src/hotspot/share/oops/klass.cpp

@@ -434,11 +434,11 @@
       set_next_sibling(prev_first_subklass);
     }
     // Note that the prev_first_subklass is always alive, meaning no sibling_next links
     // are ever created to not alive klasses. This is an important invariant of the lock-free
     // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list.
-    if (Atomic::cmpxchg(this, &super->_subklass, prev_first_subklass) == prev_first_subklass) {
+    if (Atomic::cmpxchg(&super->_subklass, prev_first_subklass, this) == prev_first_subklass) {
       return;
     }
   }
   debug_only(verify();)
 }

@@ -449,11 +449,11 @@
     Klass* subklass = Atomic::load_acquire(&_subklass);
     if (subklass == NULL || subklass->is_loader_alive()) {
       return;
     }
     // Try to fix _subklass until it points at something not dead.
-    Atomic::cmpxchg(subklass->next_sibling(), &_subklass, subklass);
+    Atomic::cmpxchg(&_subklass, subklass, subklass->next_sibling());
   }
 }
 
 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) {
   if (!ClassUnloading || !unloading_occurred) {