4 * Userspace RCU library - batch memory reclamation with kernel API
6 * Copyright (c) 2010 Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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.
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.
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
39 #include "urcu/wfcqueue.h"
40 #include "urcu-call-rcu.h"
41 #include "urcu-pointer.h"
42 #include "urcu/list.h"
43 #include "urcu/futex.h"
44 #include "urcu/tls-compat.h"
47 /* Data structure that identifies a call_rcu thread. */
49 struct call_rcu_data
{
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
57 struct cds_wfcq_tail cbs_tail
;
58 struct cds_wfcq_head cbs_head
;
61 unsigned long qlen
; /* maintained for debugging. */
64 struct cds_list_head list
;
65 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
67 struct call_rcu_completion
{
72 struct call_rcu_completion_work
{
74 struct call_rcu_completion
*completion
;
78 * List of all call_rcu_data structures to keep valgrind happy.
79 * Protected by call_rcu_mutex.
82 static CDS_LIST_HEAD(call_rcu_data_list
);
84 /* Link a thread using call_rcu() to its call_rcu thread. */
86 static DEFINE_URCU_TLS(struct call_rcu_data
*, thread_call_rcu_data
);
89 * Guard call_rcu thread creation and atfork handlers.
91 static pthread_mutex_t call_rcu_mutex
= PTHREAD_MUTEX_INITIALIZER
;
93 /* If a given thread does not have its own call_rcu thread, this is default. */
95 static struct call_rcu_data
*default_call_rcu_data
;
98 * If the sched_getcpu() and sysconf(_SC_NPROCESSORS_CONF) calls are
99 * available, then we can have call_rcu threads assigned to individual
100 * CPUs rather than only to specific threads.
103 #ifdef HAVE_SCHED_GETCPU
105 static int urcu_sched_getcpu(void)
107 return sched_getcpu();
110 #else /* #ifdef HAVE_SCHED_GETCPU */
112 static int urcu_sched_getcpu(void)
117 #endif /* #else #ifdef HAVE_SCHED_GETCPU */
119 #if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU)
122 * Pointer to array of pointers to per-CPU call_rcu_data structures
123 * and # CPUs. per_cpu_call_rcu_data is a RCU-protected pointer to an
124 * array of RCU-protected pointers to call_rcu_data. call_rcu acts as a
125 * RCU read-side and reads per_cpu_call_rcu_data and the per-cpu pointer
126 * without mutex. The call_rcu_mutex protects updates.
129 static struct call_rcu_data
**per_cpu_call_rcu_data
;
132 static void maxcpus_reset(void)
137 /* Allocate the array if it has not already been allocated. */
139 static void alloc_cpu_call_rcu_data(void)
141 struct call_rcu_data
**p
;
142 static int warned
= 0;
146 maxcpus
= sysconf(_SC_NPROCESSORS_CONF
);
150 p
= malloc(maxcpus
* sizeof(*per_cpu_call_rcu_data
));
152 memset(p
, '\0', maxcpus
* sizeof(*per_cpu_call_rcu_data
));
153 rcu_set_pointer(&per_cpu_call_rcu_data
, p
);
156 fprintf(stderr
, "[error] liburcu: unable to allocate per-CPU pointer array\n");
162 #else /* #if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU) */
165 * per_cpu_call_rcu_data should be constant, but some functions below, used both
166 * for cases where cpu number is available and not available, assume it it not
169 static struct call_rcu_data
**per_cpu_call_rcu_data
= NULL
;
170 static const long maxcpus
= -1;
172 static void maxcpus_reset(void)
176 static void alloc_cpu_call_rcu_data(void)
180 #endif /* #else #if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU) */
182 /* Acquire the specified pthread mutex. */
184 static void call_rcu_lock(pthread_mutex_t
*pmp
)
188 ret
= pthread_mutex_lock(pmp
