tcp: use tcp_jiffies32 to feed tp->lsndtime

Use tcp_jiffies32 instead of tcp_time_stamp to feed
tp->lsndtime.

tcp_time_stamp will soon be a litle bit more expensive
than simply reading 'jiffies'.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 06e2dbc..c0b3f90 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5571,7 +5571,7 @@ void tcp_finish_connect(struct sock *sk, struct sk_buff *skb)
 	/* Prevent spurious tcp_cwnd_restart() on first data
 	 * packet.
 	 */
-	tp->lsndtime = tcp_time_stamp;
+	tp->lsndtime = tcp_jiffies32;
 
 	tcp_init_buffer_space(sk);
 
@@ -6008,7 +6008,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 			tcp_update_pacing_rate(sk);
 
 		/* Prevent spurious tcp_cwnd_restart() on first data packet */
-		tp->lsndtime = tcp_time_stamp;
+		tp->lsndtime = tcp_jiffies32;
 
 		tcp_initialize_rcv_mss(sk);
 		tcp_fast_path_on(tp);