tcp: Revert "tcp: remove CA_ACK_SLOWPATH"

This change was a followup to the header prediction removal,
so first revert this as a prerequisite to back out hp removal.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 16 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 7616cd76f6f6..a0e436366d31 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3552,7 +3552,6 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
         u32 lost = tp->lost;
         int acked = 0; /* Number of packets newly acked */
         int rexmit = REXMIT_NONE; /* Flag to (re)transmit to recover losses */
-        u32 ack_ev_flags = 0;
 
         sack_state.first_sackt = 0;
         sack_state.rate = &rs;
@@ -3593,26 +3592,30 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
         if (flag & FLAG_UPDATE_TS_RECENT)
                 tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq);
 
-        if (ack_seq != TCP_SKB_CB(skb)->end_seq)
-                flag |= FLAG_DATA;
-        else
-                NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPPUREACKS);
+        {
+                u32 ack_ev_flags = CA_ACK_SLOWPATH;
 
-        flag |= tcp_ack_update_window(sk, skb, ack, ack_seq);
+                if (ack_seq != TCP_SKB_CB(skb)->end_seq)
+                        flag |= FLAG_DATA;
+                else
+                        NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPPUREACKS);
 
-        if (TCP_SKB_CB(skb)->sacked)
-                flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una,
-                                                &sack_state);
+                flag |= tcp_ack_update_window(sk, skb, ack, ack_seq);
 
-        if (tcp_ecn_rcv_ecn_echo(tp, tcp_hdr(skb))) {
-                flag |= FLAG_ECE;
-                ack_ev_flags = CA_ACK_ECE;
-        }
+                if (TCP_SKB_CB(skb)->sacked)
+                        flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una,
+                                                        &sack_state);
+
+                if (tcp_ecn_rcv_ecn_echo(tp, tcp_hdr(skb))) {
+                        flag |= FLAG_ECE;
+                        ack_ev_flags |= CA_ACK_ECE;
+                }
 
-        if (flag & FLAG_WIN_UPDATE)
-                ack_ev_flags |= CA_ACK_WIN_UPDATE;
+                if (flag & FLAG_WIN_UPDATE)
+                        ack_ev_flags |= CA_ACK_WIN_UPDATE;
 
-        tcp_in_ack_event(sk, ack_ev_flags);
+                tcp_in_ack_event(sk, ack_ev_flags);
+        }
 
         /* We passed data and got it acked, remove any soft error
          * log. Something worked...