);
193 /* Release the specified pthread mutex. */
195 static void call_rcu_unlock(pthread_mutex_t
*pmp
)
199 ret
= pthread_mutex_unlock(pmp
);
204 #if HAVE_SCHED_SETAFFINITY
206 int set_thread_cpu_affinity(struct call_rcu_data
*crdp
)
210 if (crdp
->cpu_affinity
< 0)
214 CPU_SET(crdp
->cpu_affinity
, &mask
);
215 #if SCHED_SETAFFINITY_ARGS == 2
216 return sched_setaffinity(0, &mask
);
218 return sched_setaffinity(0, sizeof(mask
), &mask
);
223 int set_thread_cpu_affinity(struct call_rcu_data
*crdp
)
229 static void call_rcu_wait(struct call_rcu_data
*crdp
)
231 /* Read call_rcu list before read futex */
233 if (uatomic_read(&crdp
->futex
) == -1)
234 futex_async(&crdp
->futex
, FUTEX_WAIT
, -1,
238 static void call_rcu_wake_up(struct call_rcu_data
*crdp
)
240 /* Write to call_rcu list before reading/writing futex */
242 if (caa_unlikely(uatomic_read(&crdp
->futex
) == -1)) {
243 uatomic_set(&crdp
->futex
, 0);
244 futex_async(&crdp
->futex
, FUTEX_WAKE
, 1,
249 static void call_rcu_completion_wait(struct call_rcu_completion
*completion
)
251 /* Read completion barrier count before read futex */
253 if (uatomic_read(&completion
->futex
) == -1)
254 futex_async(&completion
->futex
, FUTEX_WAIT
, -1,
258 static void call_rcu_completion_wake_up(struct call_rcu_completion
*completion
)
260 /* Write to completion barrier count before reading/writing futex */
262 if (caa_unlikely(uatomic_read(&completion
->futex
) == -1)) {
263 uatomic_set(&completion
->futex
, 0);
264 futex_async(&completion
->futex
, FUTEX_WAKE
, 1,
269 /* This is the code run by each call_rcu thread. */
271 static void *call_rcu_thread(void *arg
)
273 unsigned long cbcount
;
274 struct call_rcu_data
*crdp
= (struct call_rcu_data
*) arg
;
275 int rt
= !!(uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_RT
);
278 ret
= set_thread_cpu_affinity(crdp
);
283 * If callbacks take a read-side lock, we need to be registered.
285 rcu_register_thread();
287 URCU_TLS(thread_call_rcu_data
) = crdp
;
289 uatomic_dec(&crdp
->futex
);
290 /* Decrement futex before reading call_rcu list */
294 struct cds_wfcq_head cbs_tmp_head
;
295 struct cds_wfcq_tail cbs_tmp_tail
;
296 struct cds_wfcq_node
*cbs
, *cbs_tmp_n
;
297 enum cds_wfcq_ret splice_ret
;
299 if (uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_PAUSE
) {
301 * Pause requested. Become quiescent: remove
302 * ourself from all global lists, and don't
303 * process any callback. The callback lists may
304 * still be non-empty though.
306 rcu_unregister_thread();
307 cmm_smp_mb__before_uatomic_or();
308 uatomic_or(&crdp
->flags
, URCU_CALL_RCU_PAUSED
);
309 while ((uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_PAUSE
) != 0)
311 rcu_register_thread();
314 cds_wfcq_init(&cbs_tmp_head
, &cbs_tmp_tail
);
315 splice_ret
= __cds_wfcq_splice_blocking(&cbs_tmp_head
,
316 &cbs_tmp_tail
, &crdp
->cbs_head
, &crdp
->cbs_tail
);
317 assert(splice_ret
!= CDS_WFCQ_RET_WOULDBLOCK
);
318 assert(splice_ret
!= CDS_WFCQ_RET_DEST_NON_EMPTY
);
319 if (splice_ret
!= CDS_WFCQ_RET_SRC_EMPTY
) {
322 __cds_wfcq_for_each_blocking_safe(&cbs_tmp_head
,
323 &cbs_tmp_tail
, cbs
, cbs_tmp_n
) {
324 struct rcu_head
*rhp
;
326 rhp
= caa_container_of(cbs
,
327 struct rcu_head
, next
);
331 uatomic_sub(&crdp
->qlen
, cbcount
);
333 if (uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_STOP
)
335 rcu_thread_offline();
337 if (cds_wfcq_empty(&crdp
->cbs_head
,
341 uatomic_dec(&crdp
->futex
);
343 * Decrement futex before reading
357 * Read call_rcu list before write futex.
