IOAM6_IPTUNNEL_TRACE
if (!tb[IOAM6_IPTUNNEL_TRACE]) {
trace = nla_data(tb[IOAM6_IPTUNNEL_TRACE]);
NL_SET_ERR_MSG_ATTR(extack, tb[IOAM6_IPTUNNEL_TRACE],
err = nla_put(skb, IOAM6_IPTUNNEL_TRACE, sizeof(ilwt->tuninfo.traceh),
[IOAM6_IPTUNNEL_TRACE] = NLA_POLICY_EXACT_LEN(