viona_ring_num_avail
uint16_t viona_ring_num_avail(viona_vring_t *);
ndesc = viona_ring_num_avail(ring);
while (viona_ring_num_avail(ring) != 0) {
if (viona_ring_num_avail(ring) == 0 &&
if (viona_ring_num_avail(ring) != 0) {