+// SPDX-FileCopyrightText: 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+// SPDX-FileCopyrightText: 2009 Paul E. McKenney, IBM Corporation.
+//
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
/*
- * urcu-qsbr.c
- *
* Userspace RCU QSBR library
*
- * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- *
* IBM's contributions to this file may be relicensed under LGPLv2 or later.
*/
+#define URCU_NO_COMPAT_IDENTIFIERS
#define _LGPL_SOURCE
#include <stdio.h>
#include <pthread.h>
#include <signal.h>
-#include <assert.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <poll.h>
-#include "urcu/wfcqueue.h"
-#include "urcu/map/urcu-qsbr.h"
+#include <urcu/annotate.h>
+#include <urcu/assert.h>
+#include <urcu/wfcqueue.h>
+#include <urcu/map/urcu-qsbr.h>
#define BUILD_QSBR_LIB
-#include "urcu/static/urcu-qsbr.h"
-#include "urcu-pointer.h"
-#include "urcu/tls-compat.h"
+#include <urcu/static/urcu-qsbr.h>
+#include <urcu/pointer.h>
+#include <urcu/tls-compat.h>
#include "urcu-die.h"
#include "urcu-wait.h"
+#include "urcu-utils.h"
+#define URCU_API_MAP
/* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
#undef _LGPL_SOURCE
-#include "urcu-qsbr.h"
+#include <urcu/urcu-qsbr.h>
#define _LGPL_SOURCE
-void __attribute__((destructor)) rcu_exit(void);
+void __attribute__((destructor)) urcu_qsbr_exit(void);
+static void urcu_call_rcu_exit(void);
/*
* rcu_gp_lock ensures mutual exclusion between threads calling
* rcu_registry_lock may nest inside rcu_gp_lock.
*/
static pthread_mutex_t rcu_registry_lock = PTHREAD_MUTEX_INITIALIZER;
-struct rcu_gp rcu_gp = { .ctr = RCU_GP_ONLINE };
+struct urcu_gp urcu_qsbr_gp = { .ctr = URCU_QSBR_GP_ONLINE };
/*
* Active attempts to check for reader Q.S. before calling futex().
* Written to only by each individual reader. Read by both the reader and the
* writers.
*/
-DEFINE_URCU_TLS(struct rcu_reader, rcu_reader);
+DEFINE_URCU_TLS(struct urcu_qsbr_reader, urcu_qsbr_reader);
static CDS_LIST_HEAD(registry);
{
/* Read reader_gp before read futex */
cmm_smp_rmb();
- if (uatomic_read(&rcu_gp.futex) != -1)
- return;
- while (futex_noasync(&rcu_gp.futex, FUTEX_WAIT, -1,
- NULL, NULL, 0)) {
+ while (uatomic_read(&urcu_qsbr_gp.futex) == -1) {
+ if (!futex_noasync(&urcu_qsbr_gp.futex, FUTEX_WAIT, -1, NULL, NULL, 0)) {
+ /*
+ * Prior queued wakeups queued by unrelated code
+ * using the same address can cause futex wait to
+ * return 0 even through the futex value is still
+ * -1 (spurious wakeups). Check the value again
+ * in user-space to validate whether it really
+ * differs from -1.
+ */
+ continue;
+ }
switch (errno) {
- case EWOULDBLOCK:
+ case EAGAIN:
/* Value already changed. */
return;
case EINTR:
/* Retry if interrupted by signal. */
- break; /* Get out of switch. */
+ break; /* Get out of switch. Check again. */
default:
/* Unexpected error. */
urcu_die(errno);
*/
static void wait_for_readers(struct cds_list_head *input_readers,
struct cds_list_head *cur_snap_readers,
- struct cds_list_head *qsreaders)
+ struct cds_list_head *qsreaders,
+ cmm_annotate_t *group)
{
unsigned int wait_loops = 0;
- struct rcu_reader *index, *tmp;
+ struct urcu_qsbr_reader *index, *tmp;
/*
- * Wait for each thread URCU_TLS(rcu_reader).ctr to either
+ * Wait for each thread URCU_TLS(urcu_qsbr_reader).ctr to either
* indicate quiescence (offline), or for them to observe the
- * current rcu_gp.ctr value.
