How to implement async IOCTL?

NTDEV
2

Vidhya Vasudevan wrote:

I want to implement IOCTL, which returns immediately from the Dispatch
control and sends data and complete the IRP whenever data has been
received from lower layer.

I’m returning STATUS_PENDING and calling IoMarkIrpPending for the IOCTL.
But it is still working as synchronous call only.

Application side my code looks like this
>
OVERLAPPED stOverStruct;
memset(&stOverStruct,0,sizeof(OVERLAPPED));
stOverStruct.hEvent = hKernelHandle;

if(!DeviceIoControl(hDriverHandle,IOCTL_QUERY_DATA,
NULL,0, &ucBuffer[0],1024,
&dwBytesReturn,&stOverStruct))
{
dwError = GetLastError();
if(ERROR_IO_PENDING != dwError)
{
return
}
}

dwResult = WaitForSingleObjects(stOverStruct.hEvent,INFINITE);

Did you pass FILE_FLAG_OVERLAPPED to CreateFile() when
you opened hDriverHandle?

Thanks,

Joseph

3

What is the error code at GetLastError? Is the IO system rejecting the IO
request before it even gets to the driver with a bad parameter or other
error? You need to set a completion or cancel routine when pending an IRP
though that will not prevent asunc IO from working. Do you return from your
dispatch routine with STATUS_SUCCESS after pending the IRP?

–
The personal opinion of
Gary G. Little

“Vidhya Vasudevan” wrote in message
news:xxxxx@ntdev…

I’m new to the driver development. Please suggest!

Can I get some pointer on How to implement async IOCTL?

I want to implement IOCTL, which returns immediately from the Dispatch
control and sends data and complete the IRP whenever data has been received
from lower layer.
I’m returning STATUS_PENDING and calling IoMarkIrpPending for the IOCTL. But
it is still working as synchronous call only.

Application side my code looks like this

OVERLAPPED stOverStruct;

memset(&stOverStruct,0,sizeof(OVERLAPPED));
stOverStruct.hEvent = hKernelHandle;

if(!DeviceIoControl(hDriverHandle,IOCTL_QUERY_DATA,
NULL,0, &ucBuffer[0],1024,
&dwBytesReturn,&stOverStruct))
{
dwError = GetLastError();
if(ERROR_IO_PENDING != dwError)
{
return
}
}

dwResult = WaitForSingleObjects(stOverStruct.hEvent,INFINITE);

TIA.

Regards,
V Vidhya