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>

include/net/tcp.h

@@ -1245,7 +1245,7 @@ static inline void tcp_slow_start_after_idle_check(struct sock *sk)
 	if (!sysctl_tcp_slow_start_after_idle || tp->packets_out ||
 	    ca_ops->cong_control)
 		return;
-	delta = tcp_time_stamp - tp->lsndtime;
+	delta = tcp_jiffies32 - tp->lsndtime;
 	if (delta > inet_csk(sk)->icsk_rto)
 		tcp_cwnd_restart(sk, delta);
 }

net/ipv4/tcp.c

@@ -2841,7 +2841,7 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info)
 	info->tcpi_retrans = tp->retrans_out;
 	info->tcpi_fackets = tp->fackets_out;
 
-	now = tcp_time_stamp;
+	now = tcp_jiffies32;
 	info->tcpi_last_data_sent = jiffies_to_msecs(now - tp->lsndtime);
 	info->tcpi_last_data_recv = jiffies_to_msecs(now - icsk->icsk_ack.lrcvtime);
 	info->tcpi_last_ack_recv = jiffies_to_msecs(now - tp->rcv_tstamp);

net/ipv4/tcp_cubic.c

@@ -155,7 +155,7 @@ static void bictcp_cwnd_event(struct sock *sk, enum tcp_ca_event event)
 {
 	if (event == CA_EVENT_TX_START) {
 		struct bictcp *ca = inet_csk_ca(sk);
-		u32 now = tcp_time_stamp;
+		u32 now = tcp_jiffies32;
 		s32 delta;
 
 		delta = now - tcp_sk(sk)->lsndtime;

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);

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);

net/ipv4/tcp_timer.c

@@ -63,7 +63,7 @@ static int tcp_out_of_resources(struct sock *sk, bool do_reset)
 
 	/* If peer does not open window for long time, or did not transmit
 	 * anything for long time, penalize it. */
-	if ((s32)(tcp_time_stamp - tp->lsndtime) > 2*TCP_RTO_MAX || !do_reset)
+	if ((s32)(tcp_jiffies32 - tp->lsndtime) > 2*TCP_RTO_MAX || !do_reset)
 		shift++;
 
 	/* If some dubious ICMP arrived, penalize even more. */
@@ -73,7 +73,7 @@ static int tcp_out_of_resources(struct sock *sk, bool do_reset)
 	if (tcp_check_oom(sk, shift)) {
 		/* Catch exceptional cases, when connection requires reset.
 		 *      1. Last segment was sent recently. */
-		if ((s32)(tcp_time_stamp - tp->lsndtime) <= TCP_TIMEWAIT_LEN ||
+		if ((s32)(tcp_jiffies32 - tp->lsndtime) <= TCP_TIMEWAIT_LEN ||
 		    /*  2. Window is closed. */
 		    (!tp->snd_wnd && !tp->packets_out))
 			do_reset = true;