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: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/bridge/br_device.c

@@ -38,8 +38,10 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
 	}
 #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 @@ static int br_dev_stop(struct net_device *dev)
 	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 @@ static const struct net_device_ops br_netdev_ops = {
 	.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,

net/bridge/br_input.c

@@ -27,8 +27,10 @@ static int br_pass_frame_up(struct sk_buff *skb)
 	struct net_bridge *br = netdev_priv(brdev);
 	struct br_cpu_netstats *brstats = this_cpu_ptr(br->stats);
 
+	u64_stats_update_begin(&brstats->syncp);
 	brstats->rx_packets++;
 	brstats->rx_bytes += skb->len;
+	u64_stats_update_end(&brstats->syncp);
 
 	indev = skb->dev;
 	skb->dev = brdev;

net/bridge/br_private.h

@@ -16,6 +16,7 @@
 #include <linux/netdevice.h>
 #include <linux/if_bridge.h>
 #include <linux/netpoll.h>
+#include <linux/u64_stats_sync.h>
 #include <net/route.h>
 
 #define BR_HASH_BITS 8
@@ -156,10 +157,11 @@ struct net_bridge_port
 #define br_port_exists(dev) (dev->priv_flags & IFF_BRIDGE_PORT)
 
 struct br_cpu_netstats {
-	unsigned long	rx_packets;
-	unsigned long	rx_bytes;
-	unsigned long	tx_packets;
-	unsigned long	tx_bytes;
+	u64			rx_packets;
+	u64			rx_bytes;
+	u64			tx_packets;
+	u64			tx_bytes;
+	struct u64_stats_sync	syncp;
 };
 
 struct net_bridge