net-tcp_bbr: v2: factor out tx.in_flight setting into tcp_set_tx_in_f…

…light()

Factor out the code to set an skb's tx.in_flight field into its own
function, so that this code can be used for the TCP_REPAIR "fake send"
code path that inserts skbs into the rtx queue without sending
them. This is in preparation for the following patch, which fixes an
issue with TCP_REPAIR and tx.in_flight.

Tested: See last patch in series for sponge link.

Effort: net-tcp_bbr
Origin-9xx-SHA1: e880fc907d06ea7354333f60f712748ebce9497b
Change-Id: I4fbd4a6e18a51ab06d50ab1c9ad820ce5bea89af

include/net/tcp.h

@@ -1163,6 +1163,7 @@ static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
 }
 
 /* From tcp_rate.c */
+void tcp_set_tx_in_flight(struct sock *sk, struct sk_buff *skb);
 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
 			    struct rate_sample *rs);

net/ipv4/tcp_rate.c

@@ -34,13 +34,30 @@
  * ready to send in the write queue.
  */
 
+void tcp_set_tx_in_flight(struct sock *sk, struct sk_buff *skb)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	u32 in_flight;
+
+	/* Check, sanitize, and record packets in flight after skb was sent. */
+	in_flight = tcp_packets_in_flight(tp) + tcp_skb_pcount(skb);
+	if (WARN_ONCE(in_flight > TCPCB_IN_FLIGHT_MAX,
+		      "insane in_flight %u cc %s mss %u "
+		      "cwnd %u pif %u %u %u %u\n",
+		      in_flight, inet_csk(sk)->icsk_ca_ops->name,
+		      tp->mss_cache, tp->snd_cwnd,
+		      tp->packets_out, tp->retrans_out,
+		      tp->sacked_out, tp->lost_out))
+		in_flight = TCPCB_IN_FLIGHT_MAX;
+	TCP_SKB_CB(skb)->tx.in_flight = in_flight;
+}
+
 /* Snapshot the current delivery information in the skb, to generate
  * a rate sample later when the skb is (s)acked in tcp_rate_skb_delivered().
  */
 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
-	u32 in_flight;
 
 	 /* In general we need to start delivery rate samples from the
 	  * time we received the most recent ACK, to ensure we include
@@ -69,18 +86,7 @@ void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb)
 	TCP_SKB_CB(skb)->tx.delivered_ce	= tp->delivered_ce;
 	TCP_SKB_CB(skb)->tx.lost		= tp->lost;
 	TCP_SKB_CB(skb)->tx.is_app_limited	= tp->app_limited ? 1 : 0;
-
-	/* Check, sanitize, and record packets in flight after skb was sent. */
-	in_flight = tcp_packets_in_flight(tp) + tcp_skb_pcount(skb);
-	WARN_ONCE(in_flight > TCPCB_IN_FLIGHT_MAX,
-		  "insane in_flight %u cc %s mss %u "
-		  "cwnd %u pif %u %u %u %u\n",
-		  in_flight, inet_csk(sk)->icsk_ca_ops->name,
-		  tp->mss_cache, tp->snd_cwnd,
-		  tp->packets_out, tp->retrans_out,
-		  tp->sacked_out, tp->lost_out);
-	in_flight = min(in_flight, TCPCB_IN_FLIGHT_MAX);
-	TCP_SKB_CB(skb)->tx.in_flight		= in_flight;
+	tcp_set_tx_in_flight(sk, skb);
 }
 
 /* When an skb is sacked or acked, we fill in the rate sample with the (prior)