tcp: new helper function for RACK loss detection

Create a new helper tcp_rack_mark_skb_lost to prepare the
upcoming RACK reordering timer support.

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/net/ipv4/tcp_recovery.c b/net/ipv4/tcp_recovery.c
index e36df4f..f38dba5 100644 (file)
--- a/net/ipv4/tcp_recovery.c
+++ b/net/ipv4/tcp_recovery.c
@@ -3,6 +3,19 @@
 
 int sysctl_tcp_recovery __read_mostly = TCP_RACK_LOST_RETRANS;
 
+static void tcp_rack_mark_skb_lost(struct sock *sk, struct sk_buff *skb)
+{
+       struct tcp_sock *tp = tcp_sk(sk);
+
+       tcp_skb_mark_lost_uncond_verify(tp, skb);
+       if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) {
+               /* Account for retransmits that are lost again */
+               TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
+               tp->retrans_out -= tcp_skb_pcount(skb);
+               NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPLOSTRETRANSMIT);
+       }
+}
+
 /* Marks a packet lost, if some packet sent later has been (s)acked.
  * The underlying idea is similar to the traditional dupthresh and FACK
  * but they look at different metrics:
@@ -61,13 +74,7 @@ int tcp_rack_mark_lost(struct sock *sk)
                                continue;
 
                        /* skb is lost if packet sent later is sacked */
-                       tcp_skb_mark_lost_uncond_verify(tp, skb);
-                       if (scb->sacked & TCPCB_SACKED_RETRANS) {
-                               scb->sacked &= ~TCPCB_SACKED_RETRANS;
-                               tp->retrans_out -= tcp_skb_pcount(skb);
-                               NET_INC_STATS(sock_net(sk),
-                                             LINUX_MIB_TCPLOSTRETRANSMIT);
-                       }
+                       tcp_rack_mark_skb_lost(sk, skb);
                } else if (!(scb->sacked & TCPCB_RETRANS)) {
                        /* Original data are sent sequentially so stop early
                         * b/c the rest are all sent after rack_sent