waitmask.c

串口Windows驱动

                                     NewIrp);

                }

            }

        }

    } while (NewIrp);

    return FirstStatus;

}

BOOLEAN
SerialGrabWaitFromIsr(
    IN PVOID Context
    )

/*++

Routine Description:

    This routine will check to see if the ISR still knows about
    a wait irp by checking to see if the IrpMaskLocation is non-null.
    If it is then it will zero the Irpmasklocation (which in effect
    grabs the irp away from the isr).  This routine is only called
    buy the cancel code for the wait.

    NOTE: This is called by KeSynchronizeExecution.

Arguments:

    Context - A pointer to the device extension

Return Value:

    Always FALSE.

--*/

{

    PSERIAL_DEVICE_EXTENSION Extension = Context;
    SERIAL_LOCKED_PAGED_CODE();

    SerialDbgPrintEx(SERDIAG3, "In SerialGrabWaitFromIsr\n");

    if (Extension->IrpMaskLocation) {

        SerialDbgPrintEx(SERDIAG4, "The isr still owns the irp %x, mask "
                         "location is %x\n"
                         "------- and system buffer is %x\n",
                         Extension->CurrentWaitIrp,Extension->IrpMaskLocation,
                         Extension->CurrentWaitIrp->AssociatedIrp.SystemBuffer);

        //
        // The isr still "owns" the irp.
        //

        *Extension->IrpMaskLocation = 0;
        Extension->IrpMaskLocation = NULL;

        Extension->CurrentWaitIrp->IoStatus.Information = sizeof(ULONG);

        //
        // Since the isr no longer references the irp we need to
        // decrement the reference count.
        //

        SERIAL_CLEAR_REFERENCE(
            Extension->CurrentWaitIrp,
            SERIAL_REF_ISR
            );

    }

    return FALSE;
}

BOOLEAN
SerialGiveWaitToIsr(
    IN PVOID Context
    )

/*++

Routine Description:

    This routine simply sets a variable in the device extension
    so that the isr knows that we have a wait irp.

    NOTE: This is called by KeSynchronizeExecution.

    NOTE: This routine assumes that it is called with the
          cancel spinlock held.

Arguments:

    Context - Simply a pointer to the device extension.

Return Value:

    Always FALSE.

--*/

{

    PSERIAL_DEVICE_EXTENSION Extension = Context;
    SERIAL_LOCKED_PAGED_CODE();

    SerialDbgPrintEx(SERDIAG3, "In SerialGiveWaitToIsr\n");
    //
    // There certainly shouldn't be a current mask location at
    // this point since we have a new current wait irp.
    //

    ASSERT(!Extension->IrpMaskLocation);

    //
    // The isr may or may not actually reference this irp.  It
    // won't if the wait can be satisfied immediately.  However,
    // since it will then go through the normal completion sequence,
    // we need to have an incremented reference count anyway.
    //

    SERIAL_SET_REFERENCE(
        Extension->CurrentWaitIrp,
        SERIAL_REF_ISR
        );

    if (!Extension->HistoryMask) {

        SerialDbgPrintEx(SERDIAG4, "No events occured prior to the wait call"
                         "\n");

        //
        // Although this wait might not be for empty transmit
        // queue, it doesn't hurt anything to set it to false.
        //

        Extension->EmptiedTransmit = FALSE;

        //
        // Record where the "completion mask" should be set.
        //

        Extension->IrpMaskLocation =
            Extension->CurrentWaitIrp->AssociatedIrp.SystemBuffer;
        SerialDbgPrintEx( SERDIAG4, "The isr owns the irp %x, mask location is "
                          "%x\n"
                          "------- and system buffer is %x\n",
                          Extension->CurrentWaitIrp,Extension->IrpMaskLocation,
                          Extension->CurrentWaitIrp->AssociatedIrp
                          .SystemBuffer);

    } else {

        SerialDbgPrintEx(SERDIAG4, "%x occurred prior to the wait - starting "
                         "the\n"
                         "------- completion code for %x\n",
                         Extension->HistoryMask,Extension->CurrentWaitIrp);

        *((ULONG *)Extension->CurrentWaitIrp->AssociatedIrp.SystemBuffer) =
            Extension->HistoryMask;
        Extension->HistoryMask = 0;
        Extension->CurrentWaitIrp->IoStatus.Information = sizeof(ULONG);
        Extension->CurrentWaitIrp->IoStatus.Status = STATUS_SUCCESS;

        SerialInsertQueueDpc(&Extension->CommWaitDpc, NULL, NULL, Extension);

    }

    return FALSE;
}

BOOLEAN
SerialFinishOldWait(
    IN PVOID Context
    )

/*++

Routine Description:

    This routine will check to see if the ISR still knows about
    a wait irp by checking to see if the Irpmasklocation is non-null.
    If it is then it will zero the Irpmasklocation (which in effect
    grabs the irp away from the isr).  This routine is only called
    buy the cancel code for the wait.

