uatomic/x86: Remove redundant memory barriers

[urcu.git] / include / urcu / tls-compat.h

diff --git a/include/urcu/tls-compat.h b/include/urcu/tls-compat.h
index 8ac1ea0615ddc2eb91ee51e9e15b89bd094d4c81..1f3ef0fbbdb5bfe8f03d58e642ccdc1373e2f54c 100644 (file)
--- a/include/urcu/tls-compat.h
+++ b/include/urcu/tls-compat.h
@@ -1,26 +1,12 @@
+// SPDX-FileCopyrightText: 2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+//
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
 #ifndef _URCU_TLS_COMPAT_H
 #define _URCU_TLS_COMPAT_H
 
 /*
- * urcu/tls-compat.h
- *
  * Userspace RCU library - Thread-Local Storage Compatibility Header
- *
- * Copyright 2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * 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
  */
 
 #include <stdlib.h>
@@ -32,7 +18,21 @@
 extern "C" {
 #endif
 
-#ifdef CONFIG_RCU_TLS  /* Based on ax_tls.m4 */
+#ifdef CONFIG_RCU_TLS
+
+/*
+ * Default to '__thread' on all C and C++ compilers except MSVC. While C11 has
+ * '_Thread_local' and C++11 has 'thread_local', only '__thread' seems to have
+ * a compatible implementation when linking public extern symbols across
+ * language boundaries.
+ *
+ * For more details, see 'https://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html'.
+ */
+#if defined(_MSC_VER)
+# define URCU_TLS_STORAGE_CLASS        __declspec(thread)
+#else
+# define URCU_TLS_STORAGE_CLASS        __thread
+#endif
 
 /*
  * Hint: How to define/declare TLS variables of compound types
@@ -65,10 +65,13 @@ extern "C" {
  */
 
 # define DECLARE_URCU_TLS(type, name)  \
-       CONFIG_RCU_TLS type name
+       URCU_TLS_STORAGE_CLASS type name
 
 # define DEFINE_URCU_TLS(type, name)   \
-       CONFIG_RCU_TLS type name
+       URCU_TLS_STORAGE_CLASS type name
+
+# define DEFINE_URCU_TLS_INIT(type, name, init)        \
+       URCU_TLS_STORAGE_CLASS type name = (init)
 
 # define URCU_TLS(name)                (name)
 
@@ -95,14 +98,15 @@ struct urcu_tls {
  * Note: we don't free memory at process exit, since it will be dealt
  * with by the OS.
  */
-# define DEFINE_URCU_TLS_1(type, name)                         \
+# define DEFINE_URCU_TLS_INIT_1(type, name, do_init)           \
        type *__tls_access_ ## name(void)                       \
        {                                                       \
                static struct urcu_tls __tls_ ## name = {       \
+                       .key = 0,                               \
                        .init_mutex = PTHREAD_MUTEX_INITIALIZER,\
                        .init_done = 0,                         \
                };                                              \
-               void *__tls_p;                                  \
+               __typeof__(type) *__tls_p;                      \
                if (!__tls_ ## name.init_done) {                \
                        /* Mutex to protect concurrent init */  \
                        pthread_mutex_lock(&__tls_ ## name.init_mutex); \
@@ -115,17 +119,24 @@ struct urcu_tls {
                        pthread_mutex_unlock(&__tls_ ## name.init_mutex); \
                }                                               \
                cmm_smp_rmb();  /* read init_done before getting key */ \
-               __tls_p = pthread_getspecific(__tls_ ## name.key); \
+               __tls_p = (__typeof__(type) *) pthread_getspecific(__tls_ ## name.key); \
                if (caa_unlikely(__tls_p == NULL)) {            \
-                       __tls_p = calloc(1, sizeof(type));      \
+                       __tls_p = (__typeof__(type) *) calloc(1, sizeof(type)); \
+                       do_init                                 \
                        (void) pthread_setspecific(__tls_ ## name.key,  \
                                __tls_p);                       \
                }                                               \
                return __tls_p;                                 \
        }
 
+# define _URCU_TLS_INIT(init)                                  \
+       *__tls_p = (init);
+
+# define DEFINE_URCU_TLS_INIT(type, name, init)                        \
+       DEFINE_URCU_TLS_INIT_1(type, name, _URCU_TLS_INIT(init))
+
 # define DEFINE_URCU_TLS(type, name)                           \
-       DEFINE_URCU_TLS_1(type, name)
+       DEFINE_URCU_TLS_INIT_1(type, name, /* empty */)
 
 # define URCU_TLS_1(name)      (*__tls_access_ ## name())