rte_pktmbuf_pool_create --> rte_pktmbuf_pool_create_by_ops -->
rte_mempool_create_empty. In rte_mempool_create_empty, there's such logic: ret
= rte_mempool_set_ops_byname(mp, "xxx", NULL); rte_mempool_set_ops_byname
doesn't set rte_errno, but use return code to indicate errno. So
rte_mempool_create_empty should set rte_errno according to ret, but it forget
to do it.