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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 6311cc44a2 (veth: convert to 64 bit
statistics)

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2011-06-19 22:48:34 -07:00 committed by David S. Miller
parent 219eb47e6f
commit cf05c700cf
1 changed files with 36 additions and 17 deletions
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53
drivers/net/veth.c
View File

@ -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>
@ -24,12 +25,13 @@
#define MAX_MTU 65535 /* Max L3 MTU (arbitrary) */
struct veth_net_stats {
u64 rx_packets;
u64 tx_packets;
u64 rx_bytes;
u64 tx_bytes;
u64 tx_dropped;
u64 rx_dropped;
u64 rx_packets;
u64 tx_packets;
u64 rx_bytes;
u64 tx_bytes;
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);
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;
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;
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;