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"
48 /* Data structure that identifies a call_rcu thread. */
50 struct call_rcu_data
{
52 * We do not align head on a different cache-line than tail
53 * mainly because call_rcu callback-invocation threads use
54 * batching ("splice") to get an entire list of callbacks, which
55 * effectively empties the queue, and requires to touch the tail
58 struct cds_wfcq_tail cbs_tail
;
59 struct cds_wfcq_head cbs_head
;
62 unsigned long qlen
; /* maintained for debugging. */
65 struct cds_list_head list
;
66 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
68 struct call_rcu_completion
{
74 struct call_rcu_completion_work
{
76 struct call_rcu_completion
*completion
;
80 * List of all call_rcu_data structures to keep valgrind happy.
81 * Protected by call_rcu_mutex.
84 static CDS_LIST_HEAD(call_rcu_data_list
);
86 /* Link a thread using call_rcu() to its call_rcu thread. */
88 static DEFINE_URCU_TLS(struct call_rcu_data
*, thread_call_rcu_data
);
91 * Guard call_rcu thread creation and atfork handlers.
93 static pthread_mutex_t call_rcu_mutex
= PTHREAD_MUTEX_INITIALIZER
;
95 /* If a given thread does not have its own call_rcu thread, this is default. */
97 static struct call_rcu_data
*default_call_rcu_data
;
100 * If the sched_getcpu() and sysconf(_SC_NPROCESSORS_CONF) calls are
101 * available, then we can have call_rcu threads assigned to individual
102 * CPUs rather than only to specific threads.
105 #ifdef HAVE_SCHED_GETCPU
107 static int urcu_sched_getcpu(void)
109 return sched_getcpu();
112 #else /* #ifdef HAVE_SCHED_GETCPU */
114 static int urcu_sched_getcpu(void)
119 #endif /* #else #ifdef HAVE_SCHED_GETCPU */
121 #if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU)
124 * Pointer to array of pointers to per-CPU call_rcu_data structures
125 * and # CPUs. per_cpu_call_rcu_data is a RCU-protected pointer to an
126 * array of RCU-protected pointers to call_rcu_data. call_rcu acts as a
127 * RCU read-side and reads per_cpu_call_rcu_data and the per-cpu pointer
128 * without mutex. The call_rcu_mutex protects updates.
131 static struct call_rcu_data
**per_cpu_call_rcu_data
;
134 static void maxcpus_reset(void)
139 /* Allocate the array if it has not already been allocated. */
141 static void alloc_cpu_call_rcu_data(void)
143 struct call_rcu_data
**p
;
144 static int warned
= 0;
148 maxcpus
= sysconf(_SC_NPROCESSORS_CONF
);
152 p
= malloc(maxcpus
* sizeof(*per_cpu_call_rcu_data
));
154 memset(p
, '\0', maxcpus
* sizeof(*per_cpu_call_rcu_data
));
155 rcu_set_pointer(&per_cpu_call_rcu_data
, p
);
158 fprintf(stderr
, "[error] liburcu: unable to allocate per-CPU pointer array\n");
164 #else /* #if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU) */
167 * per_cpu_call_rcu_data should be constant, but some functions below, used both
168 * for cases where cpu number is available and not available, assume it it not
171 static struct call_rcu_data
**per_cpu_call_rcu_data
= NULL
;
172 static const long maxcpus
= -1;
174 static void maxcpus_reset(void)
178 static void alloc_cpu_call_rcu_data(void)
182 #endif /* #else #if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU) */
184 /* Acquire the specified pthread mutex. */
186 static void call_rcu_lock(pthread_mutex_t
*pmp
)
190 ret
= pthread_mutex_lock(pmp
);
195 /* Release the specified pthread mutex. */
197 static void call_rcu_unlock(pthread_mutex_t
*pmp
)
201 ret
= pthread_mutex_unlock(pmp
);
