data != NULL) {
459 call_rcu_unlock(&call_rcu_mutex);
460 return default_call_rcu_data;
461 }
c1d2c60b 462 call_rcu_data_init(&default_call_rcu_data, 0, -1);
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463 call_rcu_unlock(&call_rcu_mutex);
464 return default_call_rcu_data;
465}
466
467/*
468 * Return the call_rcu_data structure that applies to the currently
469 * running thread. Any call_rcu_data structure assigned specifically
470 * to this thread has first priority, followed by any call_rcu_data
471 * structure assigned to the CPU on which the thread is running,
472 * followed by the default call_rcu_data structure. If there is not
473 * yet a default call_rcu_data structure, one will be created.
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474 *
475 * Calls to this function and use of the returned call_rcu_data should
476 * be protected by RCU read-side lock.
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477 */
478struct call_rcu_data *get_call_rcu_data(void)
479{
9744f3bb 480 struct call_rcu_data *crd;
b57aee66 481
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482 if (URCU_TLS(thread_call_rcu_data) != NULL)
483 return URCU_TLS(thread_call_rcu_data);
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484
485 if (maxcpus > 0) {
486 crd = get_cpu_call_rcu_data(sched_getcpu());
487 if (crd)
488 return crd;
b57aee66 489 }
9744f3bb 490
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491 return get_default_call_rcu_data();
492}
493
494/*
495 * Return a pointer to this task's call_rcu_data if there is one.
496 */
497
498struct call_rcu_data *get_thread_call_rcu_data(void)
499{
bd252a04 500 return URCU_TLS(thread_call_rcu_data);
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501}
502
503/*
504 * Set this task's call_rcu_data structure as specified, regardless
505 * of whether or not this task already had one. (This allows switching
506 * to and from real-time call_rcu threads, for example.)
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507 *
508 * Use NULL to remove a thread's call_rcu_data structure, but it is
509 * the caller's responsibility to dispose of the removed structure.
510 * Use get_thread_call_rcu_data() to obtain a pointer to the old structure
511 * (prior to NULLing it out, of course).
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512 */
513
514void set_thread_call_rcu_data(struct call_rcu_data *crdp)
515{
bd252a04 516 URCU_TLS(thread_call_rcu_data) = crdp;
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517}
518
519/*
520 * Create a separate call_rcu thread for each CPU. This does not
521 * replace a pre-existing call_rcu thread -- use the set_cpu_call_rcu_data()
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522 * function if you want that behavior. Should be paired with
523 * free_all_cpu_call_rcu_data() to teardown these call_rcu worker
524 * threads.
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525 */
526
527int create_all_cpu_call_rcu_data(unsigned long flags)
528{
529 int i;
530 struct call_rcu_data *crdp;
531 int ret;
532
533 call_rcu_lock(&call_rcu_mutex);
534 alloc_cpu_call_rcu_data();
535 call_rcu_unlock(&call_rcu_mutex);
536 if (maxcpus <= 0) {
537 errno = EINVAL;
538 return -EINVAL;
539 }
540 if (per_cpu_call_rcu_data == NULL) {
541 errno = ENOMEM;
542 return -ENOMEM;
543 }
544 for (i = 0; i < maxcpus; i++) {
545 call_rcu_lock(&call_rcu_mutex);
546 if (get_cpu_call_rcu_data(i)) {
547 call_rcu_unlock(&call_rcu_mutex);
548 continue;
549 }
c1d2c60b 550 crdp = __create_call_rcu_data(flags, i);
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551 if (crdp == NULL) {
552 call_rcu_unlock(&call_rcu_mutex);
553 errno = ENOMEM;
554 return -ENOMEM;
555 }
556 call_rcu_unlock(&call_rcu_mutex);
557 if ((ret = set_cpu_call_rcu_data(i, crdp)) != 0) {
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558 call_rcu_data_free(crdp);
559
560 /* it has been created by other thread */
561 if (ret == -EEXIST)
562 continue;
563
564 return ret;
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565 }
566 }
567 return 0;
568}
569
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570/*
571 * Wake up the call_rcu thread corresponding to the specified
572 * call_rcu_data structure.