360 uatomic_set(&crdp
->futex
, 0);
362 uatomic_or(&crdp
->flags
, URCU_CALL_RCU_STOPPED
);
363 rcu_unregister_thread();
368 * Create both a call_rcu thread and the corresponding call_rcu_data
369 * structure, linking the structure in as specified. Caller must hold
373 static void call_rcu_data_init(struct call_rcu_data
**crdpp
,
377 struct call_rcu_data
*crdp
;
380 crdp
= malloc(sizeof(*crdp
));
383 memset(crdp
, '\0', sizeof(*crdp
));
384 cds_wfcq_init(&crdp
->cbs_head
, &crdp
->cbs_tail
);
388 cds_list_add(&crdp
->list
, &call_rcu_data_list
);
389 crdp
->cpu_affinity
= cpu_affinity
;
390 cmm_smp_mb(); /* Structure initialized before pointer is planted. */
392 ret
= pthread_create(&crdp
->tid
, NULL
, call_rcu_thread
, crdp
);
398 * Return a pointer to the call_rcu_data structure for the specified
399 * CPU, returning NULL if there is none. We cannot automatically
400 * created it because the platform we are running on might not define
401 * urcu_sched_getcpu().
403 * The call to this function and use of the returned call_rcu_data
404 * should be protected by RCU read-side lock.
407 struct call_rcu_data
*get_cpu_call_rcu_data(int cpu
)
409 static int warned
= 0;
410 struct call_rcu_data
**pcpu_crdp
;
412 pcpu_crdp
= rcu_dereference(per_cpu_call_rcu_data
);
413 if (pcpu_crdp
== NULL
)
415 if (!warned
&& maxcpus
> 0 && (cpu
< 0 || maxcpus
<= cpu
)) {
416 fprintf(stderr
, "[error] liburcu: get CPU # out of range\n");
419 if (cpu
< 0 || maxcpus
<= cpu
)
421 return rcu_dereference(pcpu_crdp
[cpu
]);
425 * Return the tid corresponding to the call_rcu thread whose
426 * call_rcu_data structure is specified.
429 pthread_t
get_call_rcu_thread(struct call_rcu_data
*crdp
)
435 * Create a call_rcu_data structure (with thread) and return a pointer.
438 static struct call_rcu_data
*__create_call_rcu_data(unsigned long flags
,
441 struct call_rcu_data
*crdp
;
443 call_rcu_data_init(&crdp
, flags
, cpu_affinity
);
447 struct call_rcu_data
*create_call_rcu_data(unsigned long flags
,
450 struct call_rcu_data
*crdp
;
452 call_rcu_lock(&call_rcu_mutex
);
453 crdp
= __create_call_rcu_data(flags
, cpu_affinity
);
454 call_rcu_unlock(&call_rcu_mutex
);
459 * Set the specified CPU to use the specified call_rcu_data structure.
461 * Use NULL to remove a CPU's call_rcu_data structure, but it is
462 * the caller's responsibility to dispose of the removed structure.
463 * Use get_cpu_call_rcu_data() to obtain a pointer to the old structure
464 * (prior to NULLing it out, of course).
466 * The caller must wait for a grace-period to pass between return from
467 * set_cpu_call_rcu_data() and call to call_rcu_data_free() passing the
468 * previous call rcu data as argument.
471 int set_cpu_call_rcu_data(int cpu
, struct call_rcu_data
*crdp
)
473 static int warned
= 0;
475 call_rcu_lock(&call_rcu_mutex
);
476 alloc_cpu_call_rcu_data();
477 if (cpu
< 0 || maxcpus
<= cpu
) {
479 fprintf(stderr
, "[error] liburcu: set CPU # out of range\n");
482 call_rcu_unlock(&call_rcu_mutex
);
487 if (per_cpu_call_rcu_data
== NULL
) {
488 call_rcu_unlock(&call_rcu_mutex
);
493 if (per_cpu_call_rcu_data
[cpu
] != NULL
&& crdp
!= NULL
) {
494 call_rcu_unlock(&call_rcu_mutex
);
499 rcu_set_pointer(&per_cpu_call_rcu_data
[cpu
], crdp
);
500 call_rcu_unlock(&call_rcu_mutex
);
505 * Return a pointer to the default call_rcu_data structure, creating
506 * one if need be. Because we never free call_rcu_data structures,
507 * we don't need to be in an RCU read-side critical section.
