OPTION_MPTCP_FAIL
if (mp_opt.suboptions & OPTION_MPTCP_FAIL) {
if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions))
} else if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions)) {
mp_opt->suboptions |= OPTION_MPTCP_FAIL;
opts->suboptions |= OPTION_MPTCP_FAIL;