Fix rcu_assign_pointer() dynamic linking behavior

[urcu.git] / urcu.h

diff --git a/urcu.h b/urcu.h
index 0b0d232311a58666c8b41a9c3162b4efb8caaed4..a0aac2195feea64a90043866950cfe0322eb0df7 100644 (file)
--- a/urcu.h
+++ b/urcu.h
@@ -6,17 +6,27 @@
  *
  * Userspace RCU header
  *
- * Copyright February 2009 - Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
- *
- * Credits for Paul E. McKenney <paulmck@linux.vnet.ibm.com>
- * for inspiration coming from the Linux kernel RCU and rcu-preempt.
+ * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
  *
  * LGPL-compatible code should include this header with :
  *
  * #define _LGPL_SOURCE
  * #include <urcu.h>
  *
- * Distributed under LGPLv2.1
+ * 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.
  */
@@ -24,6 +34,14 @@
 #include <stdlib.h>
 #include <pthread.h>
 
+/*
+ * Important !
+ *
+ * Each thread containing read-side critical sections must be registered
+ * with rcu_register_thread() before calling rcu_read_lock().
+ * rcu_unregister_thread() should be called before the thread exits.
+ */
+
 #ifdef _LGPL_SOURCE
 
 #include <urcu-static.h>
@@ -38,6 +56,7 @@
 #define rcu_read_unlock                _rcu_read_unlock
 
 #define rcu_assign_pointer     _rcu_assign_pointer
+#define rcu_cmpxchg_pointer    _rcu_cmpxchg_pointer
 #define rcu_xchg_pointer       _rcu_xchg_pointer
 #define rcu_publish_content    _rcu_publish_content
 
@@ -55,7 +74,11 @@ extern void *rcu_dereference(void *p);
 extern void *rcu_assign_pointer_sym(void **p, void *v);
 
 #define rcu_assign_pointer(p, v)                       \
-       rcu_assign_pointer_sym((void **)(p), (v))
+       rcu_assign_pointer_sym((void **)(&(p)), (v))
+
+extern void *rcu_cmpxchg_pointer_sym(void **p, void *old, void *_new);
+#define rcu_cmpxchg_pointer(p, old, _new)              \
+       rcu_cmpxchg_pointer_sym((void **)(p), (old), (_new))
 
 extern void *rcu_xchg_pointer_sym(void **p, void *v);
 #define rcu_xchg_pointer(p, v)                         \
@@ -75,4 +98,9 @@ extern void synchronize_rcu(void);
 extern void rcu_register_thread(void);
 extern void rcu_unregister_thread(void);
 
+/*
+ * Explicit urcu initialization, for "early" use within library constructors.
+ */
+extern void urcu_init(void);
+
 #endif /* _URCU_H */