PDEVICE_OBJECT_POWER_EXTENSION NTAPI PopGetDope ( IN PDEVICE_OBJECT DeviceObject )
Definition at line 34 of file povolume.c.
{
    PEXTENDED_DEVOBJ_EXTENSION DeviceExtension;
    PDEVICE_OBJECT_POWER_EXTENSION Dope;
    KIRQL OldIrql;
    PAGED_CODE();

    /* If the device already has the dope, return it */
    DeviceExtension = IoGetDevObjExtension(DeviceObject);
    if (DeviceExtension->Dope) goto Return;

    /* Allocate some dope for the device */
    Dope = ExAllocatePoolWithTag(NonPagedPool,
                                 sizeof(DEVICE_OBJECT_POWER_EXTENSION),
                                 'Dope');
    if (!Dope) goto Return;

    /* Initialize the initial contents of the dope */
    RtlZeroMemory(Dope, sizeof(DEVICE_OBJECT_POWER_EXTENSION));
    Dope->DeviceObject = DeviceObject;
    Dope->State = PowerDeviceUnspecified;
    InitializeListHead(&Dope->IdleList);

    /* Make sure only one caller can assign dope to a device */
    KeAcquireSpinLock(&PopDopeGlobalLock, &OldIrql);
    
    /* Make sure the device still has no dope */
    if (!DeviceExtension->Dope)
    {
        /* Give the local dope to this device, and remember we won the race */
        DeviceExtension->Dope = (PVOID)Dope;
        Dope = NULL;
    }

    /* Allow other dope transactions now */
    KeReleaseSpinLock(&PopDopeGlobalLock, OldIrql);
    
    /* Check if someone other than us already assigned the dope, so free ours */
    if (Dope) ExFreePoolWithTag(Dope, 'Dope');

    /* Return the dope to the caller */
Return:
    return (PDEVICE_OBJECT_POWER_EXTENSION)DeviceExtension->Dope;
}
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