fack              889 net/ipv4/tcp_input.c 	u32 fack, metric;
fack              891 net/ipv4/tcp_input.c 	fack = tcp_highest_sack_seq(tp);
fack              892 net/ipv4/tcp_input.c 	if (!before(low_seq, fack))
fack              895 net/ipv4/tcp_input.c 	metric = fack - low_seq;