1 files changed, 24 insertions, 8 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 00e5a300ddb9..c4172c1fb198 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -160,7 +160,8 @@ static void tcp_event_data_sent(struct tcp_sock *tp,
 }
 
 /* Account for an ACK we sent. */
-static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts)
+static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts,
+                                      u32 rcv_nxt)
 {
         struct tcp_sock *tp = tcp_sk(sk);
 
@@ -171,6 +172,9 @@ static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts)
                 if (hrtimer_try_to_cancel(&tp->compressed_ack_timer) == 1)
                         __sock_put(sk);
         }
+
+        if (unlikely(rcv_nxt != tp->rcv_nxt))
+                return;  /* Special ACK sent by DCTCP to reflect ECN */
         tcp_dec_quickack_mode(sk, pkts);
         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
 }
@@ -1023,8 +1027,8 @@ static void tcp_update_skb_after_send(struct tcp_sock *tp, struct sk_buff *skb)
  * We are working here with either a clone of the original
  * SKB, or a fresh unique copy made by the retransmit engine.
  */
-static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
-                            gfp_t gfp_mask)
+static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
+                              int clone_it, gfp_t gfp_mask, u32 rcv_nxt)
 {
         const struct inet_connection_sock *icsk = inet_csk(sk);
         struct inet_sock *inet;
@@ -1100,7 +1104,7 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
         th->source              = inet->inet_sport;
         th->dest                = inet->inet_dport;
         th->seq                 = htonl(tcb->seq);
-        th->ack_seq             = htonl(tp->rcv_nxt);
+        th->ack_seq             = htonl(rcv_nxt);
         *(((__be16 *)th) + 6)   = htons(((tcp_header_size >> 2) << 12) |
                                         tcb->tcp_flags);
 
@@ -1141,7 +1145,7 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
         icsk->icsk_af_ops->send_check(sk, skb);
 
         if (likely(tcb->tcp_flags & TCPHDR_ACK))
-                tcp_event_ack_sent(sk, tcp_skb_pcount(skb));
+                tcp_event_ack_sent(sk, tcp_skb_pcount(skb), rcv_nxt);
 
         if (skb->len != tcp_header_size) {
                 tcp_event_data_sent(tp, sk);
@@ -1178,6 +1182,13 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
         return err;
 }
 
+static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
+                            gfp_t gfp_mask)
+{
+        return __tcp_transmit_skb(sk, skb, clone_it, gfp_mask,
+                                  tcp_sk(sk)->rcv_nxt);
+}
+
 /* This routine just queues the buffer for sending.
  *
  * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames,
@@ -3571,7 +3582,7 @@ void tcp_send_delayed_ack(struct sock *sk)
 }
 
 /* This routine sends an ack and also updates the window. */
-void tcp_send_ack(struct sock *sk)
+void __tcp_send_ack(struct sock *sk, u32 rcv_nxt)
 {
         struct sk_buff *buff;
 
@@ -3604,9 +3615,14 @@ void tcp_send_ack(struct sock *sk)
         skb_set_tcp_pure_ack(buff);
 
         /* Send it off, this clears delayed acks for us. */
-        tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0);
+        __tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0, rcv_nxt);
+}
+EXPORT_SYMBOL_GPL(__tcp_send_ack);
+
+void tcp_send_ack(struct sock *sk)
+{
+        __tcp_send_ack(sk, tcp_sk(sk)->rcv_nxt);
 }
-EXPORT_SYMBOL_GPL(tcp_send_ack);
 
 /* This routine sends a packet with an out of date sequence
  * number. It assumes the other end will try to ack it.