IRP与LIST_ENTRY的关联使用

IRP是Windows内核中的一个很重要的概念，代表着应用或内核对设备的请求。
LIST_ENTRY又是Windows内核提供的一个链表。

IRP挂入LIST_ENTRY

VOID RecyleFrame(PFDO_DEVICE_EXTENSION deviceExtension, FrameHeader* frame)
{
    KIRQL oldIrql;
    KeAcquireSpinLock(&deviceExtension->FrameLock, &oldIrql);
    if (deviceExtension->FrameCount > 50)
    {
        ExFreePool(frame);
    }
    else
    {
        ++deviceExtension->FrameCount;
        InsertTailList(&deviceExtension->FrameList, &frame->ListEntry);
    }
    KeReleaseSpinLock(&deviceExtension->FrameLock, oldIrql);
}

VOID RecycleIrp(PFDO_DEVICE_EXTENSION DeviceExtension, PIRP Irp)
{
    KIRQL OldLevel;
    KeAcquireSpinLock(&DeviceExtension->IrpRecyledListLock, &OldLevel);
    InsertTailList(&DeviceExtension->IrpRecyledListHead, &Irp->Tail.Overlay.ListEntry);
    KeReleaseSpinLock(&DeviceExtension->IrpRecyledListLock, OldLevel);
}

将IRP从LIST_ENTRY中摘取

PIRP
GetIrp(
    IN PFDO_DEVICE_EXTENSION DeviceExtension)
{
    KIRQL OldLevel;
    PIRP Irp = NULL;
    PLIST_ENTRY ListEntry;

    KeAcquireSpinLock(&DeviceExtension->IrpRecyledListLock, &OldLevel);
    if (!IsListEmpty(&DeviceExtension->IrpRecyledListHead))
    {
        ListEntry = RemoveHeadList(&DeviceExtension->IrpRecyledListHead);
        Irp = CONTAINING_RECORD(ListEntry, IRP, Tail.Overlay.ListEntry);
    }

    KeReleaseSpinLock(&DeviceExtension->IrpRecyledListLock, OldLevel);
    return Irp;
}