NETLINK_ALIGN
attrs_len -= NETLINK_ALIGN(sizeof(struct rtmsg));
nla_head = (struct nlattr *)((char *)rtm + NETLINK_ALIGN(sizeof(struct rtmsg)));
int hdrlen = NETLINK_ALIGN(raw_hdrlen);
int hdrlen = NETLINK_ALIGN(sizeof(struct rtmsg));
required_len = NETLINK_ALIGN(len + sizeof(struct nlmsghdr));
payload_len = NETLINK_ALIGN(payload_len);
sz = NETLINK_ALIGN(sz);
sz = NETLINK_ALIGN(sz);
nla->nla_len = NETLINK_ALIGN(snl_get_msg_offset(nw) - off);
int off = NLMSG_HDRLEN + NETLINK_ALIGN(hdrlen);
nla_len += NETLINK_ALIGN(num_nhops * sizeof(struct nexthop_grp));