--- a/boost/smart_ptr/detail/spinlock_gcc_arm.hpp	2009-03-02 08:22:16.000000000 -0800
+++ b/boost/smart_ptr/detail/spinlock_gcc_arm.hpp	2012-06-28 16:39:55.000000000 -0700
@@ -2,7 +2,7 @@
 #define BOOST_SMART_PTR_DETAIL_SPINLOCK_GCC_ARM_HPP_INCLUDED
 
 //
-//  Copyright (c) 2008 Peter Dimov
+//  Copyright (c) 2008, 2011 Peter Dimov
 //
 //  Distributed under the Boost Software License, Version 1.0.
 //  See accompanying file LICENSE_1_0.txt or copy at
@@ -11,6 +11,20 @@
 
 #include <boost/smart_ptr/detail/yield_k.hpp>
 
+#if defined(__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__) || defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7EM__)
+
+# define BOOST_SP_ARM_BARRIER "dmb"
+
+#elif defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) || defined(__ARM_ARCH_6K__) || defined(__ARM_ARCH_6Z__) || defined(__ARM_ARCH_6ZK__) || defined(__ARM_ARCH_6T2__)
+
+# define BOOST_SP_ARM_BARRIER "mcr p15, 0, r0, c7, c10, 5"
+
+#else
+
+# define BOOST_SP_ARM_BARRIER ""
+
+#endif
+
 namespace boost
 {
 
@@ -29,12 +43,38 @@
     {
         int r;
 
+#if defined(__ARM_ARCH_6__) \
+    || defined(__ARM_ARCH_6J__) \
+    || defined(__ARM_ARCH_6K__) \
+    || defined(__ARM_ARCH_6Z__) \
+    || defined(__ARM_ARCH_6ZK__) \
+    || defined(__ARM_ARCH_6T2__) \
+    || defined(__ARM_ARCH_7__) \
+    || defined(__ARM_ARCH_7A__) \
+    || defined(__ARM_ARCH_7R__) \
+    || defined(__ARM_ARCH_7M__) \
+    || defined(__ARM_ARCH_7EM__)
+
         __asm__ __volatile__(
-            "swp %0, %1, [%2]":
+            "ldrex %0, [%2]; \n"
+            "cmp %0, %1; \n"
+            "strexne %0, %1, [%2]; \n"
+            BOOST_SP_ARM_BARRIER :
             "=&r"( r ): // outputs
             "r"( 1 ), "r"( &v_ ): // inputs
             "memory", "cc" );
 
+#else
+
+        __asm__ __volatile__(
+            "swp %0, %1, [%2];\n"
+            BOOST_SP_ARM_BARRIER :
+            "=&r"( r ): // outputs
+            "r"( 1 ), "r"( &v_ ): // inputs
+            "memory", "cc" );
+
+#endif
+
         return r == 0;
     }
 
@@ -48,7 +88,7 @@
 
     void unlock()
     {
-        __asm__ __volatile__( "" ::: "memory" );
+        __asm__ __volatile__( BOOST_SP_ARM_BARRIER ::: "memory" );
         *const_cast< int volatile* >( &v_ ) = 0;
     }
 
@@ -82,4 +122,6 @@
 
 #define BOOST_DETAIL_SPINLOCK_INIT {0}
 
+#undef BOOST_SP_ARM_BARRIER
+
 #endif // #ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_GCC_ARM_HPP_INCLUDED