17911747bSPaolo Bonzini /* 27911747bSPaolo Bonzini * urcu-mb.c 37911747bSPaolo Bonzini * 47911747bSPaolo Bonzini * Userspace RCU library with explicit memory barriers 57911747bSPaolo Bonzini * 67911747bSPaolo Bonzini * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> 77911747bSPaolo Bonzini * Copyright (c) 2009 Paul E. McKenney, IBM Corporation. 87911747bSPaolo Bonzini * Copyright 2015 Red Hat, Inc. 97911747bSPaolo Bonzini * 107911747bSPaolo Bonzini * Ported to QEMU by Paolo Bonzini <pbonzini@redhat.com> 117911747bSPaolo Bonzini * 127911747bSPaolo Bonzini * This library is free software; you can redistribute it and/or 137911747bSPaolo Bonzini * modify it under the terms of the GNU Lesser General Public 147911747bSPaolo Bonzini * License as published by the Free Software Foundation; either 157911747bSPaolo Bonzini * version 2.1 of the License, or (at your option) any later version. 167911747bSPaolo Bonzini * 177911747bSPaolo Bonzini * This library is distributed in the hope that it will be useful, 187911747bSPaolo Bonzini * but WITHOUT ANY WARRANTY; without even the implied warranty of 197911747bSPaolo Bonzini * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 207911747bSPaolo Bonzini * Lesser General Public License for more details. 217911747bSPaolo Bonzini * 227911747bSPaolo Bonzini * You should have received a copy of the GNU Lesser General Public 237911747bSPaolo Bonzini * License along with this library; if not, write to the Free Software 247911747bSPaolo Bonzini * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 257911747bSPaolo Bonzini * 267911747bSPaolo Bonzini * IBM's contributions to this file may be relicensed under LGPLv2 or later. 277911747bSPaolo Bonzini */ 287911747bSPaolo Bonzini 29aafd7584SPeter Maydell #include "qemu/osdep.h" 3026387f86SPaolo Bonzini #include "qemu-common.h" 317911747bSPaolo Bonzini #include "qemu/rcu.h" 327911747bSPaolo Bonzini #include "qemu/atomic.h" 3326387f86SPaolo Bonzini #include "qemu/thread.h" 34a4649824SPaolo Bonzini #include "qemu/main-loop.h" 355a22ab71SYang Zhong #if defined(CONFIG_MALLOC_TRIM) 365a22ab71SYang Zhong #include <malloc.h> 375a22ab71SYang Zhong #endif 387911747bSPaolo Bonzini 397911747bSPaolo Bonzini /* 407911747bSPaolo Bonzini * Global grace period counter. Bit 0 is always one in rcu_gp_ctr. 417911747bSPaolo Bonzini * Bits 1 and above are defined in synchronize_rcu. 427911747bSPaolo Bonzini */ 437911747bSPaolo Bonzini #define RCU_GP_LOCKED (1UL << 0) 447911747bSPaolo Bonzini #define RCU_GP_CTR (1UL << 1) 457911747bSPaolo Bonzini 467911747bSPaolo Bonzini unsigned long rcu_gp_ctr = RCU_GP_LOCKED; 477911747bSPaolo Bonzini 487911747bSPaolo Bonzini QemuEvent rcu_gp_event; 49c097a60bSWen Congyang static QemuMutex rcu_registry_lock; 50c097a60bSWen Congyang static QemuMutex rcu_sync_lock; 517911747bSPaolo Bonzini 527911747bSPaolo Bonzini /* 537911747bSPaolo Bonzini * Check whether a quiescent state was crossed between the beginning of 547911747bSPaolo Bonzini * update_counter_and_wait and now. 557911747bSPaolo Bonzini */ 567911747bSPaolo Bonzini static inline int rcu_gp_ongoing(unsigned long *ctr) 577911747bSPaolo Bonzini { 587911747bSPaolo Bonzini unsigned long v; 597911747bSPaolo Bonzini 607911747bSPaolo Bonzini v = atomic_read(ctr); 617911747bSPaolo Bonzini return v && (v != rcu_gp_ctr); 627911747bSPaolo Bonzini } 637911747bSPaolo Bonzini 647911747bSPaolo Bonzini /* Written to only by each individual reader. Read by both the reader and the 657911747bSPaolo Bonzini * writers. 