[TCP]: Verify the presence of RETRANS bit when leaving FRTO

For yet unknown reason, something cleared SACKED_RETRANS bit
underneath FRTO.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 69f9f1ef3ef6..4e5884ac8f29 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1398,7 +1398,9 @@ static void tcp_enter_frto_loss(struct sock *sk, int allowed_segments, int flag)
                  * waiting for the first ACK and did not get it)...
                  */
                 if ((tp->frto_counter == 1) && !(flag&FLAG_DATA_ACKED)) {
-                        tp->retrans_out += tcp_skb_pcount(skb);
+                        /* For some reason this R-bit might get cleared? */
+                        if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS)
+                                tp->retrans_out += tcp_skb_pcount(skb);
                         /* ...enter this if branch just for the first segment */
                         flag |= FLAG_DATA_ACKED;
                 } else {