BR_PROMISC_BIT
#define BR_PROMISC BIT(BR_PROMISC_BIT)
set_bit(BR_PROMISC_BIT, &p->flags);
clear_bit(BR_PROMISC_BIT, &p->flags);
#define br_promisc_port(p) test_bit(BR_PROMISC_BIT, &(p)->flags)