667911747bSPaolo Bonzini */ 677911747bSPaolo Bonzini __thread struct rcu_reader_data rcu_reader; 687911747bSPaolo Bonzini 69c097a60bSWen Congyang /* Protected by rcu_registry_lock. */ 707911747bSPaolo Bonzini typedef QLIST_HEAD(, rcu_reader_data) ThreadList; 717911747bSPaolo Bonzini static ThreadList registry = QLIST_HEAD_INITIALIZER(registry); 727911747bSPaolo Bonzini 737911747bSPaolo Bonzini /* Wait for previous parity/grace period to be empty of readers. */ 747911747bSPaolo Bonzini static void wait_for_readers(void) 757911747bSPaolo Bonzini { 767911747bSPaolo Bonzini ThreadList qsreaders = QLIST_HEAD_INITIALIZER(qsreaders); 777911747bSPaolo Bonzini struct rcu_reader_data *index, *tmp; 787911747bSPaolo Bonzini 797911747bSPaolo Bonzini for (;;) { 807911747bSPaolo Bonzini /* We want to be notified of changes made to rcu_gp_ongoing 817911747bSPaolo Bonzini * while we walk the list. 827911747bSPaolo Bonzini */ 837911747bSPaolo Bonzini qemu_event_reset(&rcu_gp_event); 847911747bSPaolo Bonzini 857911747bSPaolo Bonzini /* Instead of using atomic_mb_set for index->waiting, and 867911747bSPaolo Bonzini * atomic_mb_read for index->ctr, memory barriers are placed 877911747bSPaolo Bonzini * manually since writes to different threads are independent. 88e11131b0SPaolo Bonzini * qemu_event_reset has acquire semantics, so no memory barrier 89e11131b0SPaolo Bonzini * is needed here. 907911747bSPaolo Bonzini */ 917911747bSPaolo Bonzini QLIST_FOREACH(index, ®istry, node) { 927911747bSPaolo Bonzini atomic_set(&index->waiting, true); 937911747bSPaolo Bonzini } 947911747bSPaolo Bonzini 95*77a8b846SPaolo Bonzini /* Here, order the stores to index->waiting before the loads of 96*77a8b846SPaolo Bonzini * index->ctr. Pairs with smp_mb() in rcu_read_unlock(), 97*77a8b846SPaolo Bonzini * ensuring that the loads of index->ctr are sequentially consistent. 98e11131b0SPaolo Bonzini */ 997911747bSPaolo Bonzini smp_mb(); 1007911747bSPaolo Bonzini 1017911747bSPaolo Bonzini QLIST_FOREACH_SAFE(index, ®istry, node, tmp) { 1027911747bSPaolo Bonzini if (!rcu_gp_ongoing(&index->ctr)) { 1037911747bSPaolo Bonzini QLIST_REMOVE(index, node); 1047911747bSPaolo Bonzini QLIST_INSERT_HEAD(&qsreaders, index, node); 1057911747bSPaolo Bonzini 1067911747bSPaolo Bonzini /* No need for mb_set here, worst of all we 1077911747bSPaolo Bonzini * get some extra futex wakeups. 1087911747bSPaolo Bonzini */ 1097911747bSPaolo Bonzini atomic_set(&index->waiting, false); 1107911747bSPaolo Bonzini } 1117911747bSPaolo Bonzini } 1127911747bSPaolo Bonzini 1137911747bSPaolo Bonzini if (QLIST_EMPTY(®istry)) { 1147911747bSPaolo Bonzini break; 1157911747bSPaolo Bonzini } 1167911747bSPaolo Bonzini 117c097a60bSWen Congyang /* Wait for one thread to report a quiescent state and try again. 