flow_lookup
return flow_lookup(tbl, ti, ma, key, n_mask_hit, &cache,
flow = flow_lookup(tbl, ti, ma, key, n_mask_hit,
flow = flow_lookup(tbl, ti, ma, key, n_mask_hit, n_cache_hit,
flow = flow_lookup(tbl, ti, ma, key, &n_mask_hit, &n_cache_hit, &index);