tcp: new helper for RACK to detect loss

Create a new helper tcp_rack_detect_loss to prepare the upcoming
RACK reordering timer patch.

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

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 1da0aa7249291f77e35feb2efc2531627c096f93..51183bba3835021929a1bf86070f7ebe8d04a429 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1863,8 +1863,7 @@ extern int sysctl_tcp_recovery;
 /* Use TCP RACK to detect (some) tail and retransmit losses */
 #define TCP_RACK_LOST_RETRANS  0x1
 
-extern int tcp_rack_mark_lost(struct sock *sk);
-
+extern void tcp_rack_mark_lost(struct sock *sk);
 extern void tcp_rack_advance(struct tcp_sock *tp,
                             const struct skb_mstamp *xmit_time, u8 sacked);
 

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index ec6d843630242074421994b17a851429a51a926c..bb24b93e64bc1ba3608173f5fd3c1a144a744577 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2865,10 +2865,14 @@ static void tcp_fastretrans_alert(struct sock *sk, const int acked,
        }
 
        /* Use RACK to detect loss */
-       if (sysctl_tcp_recovery & TCP_RACK_LOST_RETRANS &&
-           tcp_rack_mark_lost(sk)) {
-               flag |= FLAG_LOST_RETRANS;
-               *ack_flag |= FLAG_LOST_RETRANS;
+       if (sysctl_tcp_recovery & TCP_RACK_LOST_RETRANS) {
+               u32 prior_retrans = tp->retrans_out;
+
+               tcp_rack_mark_lost(sk);
+               if (prior_retrans > tp->retrans_out) {
+                       flag |= FLAG_LOST_RETRANS;
+                       *ack_flag |= FLAG_LOST_RETRANS;
+               }
        }
 
        /* E. Process state. */

diff --git a/net/ipv4/tcp_recovery.c b/net/ipv4/tcp_recovery.c
index f38dba5aed7a70f35198195e9ec7c30f0782419f..7ea0377229c0f65c1b2b3b08189eac7f3ada99b8 100644 (file)
--- a/net/ipv4/tcp_recovery.c
+++ b/net/ipv4/tcp_recovery.c
@@ -32,17 +32,11 @@ static void tcp_rack_mark_skb_lost(struct sock *sk, struct sk_buff *skb)
  * The current version is only used after recovery starts but can be
  * easily extended to detect the first loss.
  */
-int tcp_rack_mark_lost(struct sock *sk)
+static void tcp_rack_detect_loss(struct sock *sk)
 {
        struct tcp_sock *tp = tcp_sk(sk);
        struct sk_buff *skb;
-       u32 reo_wnd, prior_retrans = tp->retrans_out;
-
-       if (inet_csk(sk)->icsk_ca_state < TCP_CA_Recovery || !tp->rack.advanced)
-               return 0;
-
-       /* Reset the advanced flag to avoid unnecessary queue scanning */
-       tp->rack.advanced = 0;
+       u32 reo_wnd;
 
        /* To be more reordering resilient, allow min_rtt/4 settling delay
         * (lower-bounded to 1000uS). We use min_rtt instead of the smoothed
@@ -82,7 +76,17 @@ int tcp_rack_mark_lost(struct sock *sk)
                        break;
                }
        }
-       return prior_retrans - tp->retrans_out;
+}
+
+void tcp_rack_mark_lost(struct sock *sk)
+{
+       struct tcp_sock *tp = tcp_sk(sk);
+
+       if (inet_csk(sk)->icsk_ca_state < TCP_CA_Recovery || !tp->rack.advanced)
+               return;
+       /* Reset the advanced flag to avoid unnecessary queue scanning */
+       tp->rack.advanced = 0;
+       tcp_rack_detect_loss(sk);
 }
 
 /* Record the most recently (re)sent time among the (s)acked packets */