IRP完成例程与KeWaitXxx配合出现的同步问题

非常感谢王老五老兄的解答，其实这个问题在发帖当天就已经解决了，但是用了别的变通的方法，这个疑问还是成立的，所以一直没有结贴，我的最终解决方案依然是在PacketCompletion中释放了我为IRP分配的内存，并恢复了IRP原来的内容，因为都是非分页内存，所以在DISPATCH_LEVEL也不会有什么问题，让我纳闷的依然是，在DISPATCH线程中，IRQL的级别怎么会随便变换的，没有采取任何提升IRQL的动作，只是在一个事件上等待，我是最顶层的驱动，也不是DPC。如果IRQL随机变换的话，微软演示的例程也一样会死机蓝屏，难道大家都在以讹传讹？

下面是微软例程：

Scenario 2: Forward and wait
Use the following code if a driver wants to forward the IRP to a lower driver and wait for it to return so that it can process the IRP. This is frequently done when handling PNP IRPs. For example, when you receive a IRP_MN_START_DEVICE IRP, you must forward the IRP down to the bus driver and wait for it to complete before you can start your device. The Windows XP system has a new function named IoForwardIrpSynchronously that you can use to do this operation easily.
NTSTATUS
DispatchRoutine_2(
    IN PDEVICE_OBJECT DeviceObject,
    IN PIRP Irp
    )
{
    KEVENT   event;
    NTSTATUS status;

    KeInitializeEvent(&event, NotificationEvent, FALSE);

    //
    // You are setting completion routine, so you must copy
    // current stack location to the next. You cannot skip a location
    // here.
    //
    IoCopyCurrentIrpStackLocationToNext(Irp);

    IoSetCompletionRoutine(Irp,
                           CompletionRoutine_2,
                           &event,
                           TRUE,
                           TRUE,
                           TRUE
                           );

    status = IoCallDriver(TopOfDeviceStack, Irp);

    if (status == STATUS_PENDING) {
        
       KeWaitForSingleObject(&event,
                             Executive, // WaitReason
                             KernelMode, // must be Kernelmode to prevent the stack getting paged out
                             FALSE,
                             NULL // indefinite wait
                             );
       status = Irp->IoStatus.Status;
    }
   
    // <---- Do your own work here.


    //
    // Because you stopped the completion of the IRP in the CompletionRoutine
    // by returning STATUS_MORE_PROCESSING_REQUIRED, you must call
    // IoCompleteRequest here.
    //
    IoCompleteRequest (Irp, IO_NO_INCREMENT);
    return status;

}
NTSTATUS
CompletionRoutine_2(
    IN PDEVICE_OBJECT   DeviceObject,
    IN PIRP             Irp,
    IN PVOID            Context
    )
{
  if (Irp->PendingReturned == TRUE) {
    //
    // You will set the event only if the lower driver has returned
    // STATUS_PENDING earlier. This optimization removes the need to
    // call KeSetEvent unnecessarily and improves performance because the
    // system does not have to acquire an internal lock.  
    //
    KeSetEvent ((PKEVENT) Context, IO_NO_INCREMENT, FALSE);
  }
  // This is the only status you can return.
  return STATUS_MORE_PROCESSING_REQUIRED;  
}

不同类型的设备和IRP，其可能的IRQL也不同。