Using NewReno, if a sk_buff is timed out and is accounted as lost_out,
it should also be removed from the sacked_out.
This is necessary because recovery using NewReno fast retransmit could
take up to a lot RTTs and the sk_buff RTO can expire without actually
being really lost.
left_out = sacked_out + lost_out
in_flight = packets_out - left_out + retrans_out
Using NewReno without this patch, on very large network losses,
left_out becames bigger than packets_out + retrans_out (!!).
For this reason unsigned integer in_flight overflows to 2^32 - something.
Regards,
Angelo P. Castellani
diff -urd ../linux-2.6.16-orig/net/ipv4/tcp_input.c ./net/ipv4/tcp_input.c
--- ../linux-2.6.16-orig/net/ipv4/tcp_input.c 2006-05-15 15:42:39.000000000 +0200
+++ ./net/ipv4/tcp_input.c 2006-05-16 11:18:21.000000000 +0200
@@ -1676,6 +1676,8 @@
if (!(TCP_SKB_CB(skb)->sacked&TCPCB_TAGBITS)) {
TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
tp->lost_out += tcp_skb_pcount(skb);
+ if (IsReno(tp))
+ tcp_remove_reno_sacks(sk, tp, tcp_skb_pcount(skb) + 1);
/* clear xmit_retrans hint */
if (tp->retransmit_skb_hint &&
