Commit 8f65b535 authored Nov 12, 2008 by Doug Leith Committed by David S. Miller Nov 12, 2008

tcp_htcp: last_cong bug fix



This patch fixes a minor bug in tcp_htcp.c which has been
highlighted by Lachlan Andrew and Lawrence Stewart.  Currently, the
time since the last congestion event, which is stored in variable
last_cong, is reset whenever there is a state change into
TCP_CA_Open.  This includes transitions of the type
TCP_CA_Open->TCP_CA_Disorder->TCP_CA_Open which are not associated
with backoff of cwnd.  The patch changes last_cong to be updated
only on transitions into TCP_CA_Open that occur after experiencing
the congestion-related states TCP_CA_Loss, TCP_CA_Recovery,
TCP_CA_CWR.

Signed-off-by: Doug Leith <doug.leith@nuim.ie>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent d809a159

net/ipv4/tcp_htcp.c

+10 −4

Original line number	Diff line number	Diff line
		@@ -69,9 +69,12 @@ static u32 htcp_cwnd_undo(struct sock *sk)
		const struct tcp_sock *tp = tcp_sk(sk);
		struct htcp *ca = inet_csk_ca(sk);

		if (ca->undo_last_cong) {
		ca->last_cong = ca->undo_last_cong;
		ca->maxRTT = ca->undo_maxRTT;
		ca->old_maxB = ca->undo_old_maxB;
		ca->undo_last_cong = 0;
		}

		return max(tp->snd_cwnd, (tp->snd_ssthresh << 7) / ca->beta);
		}
		@@ -268,7 +271,10 @@ static void htcp_state(struct sock *sk, u8 new_state)
		case TCP_CA_Open:
		{
		struct htcp *ca = inet_csk_ca(sk);
		if (ca->undo_last_cong) {
		ca->last_cong = jiffies;
		ca->undo_last_cong = 0;
		}
		}
		break;
		case TCP_CA_CWR: