CONN_REMOVED
atomic_or_uint(&con->c_flags, CONN_REMOVED | CONN_EXPIRE);
KASSERT((flags & CONN_REMOVED) == 0);
atomic_or_uint(&con->c_flags, CONN_REMOVED | CONN_EXPIRE);
if ((atomic_load_relaxed(&con->c_flags) & CONN_REMOVED) == 0) {
atomic_or_uint(&con->c_flags, CONN_REMOVED | CONN_EXPIRE);