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_output.c b/net/ipv4/tcp_output.c
index 4c8a6ea..be9f8f4 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -160,7 +160,7 @@ static void tcp_event_data_sent(struct tcp_sock *tp,
 				struct sock *sk)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
-	const u32 now = tcp_time_stamp;
+	const u32 now = tcp_jiffies32;
 
 	if (tcp_packets_in_flight(tp) == 0)
 		tcp_ca_event(sk, CA_EVENT_TX_START);
@@ -1918,7 +1918,7 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
 	/* Avoid bursty behavior by allowing defer
 	 * only if the last write was recent.
 	 */
-	if ((s32)(tcp_time_stamp - tp->lsndtime) > 0)
+	if ((s32)(tcp_jiffies32 - tp->lsndtime) > 0)
 		goto send_now;
 
 	in_flight = tcp_packets_in_flight(tp);