TIPC_GENL_HDRLEN
msg.req = nlmsg_data(req_nlh) + GENL_HDRLEN + TIPC_GENL_HDRLEN;
msg.req_size = nlmsg_attrlen(req_nlh, GENL_HDRLEN + TIPC_GENL_HDRLEN);
len = nlmsg_total_size(GENL_HDRLEN + TIPC_GENL_HDRLEN);
.hdrsize = TIPC_GENL_HDRLEN,
hdr_len = nlmsg_total_size(GENL_HDRLEN + TIPC_GENL_HDRLEN);