118c097a60bSWen Congyang * Release rcu_registry_lock, so rcu_(un)register_thread() doesn't 119c097a60bSWen Congyang * wait too much time. 120c097a60bSWen Congyang * 121c097a60bSWen Congyang * rcu_register_thread() may add nodes to ®istry; it will not 122c097a60bSWen Congyang * wake up synchronize_rcu, but that is okay because at least another 123c097a60bSWen Congyang * thread must exit its RCU read-side critical section before 124c097a60bSWen Congyang * synchronize_rcu is done. The next iteration of the loop will 125c097a60bSWen Congyang * move the new thread's rcu_reader from ®istry to &qsreaders, 126c097a60bSWen Congyang * because rcu_gp_ongoing() will return false. 127c097a60bSWen Congyang * 128c097a60bSWen Congyang * rcu_unregister_thread() may remove nodes from &qsreaders instead 129c097a60bSWen Congyang * of ®istry if it runs during qemu_event_wait. That's okay; 130c097a60bSWen Congyang * the node then will not be added back to ®istry by QLIST_SWAP 131c097a60bSWen Congyang * below. The invariant is that the node is part of one list when 132c097a60bSWen Congyang * rcu_registry_lock is released. 1337911747bSPaolo Bonzini */ 134c097a60bSWen Congyang qemu_mutex_unlock(&rcu_registry_lock); 1357911747bSPaolo Bonzini qemu_event_wait(&rcu_gp_event); 136c097a60bSWen Congyang qemu_mutex_lock(&rcu_registry_lock); 1377911747bSPaolo Bonzini } 1387911747bSPaolo Bonzini 1397911747bSPaolo Bonzini /* put back the reader list in the registry */ 1407911747bSPaolo Bonzini QLIST_SWAP(®istry, &qsreaders, node); 1417911747bSPaolo Bonzini } 1427911747bSPaolo Bonzini 1437911747bSPaolo Bonzini void synchronize_rcu(void) 1447911747bSPaolo Bonzini { 145c097a60bSWen Congyang qemu_mutex_lock(&rcu_sync_lock); 1467911747bSPaolo Bonzini 147*77a8b846SPaolo Bonzini /* Write RCU-protected pointers before reading p_rcu_reader->ctr. 148*77a8b846SPaolo Bonzini * Pairs with smp_mb() in rcu_read_lock(). 149*77a8b846SPaolo Bonzini */ 150*77a8b846SPaolo Bonzini smp_mb(); 151*77a8b846SPaolo Bonzini 152*77a8b846SPaolo Bonzini qemu_mutex_lock(&rcu_registry_lock); 1537911747bSPaolo Bonzini if (!QLIST_EMPTY(®istry)) { 1547911747bSPaolo Bonzini /* In either case, the atomic_mb_set below blocks stores that free 1557911747bSPaolo Bonzini * old RCU-protected pointers. 1567911747bSPaolo Bonzini */ 1577911747bSPaolo Bonzini if (sizeof(rcu_gp_ctr) < 8) { 1587911747bSPaolo Bonzini /* For architectures with 32-bit longs, a two-subphases algorithm 1597911747bSPaolo Bonzini * ensures we do not encounter overflow bugs. 1607911747bSPaolo Bonzini * 1617911747bSPaolo Bonzini * Switch parity: 0 -> 1, 1 -> 0. 1627911747bSPaolo Bonzini */ 1637911747bSPaolo Bonzini atomic_mb_set(&rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR); 1647911747bSPaolo Bonzini wait_for_readers(); 1657911747bSPaolo Bonzini atomic_mb_set(&rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR); 1667911747bSPaolo Bonzini } else { 1677911747bSPaolo Bonzini /* Increment current grace period. */ 1687911747bSPaolo Bonzini atomic_mb_set(&rcu_gp_ctr, rcu_gp_ctr + RCU_GP_CTR); 1697911747bSPaolo Bonzini } 1707911747bSPaolo Bonzini 1717911747bSPaolo Bonzini wait_for_readers(); 1727911747bSPaolo Bonzini } 1737911747bSPaolo Bonzini 174c097a60bSWen Congyang qemu_mutex_unlock(&rcu_registry_lock); 175c097a60bSWen Congyang qemu_mutex_unlock(&rcu_sync_lock); 1767911747bSPaolo Bonzini } 1777911747bSPaolo Bonzini 17826387f86SPaolo Bonzini 17926387f86SPaolo Bonzini #define RCU_CALL_MIN_SIZE 30 18026387f86SPaolo Bonzini 18126387f86SPaolo Bonzini /* Multi-producer, single-consumer queue based on urcu/static/wfqueue.h 18226387f86SPaolo Bonzini * from liburcu. Note that head is only used by the consumer. 