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>

1 files changed, 2 insertions, 1 deletions

diff --git a/arch/s390/appldata/appldata_net_sum.c b/arch/s390/appldata/appldata_net_sum.c
index 9a9586f..f02e89c 100644
--- a/arch/s390/appldata/appldata_net_sum.c
+++ b/arch/s390/appldata/appldata_net_sum.c
@@ -85,7 +85,8 @@ static void appldata_get_net_sum_data(void *data)
 
 	rcu_read_lock();
 	for_each_netdev_rcu(&init_net, dev) {
-		const struct net_device_stats *stats = dev_get_stats(dev);
+		struct rtnl_link_stats64 temp;
+		const struct net_device_stats *stats = dev_get_stats(dev, &temp);
 
 		rx_packets += stats->rx_packets;
 		tx_packets += stats->tx_packets;