src/share/vm/runtime/objectMonitor.cpp

*** 651,662 ****
      if (_succ == Self) _succ = NULL ;
  
      assert (_succ != Self, "invariant") ;
      if (_Responsible == Self) {
          _Responsible = NULL ;
!         // Dekker pivot-point.
!         // Consider OrderAccess::storeload() here
  
          // We may leave threads on cxq|EntryList without a designated
          // "Responsible" thread.  This is benign.  When this thread subsequently
          // exits the monitor it can "see" such preexisting "old" threads --
          // threads that arrived on the cxq|EntryList before the fence, above --
--- 651,661 ----
      if (_succ == Self) _succ = NULL ;
  
      assert (_succ != Self, "invariant") ;
      if (_Responsible == Self) {
          _Responsible = NULL ;
!         OrderAccess::fence(); // Dekker pivot-point
  
          // We may leave threads on cxq|EntryList without a designated
          // "Responsible" thread.  This is benign.  When this thread subsequently
          // exits the monitor it can "see" such preexisting "old" threads --
          // threads that arrived on the cxq|EntryList before the fence, above --
*** 672,685 ****
          //    ST cxq=nonnull; MEMBAR; LD Responsible (in enter prolog)
          //    The (ST cxq; MEMBAR) is accomplished with CAS().
          //
          // The MEMBAR, above, prevents the LD of cxq|EntryList in the subsequent
          // exit operation from floating above the ST Responsible=null.
-         //
-         // In *practice* however, EnterI() is always followed by some atomic
-         // operation such as the decrement of _count in ::enter().  Those atomics
-         // obviate the need for the explicit MEMBAR, above.
      }
  
      // We've acquired ownership with CAS().
      // CAS is serializing -- it has MEMBAR/FENCE-equivalent semantics.
      // But since the CAS() this thread may have also stored into _succ,
--- 671,680 ----