18326387f86SPaolo Bonzini */ 18426387f86SPaolo Bonzini static struct rcu_head dummy; 18526387f86SPaolo Bonzini static struct rcu_head *head = &dummy, **tail = &dummy.next; 18626387f86SPaolo Bonzini static int rcu_call_count; 18726387f86SPaolo Bonzini static QemuEvent rcu_call_ready_event; 18826387f86SPaolo Bonzini 18926387f86SPaolo Bonzini static void enqueue(struct rcu_head *node) 19026387f86SPaolo Bonzini { 19126387f86SPaolo Bonzini struct rcu_head **old_tail; 19226387f86SPaolo Bonzini 19326387f86SPaolo Bonzini node->next = NULL; 19426387f86SPaolo Bonzini old_tail = atomic_xchg(&tail, &node->next); 19526387f86SPaolo Bonzini atomic_mb_set(old_tail, node); 19626387f86SPaolo Bonzini } 19726387f86SPaolo Bonzini 19826387f86SPaolo Bonzini static struct rcu_head *try_dequeue(void) 19926387f86SPaolo Bonzini { 20026387f86SPaolo Bonzini struct rcu_head *node, *next; 20126387f86SPaolo Bonzini 20226387f86SPaolo Bonzini retry: 20326387f86SPaolo Bonzini /* Test for an empty list, which we do not expect. Note that for 20426387f86SPaolo Bonzini * the consumer head and tail are always consistent. The head 20526387f86SPaolo Bonzini * is consistent because only the consumer reads/writes it. 20626387f86SPaolo Bonzini * The tail, because it is the first step in the enqueuing. 20726387f86SPaolo Bonzini * It is only the next pointers that might be inconsistent. 20826387f86SPaolo Bonzini */ 20926387f86SPaolo Bonzini if (head == &dummy && atomic_mb_read(&tail) == &dummy.next) { 21026387f86SPaolo Bonzini abort(); 21126387f86SPaolo Bonzini } 21226387f86SPaolo Bonzini 21326387f86SPaolo Bonzini /* If the head node has NULL in its next pointer, the value is 21426387f86SPaolo Bonzini * wrong and we need to wait until its enqueuer finishes the update. 21526387f86SPaolo Bonzini */ 21626387f86SPaolo Bonzini node = head; 21726387f86SPaolo Bonzini next = atomic_mb_read(&head->next); 21826387f86SPaolo Bonzini if (!next) { 21926387f86SPaolo Bonzini return NULL; 22026387f86SPaolo Bonzini } 22126387f86SPaolo Bonzini 22226387f86SPaolo Bonzini /* Since we are the sole consumer, and we excluded the empty case 22326387f86SPaolo Bonzini * above, the queue will always have at least two nodes: the 22426387f86SPaolo Bonzini * dummy node, and the one being removed. So we do not need to update 22526387f86SPaolo Bonzini * the tail pointer. 22626387f86SPaolo Bonzini */ 22726387f86SPaolo Bonzini head = next; 22826387f86SPaolo Bonzini 22926387f86SPaolo Bonzini /* If we dequeued the dummy node, add it back at the end and retry. */ 23026387f86SPaolo Bonzini if (node == &dummy) { 23126387f86SPaolo Bonzini enqueue(node); 23226387f86SPaolo Bonzini goto retry; 23326387f86SPaolo Bonzini } 23426387f86SPaolo Bonzini 23526387f86SPaolo Bonzini return node; 23626387f86SPaolo Bonzini } 23726387f86SPaolo Bonzini 23826387f86SPaolo Bonzini static void *call_rcu_thread(void *opaque) 23926387f86SPaolo Bonzini { 24026387f86SPaolo Bonzini struct