tcp: new helper tcp_timeout_mark_lost

Refactor using a new helper, tcp_timeout_mark_loss(), that marks packets
lost upon RTO.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Priyaranjan Jha <priyarjha@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 29 insertions, 21 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 6fb0a28977a0..af32accda2a9 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1917,18 +1917,43 @@ static inline void tcp_init_undo(struct tcp_sock *tp)
         tp->undo_retrans = tp->retrans_out ? : -1;
 }
 
-/* Enter Loss state. If we detect SACK reneging, forget all SACK information
+/* If we detect SACK reneging, forget all SACK information
  * and reset tags completely, otherwise preserve SACKs. If receiver
  * dropped its ofo queue, we will know this due to reneging detection.
  */
+static void tcp_timeout_mark_lost(struct sock *sk)
+{
+        struct tcp_sock *tp = tcp_sk(sk);
+        struct sk_buff *skb;
+        bool is_reneg;                  /* is receiver reneging on SACKs? */
+
+        skb = tcp_rtx_queue_head(sk);
+        is_reneg = skb && (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED);
+        if (is_reneg) {
+                NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSACKRENEGING);
+                tp->sacked_out = 0;
+                /* Mark SACK reneging until we recover from this loss event. */
+                tp->is_sack_reneg = 1;
+        } else if (tcp_is_reno(tp)) {
+                tcp_reset_reno_sack(tp);
+        }
+
+        skb_rbtree_walk_from(skb) {
+                if (is_reneg)
+                        TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_ACKED;
+                tcp_mark_skb_lost(sk, skb);
+        }
+        tcp_verify_left_out(tp);
+        tcp_clear_all_retrans_hints(tp);
+}
+
+/* Enter Loss state. */
 void tcp_enter_loss(struct sock *sk)
 {
         const struct inet_connection_sock *icsk = inet_csk(sk);
         struct tcp_sock *tp = tcp_sk(sk);
         struct net *net = sock_net(sk);
-        struct sk_buff *skb;
         bool new_recovery = icsk->icsk_ca_state < TCP_CA_Recovery;
-        bool is_reneg;                  /* is receiver reneging on SACKs? */
 
         /* Reduce ssthresh if it has not yet been made inside this window. */
         if (icsk->icsk_ca_state <= TCP_CA_Disorder ||
@@ -1944,24 +1969,7 @@ void tcp_enter_loss(struct sock *sk)
         tp->snd_cwnd_cnt   = 0;
         tp->snd_cwnd_stamp = tcp_jiffies32;
 
-        if (tcp_is_reno(tp))
-                tcp_reset_reno_sack(tp);
-
-        skb = tcp_rtx_queue_head(sk);
-        is_reneg = skb && (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED);
-        if (is_reneg) {
-                NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSACKRENEGING);
-                tp->sacked_out = 0;
-                /* Mark SACK reneging until we recover from this loss event. */
-                tp->is_sack_reneg = 1;
-        }
-        skb_rbtree_walk_from(skb) {
-                if (is_reneg)
-                        TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_ACKED;
-                tcp_mark_skb_lost(sk, skb);
-        }
-        tcp_verify_left_out(tp);
-        tcp_clear_all_retrans_hints(tp);
+        tcp_timeout_mark_lost(sk);
 
         /* Timeout in disordered state after receiving substantial DUPACKs
          * suggests that the degree of reordering is over-estimated.