+// 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 <poll.h>
#include <urcu/config.h>
+#include <urcu/annotate.h>
#include <urcu/assert.h>
#include <urcu/arch.h>
#include <urcu/wfcqueue.h>
void __attribute__((constructor)) rcu_init(void);
#endif
-#ifdef RCU_MB
+#if defined(RCU_MB)
void 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
+static void urcu_call_rcu_exit(void);
/*
* rcu_gp_lock ensures mutual exclusion between threads calling
}
#endif
-#ifdef RCU_MB
+#if defined(RCU_MB)
static void smp_mb_master(void)
{
cmm_smp_mb();
}
#endif
-#ifdef RCU_SIGNAL
-static void force_mb_all_readers(void)
-{
- struct urcu_reader *index;
-
- /*
- * Ask for each threads to execute a cmm_smp_mb() so we can consider the
- * compiler barriers around rcu read lock as real memory barriers.
- */
- if (cds_list_empty(®istry))
- return;
- /*
- * pthread_kill has a cmm_smp_mb(). But beware, we assume it performs
- * a cache flush on architectures with non-coherent cache. Let's play
- * safe and don't assume anything : we use cmm_smp_mc() to make sure the
- * cache flush is enforced.
- */
- cds_list_for_each_entry(index, ®istry, node) {
- CMM_STORE_SHARED(index->need_mb, 1);
- pthread_kill(index->tid, SIGRCU);
- }
- /*
- * Wait for sighandler (and thus mb()) to execute on every thread.
- *
- * Note that the pthread_kill() will never be executed on systems
- * that correctly deliver signals in a timely manner. However, it
- * is not uncommon for kernels to have bugs that can result in
- * lost or unduly delayed signals.
- *
- * If you are seeing the below pthread_kill() executing much at
- * all, we suggest testing the underlying kernel and filing the
- * relevant bug report. For Linux kernels, we recommend getting
- * the Linux Test Project (LTP).
- */
- cds_list_for_each_entry(index, ®istry, node) {
- while (CMM_LOAD_SHARED(index->need_mb)) {
- pthread_kill(index->tid, SIGRCU);
- (void) poll(NULL, 0, 1);
- }
- }
- cmm_smp_mb(); /* read ->need_mb before ending the barrier */
-}
-
-static void smp_mb_master(void)
-{
- force_mb_all_readers();
-}
-#endif /* #ifdef RCU_SIGNAL */
-
/*
* synchronize_rcu() waiting. Single thread.
* Always called with rcu_registry lock held. Releases this lock and
static void wait_gp(void)
{
/*
- * Read reader_gp before read futex. smp_mb_master() needs to
- * be called with the rcu registry lock held in RCU_SIGNAL
- * flavor.
+ * Read reader_gp before read futex.
*/
smp_mb_master();
/* Temporarily unlock the registry lock. */
*/
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 urcu_reader *index, *tmp;
}
cds_list_for_each_entry_safe(index, tmp, input_readers, node) {
- switch (urcu_common_reader_state(&rcu_gp, &index->ctr)) {
+ switch (urcu_common_reader_state(&rcu_gp, &index->ctr, group)) {
case URCU_READER_ACTIVE_CURRENT:
if (cur_snap_readers) {
cds_list_move(&index->node,
void synchronize_rcu(void)
{
+ cmm_annotate_define(acquire_group);
+ cmm_annotate_define(release_group);
CDS_LIST_HEAD(cur_snap_readers);
CDS_LIST_HEAD(qsreaders);
DEFINE_URCU_WAIT_NODE(wait, URCU_WAIT_WAITING);
* queue before their insertion into the wait queue.
*/
if (urcu_wait_add(&gp_waiters, &wait) != 0) {
- /* Not first in queue: will be awakened by another thread. */
+ /*
+ * Not first in queue: will be awakened by another thread.
+ * Implies a memory barrier after grace period.
+ */
urcu_adaptative_busy_wait(&wait);
- /* Order following memory accesses after grace period. */
- cmm_smp_mb();
return;
}
/* We won't need to wake ourself up */
*/
/* Write new ptr before changing the qparity */
smp_mb_master();
+ cmm_annotate_group_mb_release(&release_group);
/*
* Wait for readers to observe original parity or be quiescent.
* wait_for_readers() can release and grab again rcu_registry_lock
* 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
cmm_smp_mb();
/* Switch parity: 0 -> 1, 1 -> 0 */
- CMM_STORE_SHARED(rcu_gp.ctr, rcu_gp.ctr ^ URCU_GP_CTR_PHASE);
+ cmm_annotate_group_mem_release(&release_group, &rcu_gp.ctr);
+ uatomic_store(&rcu_gp.ctr, rcu_gp.ctr ^ URCU_GP_CTR_PHASE, CMM_RELAXED);
/*
* Must commit rcu_gp.ctr update to memory before waiting for quiescent
* wait_for_readers() can release and grab again rcu_registry_lock
* 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.
* iterates on reader threads.
*/
smp_mb_master();
+ cmm_annotate_group_mb_acquire(&acquire_group);
out:
mutex_unlock(&rcu_registry_lock);
mutex_unlock(&rcu_gp_lock);
return _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();
urcu_posix_assert(URCU_TLS(rcu_reader).need_mb == 0);
urcu_posix_assert(!(URCU_TLS(rcu_reader).ctr & URCU_GP_CTR_NEST_MASK));
URCU_TLS(rcu_reader).registered = 0;
cds_list_del(&URCU_TLS(rcu_reader).node);
mutex_unlock(&rcu_registry_lock);
-
- urcu_signal_restore();
}
#ifdef RCU_MEMBARRIER
}
#endif
-#ifdef RCU_SIGNAL
-static void sigrcu_handler(int signo __attribute__((unused)),
- siginfo_t *siginfo __attribute__((unused)),
- void *context __attribute__((unused)))
-{
- /*
- * Executing this cmm_smp_mb() is the only purpose of this signal handler.
- * It punctually promotes cmm_barrier() into cmm_smp_mb() on every thread it is
- * executed on.
- */
- cmm_smp_mb();
- _CMM_STORE_SHARED(URCU_TLS(rcu_reader).need_mb, 0);
- cmm_smp_mb();
-}
-
-/*
- * rcu_init constructor. Called when the library is linked, but also when
- * reader threads are calling rcu_register_thread().
- * Should only be called by a single thread at a given time. This is ensured by
- * holing the rcu_registry_lock from rcu_register_thread() or by running
- * at library load time, which should not be executed by multiple
- * threads nor concurrently with rcu_register_thread() anyway.
- */
-void rcu_init(void)
-{
- struct sigaction act;
- int ret;
-
- if (init_done)
- return;
- init_done = 1;
-
- act.sa_sigaction = sigrcu_handler;
- act.sa_flags = SA_SIGINFO | SA_RESTART;
- sigemptyset(&act.sa_mask);
- ret = sigaction(SIGRCU, &act, NULL);
- if (ret)
- urcu_die(errno);
-}
-
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.
- * urcu_posix_assert(cds_list_empty(®istry));
- */
+ urcu_call_rcu_exit();
}
-#endif /* #ifdef RCU_SIGNAL */
-
DEFINE_RCU_FLAVOR(rcu_flavor);
#include "urcu-call-rcu-impl.h"
projects / urcu.git / blobdiff