X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=include%2Furcu%2Farch%2Fgeneric.h;h=ac15a3bf7a378dab57cec797bb19a223fd10a634;hb=HEAD;hp=4b56ed7aaff00788a5fb4fbce712a146c5198a5d;hpb=6893800a4d1cc14dff0395ddcd660a5138db183d;p=urcu.git

diff --git a/include/urcu/arch/generic.h b/include/urcu/arch/generic.h
index 4b56ed7..ac15a3b 100644
--- a/include/urcu/arch/generic.h
+++ b/include/urcu/arch/generic.h
@@ -1,24 +1,12 @@
+// SPDX-FileCopyrightText: 2010 Paolo Bonzini <pbonzini@redhat.com>
+//
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
 #ifndef _URCU_ARCH_GENERIC_H
 #define _URCU_ARCH_GENERIC_H
 
 /*
  * arch_generic.h: common definitions for multiple architectures.
- *
- * Copyright (c) 2010 Paolo Bonzini <pbonzini@redhat.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 <urcu/compiler.h>
@@ -43,6 +31,57 @@ extern "C" {
  * GCC builtins) as well as cmm_rmb and cmm_wmb (defaulting to cmm_mb).
  */
 
+#ifdef CONFIG_RCU_USE_ATOMIC_BUILTINS
+
+# ifdef CMM_SANITIZE_THREAD
+/*
+ * This makes TSAN quiet about unsupported thread fence.
+ */
+static inline void _cmm_thread_fence_wrapper(void)
+{
+#   if defined(__clang__)
+#    pragma clang diagnostic push
+#    pragma clang diagnostic ignored "-Wpragmas"
+#    pragma clang diagnostic ignored "-Wunknown-warning-option"
+#    pragma clang diagnostic ignored "-Wtsan"
+#   elif defined(__GNUC__)
+#    pragma GCC diagnostic push
+#    pragma GCC diagnostic ignored "-Wpragmas"
+#    pragma GCC diagnostic ignored "-Wtsan"
+#   endif
+	__atomic_thread_fence(__ATOMIC_SEQ_CST);
+#   if defined(__clang__)
+#    pragma clang diagnostic pop
+#   elif defined(__GNUC__)
+#    pragma GCC diagnostic pop
+#   endif
+}
+# endif	 /* CMM_SANITIZE_THREAD */
+
+# ifndef cmm_smp_mb
+#  ifdef CMM_SANITIZE_THREAD
+#   define cmm_smp_mb() _cmm_thread_fence_wrapper()
+#  else
+#   define cmm_smp_mb() __atomic_thread_fence(__ATOMIC_SEQ_CST)
+#  endif /* CMM_SANITIZE_THREAD */
+# endif /* !cmm_smp_mb */
+
+#endif	/* CONFIG_RCU_USE_ATOMIC_BUILTINS */
+
+
+/*
+ * cmm_mb() expands to __sync_synchronize() instead of __atomic_thread_fence
+ * with SEQ_CST because the former "issues a full memory barrier" while the
+ * latter "acts as a synchronization fence between threads" which is too weak
+ * for what we want, for example with I/O devices.
+ *
+ * Even though sync_synchronize seems to be an alias for a sequential consistent
+ * atomic thread fence on every architecture on GCC and Clang, this assumption
+ * might be untrue in future.  Therefore, the definitions above are used to
+ * ensure correct behavior in the future.
+ *
+ * The above defintions are quoted from the GCC manual.
+ */
 #ifndef cmm_mb
 #define cmm_mb()    __sync_synchronize()
 #endif
@@ -153,8 +192,11 @@ extern "C" {
 #ifndef HAS_CAA_GET_CYCLES
 #define HAS_CAA_GET_CYCLES
 
-#ifdef CONFIG_RCU_HAVE_CLOCK_GETTIME
+#if defined(__APPLE__)
 
+#include <mach/mach.h>
+#include <mach/clock.h>
+#include <mach/mach_time.h>
 #include <time.h>
 #include <stdint.h>
 
@@ -162,18 +204,21 @@ typedef uint64_t caa_cycles_t;
 
 static inline caa_cycles_t caa_get_cycles (void)
 {
-	struct timespec ts;
+	mach_timespec_t ts = { 0, 0 };
+	static clock_serv_t clock_service;
 
-	if (caa_unlikely(clock_gettime(CLOCK_MONOTONIC, &ts)))
+	if (caa_unlikely(!clock_service)) {
+		if (host_get_clock_service(mach_host_self(),
+				SYSTEM_CLOCK, &clock_service))
+			return -1ULL;
+	}
+	if (caa_unlikely(clock_get_time(clock_service, &ts)))
 		return -1ULL;
 	return ((uint64_t) ts.tv_sec * 1000000000ULL) + ts.tv_nsec;
 }
 
-#elif defined(__APPLE__)
+#elif defined(CONFIG_RCU_HAVE_CLOCK_GETTIME)
 
-#include <mach/mach.h>
-#include <mach/clock.h>
-#include <mach/mach_time.h>
 #include <time.h>
 #include <stdint.h>
 
@@ -181,15 +226,9 @@ typedef uint64_t caa_cycles_t;
 
 static inline caa_cycles_t caa_get_cycles (void)
 {
-	mach_timespec_t ts = { 0, 0 };
-	static clock_serv_t clock_service;
+	struct timespec ts;
 
-	if (caa_unlikely(!clock_service)) {
-		if (host_get_clock_service(mach_host_self(),
-				SYSTEM_CLOCK, &clock_service))
-			return -1ULL;
-	}
-	if (caa_unlikely(clock_get_time(clock_service, &ts)))
+	if (caa_unlikely(clock_gettime(CLOCK_MONOTONIC, &ts)))
 		return -1ULL;
 	return ((uint64_t) ts.tv_sec * 1000000000ULL) + ts.tv_nsec;
 }