tcp: early retransmit: tcp_enter_recovery()

This a prepartion patch that refactors the code to enter recovery
into a new function tcp_enter_recovery(). It's needed to implement
the delayed fast retransmit in ER.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 34 insertions, 27 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 96a631deb4e6..be8e09d2c6b1 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3022,6 +3022,38 @@ static void tcp_update_cwnd_in_recovery(struct sock *sk, int newly_acked_sacked,
         tp->snd_cwnd = tcp_packets_in_flight(tp) + sndcnt;
 }
 
+static void tcp_enter_recovery(struct sock *sk, bool ece_ack)
+{
+        struct tcp_sock *tp = tcp_sk(sk);
+        int mib_idx;
+
+        if (tcp_is_reno(tp))
+                mib_idx = LINUX_MIB_TCPRENORECOVERY;
+        else
+                mib_idx = LINUX_MIB_TCPSACKRECOVERY;
+
+        NET_INC_STATS_BH(sock_net(sk), mib_idx);
+
+        tp->high_seq = tp->snd_nxt;
+        tp->prior_ssthresh = 0;
+        tp->undo_marker = tp->snd_una;
+        tp->undo_retrans = tp->retrans_out;
+
+        if (inet_csk(sk)->icsk_ca_state < TCP_CA_CWR) {
+                if (!ece_ack)
+                        tp->prior_ssthresh = tcp_current_ssthresh(sk);
+                tp->snd_ssthresh = inet_csk(sk)->icsk_ca_ops->ssthresh(sk);
+                TCP_ECN_queue_cwr(tp);
+        }
+
+        tp->bytes_acked = 0;
+        tp->snd_cwnd_cnt = 0;
+        tp->prior_cwnd = tp->snd_cwnd;
+        tp->prr_delivered = 0;
+        tp->prr_out = 0;
+        tcp_set_ca_state(sk, TCP_CA_Recovery);
+}
+
 /* Process an event, which can update packets-in-flight not trivially.
  * Main goal of this function is to calculate new estimate for left_out,
  * taking into account both packets sitting in receiver's buffer and
@@ -3041,7 +3073,7 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
         struct tcp_sock *tp = tcp_sk(sk);
         int do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) &&
                                     (tcp_fackets_out(tp) > tp->reordering));
-        int fast_rexmit = 0, mib_idx;
+        int fast_rexmit = 0;
 
         if (WARN_ON(!tp->packets_out && tp->sacked_out))
                 tp->sacked_out = 0;
@@ -3142,32 +3174,7 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
                 }
 
                 /* Otherwise enter Recovery state */
-
-                if (tcp_is_reno(tp))
-                        mib_idx = LINUX_MIB_TCPRENORECOVERY;
-                else
-                        mib_idx = LINUX_MIB_TCPSACKRECOVERY;
-
-                NET_INC_STATS_BH(sock_net(sk), mib_idx);
-
-                tp->high_seq = tp->snd_nxt;
-                tp->prior_ssthresh = 0;
-                tp->undo_marker = tp->snd_una;
-                tp->undo_retrans = tp->retrans_out;
-
-                if (icsk->icsk_ca_state < TCP_CA_CWR) {
-                        if (!(flag & FLAG_ECE))
-                                tp->prior_ssthresh = tcp_current_ssthresh(sk);
-                        tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk);
-                        TCP_ECN_queue_cwr(tp);
-                }
-
-                tp->bytes_acked = 0;
-                tp->snd_cwnd_cnt = 0;
-                tp->prior_cwnd = tp->snd_cwnd;
-                tp->prr_delivered = 0;
-                tp->prr_out = 0;
-                tcp_set_ca_state(sk, TCP_CA_Recovery);
+                tcp_enter_recovery(sk, (flag & FLAG_ECE));
                 fast_rexmit = 1;
         }