l_volctrl
error = copyin(SCARG(uap, data), &l_volctrl, sizeof l_volctrl);
t_vol.vol[0] = l_volctrl.channel0;
t_vol.vol[1] = l_volctrl.channel1;
t_vol.vol[2] = l_volctrl.channel2;
t_vol.vol[3] = l_volctrl.channel3;
memset(&l_volctrl, 0, sizeof(l_volctrl));
l_volctrl.channel0 = t_vol.vol[0];
l_volctrl.channel1 = t_vol.vol[1];
l_volctrl.channel2 = t_vol.vol[2];
l_volctrl.channel3 = t_vol.vol[3];
error = copyout(&l_volctrl, SCARG(uap, data), sizeof l_volctrl);