tcp: move tcp_mark_skb_lost

A pure refactor to move tcp_mark_skb_lost to tcp_input.c to prepare
for the later loss marking consolidation.

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

net/ipv4/tcp_input.c

@@ -1016,6 +1016,20 @@ static void tcp_verify_retransmit_hint(struct tcp_sock *tp, struct sk_buff *skb)
 		tp->retransmit_skb_hint = skb;
 }
 
+void tcp_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_ADD_STATS(sock_net(sk), LINUX_MIB_TCPLOSTRETRANSMIT,
+			      tcp_skb_pcount(skb));
+	}
+}
+
 /* Sum the number of packets on the wire we have marked as lost.
  * There are two cases we care about here:
  * a) Packet hasn't been marked lost (nor retransmitted),

net/ipv4/tcp_recovery.c

@@ -2,20 +2,6 @@
 #include <linux/tcp.h>
 #include <net/tcp.h>
 
-void tcp_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_ADD_STATS(sock_net(sk), LINUX_MIB_TCPLOSTRETRANSMIT,
-			      tcp_skb_pcount(skb));
-	}
-}
-
 static bool tcp_rack_sent_after(u64 t1, u64 t2, u32 seq1, u32 seq2)
 {
 	return t1 > t2 || (t1 == t2 && after(seq1, seq2));