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, 31 insertions, 33 deletions

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index a95a41b74b4e..9bb9bfa225b6 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3804,51 +3804,49 @@ static int bond_close(struct net_device *bond_dev)
 	return 0;
 }
 
-static struct rtnl_link_stats64 *bond_get_stats(struct net_device *bond_dev)
+static struct rtnl_link_stats64 *bond_get_stats(struct net_device *bond_dev,
+						struct rtnl_link_stats64 *stats)
 {
 	struct bonding *bond = netdev_priv(bond_dev);
-	struct rtnl_link_stats64 *stats = &bond_dev->stats64;
-	struct rtnl_link_stats64 local_stats;
+	struct rtnl_link_stats64 temp;
 	struct slave *slave;
 	int i;
 
-	memset(&local_stats, 0, sizeof(local_stats));
+	memset(stats, 0, sizeof(*stats));
 
 	read_lock_bh(&bond->lock);
 
 	bond_for_each_slave(bond, slave, i) {
 		const struct rtnl_link_stats64 *sstats =
-			dev_get_stats(slave->dev);
-
-		local_stats.rx_packets += sstats->rx_packets;
-		local_stats.rx_bytes += sstats->rx_bytes;
-		local_stats.rx_errors += sstats->rx_errors;
-		local_stats.rx_dropped += sstats->rx_dropped;
-
-		local_stats.tx_packets += sstats->tx_packets;
-		local_stats.tx_bytes += sstats->tx_bytes;
-		local_stats.tx_errors += sstats->tx_errors;
-		local_stats.tx_dropped += sstats->tx_dropped;
-
-		local_stats.multicast += sstats->multicast;
-		local_stats.collisions += sstats->collisions;
-
-		local_stats.rx_length_errors += sstats->rx_length_errors;
-		local_stats.rx_over_errors += sstats->rx_over_errors;
-		local_stats.rx_crc_errors += sstats->rx_crc_errors;
-		local_stats.rx_frame_errors += sstats->rx_frame_errors;
-		local_stats.rx_fifo_errors += sstats->rx_fifo_errors;
-		local_stats.rx_missed_errors += sstats->rx_missed_errors;
-
-		local_stats.tx_aborted_errors += sstats->tx_aborted_errors;
-		local_stats.tx_carrier_errors += sstats->tx_carrier_errors;
-		local_stats.tx_fifo_errors += sstats->tx_fifo_errors;
-		local_stats.tx_heartbeat_errors += sstats->tx_heartbeat_errors;
-		local_stats.tx_window_errors += sstats->tx_window_errors;
+			dev_get_stats(slave->dev, &temp);
+
+		stats->rx_packets += sstats->rx_packets;
+		stats->rx_bytes += sstats->rx_bytes;
+		stats->rx_errors += sstats->rx_errors;
+		stats->rx_dropped += sstats->rx_dropped;
+
+		stats->tx_packets += sstats->tx_packets;
+		stats->tx_bytes += sstats->tx_bytes;
+		stats->tx_errors += sstats->tx_errors;
+		stats->tx_dropped += sstats->tx_dropped;
+
+		stats->multicast += sstats->multicast;
+		stats->collisions += sstats->collisions;
+
+		stats->rx_length_errors += sstats->rx_length_errors;
+		stats->rx_over_errors += sstats->rx_over_errors;
+		stats->rx_crc_errors += sstats->rx_crc_errors;
+		stats->rx_frame_errors += sstats->rx_frame_errors;
+		stats->rx_fifo_errors += sstats->rx_fifo_errors;
+		stats->rx_missed_errors += sstats->rx_missed_errors;
+
+		stats->tx_aborted_errors += sstats->tx_aborted_errors;
+		stats->tx_carrier_errors += sstats->tx_carrier_errors;
+		stats->tx_fifo_errors += sstats->tx_fifo_errors;
+		stats->tx_heartbeat_errors += sstats->tx_heartbeat_errors;
+		stats->tx_window_errors += sstats->tx_window_errors;
 	}
 
-	memcpy(stats, &local_stats, sizeof(struct net_device_stats));
-
 	read_unlock_bh(&bond->lock);
 
 	return stats;