reactos/media/doc/irp cancel boilerplate.c

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/*
Boiler plate for irp cancelation, for irp queues you manage yourself
-Gunnar
*/
CancelRoutine(
DEV_OBJ Dev,
Irp
)
{
//don't need this since we have our own sync. protecting irp cancellation
IoReleaseCancelSpinLock(Irp->CancelIrql);
theLock = Irp->Tail.Overlay.DriverContext[3];
Lock(theLock);
RemoveEntryList(&Irp->Tail.Overlay.ListEntry);
Unlock(theLock);
Irp->IoStatus.Status = STATUS_CANCELLED;
Irp->IoStatus.Information = 0;
IoCompleteRequest(Irp, IO_NO_INCREMENT);
}
QUEUE_BOLIERPLATE
{
Lock(theLock);
Irp->Tail.Overlay.DriverContext[3] = &theLock;
IoSetCancelRoutine(Irp, CancelRoutine);
if (Irp->Cancel && IoSetCancelRoutine(Irp, NULL))
{
/*
Irp has already been cancelled (before we got to queue it),
and we got to remove the cancel routine before the canceler could,
so we cancel/complete the irp ourself.
*/
Unlock(theLock);
Irp->IoStatus.Status = STATUS_CANCELLED;
Irp->IoStatus.Information = 0;
IoCompleteRequest(Irp, IO_NO_INCREMENT);
return FALSE;
}
//else were ok
Irp->IoStatus.Status = STATUS_PENDING;
IoMarkIrpPending(Irp);
InsertTailList(Queue);
Unlock(theLock);
}
DEQUEUE_BOILERPLATE
{
Lock(theLock);
Irp = RemoveHeadList(Queue);
if (!IoSetCancelRoutine(Irp, NULL))
{
/*
Cancel routine WILL be called after we release the spinlock. It will try to remove
the irp from the list and cancel/complete this irp. Since we allready removed it,
make its ListEntry point to itself.
*/
InitializeListHead(&Irp->Tail.Overlay.ListEntry);
Unlock(theLock);
return;
}
/*
Cancel routine will NOT be called, canceled or not.
The Irp might have been canceled (Irp->Cancel flag set) but we don't care,
since we are to complete this Irp now anyways.
*/
Unlock(theLock);
Irp->IoStatus.Status = STATUS_SUCCESS;
Irp->IoStatus.Information = 0;
IoCompleteRequest(Irp, IO_NO_INCREMENT);
}