1 files changed, 12 insertions, 2 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index e695584bb33f..1e37c1388189 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4268,7 +4268,7 @@ static void tcp_sack_new_ofo_skb(struct sock *sk, u32 seq, u32 end_seq)
          * If the sack array is full, forget about the last one.
          */
         if (this_sack >= TCP_NUM_SACKS) {
-                if (tp->compressed_ack)
+                if (tp->compressed_ack > TCP_FASTRETRANS_THRESH)
                         tcp_send_ack(sk);
                 this_sack--;
                 tp->rx_opt.num_sacks--;
@@ -5189,7 +5189,17 @@ send_now:
         if (!tcp_is_sack(tp) ||
             tp->compressed_ack >= sock_net(sk)->ipv4.sysctl_tcp_comp_sack_nr)
                 goto send_now;
-        tp->compressed_ack++;
+
+        if (tp->compressed_ack_rcv_nxt != tp->rcv_nxt) {
+                tp->compressed_ack_rcv_nxt = tp->rcv_nxt;
+                if (tp->compressed_ack > TCP_FASTRETRANS_THRESH)
+                        NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPACKCOMPRESSED,
+                                      tp->compressed_ack - TCP_FASTRETRANS_THRESH);
+                tp->compressed_ack = 0;
+        }
+
+        if (++tp->compressed_ack <= TCP_FASTRETRANS_THRESH)
+                goto send_now;
 
         if (hrtimer_is_queued(&tp->compressed_ack_timer))
                 return;