    NOTE: This is called by KeSynchronizeExecution.

Arguments:

    Context - A pointer to the device extension

Return Value:

    Always FALSE.

--*/

{

    PSERIAL_DEVICE_EXTENSION Extension = Context;
    SERIAL_LOCKED_PAGED_CODE();

    SerialDbgPrintEx(SERDIAG3, "In SerialFinishOldWait\n");

    if (Extension->IrpMaskLocation) {

        SerialDbgPrintEx(SERDIAG4, "The isr still owns the irp %x, mask "
                         "location is %x\n"
                         "------- and system buffer is %x\n",
                         Extension->CurrentWaitIrp,Extension->IrpMaskLocation,
                         Extension->CurrentWaitIrp->AssociatedIrp.SystemBuffer);
        //
        // The isr still "owns" the irp.
        //

        *Extension->IrpMaskLocation = 0;
        Extension->IrpMaskLocation = NULL;

        Extension->CurrentWaitIrp->IoStatus.Information = sizeof(ULONG);

        //
        // We don't decrement the reference since the completion routine
        // will do that.
        //

        SerialInsertQueueDpc(&Extension->CommWaitDpc, NULL, NULL, Extension);

    }

    //
    // Don't wipe out any historical data we are still interested in.
    //

    Extension->HistoryMask &= *((ULONG *)Extension->CurrentMaskIrp->
                                            AssociatedIrp.SystemBuffer);

    Extension->IsrWaitMask = *((ULONG *)Extension->CurrentMaskIrp->
                                            AssociatedIrp.SystemBuffer);
    SerialDbgPrintEx( SERDIAG4, "Set mask location of %x, in irp %x, with "
                      "system buffer of %x\n",
                      Extension->IrpMaskLocation, Extension->CurrentMaskIrp,
                      Extension->CurrentMaskIrp->AssociatedIrp.SystemBuffer);
    return FALSE;
}

VOID
SerialCancelWait(
    IN PDEVICE_OBJECT DeviceObject,
    IN PIRP Irp
    )

/*++

Routine Description:

    This routine is used to cancel a irp that is waiting on
    a comm event.

Arguments:

    DeviceObject - Pointer to the device object for this device

    Irp - Pointer to the IRP for the current request

Return Value:

    None.

--*/

{

    PSERIAL_DEVICE_EXTENSION Extension = DeviceObject->DeviceExtension;
    SERIAL_LOCKED_PAGED_CODE();

    SerialDbgPrintEx(SERDIAG3, "In SerialCancelWait\n");

    SerialDbgPrintEx(SERDIAG4, "Canceling wait for irp %x\n",
                     Extension->CurrentWaitIrp);

    SerialTryToCompleteCurrent(Extension, SerialGrabWaitFromIsr,
                               Irp->CancelIrql, STATUS_CANCELLED,
                               &Extension->CurrentWaitIrp, NULL, NULL, NULL,
                               NULL, NULL, SERIAL_REF_CANCEL);

}

VOID
SerialCompleteWait(
    IN PKDPC Dpc,
    IN PVOID DeferredContext,
    IN PVOID SystemContext1,
    IN PVOID SystemContext2
    )

{
    PSERIAL_DEVICE_EXTENSION Extension = DeferredContext;
    KIRQL OldIrql;


    SerialDbgPrintEx(DPFLTR_TRACE_LEVEL, ">SerialCompleteWait(%X)\n",
                     Extension);

    SerialDbgPrintEx(SERDIAG3, "In SerialCompleteWait\n");

    UNREFERENCED_PARAMETER(SystemContext1);
    UNREFERENCED_PARAMETER(SystemContext2);

    IoAcquireCancelSpinLock(&OldIrql);

    SerialDbgPrintEx(SERDIAG4, "Completing wait for irp %x\n",
                     Extension->CurrentWaitIrp);

    SerialTryToCompleteCurrent(Extension, NULL, OldIrql, STATUS_SUCCESS,
                               &Extension->CurrentWaitIrp, NULL, NULL, NULL,
                               NULL, NULL, SERIAL_REF_ISR);

    SerialDpcEpilogue(Extension, Dpc);


    SerialDbgPrintEx(DPFLTR_TRACE_LEVEL, "<SerialCompleteWait\n");
}