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Commit cf05c700 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

veth: fix 64bit stats on 32bit arches 



Using 64bit stats on 32bit arches must use a synchronization or readers
can get transient values.

Fixes bug introduced in commit 6311cc44 (veth: convert to 64 bit
statistics)

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 219eb47e

drivers/net/veth.c

+37 −18
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <linux/slab.h>

#include <linux/ethtool.h>

#include <linux/etherdevice.h>

#include <linux/u64_stats_sync.h>



#include <net/dst.h>

#include <net/xfrm.h>
@@ -28,8 +29,9 @@ struct veth_net_stats { 
	u64			tx_packets;

	u64			rx_bytes;

	u64			tx_bytes;

	u64	tx_dropped;

	u64			rx_dropped;

	u64			tx_dropped;

	struct u64_stats_sync	syncp;

};



struct veth_priv {
@@ -137,21 +139,29 @@ static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev) 
	if (dev_forward_skb(rcv, skb) != NET_RX_SUCCESS)

		goto rx_drop;



	u64_stats_update_begin(&stats->syncp);

	stats->tx_bytes += length;

	stats->tx_packets++;

	u64_stats_update_end(&stats->syncp);



	u64_stats_update_begin(&rcv_stats->syncp);

	rcv_stats->rx_bytes += length;

	rcv_stats->rx_packets++;

	u64_stats_update_end(&rcv_stats->syncp);



	return NETDEV_TX_OK;



tx_drop:

	kfree_skb(skb);

	u64_stats_update_begin(&stats->syncp);

	stats->tx_dropped++;

	u64_stats_update_end(&stats->syncp);

	return NETDEV_TX_OK;



rx_drop:

	u64_stats_update_begin(&rcv_stats->syncp);

	rcv_stats->rx_dropped++;

	u64_stats_update_end(&rcv_stats->syncp);

	return NETDEV_TX_OK;

}
@@ -162,21 +172,30 @@ static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev) 
static struct rtnl_link_stats64 *veth_get_stats64(struct net_device *dev,

						  struct rtnl_link_stats64 *tot)

{

	struct veth_priv *priv;

	struct veth_priv *priv = netdev_priv(dev);

	int cpu;

	struct veth_net_stats *stats;



	priv = netdev_priv(dev);



	for_each_possible_cpu(cpu) {

		stats = per_cpu_ptr(priv->stats, cpu);



		tot->rx_packets += stats->rx_packets;

		tot->tx_packets += stats->tx_packets;

		tot->rx_bytes   += stats->rx_bytes;

		tot->tx_bytes   += stats->tx_bytes;

		tot->tx_dropped += stats->tx_dropped;

		tot->rx_dropped += stats->rx_dropped;

		struct veth_net_stats *stats = per_cpu_ptr(priv->stats, cpu);

		u64 rx_packets, rx_bytes, rx_dropped;

		u64 tx_packets, tx_bytes, tx_dropped;

		unsigned int start;



		do {

			start = u64_stats_fetch_begin_bh(&stats->syncp);

			rx_packets = stats->rx_packets;

			tx_packets = stats->tx_packets;

			rx_bytes = stats->rx_bytes;

			tx_bytes = stats->tx_bytes;

			rx_dropped = stats->rx_dropped;

			tx_dropped = stats->tx_dropped;

		} while (u64_stats_fetch_retry_bh(&stats->syncp, start));

		tot->rx_packets += rx_packets;

		tot->tx_packets += tx_packets;

		tot->rx_bytes   += rx_bytes;

		tot->tx_bytes   += tx_bytes;

		tot->rx_dropped += rx_dropped;

		tot->tx_dropped += tx_dropped;

	}



	return tot;