static long evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc)
{
    struct domain *d;
    long           rc;

    d = rcu_lock_domain_by_any_id(alloc->dom);
    if ( d == NULL )
        return -ESRCH;

    rc = evtchn_alloc_unbound_domain(d, &alloc->port, alloc->remote_dom);
    if ( rc )
        ERROR_EXIT_DOM((int)rc, d);

 out:
    rcu_unlock_domain(d);

    return rc;
}

int evtchn_alloc_unbound_domain(struct domain *d, evtchn_port_t *port,
                                domid_t remote_domid)
{
    struct evtchn *chn;
    int           rc;
    int           free_port;

    spin_lock(&d->event_lock);

    rc = free_port = get_free_port(d);
    if ( free_port < 0 )
        goto out;

    chn = evtchn_from_port(d, free_port);
    rc = xsm_evtchn_unbound(XSM_TARGET, d, chn, remote_domid);
    if ( rc )
        goto out;

    chn->state = ECS_UNBOUND;
    if ( (chn->u.unbound.remote_domid = remote_domid) == DOMID_SELF )
        chn->u.unbound.remote_domid = current->domain->domain_id;

    *port = free_port;
    /* Everything is fine, returns 0 */
    rc = 0;

 out:
    spin_unlock(&d->event_lock);

    return rc;
}