src/hotspot/os/posix/os_posix.cpp

@@ -1898,11 +1898,11 @@
   int v;
 
   // atomically decrement _event
   for (;;) {
     v = _event;
-    if (Atomic::cmpxchg(v - 1, &_event, v) == v) break;
+    if (Atomic::cmpxchg(&_event, v, v - 1) == v) break;
   }
   guarantee(v >= 0, "invariant");
 
   if (v == 0) { // Do this the hard way by blocking ...
     int status = pthread_mutex_lock(_mutex);

@@ -1938,11 +1938,11 @@
 
   int v;
   // atomically decrement _event
   for (;;) {
     v = _event;
-    if (Atomic::cmpxchg(v - 1, &_event, v) == v) break;
+    if (Atomic::cmpxchg(&_event, v, v - 1) == v) break;
   }
   guarantee(v >= 0, "invariant");
 
   if (v == 0) { // Do this the hard way by blocking ...
     struct timespec abst;

@@ -1996,11 +1996,11 @@
   // shake out uses of park() and unpark() without checking state conditions
   // properly. This spurious return doesn't manifest itself in any user code
   // but only in the correctly written condition checking loops of ObjectMonitor,
   // Mutex/Monitor, Thread::muxAcquire and JavaThread::sleep
 
-  if (Atomic::xchg(1, &_event) >= 0) return;
+  if (Atomic::xchg(&_event, 1) >= 0) return;
 
   int status = pthread_mutex_lock(_mutex);
   assert_status(status == 0, status, "mutex_lock");
   int anyWaiters = _nParked;
   assert(anyWaiters == 0 || anyWaiters == 1, "invariant");

@@ -2044,11 +2044,11 @@
 
   // Optional fast-path check:
   // Return immediately if a permit is available.
   // We depend on Atomic::xchg() having full barrier semantics
   // since we are doing a lock-free update to _counter.
-  if (Atomic::xchg(0, &_counter) > 0) return;
+  if (Atomic::xchg(&_counter, 0) > 0) return;
 
   Thread* thread = Thread::current();
   assert(thread->is_Java_thread(), "Must be JavaThread");
   JavaThread *jt = (JavaThread *)thread;