206 #if HAVE_SCHED_SETAFFINITY
208 int set_thread_cpu_affinity(struct call_rcu_data
*crdp
)
212 if (crdp
->cpu_affinity
< 0)
216 CPU_SET(crdp
->cpu_affinity
, &mask
);
217 #if SCHED_SETAFFINITY_ARGS == 2
218 return sched_setaffinity(0, &mask
);
220 return sched_setaffinity(0, sizeof(mask
), &mask
);
225 int set_thread_cpu_affinity(struct call_rcu_data
*crdp
)
231 static void call_rcu_wait(struct call_rcu_data
*crdp
)
233 /* Read call_rcu list before read futex */
235 if (uatomic_read(&crdp
->futex
) == -1)
236 futex_async(&crdp
->futex
, FUTEX_WAIT
, -1,
240 static void call_rcu_wake_up(struct call_rcu_data
*crdp
)
242 /* Write to call_rcu list before reading/writing futex */
244 if (caa_unlikely(uatomic_read(&crdp
->futex
) == -1)) {
245 uatomic_set(&crdp
->futex
, 0);
246 futex_async(&crdp
->futex
, FUTEX_WAKE
, 1,
251 static void call_rcu_completion_wait(struct call_rcu_completion
*completion
)
253 /* Read completion barrier count before read futex */
255 if (uatomic_read(&completion
->futex
) == -1)
256 futex_async(&completion
->futex
, FUTEX_WAIT
, -1,
260 static void call_rcu_completion_wake_up(struct call_rcu_completion
*completion
)
262 /* Write to completion barrier count before reading/writing futex */
264 if (caa_unlikely(uatomic_read(&completion
->futex
) == -1)) {
265 uatomic_set(&completion
->futex
, 0);
266 futex_async(&completion
->futex
, FUTEX_WAKE
, 1,
271 /* This is the code run by each call_rcu thread. */
273 static void *call_rcu_thread(void *arg
)
275 unsigned long cbcount
;
276 struct call_rcu_data
*crdp
= (struct call_rcu_data
*) arg
;
277 int rt
= !!(uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_RT
);
280 ret
= set_thread_cpu_affinity(crdp
);
285 * If callbacks take a read-side lock, we need to be registered.
287 rcu_register_thread();
289 URCU_TLS(thread_call_rcu_data
) = crdp
;
291 uatomic_dec(&crdp
->futex
);
292 /* Decrement futex before reading call_rcu list */
296 struct cds_wfcq_head cbs_tmp_head
;
297 struct cds_wfcq_tail cbs_tmp_tail
;
298 struct cds_wfcq_node
*cbs
, *cbs_tmp_n
;
299 enum cds_wfcq_ret splice_ret
;
301 if (uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_PAUSE
) {
303 * Pause requested. Become quiescent: remove
304 * ourself from all global lists, and don't
305 * process any callback. The callback lists may
306 * still be non-empty though.
308 rcu_unregister_thread();
309 cmm_smp_mb__before_uatomic_or();
310 uatomic_or(&crdp
->flags
, URCU_CALL_RCU_PAUSED
);
311 while ((uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_PAUSE
) != 0)
313 uatomic_and(&crdp
->flags
, ~URCU_CALL_RCU_PAUSED
);
314 cmm_smp_mb__after_uatomic_and();
315 rcu_register_thread();
318 cds_wfcq_init(&cbs_tmp_head
, &cbs_tmp_tail
);
319 splice_ret
= __cds_wfcq_splice_blocking(&cbs_tmp_head
,
320 &cbs_tmp_tail
, &crdp
->cbs_head
, &crdp
->cbs_tail
);
321 assert(splice_ret
!= CDS_WFCQ_RET_WOULDBLOCK
);
322 assert(splice_ret
!= CDS_WFCQ_RET_DEST_NON_EMPTY
);
323 if (splice_ret
!= CDS_WFCQ_RET_SRC_EMPTY
) {
326 __cds_wfcq_for_each_blocking_safe(&cbs_tmp_head
,
327 &cbs_tmp_tail
, cbs
, cbs_tmp_n
) {
328 struct rcu_head
*rhp
;
330 rhp
= caa_container_of(cbs
,
331 struct rcu_head
, next
);
335 uatomic_sub(&crdp
->qlen
, cbcount
);
337 if (uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_STOP
)
339 rcu_thread_offline();
341 if (cds_wfcq_empty(&crdp
->cbs_head
,
345 uatomic_dec(&crdp
->futex
);
347 * Decrement futex before reading
361 * Read call_rcu list before write futex.
