2 files changed, 14 insertions, 2 deletions

diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index c91476ce314a..dff3192374f8 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -351,6 +351,8 @@ enum
 #define RTAX_INITCWND RTAX_INITCWND
         RTAX_FEATURES,
 #define RTAX_FEATURES RTAX_FEATURES
+        RTAX_RTO_MIN,
+#define RTAX_RTO_MIN RTAX_RTO_MIN
         __RTAX_MAX
 };
 
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 9785df37a65f..1ee72127462b 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -555,6 +555,16 @@ static void tcp_event_data_recv(struct sock *sk, struct sk_buff *skb)
                 tcp_grow_window(sk, skb);
 }
 
+static u32 tcp_rto_min(struct sock *sk)
+{
+        struct dst_entry *dst = __sk_dst_get(sk);
+        u32 rto_min = TCP_RTO_MIN;
+
+        if (dst_metric_locked(dst, RTAX_RTO_MIN))
+                rto_min = dst->metrics[RTAX_RTO_MIN-1];
+        return rto_min;
+}
+
 /* Called to compute a smoothed rtt estimate. The data fed to this
  * routine either comes from timestamps, or from segments that were
  * known _not_ to have been retransmitted [see Karn/Partridge
@@ -616,13 +626,13 @@ static void tcp_rtt_estimator(struct sock *sk, const __u32 mrtt)
                         if (tp->mdev_max < tp->rttvar)
                                 tp->rttvar -= (tp->rttvar-tp->mdev_max)>>2;
                         tp->rtt_seq = tp->snd_nxt;
-                        tp->mdev_max = TCP_RTO_MIN;
+                        tp->mdev_max = tcp_rto_min(sk);
                 }
         } else {
                 /* no previous measure. */
                 tp->srtt = m<<3;        /* take the measured time to be rtt */
                 tp->mdev = m<<1;        /* make sure rto = 3*rtt */
-                tp->mdev_max = tp->rttvar = max(tp->mdev, TCP_RTO_MIN);
+                tp->mdev_max = tp->rttvar = max(tp->mdev, tcp_rto_min(sk));
                 tp->rtt_seq = tp->snd_nxt;
         }
 }