4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Yuchung Cheng <ych...@google.com>

[ Upstream commit a69258f7aa2623e0930212f09c586fd06674ad79 ]

After fixing the way DCTCP tracking delayed ACKs, the delayed-ACK
related callbacks are no longer needed

Signed-off-by: Yuchung Cheng <ych...@google.com>
Signed-off-by: Eric Dumazet <eduma...@google.com>
Acked-by: Neal Cardwell <ncardw...@google.com>
Acked-by: Lawrence Brakmo <bra...@fb.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 include/net/tcp.h     |    2 --
 net/ipv4/tcp_dctcp.c  |   25 -------------------------
 net/ipv4/tcp_output.c |    4 ----
 3 files changed, 31 deletions(-)

--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -850,8 +850,6 @@ enum tcp_ca_event {
        CA_EVENT_LOSS,          /* loss timeout */
        CA_EVENT_ECN_NO_CE,     /* ECT set, but not CE marked */
        CA_EVENT_ECN_IS_CE,     /* received CE marked IP packet */
-       CA_EVENT_DELAYED_ACK,   /* Delayed ack is sent */
-       CA_EVENT_NON_DELAYED_ACK,
 };
 
 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */
--- a/net/ipv4/tcp_dctcp.c
+++ b/net/ipv4/tcp_dctcp.c
@@ -55,7 +55,6 @@ struct dctcp {
        u32 dctcp_alpha;
        u32 next_seq;
        u32 ce_state;
-       u32 delayed_ack_reserved;
        u32 loss_cwnd;
 };
 
@@ -96,7 +95,6 @@ static void dctcp_init(struct sock *sk)
 
                ca->dctcp_alpha = min(dctcp_alpha_on_init, DCTCP_MAX_ALPHA);
 
-               ca->delayed_ack_reserved = 0;
                ca->loss_cwnd = 0;
                ca->ce_state = 0;
 
@@ -230,25 +228,6 @@ static void dctcp_state(struct sock *sk,
        }
 }
 
-static void dctcp_update_ack_reserved(struct sock *sk, enum tcp_ca_event ev)
-{
-       struct dctcp *ca = inet_csk_ca(sk);
-
-       switch (ev) {
-       case CA_EVENT_DELAYED_ACK:
-               if (!ca->delayed_ack_reserved)
-                       ca->delayed_ack_reserved = 1;
-               break;
-       case CA_EVENT_NON_DELAYED_ACK:
-               if (ca->delayed_ack_reserved)
-                       ca->delayed_ack_reserved = 0;
-               break;
-       default:
-               /* Don't care for the rest. */
-               break;
-       }
-}
-
 static void dctcp_cwnd_event(struct sock *sk, enum tcp_ca_event ev)
 {
        switch (ev) {
@@ -258,10 +237,6 @@ static void dctcp_cwnd_event(struct sock
        case CA_EVENT_ECN_NO_CE:
                dctcp_ce_state_1_to_0(sk);
                break;
-       case CA_EVENT_DELAYED_ACK:
-       case CA_EVENT_NON_DELAYED_ACK:
-               dctcp_update_ack_reserved(sk, ev);
-               break;
        default:
                /* Don't care for the rest. */
                break;
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3444,8 +3444,6 @@ void tcp_send_delayed_ack(struct sock *s
        int ato = icsk->icsk_ack.ato;
        unsigned long timeout;
 
-       tcp_ca_event(sk, CA_EVENT_DELAYED_ACK);
-
        if (ato > TCP_DELACK_MIN) {
                const struct tcp_sock *tp = tcp_sk(sk);
                int max_ato = HZ / 2;
@@ -3502,8 +3500,6 @@ void __tcp_send_ack(struct sock *sk, u32
        if (sk->sk_state == TCP_CLOSE)
                return;
 
-       tcp_ca_event(sk, CA_EVENT_NON_DELAYED_ACK);
-
        /* We are not putting this on the write queue, so
         * tcp_transmit_skb() will set the ownership to this
         * sock.


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