rcu_head *node; 24126387f86SPaolo Bonzini 242ab28bd23SPaolo Bonzini rcu_register_thread(); 243ab28bd23SPaolo Bonzini 24426387f86SPaolo Bonzini for (;;) { 24526387f86SPaolo Bonzini int tries = 0; 24626387f86SPaolo Bonzini int n = atomic_read(&rcu_call_count); 24726387f86SPaolo Bonzini 24826387f86SPaolo Bonzini /* Heuristically wait for a decent number of callbacks to pile up. 24926387f86SPaolo Bonzini * Fetch rcu_call_count now, we only must process elements that were 25026387f86SPaolo Bonzini * added before synchronize_rcu() starts. 25126387f86SPaolo Bonzini */ 252a7d1d636SPaolo Bonzini while (n == 0 || (n < RCU_CALL_MIN_SIZE && ++tries <= 5)) { 253a7d1d636SPaolo Bonzini g_usleep(10000); 254a7d1d636SPaolo Bonzini if (n == 0) { 25526387f86SPaolo Bonzini qemu_event_reset(&rcu_call_ready_event); 25626387f86SPaolo Bonzini n = atomic_read(&rcu_call_count); 257a7d1d636SPaolo Bonzini if (n == 0) { 2585a22ab71SYang Zhong #if defined(CONFIG_MALLOC_TRIM) 2595a22ab71SYang Zhong malloc_trim(4 * 1024 * 1024); 2605a22ab71SYang Zhong #endif 26126387f86SPaolo Bonzini qemu_event_wait(&rcu_call_ready_event); 26226387f86SPaolo Bonzini } 26326387f86SPaolo Bonzini } 264a7d1d636SPaolo Bonzini n = atomic_read(&rcu_call_count); 265a7d1d636SPaolo Bonzini } 26626387f86SPaolo Bonzini 26726387f86SPaolo Bonzini atomic_sub(&rcu_call_count, n); 26826387f86SPaolo Bonzini synchronize_rcu(); 269a4649824SPaolo Bonzini qemu_mutex_lock_iothread(); 27026387f86SPaolo Bonzini while (n > 0) { 27126387f86SPaolo Bonzini node = try_dequeue(); 27226387f86SPaolo Bonzini while (!node) { 273a4649824SPaolo Bonzini qemu_mutex_unlock_iothread(); 27426387f86SPaolo Bonzini qemu_event_reset(&rcu_call_ready_event); 27526387f86SPaolo Bonzini node = try_dequeue(); 27626387f86SPaolo Bonzini if (!node) { 27726387f86SPaolo Bonzini qemu_event_wait(&rcu_call_ready_event); 27826387f86SPaolo Bonzini node = try_dequeue(); 27926387f86SPaolo Bonzini } 280a4649824SPaolo Bonzini qemu_mutex_lock_iothread(); 28126387f86SPaolo Bonzini } 28226387f86SPaolo Bonzini 28326387f86SPaolo Bonzini n--; 28426387f86SPaolo Bonzini node->func(node); 28526387f86SPaolo Bonzini } 286a4649824SPaolo Bonzini qemu_mutex_unlock_iothread(); 28726387f86SPaolo Bonzini } 28826387f86SPaolo Bonzini abort(); 28926387f86SPaolo Bonzini } 29026387f86SPaolo Bonzini 29126387f86SPaolo Bonzini void call_rcu1(struct rcu_head *node, void (*func)(struct rcu_head *node)) 29226387f86SPaolo Bonzini { 29326387f86SPaolo Bonzini node->func = func; 29426387f86SPaolo Bonzini enqueue(node); 29526387f86SPaolo Bonzini atomic_inc(&rcu_call_count); 29626387f86SPaolo Bonzini qemu_event_set(&rcu_call_ready_event); 29726387f86SPaolo Bonzini } 29826387f86SPaolo Bonzini 2997911747bSPaolo Bonzini void rcu_register_thread(void) 3007911747bSPaolo Bonzini { 3017911747bSPaolo Bonzini assert(rcu_reader.ctr == 0); 302c097a60bSWen Congyang qemu_mutex_lock(&rcu_registry_lock); 3037911747bSPaolo Bonzini QLIST_INSERT_HEAD(®istry, &rcu_reader, node); 304c097a60bSWen Congyang qemu_mutex_unlock(&rcu_registry_lock); 3057911747bSPaolo Bonzini } 3067911747bSPaolo Bonzini 3077911747bSPaolo Bonzini void rcu_unregister_thread(void) 3087911747bSPaolo Bonzini { 309c097a60bSWen Congyang qemu_mutex_lock(&rcu_registry_lock); 