+// 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.c
- *
* Userspace RCU 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.
*/
#include <stdio.h>
#include <pthread.h>
#include <signal.h>
-#include <assert.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <poll.h>
#include <urcu/config.h>
+#include <urcu/assert.h>
#include <urcu/arch.h>
#include <urcu/wfcqueue.h>
#include <urcu/map/urcu.h>
* uninitialized variable.
*/
int urcu_memb_has_sys_membarrier = 0;
-URCU_ATTR_ALIAS("urcu_memb_has_sys_membarrier")
-extern int rcu_has_sys_membarrier_memb;
#endif
void __attribute__((constructor)) rcu_init(void);
void rcu_init(void)
{
}
-URCU_ATTR_ALIAS(urcu_stringify(rcu_init))
-void alias_rcu_init(void);
#endif
#ifdef RCU_SIGNAL
static int init_done;
void __attribute__((constructor)) rcu_init(void);
-void __attribute__((destructor)) rcu_exit(void);
+
+static DEFINE_URCU_TLS(int, rcu_signal_was_blocked);
#endif
+void __attribute__((destructor)) rcu_exit(void);
+static void urcu_call_rcu_exit(void);
+
/*
* rcu_gp_lock ensures mutual exclusion between threads calling
* synchronize_rcu().
*/
static pthread_mutex_t rcu_registry_lock = PTHREAD_MUTEX_INITIALIZER;
struct urcu_gp rcu_gp = { .ctr = URCU_GP_COUNT };
-URCU_ATTR_ALIAS(urcu_stringify(rcu_gp))
-extern struct urcu_gp alias_rcu_gp;
/*
* Written to only by each individual reader. Read by both the reader and the
* writers.
*/
DEFINE_URCU_TLS(struct urcu_reader, rcu_reader);
-DEFINE_URCU_TLS_ALIAS(struct urcu_reader, rcu_reader, alias_rcu_reader);
static CDS_LIST_HEAD(registry);
smp_mb_master();
/* Temporarily unlock the registry lock. */
mutex_unlock(&rcu_registry_lock);
- if (uatomic_read(&rcu_gp.futex) != -1)
- goto end;
- while (futex_async(&rcu_gp.futex, FUTEX_WAIT, -1,
- NULL, NULL, 0)) {
+ while (uatomic_read(&rcu_gp.futex) == -1) {
+ if (!futex_async(&rcu_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. */
goto end;
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);
/*
* 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 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);
*/
urcu_wake_all_waiters(&waiters);
}
-URCU_ATTR_ALIAS(urcu_stringify(synchronize_rcu))
-void alias_synchronize_rcu();
/*
* library wrappers to be used by non-LGPL compatible source code.
{
_rcu_read_lock();
}
-URCU_ATTR_ALIAS(urcu_stringify(rcu_read_lock))
-void alias_rcu_read_lock();
void rcu_read_unlock(void)
{
_rcu_read_unlock();
}
-URCU_ATTR_ALIAS(urcu_stringify(rcu_read_unlock))
-void alias_rcu_read_unlock();
int rcu_read_ongoing(void)
{
return _rcu_read_ongoing();
}
-URCU_ATTR_ALIAS(urcu_stringify(rcu_read_ongoing))
-void alias_rcu_read_ongoing();
+
+#ifdef RCU_SIGNAL
+/*
+ * Make sure the signal used by the urcu-signal flavor is unblocked
+ * while the thread is registered.
