_IF_QFULL
if (_IF_QFULL(ifq)) {
if (_IF_QFULL(ifq)) { \
if (_IF_QFULL(&priv->readq)) {
if (_IF_QFULL(&sc->outq)) {
# define IF_QFULL _IF_QFULL
if (!_IF_QFULL(&b->b_snd))