flow_l2_accept
if (new_ops->fo_accept[0] == flow_l2_accept)
{flow_l2_accept}
{flow_l2_accept, flow_ip_accept}
{flow_l2_accept, flow_ip_accept}
{flow_l2_accept, flow_ip_accept, flow_transport_accept}
static int flow_l2_accept(flow_tab_t *, flow_state_t *);