net: fix 64 bit counters on 32 bit arches

There is a small possibility that a reader gets incorrect values on 32
bit arches. SNMP applications could catch incorrect counters when a
32bit high part is changed by another stats consumer/provider.

One way to solve this is to add a rtnl_link_stats64 param to all
ndo_get_stats64() methods, and also add such a parameter to
dev_get_stats().

Rule is that we are not allowed to use dev->stats64 as a temporary
storage for 64bit stats, but a caller provided area (usually on stack)

Old drivers (only providing get_stats() method) need no changes.

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

2 files changed, 3 insertions, 3 deletions

diff --git a/drivers/net/sfc/efx.c b/drivers/net/sfc/efx.c
index 35b3f2922e5c..ba674c5ca29e 100644
--- a/drivers/net/sfc/efx.c
+++ b/drivers/net/sfc/efx.c
@@ -1533,11 +1533,10 @@ static int efx_net_stop(struct net_device *net_dev)
 }
 
 /* Context: process, dev_base_lock or RTNL held, non-blocking. */
-static struct rtnl_link_stats64 *efx_net_stats(struct net_device *net_dev)
+static struct rtnl_link_stats64 *efx_net_stats(struct net_device *net_dev, struct rtnl_link_stats64 *stats)
 {
         struct efx_nic *efx = netdev_priv(net_dev);
         struct efx_mac_stats *mac_stats = &efx->mac_stats;
-        struct rtnl_link_stats64 *stats = &net_dev->stats64;
 
         spin_lock_bh(&efx->stats_lock);
         efx->type->update_stats(efx);
diff --git a/drivers/net/sfc/ethtool.c b/drivers/net/sfc/ethtool.c
index 3b8b0a062749..fd19d6ab97a2 100644
--- a/drivers/net/sfc/ethtool.c
+++ b/drivers/net/sfc/ethtool.c
@@ -469,12 +469,13 @@ static void efx_ethtool_get_stats(struct net_device *net_dev,
         struct efx_mac_stats *mac_stats = &efx->mac_stats;
         struct efx_ethtool_stat *stat;
         struct efx_channel *channel;
+        struct rtnl_link_stats64 temp;
         int i;
 
         EFX_BUG_ON_PARANOID(stats->n_stats != EFX_ETHTOOL_NUM_STATS);
 
         /* Update MAC and NIC statistics */
-        dev_get_stats(net_dev);
+        dev_get_stats(net_dev, &temp);
 
         /* Fill detailed statistics buffer */
         for (i = 0; i < EFX_ETHTOOL_NUM_STATS; i++) {