WDFREQUEST handle changing in the lower level driver

OSR_Community_User · March 1, 2009, 11:20pm

I am sending an IOCTL like this to a lower level driver (driver below) along with a WDFREQUEST -- the WDFREQUEST handle is showing a different address (in the lower level driver) from what I sent.

status = WdfIoTargetFormatRequestForInternalIoctl(
WdfUsbTargetDeviceGetIoTarget(fdoData->WdfUsbTargetDevice),
fdoData->WdfRequest,
IoctlControlCode,
inputMem,
NULL,
outputMem,
NULL
);
if (!NT_SUCCESS(status)) {
return status;
}

WdfRequestSetCompletionRoutine(
fdoData->WdfRequest,
SendIOCTLToTargetAsyncComplete,
NULL
);

if (WdfRequestSend(
fdoData->WdfRequest,
WdfUsbTargetDeviceGetIoTarget(fdoData->WdfUsbTargetDevice),
WDF_NO_SEND_OPTIONS
) == FALSE) {
status = WdfRequestGetStatus(fdoData->WdfRequest);
}

I have also associated the WDFREQUEST with a "requestContext" like this:

WDF_OBJECT_ATTRIBUTES_INIT(&attrib);
WDF_OBJECT_ATTRIBUTES_INIT_CONTEXT_TYPE(
&attrib,
REQUEST_CONTEXT
);
status = WdfObjectAllocateContext(
fdoData->WdfRequest,
&attrib,
&reqContext
);
attribsTwo.ParentObject = fdoData->WdfRequest;

I made sure the "reqContext" is valid and associated with fdoData->WdfRequest by getting the context with reqContext = GetRequestContext(fdoData->WdfRequest);

This is the debugger info about the WDFREQUEST at this point (driver that is sending the IOCTL):

kd> !wdfrequest 0x76967dd0
!IRP 0x89263150

State: Allocated by driver, IRP allocated by WDF
!WDFIOTARGET 0x763cea98

After I receive the IOCTL_I_Sent, in the lower level driver, somehow the WDFREQUEST address is different in the lower driver than when it was created and sent from the driver above. Also, when I try to do --
reqContext = GetRequestContext(fdoData->WdfRequest), this gives me a NULL reqContext.

This is associated debug output:

3: kd> g
Breakpoint 7 hit
MyDrv!SendIOCTLToTargetAsync+0x10d:
bac29ffd 6a00 push 0
3: kd> g
==> PORT_EvtInternalIoDeviceControl
==> PORT_PDOInternalIoControl
InternalIoCntl: 0x222460
Breakpoint 1 hit
Port!PORT_PDOInternalIoControl+0x2d7:
b9b47167 8b550c mov edx,dword ptr [ebp+0Ch]

This shows the WDFREQUEST in the lower level driver:-

3: kd> !wdfrequest 0x76dd0918
!IRP 0x89263150

!WDFQUEUE 0x762ece08
State: Pending, Allocated by WDF for incoming IRP

3: kd> p
Port!PORT_PDOInternalIoControl+0x2e3:
b9b47173 6a00 push 0
3: kd> !wdfqueue 0x762ece08

Dumping WDFQUEUE 0x762ece08

Parallel, Default, Power-managed, PowerOn, Can accept, Can dispatch, ExecutionLevelDispatch, SynchronizationScopeNone
Number of driver owned requests: 2
!WDFREQUEST 0x76d5a408 !IRP 0x00000000
!WDFREQUEST 0x76dd0918 !IRP 0x89263150
Number of waiting requests: 0

Any clue on what may be going wrong and why the WDFREQUEST passed is "DIFFERENT" from what I sent, obviously that is why I am not able to fetch the "reqContext" associated with the WDFREQUEST.

Any ideas?

Thanks!
Vidya

Doron_Holan · March 1, 2009, 11:35pm

Completely by design. All handles are specific to the driver, usually specific to the WDFDEVICE. Underneath the covers, KMDF uses WDM when sending io so all the lower driver sees is a PIRP which the lower driver allocates its own WDFREQUEST for.

WDF object handles are not a way to share state/information across different drivers. Put your additional data in the request input buffer itself.

d

-----Original Message-----
From: xxxxx@lists.osr.com [mailto:xxxxx@lists.osr.com] On Behalf Of Dharmaraju, Vidyadhari
Sent: Sunday, March 01, 2009 8:20 PM
To: Windows System Software Devs Interest List
Subject: [ntdev] WDFREQUEST handle changing in the lower level driver