iptunnel: use new function dev_fetch_sw_netstats

Simplify the code by using new function dev_fetch_sw_netstats().
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/050f9a83-b195-a3d6-edbd-91a59040be21@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/ipv4/ip_tunnel_core.c

@@ -433,29 +433,8 @@ EXPORT_SYMBOL(skb_tunnel_check_pmtu);
 void ip_tunnel_get_stats64(struct net_device *dev,
 			   struct rtnl_link_stats64 *tot)
 {
-	int i;
-
 	netdev_stats_to_stats64(tot, &dev->stats);
-
-	for_each_possible_cpu(i) {
-		const struct pcpu_sw_netstats *tstats =
-						   per_cpu_ptr(dev->tstats, i);
-		u64 rx_packets, rx_bytes, tx_packets, tx_bytes;
-		unsigned int start;
-
-		do {
-			start = u64_stats_fetch_begin_irq(&tstats->syncp);
-			rx_packets = tstats->rx_packets;
-			tx_packets = tstats->tx_packets;
-			rx_bytes = tstats->rx_bytes;
-			tx_bytes = tstats->tx_bytes;
-		} while (u64_stats_fetch_retry_irq(&tstats->syncp, start));
-
-		tot->rx_packets += rx_packets;
-		tot->tx_packets += tx_packets;
-		tot->rx_bytes   += rx_bytes;
-		tot->tx_bytes   += tx_bytes;
-	}
+	dev_fetch_sw_netstats(tot, dev->tstats);
 }
 EXPORT_SYMBOL_GPL(ip_tunnel_get_stats64);