inet: Turn ->remember_stamp into ->get_peer in connection AF ops.

Then we can make a completely generic tcp_remember_stamp()
that uses ->get_peer() as a helper, minimizing the AF specific
code and minimizing the eventual code duplication when we implement
the ipv6 side of TW recycling.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 30 insertions, 1 deletions

diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 43cf901d765..059082c873c 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);