510 struct call_rcu_data
*get_default_call_rcu_data(void)
512 if (default_call_rcu_data
!= NULL
)
513 return rcu_dereference(default_call_rcu_data
);
514 call_rcu_lock(&call_rcu_mutex
);
515 if (default_call_rcu_data
!= NULL
) {
516 call_rcu_unlock(&call_rcu_mutex
);
517 return default_call_rcu_data
;
519 call_rcu_data_init(&default_call_rcu_data
, 0, -1);
520 call_rcu_unlock(&call_rcu_mutex
);
521 return default_call_rcu_data
;
525 * Return the call_rcu_data structure that applies to the currently
526 * running thread. Any call_rcu_data structure assigned specifically
527 * to this thread has first priority, followed by any call_rcu_data
528 * structure assigned to the CPU on which the thread is running,
529 * followed by the default call_rcu_data structure. If there is not
530 * yet a default call_rcu_data structure, one will be created.
532 * Calls to this function and use of the returned call_rcu_data should
533 * be protected by RCU read-side lock.
535 struct call_rcu_data
*get_call_rcu_data(void)
537 struct call_rcu_data
*crd
;
539 if (URCU_TLS(thread_call_rcu_data
) != NULL
)
540 return URCU_TLS(thread_call_rcu_data
);
543 crd
= get_cpu_call_rcu_data(urcu_sched_getcpu());
548 return get_default_call_rcu_data();
552 * Return a pointer to this task's call_rcu_data if there is one.
555 struct call_rcu_data
*get_thread_call_rcu_data(void)
557 return URCU_TLS(thread_call_rcu_data
);
561 * Set this task's call_rcu_data structure as specified, regardless
562 * of whether or not this task already had one. (This allows switching
563 * to and from real-time call_rcu threads, for example.)
565 * Use NULL to remove a thread's call_rcu_data structure, but it is
566 * the caller's responsibility to dispose of the removed structure.
567 * Use get_thread_call_rcu_data() to obtain a pointer to the old structure
568 * (prior to NULLing it out, of course).
571 void set_thread_call_rcu_data(struct call_rcu_data
*crdp
)
573 URCU_TLS(thread_call_rcu_data
) = crdp
;
577 * Create a separate call_rcu thread for each CPU. This does not
578 * replace a pre-existing call_rcu thread -- use the set_cpu_call_rcu_data()
579 * function if you want that behavior. Should be paired with
580 * free_all_cpu_call_rcu_data() to teardown these call_rcu worker
584 int create_all_cpu_call_rcu_data(unsigned long flags
)
587 struct call_rcu_data
*crdp
;
590 call_rcu_lock(&call_rcu_mutex
);
591 alloc_cpu_call_rcu_data();
592 call_rcu_unlock(&call_rcu_mutex
);
597 if (per_cpu_call_rcu_data
== NULL
) {
601 for (i
= 0; i
< maxcpus
; i
++) {
602 call_rcu_lock(&call_rcu_mutex
);
603 if (get_cpu_call_rcu_data(i
)) {
604 call_rcu_unlock(&call_rcu_mutex
);
607 crdp
= __create_call_rcu_data(flags
, i
);
609 call_rcu_unlock(&call_rcu_mutex
);
613 call_rcu_unlock(&call_rcu_mutex
);
614 if ((ret
= set_cpu_call_rcu_data(i
, crdp
)) != 0) {
615 call_rcu_data_free(crdp
);
617 /* it has been created by other thread */
628 * Wake up the call_rcu thread corresponding to the specified
629 * call_rcu_data structure.
631 static void wake_call_rcu_thread(struct call_rcu_data
*crdp
)
633 if (!(_CMM_LOAD_SHARED(crdp
->flags
) & URCU_CALL_RCU_RT
))
634 call_rcu_wake_up(crdp
);
637 static void _call_rcu(struct rcu_head
*head
,
638 void (*func
)(struct rcu_head
*head
),
639 struct call_rcu_data
*crdp
)
641 cds_wfcq_node_init(&head
->next
);
643 cds_wfcq_enqueue(&crdp
->cbs_head
, &crdp
->cbs_tail
, &head
->next
);
644 uatomic_inc(&crdp
->qlen
);
645 wake_call_rcu_thread(crdp
);
649 * Schedule a function to be invoked after a following grace period.
650 * This is the only function that must be called -- the others are
651 * only present to allow applications to tune their use of RCU for
652 * maximum performance.