364 uatomic_set(&crdp
->futex
, 0);
366 uatomic_or(&crdp
->flags
, URCU_CALL_RCU_STOPPED
);
367 rcu_unregister_thread();
372 * Create both a call_rcu thread and the corresponding call_rcu_data
373 * structure, linking the structure in as specified. Caller must hold
377 static void call_rcu_data_init(struct call_rcu_data
**crdpp
,
381 struct call_rcu_data
*crdp
;
384 crdp
= malloc(sizeof(*crdp
));
387 memset(crdp
, '\0', sizeof(*crdp
));
388 cds_wfcq_init(&crdp
->cbs_head
, &crdp
->cbs_tail
);
392 cds_list_add(&crdp
->list
, &call_rcu_data_list
);
393 crdp
->cpu_affinity
= cpu_affinity
;
394 cmm_smp_mb(); /* Structure initialized before pointer is planted. */
396 ret
= pthread_create(&crdp
->tid
, NULL
, call_rcu_thread
, crdp
);
402 * Return a pointer to the call_rcu_data structure for the specified
403 * CPU, returning NULL if there is none. We cannot automatically
404 * created it because the platform we are running on might not define
405 * urcu_sched_getcpu().
407 * The call to this function and use of the returned call_rcu_data
408 * should be protected by RCU read-side lock.
411 struct call_rcu_data
*get_cpu_call_rcu_data(int cpu
)
413 static int warned
= 0;
414 struct call_rcu_data
**pcpu_crdp
;
416 pcpu_crdp
= rcu_dereference(per_cpu_call_rcu_data
);
417 if (pcpu_crdp
== NULL
)
419 if (!warned
&& maxcpus
> 0 && (cpu
< 0 || maxcpus
<= cpu
)) {
420 fprintf(stderr
, "[error] liburcu: get CPU # out of range\n");
423 if (cpu
< 0 || maxcpus
<= cpu
)
425 return rcu_dereference(pcpu_crdp
[cpu
]);
429 * Return the tid corresponding to the call_rcu thread whose
430 * call_rcu_data structure is specified.
433 pthread_t
get_call_rcu_thread(struct call_rcu_data
*crdp
)
439 * Create a call_rcu_data structure (with thread) and return a pointer.
442 static struct call_rcu_data
*__create_call_rcu_data(unsigned long flags
,
445 struct call_rcu_data
*crdp
;
447 call_rcu_data_init(&crdp
, flags
, cpu_affinity
);
451 struct call_rcu_data
*create_call_rcu_data(unsigned long flags
,
454 struct call_rcu_data
*crdp
;
456 call_rcu_lock(&call_rcu_mutex
);
457 crdp
= __create_call_rcu_data(flags
, cpu_affinity
);
458 call_rcu_unlock(&call_rcu_mutex
);
463 * Set the specified CPU to use the specified call_rcu_data structure.
465 * Use NULL to remove a CPU's call_rcu_data structure, but it is
466 * the caller's responsibility to dispose of the removed structure.
467 * Use get_cpu_call_rcu_data() to obtain a pointer to the old structure
468 * (prior to NULLing it out, of course).
470 * The caller must wait for a grace-period to pass between return from
471 * set_cpu_call_rcu_data() and call to call_rcu_data_free() passing the
472 * previous call rcu data as argument.
475 int set_cpu_call_rcu_data(int cpu
, struct call_rcu_data
*crdp
)
477 static int warned
= 0;
479 call_rcu_lock(&call_rcu_mutex
);
480 alloc_cpu_call_rcu_data();
481 if (cpu
< 0 || maxcpus
<= cpu
) {
483 fprintf(stderr
, "[error] liburcu: set CPU # out of range\n");
486 call_rcu_unlock(&call_rcu_mutex
);
491 if (per_cpu_call_rcu_data
== NULL
) {
492 call_rcu_unlock(&call_rcu_mutex
);
497 if (per_cpu_call_rcu_data
[cpu
] != NULL
&& crdp
!= NULL
) {
498 call_rcu_unlock(&call_rcu_mutex
);
503 rcu_set_pointer(&per_cpu_call_rcu_data
[cpu
], crdp
);
504 call_rcu_unlock(&call_rcu_mutex
);
509 * Return a pointer to the default call_rcu_data structure, creating
510 * one if need be. Because we never free call_rcu_data structures,
511 * we don't need to be in an RCU read-side critical section.
514 struct call_rcu_data
*get_default_call_rcu_data(void)
516 if (default_call_rcu_data
!= NULL
)
517 return rcu_dereference(default_call_rcu_data
);
518 call_rcu_lock(&call_rcu_mutex
);
519 if (default_call_rcu_data
!= NULL
) {
520 call_rcu_unlock(&call_rcu_mutex
);
521 return default_call_rcu_data
;
523 call_rcu_data_init(&default_call_rcu_data
, 0, -1);
524 call_rcu_unlock(&call_rcu_mutex
);
525 return default_call_rcu_data
;
529 * Return the call_rcu_data structure that applies to the currently
530 * running thread. Any call_rcu_data structure assigned specifically
531 * to this thread has first priority, followed by any call_rcu_data
532 * structure assigned to the CPU on which the thread is running,
533 * followed by the default call_rcu_data structure. If there is not
534 * yet a default call_rcu_data structure, one will be created.
