1 files changed, 30 insertions, 1 deletions

diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 43cf901d7659..059082c873cf 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -49,6 +49,35 @@ struct inet_timewait_death_row tcp_death_row = {
 };
 EXPORT_SYMBOL_GPL(tcp_death_row);
 
+/* VJ's idea. Save last timestamp seen from this destination
+ * and hold it at least for normal timewait interval to use for duplicate
+ * segment detection in subsequent connections, before they enter synchronized
+ * state.
+ */
+
+static int tcp_remember_stamp(struct sock *sk)
+{
+        const struct inet_connection_sock *icsk = inet_csk(sk);
+        struct tcp_sock *tp = tcp_sk(sk);
+        struct inet_peer *peer;
+        bool release_it;
+
+        peer = icsk->icsk_af_ops->get_peer(sk, &release_it);
+        if (peer) {
+                if ((s32)(peer->tcp_ts - tp->rx_opt.ts_recent) <= 0 ||
+                    ((u32)get_seconds() - peer->tcp_ts_stamp > TCP_PAWS_MSL &&
+                     peer->tcp_ts_stamp <= (u32)tp->rx_opt.ts_recent_stamp)) {
+                        peer->tcp_ts_stamp = (u32)tp->rx_opt.ts_recent_stamp;
+                        peer->tcp_ts = tp->rx_opt.ts_recent;
+                }
+                if (release_it)
+                        inet_putpeer(peer);
+                return 1;
+        }
+
+        return 0;
+}
+
 static __inline__ int tcp_in_window(u32 seq, u32 end_seq, u32 s_win, u32 e_win)
 {
         if (seq == s_win)
@@ -274,7 +303,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
         int recycle_ok = 0;
 
         if (tcp_death_row.sysctl_tw_recycle && tp->rx_opt.ts_recent_stamp)
-                recycle_ok = icsk->icsk_af_ops->remember_stamp(sk);
+                recycle_ok = tcp_remember_stamp(sk);
 
         if (tcp_death_row.tw_count < tcp_death_row.sysctl_max_tw_buckets)
                 tw = inet_twsk_alloc(sk, state);