3107911747bSPaolo Bonzini QLIST_REMOVE(&rcu_reader, node); 311c097a60bSWen Congyang qemu_mutex_unlock(&rcu_registry_lock); 3127911747bSPaolo Bonzini } 3137911747bSPaolo Bonzini 31421b7cf9eSPaolo Bonzini static void rcu_init_complete(void) 3157911747bSPaolo Bonzini { 31626387f86SPaolo Bonzini QemuThread thread; 31726387f86SPaolo Bonzini 318c097a60bSWen Congyang qemu_mutex_init(&rcu_registry_lock); 319c097a60bSWen Congyang qemu_mutex_init(&rcu_sync_lock); 3207911747bSPaolo Bonzini qemu_event_init(&rcu_gp_event, true); 32126387f86SPaolo Bonzini 32226387f86SPaolo Bonzini qemu_event_init(&rcu_call_ready_event, false); 32321b7cf9eSPaolo Bonzini 32421b7cf9eSPaolo Bonzini /* The caller is assumed to have iothread lock, so the call_rcu thread 32521b7cf9eSPaolo Bonzini * must have been quiescent even after forking, just recreate it. 32621b7cf9eSPaolo Bonzini */ 32726387f86SPaolo Bonzini qemu_thread_create(&thread, "call_rcu", call_rcu_thread, 32826387f86SPaolo Bonzini NULL, QEMU_THREAD_DETACHED); 32926387f86SPaolo Bonzini 3307911747bSPaolo Bonzini rcu_register_thread(); 3317911747bSPaolo Bonzini } 33221b7cf9eSPaolo Bonzini 33373c6e401SPaolo Bonzini static int atfork_depth = 1; 33473c6e401SPaolo Bonzini 33573c6e401SPaolo Bonzini void rcu_enable_atfork(void) 33673c6e401SPaolo Bonzini { 33773c6e401SPaolo Bonzini atfork_depth++; 33873c6e401SPaolo Bonzini } 33973c6e401SPaolo Bonzini 34073c6e401SPaolo Bonzini void rcu_disable_atfork(void) 34173c6e401SPaolo Bonzini { 34273c6e401SPaolo Bonzini atfork_depth--; 34373c6e401SPaolo Bonzini } 34473c6e401SPaolo Bonzini 34521b7cf9eSPaolo Bonzini #ifdef CONFIG_POSIX 34621b7cf9eSPaolo Bonzini static void rcu_init_lock(void) 34721b7cf9eSPaolo Bonzini { 34873c6e401SPaolo Bonzini if (atfork_depth < 1) { 34973c6e401SPaolo Bonzini return; 35073c6e401SPaolo Bonzini } 35173c6e401SPaolo Bonzini 352c097a60bSWen Congyang qemu_mutex_lock(&rcu_sync_lock); 353c097a60bSWen Congyang qemu_mutex_lock(&rcu_registry_lock); 35421b7cf9eSPaolo Bonzini } 35521b7cf9eSPaolo Bonzini 35621b7cf9eSPaolo Bonzini static void rcu_init_unlock(void) 35721b7cf9eSPaolo Bonzini { 35873c6e401SPaolo Bonzini if (atfork_depth < 1) { 35973c6e401SPaolo Bonzini return; 36073c6e401SPaolo Bonzini } 36173c6e401SPaolo Bonzini 362c097a60bSWen Congyang qemu_mutex_unlock(&rcu_registry_lock); 363c097a60bSWen Congyang qemu_mutex_unlock(&rcu_sync_lock); 36421b7cf9eSPaolo Bonzini } 36521b7cf9eSPaolo Bonzini 3662a96a552SPaolo Bonzini static void rcu_init_child(void) 36721b7cf9eSPaolo Bonzini { 3682a96a552SPaolo Bonzini if (atfork_depth < 1) { 3692a96a552SPaolo Bonzini return; 3702a96a552SPaolo Bonzini } 3712a96a552SPaolo Bonzini 37221b7cf9eSPaolo Bonzini memset(®istry, 0, sizeof(registry)); 37321b7cf9eSPaolo Bonzini rcu_init_complete(); 37421b7cf9eSPaolo Bonzini } 3752a96a552SPaolo Bonzini #endif 37621b7cf9eSPaolo Bonzini 37721b7cf9eSPaolo Bonzini static void __attribute__((__constructor__)) rcu_init(void) 37821b7cf9eSPaolo Bonzini { 37921b7cf9eSPaolo Bonzini #ifdef CONFIG_POSIX 3802a96a552SPaolo Bonzini pthread_atfork(rcu_init_lock, rcu_init_unlock, rcu_init_child); 38121b7cf9eSPaolo Bonzini #endif 38221b7cf9eSPaolo Bonzini rcu_init_complete(); 38321b7cf9eSPaolo Bonzini } 384