573 */
574static void wake_call_rcu_thread(struct call_rcu_data *crdp)
575{
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576 if (!(_CMM_LOAD_SHARED(crdp->flags) & URCU_CALL_RCU_RT))
577 call_rcu_wake_up(crdp);
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578}
579
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580/*
581 * Schedule a function to be invoked after a following grace period.
582 * This is the only function that must be called -- the others are
583 * only present to allow applications to tune their use of RCU for
584 * maximum performance.
585 *
586 * Note that unless a call_rcu thread has not already been created,
587 * the first invocation of call_rcu() will create one. So, if you
588 * need the first invocation of call_rcu() to be fast, make sure
589 * to create a call_rcu thread first. One way to accomplish this is
590 * "get_call_rcu_data();", and another is create_all_cpu_call_rcu_data().
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591 *
592 * call_rcu must be called by registered RCU read-side threads.
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593 */
594
595void call_rcu(struct rcu_head *head,
596 void (*func)(struct rcu_head *head))
597{
598 struct call_rcu_data *crdp;
599
5161f31e 600 cds_wfcq_node_init(&head->next);
b57aee66 601 head->func = func;
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602 /* Holding rcu read-side lock across use of per-cpu crdp */
603 rcu_read_lock();
b57aee66 604 crdp = get_call_rcu_data();
5161f31e 605 cds_wfcq_enqueue(&crdp->cbs_head, &crdp->cbs_tail, &head->next);
b57aee66 606 uatomic_inc(&crdp->qlen);
7106ddf8 607 wake_call_rcu_thread(crdp);
618b2595 608 rcu_read_unlock();
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609}
610
611/*
612 * Free up the specified call_rcu_data structure, terminating the
613 * associated call_rcu thread. The caller must have previously
614 * removed the call_rcu_data structure from per-thread or per-CPU
615 * usage. For example, set_cpu_call_rcu_data(cpu, NULL) for per-CPU
616 * call_rcu_data structures or set_thread_call_rcu_data(NULL) for
617 * per-thread call_rcu_data structures.
618 *
619 * We silently refuse to free up the default call_rcu_data structure
620 * because that is where we put any leftover callbacks. Note that
621 * the possibility of self-spawning callbacks makes it impossible
622 * to execute all the callbacks in finite time without putting any
623 * newly spawned callbacks somewhere else. The "somewhere else" of
624 * last resort is the default call_rcu_data structure.
625 *
626 * We also silently refuse to free NULL pointers. This simplifies
627 * the calling code.
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628 *
629 * The caller must wait for a grace-period to pass between return from
630 * set_cpu_call_rcu_data() and call to call_rcu_data_free() passing the
631 * previous call rcu data as argument.
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632 *
633 * Note: introducing __cds_wfcq_splice_blocking() in this function fixed
634 * a list corruption bug in the 0.7.x series. The equivalent fix
635 * appeared in 0.6.8 for the stable-0.6 branch.
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636 */
637void call_rcu_data_free(struct call_rcu_data *crdp)
638{
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639 if (crdp == NULL || crdp == default_call_rcu_data) {
640 return;
641 }
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642 if ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOPPED) == 0) {
643 uatomic_or(&crdp->flags, URCU_CALL_RCU_STOP);
7106ddf8 644 wake_call_rcu_thread(crdp);
2870aa1e 645 while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOPPED) == 0)
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646 poll(NULL, 0, 1);
647 }
5161f31e 648 if (!cds_wfcq_empty(&crdp->cbs_head, &crdp->cbs_tail)) {
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649 /* Create default call rcu data if need be */
650 (void) get_default_call_rcu_data();
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651 __cds_wfcq_splice_blocking(&default_call_rcu_data->cbs_head,
652 &default_call_rcu_data->cbs_tail,
653 &crdp->cbs_head, &crdp->cbs_tail);
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654 uatomic_add(&default_call_rcu_data->qlen,
655 uatomic_read(&crdp->qlen));
1e92aa15 656 wake_call_rcu_thread(default_call_rcu_data);
7106ddf8 657 }
59dc9e9d 658
b75dffe6 659 call_rcu_lock(&call_rcu_mutex);
59dc9e9d 660 cds_list_del(&crdp->list);
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661 call_rcu_unlock(&call_rcu_mutex);
662
59dc9e9d 663 free(crdp);
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664}
665
666/*
667 * Clean up all the per-CPU call_rcu threads.