654 * Note that unless a call_rcu thread has not already been created,
655 * the first invocation of call_rcu() will create one. So, if you
656 * need the first invocation of call_rcu() to be fast, make sure
657 * to create a call_rcu thread first. One way to accomplish this is
658 * "get_call_rcu_data();", and another is create_all_cpu_call_rcu_data().
660 * call_rcu must be called by registered RCU read-side threads.
662 void call_rcu(struct rcu_head
*head
,
663 void (*func
)(struct rcu_head
*head
))
665 struct call_rcu_data
*crdp
;
667 /* Holding rcu read-side lock across use of per-cpu crdp */
669 crdp
= get_call_rcu_data();
670 _call_rcu(head
, func
, crdp
);
675 * Free up the specified call_rcu_data structure, terminating the
676 * associated call_rcu thread. The caller must have previously
677 * removed the call_rcu_data structure from per-thread or per-CPU
678 * usage. For example, set_cpu_call_rcu_data(cpu, NULL) for per-CPU
679 * call_rcu_data structures or set_thread_call_rcu_data(NULL) for
680 * per-thread call_rcu_data structures.
682 * We silently refuse to free up the default call_rcu_data structure
683 * because that is where we put any leftover callbacks. Note that
684 * the possibility of self-spawning callbacks makes it impossible
685 * to execute all the callbacks in finite time without putting any
686 * newly spawned callbacks somewhere else. The "somewhere else" of
687 * last resort is the default call_rcu_data structure.
689 * We also silently refuse to free NULL pointers. This simplifies
692 * The caller must wait for a grace-period to pass between return from
693 * set_cpu_call_rcu_data() and call to call_rcu_data_free() passing the
694 * previous call rcu data as argument.
696 * Note: introducing __cds_wfcq_splice_blocking() in this function fixed
697 * a list corruption bug in the 0.7.x series. The equivalent fix
698 * appeared in 0.6.8 for the stable-0.6 branch.
700 void call_rcu_data_free(struct call_rcu_data
*crdp
)
702 if (crdp
== NULL
|| crdp
== default_call_rcu_data
) {
705 if ((uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_STOPPED
) == 0) {
706 uatomic_or(&crdp
->flags
, URCU_CALL_RCU_STOP
);
707 wake_call_rcu_thread(crdp
);
708 while ((uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_STOPPED
) == 0)
711 if (!cds_wfcq_empty(&crdp
->cbs_head
, &crdp
->cbs_tail
)) {
712 /* Create default call rcu data if need be */
713 (void) get_default_call_rcu_data();
714 __cds_wfcq_splice_blocking(&default_call_rcu_data
->cbs_head
,
715 &default_call_rcu_data
->cbs_tail
,
716 &crdp
->cbs_head
, &crdp
->cbs_tail
);
717 uatomic_add(&default_call_rcu_data
->qlen
,
718 uatomic_read(&crdp
->qlen
));
719 wake_call_rcu_thread(default_call_rcu_data
);
722 call_rcu_lock(&call_rcu_mutex
);
723 cds_list_del(&crdp
->list
);
724 call_rcu_unlock(&call_rcu_mutex
);
730 * Clean up all the per-CPU call_rcu threads.
732 void free_all_cpu_call_rcu_data(void)
735 struct call_rcu_data
**crdp
;
736 static int warned
= 0;
741 crdp
= malloc(sizeof(*crdp
) * maxcpus
);
744 fprintf(stderr
, "[error] liburcu: unable to allocate per-CPU pointer array\n");
750 for (cpu
= 0; cpu
< maxcpus
; cpu
++) {
751 crdp
[cpu
] = get_cpu_call_rcu_data(cpu
);
752 if (crdp
[cpu
] == NULL
)
754 set_cpu_call_rcu_data(cpu
, NULL
);
757 * Wait for call_rcu sites acting as RCU readers of the
758 * call_rcu_data to become quiescent.
761 for (cpu
= 0; cpu
< maxcpus
; cpu
++) {
762 if (crdp
[cpu
] == NULL
)
764 call_rcu_data_free(crdp
[cpu
]);
770 void _rcu_barrier_complete(struct rcu_head
*head
)
772 struct call_rcu_completion_work
*work
;
773 struct call_rcu_completion
*completion
;
775 work
= caa_container_of(head
, struct call_rcu_completion_work
, head
);
776 completion
= work
->completion
;
777 uatomic_dec(&completion
->barrier_count
);
778 call_rcu_completion_wake_up(completion
);
783 * Wait for all in-flight call_rcu callbacks to complete execution.
