Is it windows bug ? Callback routine get wrong argument ?!

It's a strange problem.
I use IoQueueWorkItem( ) and pass a structure DATA to it's callback routine
ROUTINE_XXX.
ROUTINE_XXX get pointer by argument Context.
But I always can't catch correct data from DATA, so I check the address of
variable and find an interesting thing.
The address of DATA and Context are different !
That's why I can't get correct data inside ROUTINE_XXX.
I have no idea about this strange situation.
Could anyone give me a hint?

 

Post some code here, this description is useless except to indicate that you
are doing something wrong.

 

I suppose your IO_WORKITEM is not allocated on stack?

 

Driver is base on USBCAMD code inside DDK sample.
Before I replace ExXxxxWorkItem with IoXxxxWorkItem, the address is match
and data is correct too.
I don't know why.

////////////////////////////////////////////////////////////////////////////
/////////////////////
typedef struct _USBCAMD_WORK_ITEM {
PIO_WORKITEM WorkItem;
PUSBCAMD_READ_EXTENSION Request;
PUSBCAMD_CHANNEL_EXTENSION ChannelExtension;
ULONG StreamNumber;
BOOLEAN CopyFrameToStillPin;
NTSTATUS status;
PHW_STREAM_REQUEST_BLOCK Srb;
} USBCAMD_WORK_ITEM, *PUSBCAMD_WORK_ITEM;
////////////////////////////////////////////////////////////////////////////
/////////////////////
ROUTINE_A(...) {
PUSBCAMD_WORK_ITEM usbWorkItem;
usbWorkItem = (PUSBCAMD_WORK_ITEM) USBCAMD_ExAllocatePool(NonPagedPool,
sizeof(USBCAMD_WORK_ITEM));
if (usbWorkItem) {
usbWorkItem->WorkItem = IoAllocateWorkItem(
ChannelExtension->DeviceExtension->SCDeviceObject);
usbWorkItem->Request = NULL;
usbWorkItem->ChannelExtension = ChannelExtension;
usbWorkItem->status = ntStatus;
DbgPrint("Address before callback routine = %x\n", usbWorkItem);
if (usbWorkItem->WorkItem && !IsStop) {
IoQueueWorkItem(usbWorkItem->WorkItem,
(PIO_WORKITEM_ROUTINE)
USBCAMD_ProcessStillReadWorkItem,
DelayedWorkQueue,
usbWorkItem);
}
else
ExFreePool(usbWorkItem);
}
}
}
////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////
VOID USBCAMD_ProcessStillReadWorkITem(PVOID Context) {
PUSBCAMD_WORK_ITEM usbWorkItem = (PUSBCAMD_WORK_ITEM) Context;

//--------------------------------------------------------------------------
----
// here get wrong structure context and address isn't match also.
//--------------------------------------------------------------------------
----
DbgPrint("Address inside callback routine = %x\n", Context);

// do something ...

IoFreeWorkItem(usbWorkItem->WorkItem);
}

 

Apparently you use an explicit cast to shut up the compiler that warned you
about the type mismatch.

(PIO_WORKITEM_ROUTINE) USBCAMD_ProcessStillReadWorkItem

It must be
VOID
USBCAMD_ProcessStillReadWorkItem (
IN PDEVICE_OBJECT DeviceObject,
IN PVOID Context
);

 

Bingo !
You are right.
I miss 1 argument in callback routine.

Thank you