From cf05c700cf6dd6f28bd95586d3040f809fd365f5 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 19 Jun 2011 22:48:34 -0700 Subject: [PATCH] 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 Signed-off-by: David S. Miller --- drivers/net/veth.c | 53 +++++++++++++++++++++++++++++++--------------- 1 file changed, 36 insertions(+), 17 deletions(-) diff --git a/drivers/net/veth.c b/drivers/net/veth.c index 8730d6494633..4b6db3b6c5d5 100644 --- a/drivers/net/veth.c +++ b/drivers/net/veth.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include @@ -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;