1 files changed, 19 insertions, 19 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 075ab4d5af5e..71fb37c70581 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3358,34 +3358,34 @@ static void tcp_replace_ts_recent(struct tcp_sock *tp, u32 seq)
 }
 
 /* This routine deals with acks during a TLP episode.
+ * We mark the end of a TLP episode on receiving TLP dupack or when
+ * ack is after tlp_high_seq.
  * Ref: loss detection algorithm in draft-dukkipati-tcpm-tcp-loss-probe.
  */
 static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag)
 {
         struct tcp_sock *tp = tcp_sk(sk);
-        bool is_tlp_dupack = (ack == tp->tlp_high_seq) &&
-                             !(flag & (FLAG_SND_UNA_ADVANCED |
-                                       FLAG_NOT_DUP | FLAG_DATA_SACKED));
 
-        /* Mark the end of TLP episode on receiving TLP dupack or when
-         * ack is after tlp_high_seq.
-         */
-        if (is_tlp_dupack) {
-                tp->tlp_high_seq = 0;
+        if (before(ack, tp->tlp_high_seq))
                 return;
-        }
 
-        if (after(ack, tp->tlp_high_seq)) {
+        if (flag & FLAG_DSACKING_ACK) {
+                /* This DSACK means original and TLP probe arrived; no loss */
+                tp->tlp_high_seq = 0;
+        } else if (after(ack, tp->tlp_high_seq)) {
+                /* ACK advances: there was a loss, so reduce cwnd. Reset
+                 * tlp_high_seq in tcp_init_cwnd_reduction()
+                 */
+                tcp_init_cwnd_reduction(sk);
+                tcp_set_ca_state(sk, TCP_CA_CWR);
+                tcp_end_cwnd_reduction(sk);
+                tcp_try_keep_open(sk);
+                NET_INC_STATS_BH(sock_net(sk),
+                                 LINUX_MIB_TCPLOSSPROBERECOVERY);
+        } else if (!(flag & (FLAG_SND_UNA_ADVANCED |
+                             FLAG_NOT_DUP | FLAG_DATA_SACKED))) {
+                /* Pure dupack: original and TLP probe arrived; no loss */
                 tp->tlp_high_seq = 0;
-                /* Don't reduce cwnd if DSACK arrives for TLP retrans. */
-                if (!(flag & FLAG_DSACKING_ACK)) {
-                        tcp_init_cwnd_reduction(sk);
-                        tcp_set_ca_state(sk, TCP_CA_CWR);
-                        tcp_end_cwnd_reduction(sk);
-                        tcp_try_keep_open(sk);
-                        NET_INC_STATS_BH(sock_net(sk),
-                                         LINUX_MIB_TCPLOSSPROBERECOVERY);
-                }
         }
 }