tcp: fix data delivery rate

Now skb->mstamp_skb is updated later, we also need to call
tcp_rate_skb_sent() after the update is done.

Fixes: 8c72c65b ("tcp: update skb->skb_mstamp more carefully")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Acked-by: NSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp_output.c

@@ -1002,8 +1002,6 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 	if (clone_it) {
 		TCP_SKB_CB(skb)->tx.in_flight = TCP_SKB_CB(skb)->end_seq
 			- tp->snd_una;
-		tcp_rate_skb_sent(sk, skb);
-
 		oskb = skb;
 		if (unlikely(skb_cloned(skb)))
 			skb = pskb_copy(skb, gfp_mask);
@@ -1128,9 +1126,10 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 		tcp_enter_cwr(sk);
 		err = net_xmit_eval(err);
 	}
-	if (!err && oskb)
+	if (!err && oskb) {
 		oskb->skb_mstamp = tp->tcp_mstamp;
-
+		tcp_rate_skb_sent(sk, oskb);
+	}
 	return err;
 }