*
* Userspace RCU library
*
- * Copyright February 2009 - Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
*
- * Distributed under GPLv2
+ * 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 <errno.h>
#include <poll.h>
+#include "urcu-static.h"
+/* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
#include "urcu.h"
+#ifndef DEBUG_FULL_MB
+void __attribute__((constructor)) urcu_init(void);
+void __attribute__((destructor)) urcu_exit(void);
+#else
+static inline urcu_init(void)
+{
+}
+#endif
+
+int init_done;
+
pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER;
/*
* Ensured by STORE_SHARED and LOAD_SHARED.
*/
+ /*
+ * Adding a smp_mb() which is _not_ formally required, but makes the
+ * model easier to understand. It does not have a big performance impact
+ * anyway, given this is the write-side.
+ */
+ smp_mb();
+
/*
* Wait for previous parity to be empty of readers.
*/
* Ensured by STORE_SHARED and LOAD_SHARED.
*/
+ /*
+ * Adding a smp_mb() which is _not_ formally required, but makes the
+ * model easier to understand. It does not have a big performance impact
+ * anyway, given this is the write-side.
+ */
+ smp_mb();
+
switch_next_urcu_qparity(); /* 1 -> 0 */
/*
* Ensured by STORE_SHARED and LOAD_SHARED.
*/
+ /*
+ * Adding a smp_mb() which is _not_ formally required, but makes the
+ * model easier to understand. It does not have a big performance impact
+ * anyway, given this is the write-side.
+ */
+ smp_mb();
+
/*
* Wait for previous parity to be empty of readers.
*/
internal_urcu_unlock();
}
-void urcu_add_reader(pthread_t id)
+/*
+ * library wrappers to be used by non-LGPL compatible source code.
+ */
+
+void rcu_read_lock(void)
+{
+ _rcu_read_lock();
+}
+
+void rcu_read_unlock(void)
+{
+ _rcu_read_unlock();
+}
+
+void *rcu_dereference(void *p)
+{
+ return _rcu_dereference(p);
+}
+
+void *rcu_assign_pointer_sym(void **p, void *v)
+{
+ wmb();
+ return STORE_SHARED(p, v);
+}
+
+void *rcu_xchg_pointer_sym(void **p, void *v)
+{
+ wmb();
+ return xchg(p, v);
+}
+
+void *rcu_publish_content_sym(void **p, void *v)
+{
+ void *oldptr;
+
+ oldptr = _rcu_xchg_pointer(p, v);
+ synchronize_rcu();
+ return oldptr;
+}
+
+static void rcu_add_reader(pthread_t id)
{
struct reader_registry *oldarray;
* Never shrink (implementation limitation).
* This is O(nb threads). Eventually use a hash table.
*/
-void urcu_remove_reader(pthread_t id)
+static void rcu_remove_reader(pthread_t id)
{
struct reader_registry *index;
assert(0);
}
-void urcu_register_thread(void)
+void rcu_register_thread(void)
{
internal_urcu_lock();
- urcu_add_reader(pthread_self());
+ urcu_init(); /* In case gcc does not support constructor attribute */
+ rcu_add_reader(pthread_self());
internal_urcu_unlock();
}
-void urcu_unregister_thread(void)
+void rcu_unregister_thread(void)
{
internal_urcu_lock();
- urcu_remove_reader(pthread_self());
+ rcu_remove_reader(pthread_self());
internal_urcu_unlock();
}
#ifndef DEBUG_FULL_MB
-void sigurcu_handler(int signo, siginfo_t *siginfo, void *context)
+static void sigurcu_handler(int signo, siginfo_t *siginfo, void *context)
{
/*
* Executing this smp_mb() is the only purpose of this signal handler.
smp_mb();
}
-void __attribute__((constructor)) urcu_init(void)
+/*
+ * urcu_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 internal_urcu_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 urcu_init(void)
{
struct sigaction act;
int ret;
+ if (init_done)
+ return;
+ init_done = 1;
+
act.sa_sigaction = sigurcu_handler;
+ act.sa_flags = SA_SIGINFO;
+ sigemptyset(&act.sa_mask);
ret = sigaction(SIGURCU, &act, NULL);
if (ret) {
perror("Error in sigaction");
}
}
-void __attribute__((destructor)) urcu_exit(void)
+void urcu_exit(void)
{
struct sigaction act;
int ret;
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