668 */
669void free_all_cpu_call_rcu_data(void)
670{
671 int cpu;
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672 struct call_rcu_data **crdp;
673 static int warned = 0;
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674
675 if (maxcpus <= 0)
676 return;
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677
678 crdp = malloc(sizeof(*crdp) * maxcpus);
679 if (!crdp) {
680 if (!warned) {
681 fprintf(stderr, "[error] liburcu: unable to allocate per-CPU pointer array\n");
682 }
683 warned = 1;
d31150b4 684 return;
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685 }
686
7106ddf8 687 for (cpu = 0; cpu < maxcpus; cpu++) {
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688 crdp[cpu] = get_cpu_call_rcu_data(cpu);
689 if (crdp[cpu] == NULL)
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690 continue;
691 set_cpu_call_rcu_data(cpu, NULL);
7106ddf8 692 }
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693 /*
694 * Wait for call_rcu sites acting as RCU readers of the
695 * call_rcu_data to become quiescent.
696 */
697 synchronize_rcu();
698 for (cpu = 0; cpu < maxcpus; cpu++) {
699 if (crdp[cpu] == NULL)
700 continue;
701 call_rcu_data_free(crdp[cpu]);
702 }
703 free(crdp);
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704}
705
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706/*
707 * Acquire the call_rcu_mutex in order to ensure that the child sees
708 * all of the call_rcu() data structures in a consistent state.
709 * Suitable for pthread_atfork() and friends.
710 */
711void call_rcu_before_fork(void)
712{
713 call_rcu_lock(&call_rcu_mutex);
714}
715
716/*
717 * Clean up call_rcu data structures in the parent of a successful fork()
718 * that is not followed by exec() in the child. Suitable for
719 * pthread_atfork() and friends.
720 */
721void call_rcu_after_fork_parent(void)
722{
723 call_rcu_unlock(&call_rcu_mutex);
724}
725
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726/*
727 * Clean up call_rcu data structures in the child of a successful fork()
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728 * that is not followed by exec(). Suitable for pthread_atfork() and
729 * friends.
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730 */
731void call_rcu_after_fork_child(void)
732{
077ff173 733 struct call_rcu_data *crdp, *next;
7106ddf8 734
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735 /* Release the mutex. */
736 call_rcu_unlock(&call_rcu_mutex);
737
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738 /* Do nothing when call_rcu() has not been used */
739 if (cds_list_empty(&call_rcu_data_list))
740 return;
741
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742 /*
743 * Allocate a new default call_rcu_data structure in order
744 * to get a working call_rcu thread to go with it.
745 */
746 default_call_rcu_data = NULL;
747 (void)get_default_call_rcu_data();
748
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749 /* Cleanup call_rcu_data pointers before use */
750 maxcpus_reset();
751 free(per_cpu_call_rcu_data);
618b2595 752 rcu_set_pointer(&per_cpu_call_rcu_data, NULL);
bd252a04 753 URCU_TLS(thread_call_rcu_data) = NULL;
60af049d 754
7106ddf8 755 /* Dispose of all of the rest of the call_rcu_data structures. */
077ff173 756 cds_list_for_each_entry_safe(crdp, next, &call_rcu_data_list, list) {
7106ddf8 757 if (crdp == default_call_rcu_data)
077ff173 758 continue;
2870aa1e 759 uatomic_set(&crdp->flags, URCU_CALL_RCU_STOPPED);
7106ddf8 760 call_rcu_data_free(crdp);
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761 }
762}
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