--- old/src/hotspot/share/utilities/waitBarrier_generic.cpp	2018-12-21 09:22:37.069089343 +0100
+++ new/src/hotspot/share/utilities/waitBarrier_generic.cpp	2018-12-21 09:22:36.747078525 +0100
@@ -37,12 +37,6 @@
   OrderAccess::fence();
 }
 
-void GenericWaitBarrier::disarm() {
-  assert(_barrier_tag != 0, "Not armed");
-  _barrier_tag = 0;
-  OrderAccess::fence();
-}
-
 int GenericWaitBarrier::wake_if_needed() {
   assert(_barrier_tag == 0, "Not disarmed");
   int w = _waiters;
@@ -62,7 +56,10 @@
 }
 
 void GenericWaitBarrier::wake() {
-  assert(_barrier_tag == 0, "Not disarmed");
+  assert(_barrier_tag != 0, "Not armed");
+  _barrier_tag = 0;
+  // Loads of _barrier_threads/_waiters must not float above disarm store.
+  OrderAccess::fence();
   int left;
   SpinYield sp;
   do {
@@ -78,6 +75,10 @@
 
 void GenericWaitBarrier::wait(int barrier_tag) {
   assert(barrier_tag != 0, "Trying to wait on disarmed value");
+  if (barrier_tag == 0 && barrier_tag != _barrier_tag) {
+    OrderAccess::fence();
+    return;
+  }
   Atomic::add(1, &_barrier_threads);
   if (barrier_tag != 0 && barrier_tag == _barrier_tag) {
     Atomic::add(1, &_waiters);