[转]Checking the PendingReturned Flag

http://msdn.microsoft.com/en-us/library/windows/hardware/ff539260(v=vs.85).aspx 

If a completion routine does not signal an event, it must check the Irp‑>PendingReturned flag. If this flag is set, the completion routine must mark the IRP pending by calling IoMarkIrpPending.