Use sync_core() in the write side to match current formal verif model

[urcu.git] / urcu.c

diff --git a/urcu.c b/urcu.c
index 40514c37fc86b2c4585d732accc82d0229e47184..efbb4b7890a71524fa8264877f3da63565291591 100644 (file)
--- a/urcu.c
+++ b/urcu.c
@@ -3,9 +3,24 @@
  *
  * 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 <stdio.h>
@@ -17,6 +32,8 @@
 #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"
 
 pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER;
@@ -231,6 +248,14 @@ void synchronize_rcu(void)
         * Ensured by STORE_SHARED and LOAD_SHARED.
         */
 
+       /*
+        * Current RCU formal verification model assumes sequential execution of
+        * the write-side. Add core synchronization instructions. Can be removed
+        * if the formal model is extended to prove that reordering is still
+        * correct.
+        */
+       sync_core();    /* Formal model assumes serialized execution */
+
        /*
         * Wait for previous parity to be empty of readers.
         */
@@ -244,6 +269,8 @@ void synchronize_rcu(void)
         * Ensured by STORE_SHARED and LOAD_SHARED.
         */
 
+       sync_core();    /* Formal model assumes serialized execution */
+
        switch_next_urcu_qparity();     /* 1 -> 0 */
 
        /*
@@ -254,6 +281,8 @@ void synchronize_rcu(void)
         * Ensured by STORE_SHARED and LOAD_SHARED.
         */
 
+       sync_core();    /* Formal model assumes serialized execution */
+
        /*
         * Wait for previous parity to be empty of readers.
         */
@@ -267,7 +296,47 @@ void synchronize_rcu(void)
        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;
 
@@ -297,7 +366,7 @@ void urcu_add_reader(pthread_t id)
  * 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;
 
@@ -316,22 +385,22 @@ void urcu_remove_reader(pthread_t id)
        assert(0);
 }
 
-void urcu_register_thread(void)
+void rcu_register_thread(void)
 {
        internal_urcu_lock();
-       urcu_add_reader(pthread_self());
+       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.