IB_ACK_IN_FLIGHT
clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
if (test_and_set_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags)) {
clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);