bridge: 64bit rx/tx counters

Use u64_stats_sync infrastructure to provide 64bit rx/tx
counters even on 32bit hosts.

It is safe to use a single u64_stats_sync for rx and tx,
because BH is disabled on both, and we use per_cpu data.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index 6f3a927..edf639e 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -38,8 +38,10 @@
 	}
 #endif
 
+	u64_stats_update_begin(&brstats->syncp);
 	brstats->tx_packets++;
 	brstats->tx_bytes += skb->len;
+	u64_stats_update_end(&brstats->syncp);
 
 	BR_INPUT_SKB_CB(skb)->brdev = dev;
 
@@ -96,21 +98,25 @@
 	return 0;
 }
 
-static struct net_device_stats *br_get_stats(struct net_device *dev)
+static struct rtnl_link_stats64 *br_get_stats64(struct net_device *dev)
 {
 	struct net_bridge *br = netdev_priv(dev);
-	struct net_device_stats *stats = &dev->stats;
-	struct br_cpu_netstats sum = { 0 };
+	struct rtnl_link_stats64 *stats = &dev->stats64;
+	struct br_cpu_netstats tmp, sum = { 0 };
 	unsigned int cpu;
 
 	for_each_possible_cpu(cpu) {
+		unsigned int start;
 		const struct br_cpu_netstats *bstats
 			= per_cpu_ptr(br->stats, cpu);
-
-		sum.tx_bytes   += bstats->tx_bytes;
-		sum.tx_packets += bstats->tx_packets;
-		sum.rx_bytes   += bstats->rx_bytes;
-		sum.rx_packets += bstats->rx_packets;
+		do {
+			start = u64_stats_fetch_begin(&bstats->syncp);
+			memcpy(&tmp, bstats, sizeof(tmp));
+		} while (u64_stats_fetch_retry(&bstats->syncp, start));
+		sum.tx_bytes   += tmp.tx_bytes;
+		sum.tx_packets += tmp.tx_packets;
+		sum.rx_bytes   += tmp.rx_bytes;
+		sum.rx_packets += tmp.rx_packets;
 	}
 
 	stats->tx_bytes   = sum.tx_bytes;
@@ -300,7 +306,7 @@
 	.ndo_open		 = br_dev_open,
 	.ndo_stop		 = br_dev_stop,
 	.ndo_start_xmit		 = br_dev_xmit,
-	.ndo_get_stats		 = br_get_stats,
+	.ndo_get_stats64	 = br_get_stats64,
 	.ndo_set_mac_address	 = br_set_mac_address,
 	.ndo_set_multicast_list	 = br_dev_set_multicast_list,
 	.ndo_change_mtu		 = br_change_mtu,