键盘过滤驱动卸载时,系统蓝屏解决方法

键盘过滤驱动卸载时,系统蓝屏
由于不可重现,所以,暂时还没有拿到DUMP文件.
下面是卸载的代码,麻烦大神帮着看一下.
我找了好久,也没有发现哪块有问题.
PS: 卸载的时候,都会调用哪些个函数?IRP_MJ_POWER这个例程只是关机的时候,才会被调用吗/

VOID ClearPendingIrp(IN PDRIVER_OBJECT pDrvObj,IN BOOLEAN cancel)
{
	PDEVICE_OBJECT pDevObj = pDrvObj->DeviceObject;
	PDEVICE_EXTENSION pDevExt = NULL;
	while (pDevObj)
	{
		pDevExt = (PDEVICE_EXTENSION)pDevObj->DeviceExtension;

		if (pDevExt->et == et_normal)
		{
			if (cancel && pDevExt->pIrp)
			{
				BOOLEAN bCancel = IoCancelIrp(pDevExt->pIrp);
#ifdef DBG
				KdPrint(("IoCancelIrp Result:%d\n",bCancel));
#endif
			}
			pDevExt->pIrp = NULL;
		}

		pDevObj = pDevObj->NextDevice;
	}
}

VOID DetachDevices(IN PDEVICE_OBJECT pDevObj)
{
	PDEVICE_EXTENSION pDevExt = (PDEVICE_EXTENSION)pDevObj->DeviceExtension;
	__try
	{
		__try
		{
			if (pDevExt->et == et_filter)
			{
				PFILTER_DEVICE_EXTENSION pFilterExt = (PFILTER_DEVICE_EXTENSION)pDevExt;
				IoDetachDevice(pFilterExt->pTargetDeviceObject);
				if (pFilterExt->pIrp)
				{
					IoCancelIrp(pFilterExt->pIrp);
				}				
			}
			else if (pDevExt->et == et_normal)
			{
				if (pDevExt->pData)
				{
					ReleaseRecorder(pDevExt->pData);
				}
			}
			else if (pDevExt->et == et_none)
			{
				PFILTER_DEVICE_EXTENSION pFilterExt = (PFILTER_DEVICE_EXTENSION)pDevExt;
				IoDetachDevice(pFilterExt->pTargetDeviceObject);
			}

			IoDeleteDevice(pDevObj);
		}
		__except(EXCEPTION_EXECUTE_HANDLER){}
	}
	__finally{}
}

VOID DriverUnload(IN PDRIVER_OBJECT pDrvObj)
{
	PDEVICE_OBJECT pDevObj = NULL;
	PDEVICE_OBJECT pNextDevObj = NULL;
	UNICODE_STRING ustrSymName = {0};
	
	RtlInitUnicodeString(&ustrSymName,DOS_DEVICE_NAME_W);
	IoDeleteSymbolicLink(&ustrSymName);
	
	UNREFERENCED_PARAMETER(pDrvObj);
	KdPrint(("Driver Unloading...\n"));

	ClearPendingIrp(pDrvObj,TRUE);

	KdPrint(("DriverUnload: ClearPendingIrp.\n"));

	pDevObj = pDrvObj->DeviceObject;
	
	KdPrint(("DriverUnload: Begin DetachDevices.\n"));

	while (pDevObj)
	{
		pNextDevObj = pDevObj->NextDevice;
		DetachDevices(pDevObj);
		pDevObj = pNextDevObj;
	}


	KdPrint(("DriverUnload: End DetachDevices.\n"));

	ASSERT(!pDrvObj->DeviceObject);
	
	KdPrint(("Driver Unloaded.\n"));
}

...........

------解决方案--------------------
多加一个计数器来判断最后是否还有未结束的IRP请求