add: dprintf("close_port: invalid port_id %ld\n", id);
context: close_port(port_id id){	int 	state;	int		slot;	if(ports_active == false)		return B_BAD_PORT_ID;	if(id < 0)		return B_BAD_PORT_ID;	slot = id % MAX_PORTS;	// walk through the sem list, trying to match name	state = disable_interrupts();	GRAB_PORT_LOCK(ports[slot]);	if (ports[slot].id != id) {		RELEASE_PORT_LOCK(ports[slot]);		restore_interrupts(state);		return B_BAD_PORT_ID;	}	// mark port to disable writing	ports[slot].closed = true;	RELEASE_PORT_LOCK(ports[slot]);	restore_interrupts(state);	return B_NO_ERROR;}