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authorStephen Hemminger <shemminger@linux-foundation.org>2007-07-25 23:50:28 -0700
committerDavid S. Miller <davem@sunset.davemloft.net>2007-07-31 02:27:59 -0700
commit113bbbd8d2da61b50417a1dd06d8e7c19047e54b (patch)
treea120314c2a7b648d1a2b04788f6d0de37d20b974
parente7d0c88586a66cf03e70750a8119d984fdedf2aa (diff)
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[TCP]: htcp - use measured rtt
Change HTCP to use measured RTT rather than smooth RTT. Srtt is computed using the TCP receive timestamp options, so it is vulnerable to hostile receivers. To avoid any problems this might cause use the measured RTT instead. Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/tcp_htcp.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/net/ipv4/tcp_htcp.c b/net/ipv4/tcp_htcp.c
index fa61663..b66556c 100644
--- a/net/ipv4/tcp_htcp.c
+++ b/net/ipv4/tcp_htcp.c
@@ -76,12 +76,11 @@ static u32 htcp_cwnd_undo(struct sock *sk)
return max(tp->snd_cwnd, (tp->snd_ssthresh << 7) / ca->beta);
}
-static inline void measure_rtt(struct sock *sk)
+static inline void measure_rtt(struct sock *sk, u32 srtt)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
const struct tcp_sock *tp = tcp_sk(sk);
struct htcp *ca = inet_csk_ca(sk);
- u32 srtt = tp->srtt >> 3;
/* keep track of minimum RTT seen so far, minRTT is zero at first */
if (ca->minRTT > srtt || !ca->minRTT)
@@ -108,6 +107,9 @@ static void measure_achieved_throughput(struct sock *sk, u32 pkts_acked, s32 rtt
if (icsk->icsk_ca_state == TCP_CA_Open)
ca->pkts_acked = pkts_acked;
+ if (rtt > 0)
+ measure_rtt(sk, usecs_to_jiffies(rtt));
+
if (!use_bandwidth_switch)
return;
@@ -237,8 +239,6 @@ static void htcp_cong_avoid(struct sock *sk, u32 ack,
if (tp->snd_cwnd <= tp->snd_ssthresh)
tcp_slow_start(tp);
else {
- measure_rtt(sk);
-
/* In dangerous area, increase slowly.
* In theory this is tp->snd_cwnd += alpha / tp->snd_cwnd
*/
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