+ * current urcu_qsbr_gp.ctr value.
*/
for (;;) {
if (wait_loops < RCU_QS_ACTIVE_ATTEMPTS)
wait_loops++;
if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
- uatomic_set(&rcu_gp.futex, -1);
+ uatomic_set(&urcu_qsbr_gp.futex, -1);
/*
* Write futex before write waiting (the other side
* reads them in the opposite order).
cmm_smp_mb();
}
cds_list_for_each_entry_safe(index, tmp, input_readers, node) {
- switch (rcu_reader_state(&index->ctr)) {
- case RCU_READER_ACTIVE_CURRENT:
+ switch (urcu_qsbr_reader_state(&index->ctr, group)) {
+ case URCU_READER_ACTIVE_CURRENT:
if (cur_snap_readers) {
cds_list_move(&index->node,
cur_snap_readers);
break;
}
/* Fall-through */
- case RCU_READER_INACTIVE:
+ case URCU_READER_INACTIVE:
cds_list_move(&index->node, qsreaders);
break;
- case RCU_READER_ACTIVE_OLD:
+ case URCU_READER_ACTIVE_OLD:
/*
* Old snapshot. Leaving node in
* input_readers will make us busy-loop
if (cds_list_empty(input_readers)) {
if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
/* Read reader_gp before write futex */
- cmm_smp_mb();
- uatomic_set(&rcu_gp.futex, 0);
+ uatomic_store(&urcu_qsbr_gp.futex, 0, CMM_RELEASE);
}
break;
} else {
*/
#if (CAA_BITS_PER_LONG < 64)
-void synchronize_rcu(void)
+void urcu_qsbr_synchronize_rcu(void)
{
+ cmm_annotate_define(acquire_group);
+ cmm_annotate_define(release_group);
CDS_LIST_HEAD(cur_snap_readers);
CDS_LIST_HEAD(qsreaders);
unsigned long was_online;
DEFINE_URCU_WAIT_NODE(wait, URCU_WAIT_WAITING);
struct urcu_waiters waiters;
- was_online = rcu_read_ongoing();
+ was_online = urcu_qsbr_read_ongoing();
/* All threads should read qparity before accessing data structure
* where new ptr points to. In the "then" case, rcu_thread_offline
* in threads registered as readers.
*/
if (was_online)
- rcu_thread_offline();
+ urcu_qsbr_thread_offline();
else
cmm_smp_mb();
+ cmm_annotate_group_mb_release(&release_group);
/*
* Add ourself to gp_waiters queue of threads awaiting to wait
/*
* Wait for readers to observe original parity or be quiescent.
* wait_for_readers() can release and grab again rcu_registry_lock
- * interally.
+ * internally.
*/
- wait_for_readers(®istry, &cur_snap_readers, &qsreaders);
+ wait_for_readers(®istry, &cur_snap_readers, &qsreaders, &acquire_group);
/*
* Must finish waiting for quiescent state for original parity
- * before committing next rcu_gp.ctr update to memory. Failure
+ * before committing next urcu_qsbr_gp.ctr update to memory. Failure
* to do so could result in the writer waiting forever while new
* readers are always accessing data (no progress). Enforce
- * compiler-order of load URCU_TLS(rcu_reader).ctr before store
- * to rcu_gp.ctr.
+ * compiler-order of load URCU_TLS(urcu_qsbr_reader).ctr before store
+ * to urcu_qsbr_gp.ctr.
*/
cmm_barrier();
cmm_smp_mb();
/* Switch parity: 0 -> 1, 1 -> 0 */
- CMM_STORE_SHARED(rcu_gp.ctr, rcu_gp.ctr ^ RCU_GP_CTR);
+ cmm_annotate_group_mem_release(&release_group, &urcu_qsbr_gp.ctr);
+ uatomic_store(&urcu_qsbr_gp.ctr, urcu_qsbr_gp.ctr ^ URCU_QSBR_GP_CTR, CMM_RELAXED);
/*
- * Must commit rcu_gp.ctr update to memory before waiting for
+ * Must commit urcu_qsbr_gp.ctr update to memory before waiting for
* quiescent state. Failure to do so could result in the writer
* waiting forever while new readers are always accessing data
- * (no progress). Enforce compiler-order of store to rcu_gp.ctr
- * before load URCU_TLS(rcu_reader).ctr.
+ * (no progress). Enforce compiler-order of store to urcu_qsbr_gp.ctr
+ * before load URCU_TLS(urcu_qsbr_reader).ctr.
*/
cmm_barrier();
/*
* Wait for readers to observe new parity or be quiescent.
* wait_for_readers() can release and grab again rcu_registry_lock
- * interally.
+ * internally.
*/
- wait_for_readers(&cur_snap_readers, NULL, &qsreaders);
+ wait_for_readers(&cur_snap_readers, NULL, &qsreaders, &acquire_group);
/*
* Put quiescent reader list back into registry.
* Finish waiting for reader threads before letting the old ptr being
* freed.
*/
+ cmm_annotate_group_mb_acquire(&acquire_group);
+
if (was_online)
- rcu_thread_online();
+ urcu_qsbr_thread_online();
else
cmm_smp_mb();
}
#else /* !(CAA_BITS_PER_LONG < 64) */
-void synchronize_rcu(void)
+void urcu_qsbr_synchronize_rcu(void)
{
+ cmm_annotate_define(acquire_group);
+ cmm_annotate_define(release_group);
CDS_LIST_HEAD(qsreaders);
unsigned long was_online;
DEFINE_URCU_WAIT_NODE(wait, URCU_WAIT_WAITING);
struct urcu_waiters waiters;
- was_online = rcu_read_ongoing();
+ was_online = urcu_qsbr_read_ongoing();
/*
* Mark the writer thread offline to make sure we don't wait for
* in threads registered as readers.
*/
if (was_online)
- rcu_thread_offline();
+ urcu_qsbr_thread_offline();
else
cmm_smp_mb();
+ cmm_annotate_group_mb_release(&release_group);
/*
* Add ourself to gp_waiters queue of threads awaiting to wait
goto out;
/* Increment current G.P. */
- CMM_STORE_SHARED(rcu_gp.ctr, rcu_gp.ctr + RCU_GP_CTR);
+ cmm_annotate_group_mem_release(&release_group, &urcu_qsbr_gp.ctr);
+ uatomic_store(&urcu_qsbr_gp.ctr, urcu_qsbr_gp.ctr + URCU_QSBR_GP_CTR, CMM_RELAXED);
/*
- * Must commit rcu_gp.ctr update to memory before waiting for
+ * Must commit urcu_qsbr_gp.ctr update to memory before waiting for
* quiescent state. Failure to do so could result in the writer
* waiting forever while new readers are always accessing data
- * (no progress). Enforce compiler-order of store to rcu_gp.ctr
- * before load URCU_TLS(rcu_reader).ctr.
+ * (no progress). Enforce compiler-order of store to urcu_qsbr_gp.ctr
+ * before load URCU_TLS(urcu_qsbr_reader).ctr.
*/
cmm_barrier();
/*
* Wait for readers to observe new count of be quiescent.
* wait_for_readers() can release and grab again rcu_registry_lock
- * interally.
+ * internally.
*/
- wait_for_readers(®istry, NULL, &qsreaders);
+ wait_for_readers(®istry, NULL, &qsreaders, &acquire_group);
/*
* Put quiescent reader list back into registry.
urcu_wake_all_waiters(&waiters);
gp_end:
if (was_online)
- rcu_thread_online();
+ urcu_qsbr_thread_online();
else
cmm_smp_mb();
+
+ cmm_annotate_group_mb_acquire(&acquire_group);
}
#endif /* !(CAA_BITS_PER_LONG < 64) */
* library wrappers to be used by non-LGPL compatible source code.
*/
-void rcu_read_lock(void)
+void urcu_qsbr_read_lock(void)
{
- _rcu_read_lock();
+ _urcu_qsbr_read_lock();
}
-void rcu_read_unlock(void)
+void urcu_qsbr_read_unlock(void)
{
- _rcu_read_unlock();
+ _urcu_qsbr_read_unlock();
}
-int rcu_read_ongoing(void)
+int urcu_qsbr_read_ongoing(void)
{
- return _rcu_read_ongoing();
+ return _urcu_qsbr_read_ongoing();
}
+void rcu_read_ongoing_qsbr();
-void rcu_quiescent_state(void)
+void urcu_qsbr_quiescent_state(void)
{
- _rcu_quiescent_state();
+ _urcu_qsbr_quiescent_state();
}
+void rcu_quiescent_state_qsbr();
-void rcu_thread_offline(void)
+void urcu_qsbr_thread_offline(void)
{
- _rcu_thread_offline();
+ _urcu_qsbr_thread_offline();
}
+void rcu_thread_offline_qsbr();
-void rcu_thread_online(void)
+void urcu_qsbr_thread_online(void)
{
- _rcu_thread_online();
+ _urcu_qsbr_thread_online();
}
-void rcu_register_thread(void)
+void urcu_qsbr_register_thread(void)
{
- URCU_TLS(rcu_reader).tid = pthread_self();
- assert(URCU_TLS(rcu_reader).ctr == 0);
+ URCU_TLS(urcu_qsbr_reader).tid = pthread_self();
+ urcu_posix_assert(URCU_TLS(urcu_qsbr_reader).ctr == 0);
mutex_lock(&rcu_registry_lock);
- assert(!URCU_TLS(rcu_reader).registered);
- URCU_TLS(rcu_reader).registered = 1;
- cds_list_add(&URCU_TLS(rcu_reader).node, ®istry);
+ urcu_posix_assert(!URCU_TLS(urcu_qsbr_reader).registered);
+ URCU_TLS(urcu_qsbr_reader).registered = 1;
+ cds_list_add(&URCU_TLS(urcu_qsbr_reader).node, ®istry);
mutex_unlock(&rcu_registry_lock);
- _rcu_thread_online();
+ _urcu_qsbr_thread_online();
}
-void rcu_unregister_thread(void)
+void urcu_qsbr_unregister_thread(void)
{
/*
* We have to make the thread offline otherwise we end up dealocking
* with a waiting writer.
*/
- _rcu_thread_offline();
- assert(URCU_TLS(rcu_reader).registered);
- URCU_TLS(rcu_reader).registered = 0;
+ _urcu_qsbr_thread_offline();
+ urcu_posix_assert(URCU_TLS(urcu_qsbr_reader).registered);
+ URCU_TLS(urcu_qsbr_reader).registered = 0;
mutex_lock(&rcu_registry_lock);
- cds_list_del(&URCU_TLS(rcu_reader).node);
+ cds_list_del(&URCU_TLS(urcu_qsbr_reader).node);
mutex_unlock(&rcu_registry_lock);
}
-void rcu_exit(void)
+void urcu_qsbr_exit(void)
{
/*
* Assertion disabled because call_rcu threads are now rcu
* readers, and left running at exit.
- * assert(cds_list_empty(®istry));
+ * urcu_posix_assert(cds_list_empty(®istry));
*/
+ urcu_call_rcu_exit();
}
DEFINE_RCU_FLAVOR(rcu_flavor);
#include "urcu-call-rcu-impl.h"
#include "urcu-defer-impl.h"
+#include "urcu-poll-impl.h"
projects / urcu.git / blobdiff