net: add DEV_STATS_READ() helper

Companion of DEV_STATS_INC() & DEV_STATS_ADD().

This is going to be used in the series.

Use it in macsec_get_stats64().
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/macsec.c

@@ -3655,9 +3655,9 @@ static void macsec_get_stats64(struct net_device *dev,
 
 	dev_fetch_sw_netstats(s, dev->tstats);
 
-	s->rx_dropped = atomic_long_read(&dev->stats.__rx_dropped);
-	s->tx_dropped = atomic_long_read(&dev->stats.__tx_dropped);
-	s->rx_errors = atomic_long_read(&dev->stats.__rx_errors);
+	s->rx_dropped = DEV_STATS_READ(dev, rx_dropped);
+	s->tx_dropped = DEV_STATS_READ(dev, tx_dropped);
+	s->rx_errors = DEV_STATS_READ(dev, rx_errors);
 }
 
 static int macsec_get_iflink(const struct net_device *dev)

include/linux/netdevice.h

@@ -5236,5 +5236,6 @@ extern struct net_device *blackhole_netdev;
 #define DEV_STATS_INC(DEV, FIELD) atomic_long_inc(&(DEV)->stats.__##FIELD)
 #define DEV_STATS_ADD(DEV, FIELD, VAL) 	\
 		atomic_long_add((VAL), &(DEV)->stats.__##FIELD)
+#define DEV_STATS_READ(DEV, FIELD) atomic_long_read(&(DEV)->stats.__##FIELD)
 
 #endif	/* _LINUX_NETDEVICE_H */