net: add dev_txq_stats_fold() helper

Some drivers ndo_get_stats() method need to perform txqueue stats folding.

Move folding from dev_get_stats() to a new dev_txq_stats_fold() function
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -1941,6 +1941,7 @@ extern void		netdev_features_change(struct net_device *dev);
 extern void		dev_load(struct net *net, const char *name);
 extern void		dev_mcast_init(void);
 extern const struct net_device_stats *dev_get_stats(struct net_device *dev);
+extern void		dev_txq_stats_fold(const struct net_device *dev, struct net_device_stats *stats);
 
 extern int		netdev_max_backlog;
 extern int		weight_p;

net/core/dev.c

@@ -5168,6 +5168,32 @@ void netdev_run_todo(void)
 	}
 }
 
+/**
+ *	dev_txq_stats_fold - fold tx_queues stats
+ *	@dev: device to get statistics from
+ *	@stats: struct net_device_stats to hold results
+ */
+void dev_txq_stats_fold(const struct net_device *dev,
+			struct net_device_stats *stats)
+{
+	unsigned long tx_bytes = 0, tx_packets = 0, tx_dropped = 0;
+	unsigned int i;
+	struct netdev_queue *txq;
+
+	for (i = 0; i < dev->num_tx_queues; i++) {
+		txq = netdev_get_tx_queue(dev, i);
+		tx_bytes   += txq->tx_bytes;
+		tx_packets += txq->tx_packets;
+		tx_dropped += txq->tx_dropped;
+	}
+	if (tx_bytes || tx_packets || tx_dropped) {
+		stats->tx_bytes   = tx_bytes;
+		stats->tx_packets = tx_packets;
+		stats->tx_dropped = tx_dropped;
+	}
+}
+EXPORT_SYMBOL(dev_txq_stats_fold);
+
 /**
  *	dev_get_stats	- get network device statistics
  *	@dev: device to get statistics from
@@ -5182,25 +5208,9 @@ const struct net_device_stats *dev_get_stats(struct net_device *dev)
 
 	if (ops->ndo_get_stats)
 		return ops->ndo_get_stats(dev);
-	else {
-		unsigned long tx_bytes = 0, tx_packets = 0, tx_dropped = 0;
-		struct net_device_stats *stats = &dev->stats;
-		unsigned int i;
-		struct netdev_queue *txq;
-
-		for (i = 0; i < dev->num_tx_queues; i++) {
-			txq = netdev_get_tx_queue(dev, i);
-			tx_bytes   += txq->tx_bytes;
-			tx_packets += txq->tx_packets;
-			tx_dropped += txq->tx_dropped;
-		}
-		if (tx_bytes || tx_packets || tx_dropped) {
-			stats->tx_bytes   = tx_bytes;
-			stats->tx_packets = tx_packets;
-			stats->tx_dropped = tx_dropped;
-		}
-		return stats;
-	}
+
+	dev_txq_stats_fold(dev, &dev->stats);
+	return &dev->stats;
 }
 EXPORT_SYMBOL(dev_get_stats);