pktgen: Fix delay handling

After last pktgen changes, delay handling is wrong.

pktgen actually sends packets at full line speed.

Fix is to update pkt_dev->next_tx even if spin() returns early,
so that next spin() calls have a chance to see a positive delay.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/pktgen.c

@@ -2105,15 +2105,17 @@ static void pktgen_setup_inject(struct pktgen_dev *pkt_dev)
 static void spin(struct pktgen_dev *pkt_dev, ktime_t spin_until)
 {
 	ktime_t start_time, end_time;
-	s32 remaining;
+	s64 remaining;
 	struct hrtimer_sleeper t;
 
 	hrtimer_init_on_stack(&t.timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 	hrtimer_set_expires(&t.timer, spin_until);
 
 	remaining = ktime_to_us(hrtimer_expires_remaining(&t.timer));
-	if (remaining <= 0)
+	if (remaining <= 0) {
+		pkt_dev->next_tx = ktime_add_ns(spin_until, pkt_dev->delay);
 		return;
+	}
 
 	start_time = ktime_now();
 	if (remaining < 100)