+ */
+static
+void urcu_signal_unblock(void)
+{
+ sigset_t mask, oldmask;
+ int ret;
+
+ ret = sigemptyset(&mask);
+ urcu_posix_assert(!ret);
+ ret = sigaddset(&mask, SIGRCU);
+ urcu_posix_assert(!ret);
+ ret = pthread_sigmask(SIG_UNBLOCK, &mask, &oldmask);
+ urcu_posix_assert(!ret);
+ URCU_TLS(rcu_signal_was_blocked) = sigismember(&oldmask, SIGRCU);
+}
+
+static
+void urcu_signal_restore(void)
+{
+ sigset_t mask;
+ int ret;
+
+ if (!URCU_TLS(rcu_signal_was_blocked))
+ return;
+ ret = sigemptyset(&mask);
+ urcu_posix_assert(!ret);
+ ret = sigaddset(&mask, SIGRCU);
+ urcu_posix_assert(!ret);
+ ret = pthread_sigmask(SIG_BLOCK, &mask, NULL);
+ urcu_posix_assert(!ret);
+}
+#else
+static
+void urcu_signal_unblock(void) { }
+static
+void urcu_signal_restore(void) { }
+#endif
void rcu_register_thread(void)
{
+ urcu_signal_unblock();
+
URCU_TLS(rcu_reader).tid = pthread_self();
- assert(URCU_TLS(rcu_reader).need_mb == 0);
- assert(!(URCU_TLS(rcu_reader).ctr & URCU_GP_CTR_NEST_MASK));
+ urcu_posix_assert(URCU_TLS(rcu_reader).need_mb == 0);
+ urcu_posix_assert(!(URCU_TLS(rcu_reader).ctr & URCU_GP_CTR_NEST_MASK));
mutex_lock(&rcu_registry_lock);
- assert(!URCU_TLS(rcu_reader).registered);
+ urcu_posix_assert(!URCU_TLS(rcu_reader).registered);
URCU_TLS(rcu_reader).registered = 1;
rcu_init(); /* In case gcc does not support constructor attribute */
cds_list_add(&URCU_TLS(rcu_reader).node, ®istry);
mutex_unlock(&rcu_registry_lock);
}
-URCU_ATTR_ALIAS(urcu_stringify(rcu_register_thread))
-void alias_rcu_register_thread();
void rcu_unregister_thread(void)
{
mutex_lock(&rcu_registry_lock);
- assert(URCU_TLS(rcu_reader).registered);
+ urcu_posix_assert(URCU_TLS(rcu_reader).registered);
URCU_TLS(rcu_reader).registered = 0;
cds_list_del(&URCU_TLS(rcu_reader).node);
mutex_unlock(&rcu_registry_lock);
+
+ urcu_signal_restore();
}
-URCU_ATTR_ALIAS(urcu_stringify(rcu_unregister_thread))
-void alias_rcu_unregister_thread();
#ifdef RCU_MEMBARRIER
init_done = 1;
rcu_sys_membarrier_init();
}
-URCU_ATTR_ALIAS(urcu_stringify(rcu_init))
-void alias_rcu_init(void);
#endif
#ifdef RCU_SIGNAL
if (ret)
urcu_die(errno);
}
-URCU_ATTR_ALIAS(urcu_stringify(rcu_init))
-void alias_rcu_init(void);
+
+/*
+ * Don't unregister the SIGRCU signal handler anymore, because
+ * call_rcu threads could still be using it shortly before the
+ * application exits.
+ * Assertion disabled because call_rcu threads are now rcu
+ * readers, and left running at exit.
+ * urcu_posix_assert(cds_list_empty(®istry));
+ */
+
+#endif /* #ifdef RCU_SIGNAL */
void rcu_exit(void)
{
- /*
- * Don't unregister the SIGRCU signal handler anymore, because
- * call_rcu threads could still be using it shortly before the
- * application exits.
- * Assertion disabled because call_rcu threads are now rcu
- * readers, and left running at exit.
- * assert(cds_list_empty(®istry));
- */
+ urcu_call_rcu_exit();
}
-URCU_ATTR_ALIAS(urcu_stringify(rcu_exit))
-void alias_rcu_exit(void);
-
-#endif /* #ifdef RCU_SIGNAL */
DEFINE_RCU_FLAVOR(rcu_flavor);
-DEFINE_RCU_FLAVOR_ALIAS(rcu_flavor, alias_rcu_flavor);
#include "urcu-call-rcu-impl.h"
#include "urcu-defer-impl.h"
+#include "urcu-poll-impl.h"
projects / userspace-rcu.git / blobdiff