src/os_cpu/linux_zero/vm/atomic_linux_zero.inline.hpp

@  rev 7557 : 8067331: Zero: Atomic::xchg and Atomic::xchg_ptr need full memory barrier
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@@ -229,11 +229,17 @@
 #else
   // __sync_lock_test_and_set is a bizarrely named atomic exchange
   // operation.  Note that some platforms only support this with the
   // limitation that the only valid value to store is the immediate
   // constant 1.  There is a test for this in JNI_CreateJavaVM().
-  return __sync_lock_test_and_set (dest, exchange_value);
+  jint result = __sync_lock_test_and_set (dest, exchange_value);
+  // All atomic operations are expected to be full memory barriers
+  // (see atomic.hpp). However, __sync_lock_test_and_set is not
+  // a full memory barrier, but an acquire barrier. Hence, this added
+  // barrier.
+  __sync_synchronize();
+  return result;
 #endif // M68K
 #endif // ARM
 }
 
 inline intptr_t Atomic::xchg_ptr(intptr_t exchange_value,

@@ -242,11 +248,13 @@
   return arm_lock_test_and_set(dest, exchange_value);
 #else
 #ifdef M68K
   return m68k_lock_test_and_set(dest, exchange_value);
 #else
-  return __sync_lock_test_and_set (dest, exchange_value);
+  intptr_t result = __sync_lock_test_and_set (dest, exchange_value);
+  __sync_synchronize();
+  return result;
 #endif // M68K
 #endif // ARM
 }
 
 inline void* Atomic::xchg_ptr(void* exchange_value, volatile void* dest) {