785 void rcu_barrier(void)
787 struct call_rcu_data
*crdp
;
788 struct call_rcu_completion completion
;
792 /* Put in offline state in QSBR. */
793 was_online
= rcu_read_ongoing();
795 rcu_thread_offline();
797 * Calling a rcu_barrier() within a RCU read-side critical
798 * section is an error.
800 if (rcu_read_ongoing()) {
801 static int warned
= 0;
804 fprintf(stderr
, "[error] liburcu: rcu_barrier() called from within RCU read-side critical section.\n");
810 call_rcu_lock(&call_rcu_mutex
);
811 cds_list_for_each_entry(crdp
, &call_rcu_data_list
, list
)
814 completion
.barrier_count
= count
;
816 cds_list_for_each_entry(crdp
, &call_rcu_data_list
, list
) {
817 struct call_rcu_completion_work
*work
;
819 work
= calloc(sizeof(*work
), 1);
822 work
->completion
= &completion
;
823 _call_rcu(&work
->head
, _rcu_barrier_complete
, crdp
);
825 call_rcu_unlock(&call_rcu_mutex
);
829 uatomic_dec(&completion
.futex
);
830 /* Decrement futex before reading barrier_count */
832 if (!uatomic_read(&completion
.barrier_count
))
834 call_rcu_completion_wait(&completion
);
842 * Acquire the call_rcu_mutex in order to ensure that the child sees
843 * all of the call_rcu() data structures in a consistent state. Ensure
844 * that all call_rcu threads are in a quiescent state across fork.
845 * Suitable for pthread_atfork() and friends.
847 void call_rcu_before_fork(void)
849 struct call_rcu_data
*crdp
;
851 call_rcu_lock(&call_rcu_mutex
);
853 cds_list_for_each_entry(crdp
, &call_rcu_data_list
, list
) {
854 uatomic_or(&crdp
->flags
, URCU_CALL_RCU_PAUSE
);
855 cmm_smp_mb__after_uatomic_or();
856 wake_call_rcu_thread(crdp
);
858 cds_list_for_each_entry(crdp
, &call_rcu_data_list
, list
) {
859 while ((uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_PAUSED
) == 0)
865 * Clean up call_rcu data structures in the parent of a successful fork()
866 * that is not followed by exec() in the child. Suitable for
867 * pthread_atfork() and friends.
869 void call_rcu_after_fork_parent(void)
871 struct call_rcu_data
*crdp
;
873 cds_list_for_each_entry(crdp
, &call_rcu_data_list
, list
)
874 uatomic_and(&crdp
->flags
, ~URCU_CALL_RCU_PAUSE
);
875 call_rcu_unlock(&call_rcu_mutex
);
879 * Clean up call_rcu data structures in the child of a successful fork()
880 * that is not followed by exec(). Suitable for pthread_atfork() and
883 void call_rcu_after_fork_child(void)
885 struct call_rcu_data
*crdp
, *next
;
887 /* Release the mutex. */
888 call_rcu_unlock(&call_rcu_mutex
);
890 /* Do nothing when call_rcu() has not been used */
891 if (cds_list_empty(&call_rcu_data_list
))
895 * Allocate a new default call_rcu_data structure in order
896 * to get a working call_rcu thread to go with it.
898 default_call_rcu_data
= NULL
;
899 (void)get_default_call_rcu_data();
901 /* Cleanup call_rcu_data pointers before use */
903 free(per_cpu_call_rcu_data
);
904 rcu_set_pointer(&per_cpu_call_rcu_data
, NULL
);
905 URCU_TLS(thread_call_rcu_data
) = NULL
;
908 * Dispose of all of the rest of the call_rcu_data structures.
909 * Leftover call_rcu callbacks will be merged into the new
910 * default call_rcu thread queue.
912 cds_list_for_each_entry_safe(crdp
, next
, &call_rcu_data_list
, list
) {
913 if (crdp
== default_call_rcu_data
)
915 uatomic_set(&crdp
->flags
, URCU_CALL_RCU_STOPPED
);
916 call_rcu_data_free(crdp
);