acd_prevent_allow
acd_prevent_allow(dev, 1);
acd_prevent_allow(dev, 0);
acd_prevent_allow(dev, 1);
acd_prevent_allow(dev, 0);
acd_prevent_allow(dev, 1);
error = acd_prevent_allow(dev, 0);
error = acd_prevent_allow(dev, 1);
static int acd_prevent_allow(device_t, int);