536 * Calls to this function and use of the returned call_rcu_data should
537 * be protected by RCU read-side lock.
539 struct call_rcu_data
*get_call_rcu_data(void)
541 struct call_rcu_data
*crd
;
543 if (URCU_TLS(thread_call_rcu_data
) != NULL
)
544 return URCU_TLS(thread_call_rcu_data
);
547 crd
= get_cpu_call_rcu_data(urcu_sched_getcpu());
552 return get_default_call_rcu_data();
556 * Return a pointer to this task's call_rcu_data if there is one.
559 struct call_rcu_data
*get_thread_call_rcu_data(void)
561 return URCU_TLS(thread_call_rcu_data
);
565 * Set this task's call_rcu_data structure as specified, regardless
566 * of whether or not this task already had one. (This allows switching
567 * to and from real-time call_rcu threads, for example.)
569 * Use NULL to remove a thread's call_rcu_data structure, but it is
570 * the caller's responsibility to dispose of the removed structure.
571 * Use get_thread_call_rcu_data() to obtain a pointer to the old structure
572 * (prior to NULLing it out, of course).
575 void set_thread_call_rcu_data(struct call_rcu_data
*crdp
)
577 URCU_TLS(thread_call_rcu_data
) = crdp
;
581 * Create a separate call_rcu thread for each CPU. This does not
582 * replace a pre-existing call_rcu thread -- use the set_cpu_call_rcu_data()
583 * function if you want that behavior. Should be paired with
584 * free_all_cpu_call_rcu_data() to teardown these call_rcu worker
588 int create_all_cpu_call_rcu_data(unsigned long flags
)
591 struct call_rcu_data
*crdp
;
594 call_rcu_lock(&call_rcu_mutex
);
595 alloc_cpu_call_rcu_data();
596 call_rcu_unlock(&call_rcu_mutex
);
601 if (per_cpu_call_rcu_data
== NULL
) {
605 for (i
= 0; i
< maxcpus
; i
++) {
606 call_rcu_lock(&call_rcu_mutex
);
607 if (get_cpu_call_rcu_data(i
)) {
608 call_rcu_unlock(&call_rcu_mutex
);
611 crdp
= __create_call_rcu_data(flags
, i
);
613 call_rcu_unlock(&call_rcu_mutex
);
617 call_rcu_unlock(&call_rcu_mutex
);
618 if ((ret
= set_cpu_call_rcu_data(i
, crdp
)) != 0) {
619 call_rcu_data_free(crdp
);
621 /* it has been created by other thread */
632 * Wake up the call_rcu thread corresponding to the specified
633 * call_rcu_data structure.
635 static void wake_call_rcu_thread(struct call_rcu_data
*crdp
)
637 if (!(_CMM_LOAD_SHARED(crdp
->flags
) & URCU_CALL_RCU_RT
))
638 call_rcu_wake_up(crdp
);
641 static void _call_rcu(struct rcu_head
*head
,
642 void (*func
)(struct rcu_head
*head
),
643 struct call_rcu_data
*crdp
)
645 cds_wfcq_node_init(&head
->next
);
647 cds_wfcq_enqueue(&crdp
->cbs_head
, &crdp
->cbs_tail
, &head
->next
);
648 uatomic_inc(&crdp
->qlen
);
649 wake_call_rcu_thread(crdp
);
653 * Schedule a function to be invoked after a following grace period.
654 * This is the only function that must be called -- the others are
655 * only present to allow applications to tune their use of RCU for
656 * maximum performance.
658 * Note that unless a call_rcu thread has not already been created,
659 * the first invocation of call_rcu() will create one. So, if you
660 * need the first invocation of call_rcu() to be fast, make sure
661 * to create a call_rcu thread first. One way to accomplish this is
662 * "get_call_rcu_data();", and another is create_all_cpu_call_rcu_data().
664 * call_rcu must be called by registered RCU read-side threads.
