- Add missing break in ExDereferenceCallBackBlock so ExReleaseRundownProtection does not get called more than once.

svn path=/trunk/; revision=38223

reactos/ntoskrnl/ex/callback.c

@@ -137,6 +137,9 @@ ExDereferenceCallBackBlock(IN OUT PEX_CALLBACK CallBack,
         {
             /* Release rundown protection */
             ExReleaseRundownProtection(&CallbackRoutineBlock->RundownProtect);
+
+            /* We're all done */
+            break;
         }
     }
 }