Revert "veth: prevent oops caused by netdev destructor"

This reverts commit ae0e8e82205c903978a79ebf5e31c670b61fa5b4.

This change had two problems:

1) Since it frees the stats in the drivers' close method, we
   can OOPS in the transmit routine.

2) stats are no longer remembered across ifdown/ifup which
   disagrees with how every other device operates.

Thanks to analysis and test patch from Serge E. Hallyn
and initial OOPS report by Sachin Sant.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 25 insertions, 16 deletions

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 87197dd9c788..1097c72e44d5 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -208,11 +208,14 @@ rx_drop:
 
 static struct net_device_stats *veth_get_stats(struct net_device *dev)
 {
-        struct veth_priv *priv = netdev_priv(dev);
-        struct net_device_stats *dev_stats = &dev->stats;
-        unsigned int cpu;
+        struct veth_priv *priv;
+        struct net_device_stats *dev_stats;
+        int cpu;
         struct veth_net_stats *stats;
 
+        priv = netdev_priv(dev);
+        dev_stats = &dev->stats;
+
         dev_stats->rx_packets = 0;
         dev_stats->tx_packets = 0;
         dev_stats->rx_bytes = 0;
@@ -220,17 +223,16 @@ static struct net_device_stats *veth_get_stats(struct net_device *dev)
         dev_stats->tx_dropped = 0;
         dev_stats->rx_dropped = 0;
 
-        if (priv->stats)
-                for_each_online_cpu(cpu) {
-                        stats = per_cpu_ptr(priv->stats, cpu);
+        for_each_online_cpu(cpu) {
+                stats = per_cpu_ptr(priv->stats, cpu);
 
-                        dev_stats->rx_packets += stats->rx_packets;
-                        dev_stats->tx_packets += stats->tx_packets;
-                        dev_stats->rx_bytes += stats->rx_bytes;
-                        dev_stats->tx_bytes += stats->tx_bytes;
-                        dev_stats->tx_dropped += stats->tx_dropped;
-                        dev_stats->rx_dropped += stats->rx_dropped;
-                }
+                dev_stats->rx_packets += stats->rx_packets;
+                dev_stats->tx_packets += stats->tx_packets;
+                dev_stats->rx_bytes += stats->rx_bytes;
+                dev_stats->tx_bytes += stats->tx_bytes;
+                dev_stats->tx_dropped += stats->tx_dropped;
+                dev_stats->rx_dropped += stats->rx_dropped;
+        }
 
         return dev_stats;
 }
@@ -257,8 +259,6 @@ static int veth_close(struct net_device *dev)
         netif_carrier_off(dev);
         netif_carrier_off(priv->peer);
 
-        free_percpu(priv->stats);
-        priv->stats = NULL;
         return 0;
 }
 
@@ -289,6 +289,15 @@ static int veth_dev_init(struct net_device *dev)
         return 0;
 }
 
+static void veth_dev_free(struct net_device *dev)
+{
+        struct veth_priv *priv;
+
+        priv = netdev_priv(dev);
+        free_percpu(priv->stats);
+        free_netdev(dev);
+}
+
 static const struct net_device_ops veth_netdev_ops = {
         .ndo_init            = veth_dev_init,
         .ndo_open            = veth_open,
@@ -306,7 +315,7 @@ static void veth_setup(struct net_device *dev)
         dev->netdev_ops = &veth_netdev_ops;
         dev->ethtool_ops = &veth_ethtool_ops;
         dev->features |= NETIF_F_LLTX;
-        dev->destructor = free_netdev;
+        dev->destructor = veth_dev_free;
 }
 
 /*