666 void call_rcu(struct rcu_head
*head
,
667 void (*func
)(struct rcu_head
*head
))
669 struct call_rcu_data
*crdp
;
671 /* Holding rcu read-side lock across use of per-cpu crdp */
673 crdp
= get_call_rcu_data();
674 _call_rcu(head
, func
, crdp
);
679 * Free up the specified call_rcu_data structure, terminating the
680 * associated call_rcu thread. The caller must have previously
681 * removed the call_rcu_data structure from per-thread or per-CPU
682 * usage. For example, set_cpu_call_rcu_data(cpu, NULL) for per-CPU
683 * call_rcu_data structures or set_thread_call_rcu_data(NULL) for
684 * per-thread call_rcu_data structures.
686 * We silently refuse to free up the default call_rcu_data structure
687 * because that is where we put any leftover callbacks. Note that
688 * the possibility of self-spawning callbacks makes it impossible
689 * to execute all the callbacks in finite time without putting any
690 * newly spawned callbacks somewhere else. The "somewhere else" of
691 * last resort is the default call_rcu_data structure.
693 * We also silently refuse to free NULL pointers. This simplifies
696 * The caller must wait for a grace-period to pass between return from
697 * set_cpu_call_rcu_data() and call to call_rcu_data_free() passing the
698 * previous call rcu data as argument.
700 * Note: introducing __cds_wfcq_splice_blocking() in this function fixed
701 * a list corruption bug in the 0.7.x series. The equivalent fix
702 * appeared in 0.6.8 for the stable-0.6 branch.
704 void call_rcu_data_free(struct call_rcu_data
*crdp
)
706 if (crdp
== NULL
|| crdp
== default_call_rcu_data
) {
709 if ((uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_STOPPED
) == 0) {
710 uatomic_or(&crdp
->flags
, URCU_CALL_RCU_STOP
);
711 wake_call_rcu_thread(crdp
);
712 while ((uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_STOPPED
) == 0)
715 if (!cds_wfcq_empty(&crdp
->cbs_head
, &crdp
->cbs_tail
)) {
716 /* Create default call rcu data if need be */
717 (void) get_default_call_rcu_data();
718 __cds_wfcq_splice_blocking(&default_call_rcu_data
->cbs_head
,
719 &default_call_rcu_data
->cbs_tail
,
720 &crdp
->cbs_head
, &crdp
->cbs_tail
);
721 uatomic_add(&default_call_rcu_data
->qlen
,
722 uatomic_read(&crdp
->qlen
));
723 wake_call_rcu_thread(default_call_rcu_data
);
726 call_rcu_lock(&call_rcu_mutex
);
727 cds_list_del(&crdp
->list
);
728 call_rcu_unlock(&call_rcu_mutex
);
734 * Clean up all the per-CPU call_rcu threads.
736 void free_all_cpu_call_rcu_data(void)
739 struct call_rcu_data
**crdp
;
740 static int warned
= 0;
745 crdp
= malloc(sizeof(*crdp
) * maxcpus
);
748 fprintf(stderr
, "[error] liburcu: unable to allocate per-CPU pointer array\n");
754 for (cpu
= 0; cpu
< maxcpus
; cpu
++) {
755 crdp
[cpu
] = get_cpu_call_rcu_data(cpu
);
756 if (crdp
[cpu
] == NULL
)
758 set_cpu_call_rcu_data(cpu
, NULL
);
761 * Wait for call_rcu sites acting as RCU readers of the
762 * call_rcu_data to become quiescent.
765 for (cpu
= 0; cpu
< maxcpus
; cpu
++) {
766 if (crdp
[cpu
] == NULL
)
768 call_rcu_data_free(crdp
[cpu
]);
774 void free_completion(struct urcu_ref
*ref
)
776 struct call_rcu_completion
*completion
;
778 completion
= caa_container_of(ref
, struct call_rcu_completion
, ref
);
783 void _rcu_barrier_complete(struct rcu_head
*head
)
785 struct call_rcu_completion_work
*work
;
786 struct call_rcu_completion
*completion
;
788 work
= caa_container_of(head
, struct call_rcu_completion_work
, head
);
789 completion
= work
->completion
;
790 if (!uatomic_sub_return(&completion
->barrier_count
, 1))
791 call_rcu_completion_wake_up(completion
);
792 urcu_ref_put(&completion
->ref
, free_completion
);
797 * Wait for all in-flight call_rcu callbacks to complete execution.
