TCP: avoid to send keepalive probes if receiving data

RFC 1122 says the following:
...
  Keep-alive packets MUST only be sent when no data or
  acknowledgement packets have been received for the
  connection within an interval.
...

The acknowledgement packet is reseting the keepalive
timer but the data packet isn't. This patch fixes it by
checking the timestamp of the last received data packet
too when the keepalive timer expires.

Signed-off-by: Flavio Leitner <fleitner@redhat.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 6689c61cab47..8ce29747ad9b 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2298,7 +2298,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
                         if (sock_flag(sk, SOCK_KEEPOPEN) &&
                             !((1 << sk->sk_state) &
                               (TCPF_CLOSE | TCPF_LISTEN))) {
-                                __u32 elapsed = tcp_time_stamp - tp->rcv_tstamp;
+                                u32 elapsed = keepalive_time_elapsed(tp);
                                 if (tp->keepalive_time > elapsed)
                                         elapsed = tp->keepalive_time - elapsed;
                                 else