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>
diff --git a/net/ipv4/tcp_htcp.c b/net/ipv4/tcp_htcp.c
index af99776..937549b 100644
--- a/net/ipv4/tcp_htcp.c
+++ b/net/ipv4/tcp_htcp.c
@@ -69,9 +69,12 @@
const struct tcp_sock *tp = tcp_sk(sk);
struct htcp *ca = inet_csk_ca(sk);
- ca->last_cong = ca->undo_last_cong;
- ca->maxRTT = ca->undo_maxRTT;
- ca->old_maxB = ca->undo_old_maxB;
+ 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 @@
case TCP_CA_Open:
{
struct htcp *ca = inet_csk_ca(sk);
- ca->last_cong = jiffies;
+ if (ca->undo_last_cong) {
+ ca->last_cong = jiffies;
+ ca->undo_last_cong = 0;
+ }
}
break;
case TCP_CA_CWR: