usb驱动有关问题，大家看看为什么在KeWaitForSingleObject处死等不回！

VOID IrpCancelRoutine(IN PDEVICE_OBJECT fdo, IN PIRP Irp){    PDEVICE_EXTENSION pdx = (PDEVICE_EXTENSION)fdo->DeviceExtension;    IoAcquireRemoveLock(&pdx->RemoveLock, Irp);        //  Release the global cancel spin lock.      //  Do this while not holding any other spin locks so that we exit at the right IRQL.    IoReleaseCancelSpinLock(Irp->CancelIrql);    if( Irp == pdx->pBufIrp)     {         KeInitializeEvent(&event, NotificationEvent, FALSE);        //pdx->LowerDeviceObject, 已经初始化完成        irp = IoBuildDeviceIoControlRequest(IOCTL_INTERNAL_USB_SUBMIT_URB,                        pdx->LowerDeviceObject,                        NULL,                        0,                        NULL,                        0,                        TRUE,                        &event,                        &ioStatus);        ntStatus = IoCallDriver(pdx->LowerDeviceObject, irp);        if(ntStatus == STATUS_PENDING)        {                       //在此处死等，在其他线程上先文中不存在这个问题，取消历程中，存在此问题。为啥            status = KeWaitForSingleObject(pdx->phExitEvent,Executive,ernelMode,FALSE,NULL);         }    //...其他处理    }    //取消IRP}