799 void rcu_barrier(void)
801 struct call_rcu_data
*crdp
;
802 struct call_rcu_completion
*completion
;
806 /* Put in offline state in QSBR. */
807 was_online
= _rcu_read_ongoing();
809 rcu_thread_offline();
811 * Calling a rcu_barrier() within a RCU read-side critical
812 * section is an error.
814 if (_rcu_read_ongoing()) {
815 static int warned
= 0;
818 fprintf(stderr
, "[error] liburcu: rcu_barrier() called from within RCU read-side critical section.\n");
824 completion
= calloc(sizeof(*completion
), 1);
828 call_rcu_lock(&call_rcu_mutex
);
829 cds_list_for_each_entry(crdp
, &call_rcu_data_list
, list
)
832 /* Referenced by rcu_barrier() and each call_rcu thread. */
833 urcu_ref_set(&completion
->ref
, count
+ 1);
834 completion
->barrier_count
= count
;
836 cds_list_for_each_entry(crdp
, &call_rcu_data_list
, list
) {
837 struct call_rcu_completion_work
*work
;
839 work
= calloc(sizeof(*work
), 1);
842 work
->completion
= completion
;
843 _call_rcu(&work
->head
, _rcu_barrier_complete
, crdp
);
845 call_rcu_unlock(&call_rcu_mutex
);
849 uatomic_dec(&completion
->futex
);
850 /* Decrement futex before reading barrier_count */
852 if (!uatomic_read(&completion
->barrier_count
))
854 call_rcu_completion_wait(completion
);
857 urcu_ref_put(&completion
->ref
, free_completion
);
865 * Acquire the call_rcu_mutex in order to ensure that the child sees
866 * all of the call_rcu() data structures in a consistent state. Ensure
867 * that all call_rcu threads are in a quiescent state across fork.
868 * Suitable for pthread_atfork() and friends.
870 void call_rcu_before_fork(void)
872 struct call_rcu_data
*crdp
;
874 call_rcu_lock(&call_rcu_mutex
);
876 cds_list_for_each_entry(crdp
, &call_rcu_data_list
, list
) {
877 uatomic_or(&crdp
->flags
, URCU_CALL_RCU_PAUSE
);
878 cmm_smp_mb__after_uatomic_or();
879 wake_call_rcu_thread(crdp
);
881 cds_list_for_each_entry(crdp
, &call_rcu_data_list
, list
) {
882 while ((uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_PAUSED
) == 0)
888 * Clean up call_rcu data structures in the parent of a successful fork()
889 * that is not followed by exec() in the child. Suitable for
890 * pthread_atfork() and friends.
892 void call_rcu_after_fork_parent(void)
894 struct call_rcu_data
*crdp
;
896 cds_list_for_each_entry(crdp
, &call_rcu_data_list
, list
)
897 uatomic_and(&crdp
->flags
, ~URCU_CALL_RCU_PAUSE
);
898 cds_list_for_each_entry(crdp
, &call_rcu_data_list
, list
) {
899 while ((uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_PAUSED
) != 0)
902 call_rcu_unlock(&call_rcu_mutex
);
906 * Clean up call_rcu data structures in the child of a successful fork()
907 * that is not followed by exec(). Suitable for pthread_atfork() and
910 void call_rcu_after_fork_child(void)
912 struct call_rcu_data
*crdp
, *next
;
914 /* Release the mutex. */
915 call_rcu_unlock(&call_rcu_mutex
);
917 /* Do nothing when call_rcu() has not been used */
918 if (cds_list_empty(&call_rcu_data_list
))
922 * Allocate a new default call_rcu_data structure in order
923 * to get a working call_rcu thread to go with it.
925 default_call_rcu_data
= NULL
;
926 (void)get_default_call_rcu_data();
928 /* Cleanup call_rcu_data pointers before use */
930 free(per_cpu_call_rcu_data
);
931 rcu_set_pointer(&per_cpu_call_rcu_data
, NULL
);
932 URCU_TLS(thread_call_rcu_data
) = NULL
;
935 * Dispose of all of the rest of the call_rcu_data structures.
936 * Leftover call_rcu callbacks will be merged into the new
937 * default call_rcu thread queue.
939 cds_list_for_each_entry_safe(crdp
, next
, &call_rcu_data_list
, list
) {
940 if (crdp
== default_call_rcu_data
)
942 uatomic_set(&crdp
->flags
, URCU_CALL_RCU_STOPPED
);
943 call_rcu_data_free(crdp
);