DESC0_ID
if (head_id == DESC0_ID(desc_ring->count_bits))
last_finalized_id = DESC0_ID(desc_ring->count_bits) + 1;
atomic_long_set(&rb->desc_ring.head_id, DESC0_ID(descbits));
atomic_long_set(&rb->desc_ring.tail_id, DESC0_ID(descbits));
#define DESC0_SV(ct_bits) DESC_SV(DESC0_ID(ct_bits), desc_reusable)
.head_id = ATOMIC_INIT(DESC0_ID(descbits)), \
.tail_id = ATOMIC_INIT(DESC0_ID(descbits)), \