netdev: introduce dev_get_stats()

In order for the network device ops get_stats call to be immutable, the handling
of the default internal network device stats block has to be changed. Add a new
helper function which replaces the old use of internal_get_stats.

Note: change return code to make it clear that the caller should not
go changing the returned statistics.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/s390/appldata/appldata_net_sum.c

@@ -67,7 +67,6 @@ static void appldata_get_net_sum_data(void *data)
 	int i;
 	struct appldata_net_sum_data *net_data;
 	struct net_device *dev;
-	struct net_device_stats *stats;
 	unsigned long rx_packets, tx_packets, rx_bytes, tx_bytes, rx_errors,
 			tx_errors, rx_dropped, tx_dropped, collisions;
 
@@ -86,7 +85,8 @@ static void appldata_get_net_sum_data(void *data)
 	collisions = 0;
 	read_lock(&dev_base_lock);
 	for_each_netdev(&init_net, dev) {
-		stats = dev->get_stats(dev);
+		const struct net_device_stats *stats = dev_get_stats(dev);
+
 		rx_packets += stats->rx_packets;
 		tx_packets += stats->tx_packets;
 		rx_bytes   += stats->rx_bytes;

drivers/net/bonding/bond_main.c

@@ -3899,7 +3899,7 @@ static int bond_close(struct net_device *bond_dev)
 static struct net_device_stats *bond_get_stats(struct net_device *bond_dev)
 {
 	struct bonding *bond = netdev_priv(bond_dev);
-	struct net_device_stats *stats = &(bond->stats), *sstats;
+	struct net_device_stats *stats = &bond->stats;
 	struct net_device_stats local_stats;
 	struct slave *slave;
 	int i;
@@ -3909,7 +3909,8 @@ static struct net_device_stats *bond_get_stats(struct net_device *bond_dev)
 	read_lock_bh(&bond->lock);
 
 	bond_for_each_slave(bond, slave, i) {
-		sstats = slave->dev->get_stats(slave->dev);
+		const struct net_device_stats *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;

drivers/net/sfc/ethtool.c

@@ -426,7 +426,7 @@ static void efx_ethtool_get_stats(struct net_device *net_dev,
 	EFX_BUG_ON_PARANOID(stats->n_stats != EFX_ETHTOOL_NUM_STATS);
 
 	/* Update MAC and NIC statistics */
-	net_dev->get_stats(net_dev);
+	dev_get_stats(net_dev);
 
 	/* Fill detailed statistics buffer */
 	for (i = 0; i < EFX_ETHTOOL_NUM_STATS; i++) {

drivers/parisc/led.c

@@ -360,13 +360,13 @@ static __inline__ int led_get_net_activity(void)
 	read_lock(&dev_base_lock);
 	rcu_read_lock();
 	for_each_netdev(&init_net, dev) {
-	    struct net_device_stats *stats;
+	    const struct net_device_stats *stats;
 	    struct in_device *in_dev = __in_dev_get_rcu(dev);
 	    if (!in_dev || !in_dev->ifa_list)
 		continue;
 	    if (ipv4_is_loopback(in_dev->ifa_list->ifa_local))
 		continue;
-	    stats = dev->get_stats(dev);
+	    stats = dev_get_stats(dev);
 	    rx_total += stats->rx_packets;
 	    tx_total += stats->tx_packets;
 	}

include/linux/netdevice.h

@@ -864,9 +864,9 @@ struct net_device
 							    unsigned short vid);
 #ifdef CONFIG_NET_POLL_CONTROLLER
 		void                    (*poll_controller)(struct net_device *dev);
-#endif
 #endif
 	};
+#endif
 };
 #define to_net_dev(d) container_of(d, struct net_device, dev)
 
@@ -1780,6 +1780,8 @@ extern void		netdev_features_change(struct net_device *dev);
 /* Load a device via the kmod */
 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 int		netdev_max_backlog;
 extern int		weight_p;
 extern int		netdev_set_master(struct net_device *dev, struct net_device *master);

net/core/dev.c

@@ -2620,7 +2620,7 @@ void dev_seq_stop(struct seq_file *seq, void *v)
 
 static void dev_seq_printf_stats(struct seq_file *seq, struct net_device *dev)
 {
-	struct net_device_stats *stats = dev->get_stats(dev);
+	const struct net_device_stats *stats = dev_get_stats(dev);
 
 	seq_printf(seq, "%6s:%8lu %7lu %4lu %4lu %4lu %5lu %10lu %9lu "
 		   "%8lu %7lu %4lu %4lu %4lu %5lu %7lu %10lu\n",
@@ -4288,10 +4288,24 @@ void netdev_run_todo(void)
 	}
 }
 
-static struct net_device_stats *internal_stats(struct net_device *dev)
-{
-	return &dev->stats;
+/**
+ *	dev_get_stats	- get network device statistics
+ *	@dev: device to get statistics from
+ *
+ *	Get network statistics from device. The device driver may provide
+ *	its own method by setting dev->netdev_ops->get_stats; otherwise
+ *	the internal statistics structure is used.
+ */
+const struct net_device_stats *dev_get_stats(struct net_device *dev)
+ {
+	const struct net_device_ops *ops = dev->netdev_ops;
+
+	if (ops->ndo_get_stats)
+		return ops->ndo_get_stats(dev);
+	else
+		return &dev->stats;
 }
+EXPORT_SYMBOL(dev_get_stats);
 
 static void netdev_init_one_queue(struct net_device *dev,
 				  struct netdev_queue *queue,
@@ -4370,7 +4384,6 @@ struct net_device *alloc_netdev_mq(int sizeof_priv, const char *name,
 
 	netdev_init_queues(dev);
 
-	dev->get_stats = internal_stats;
 	netpoll_netdev_init(dev);
 	setup(dev);
 	strcpy(dev->name, name);

net/core/net-sysfs.c

@@ -270,15 +270,14 @@ static ssize_t netstat_show(const struct device *d,
 			    unsigned long offset)
 {
 	struct net_device *dev = to_net_dev(d);
-	struct net_device_stats *stats;
 	ssize_t ret = -EINVAL;
 
 	WARN_ON(offset > sizeof(struct net_device_stats) ||
 			offset % sizeof(unsigned long) != 0);
 
 	read_lock(&dev_base_lock);
 	if (dev_isalive(dev)) {
-		stats = dev->get_stats(dev);
+		const struct net_device_stats *stats = dev_get_stats(dev);
 		ret = sprintf(buf, fmt_ulong,
 			      *(unsigned long *)(((u8 *) stats) + offset));
 	}

net/core/rtnetlink.c

@@ -551,7 +551,7 @@ static void set_operstate(struct net_device *dev, unsigned char transition)
 }
 
 static void copy_rtnl_link_stats(struct rtnl_link_stats *a,
-				 struct net_device_stats *b)
+				 const struct net_device_stats *b)
 {
 	a->rx_packets = b->rx_packets;
 	a->tx_packets = b->tx_packets;
@@ -609,7 +609,7 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev,
 	struct netdev_queue *txq;
 	struct ifinfomsg *ifm;
 	struct nlmsghdr *nlh;
-	struct net_device_stats *stats;
+	const struct net_device_stats *stats;
 	struct nlattr *attr;
 
 	nlh = nlmsg_put(skb, pid, seq, type, sizeof(*ifm), flags);
@@ -666,7 +666,7 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev,
 	if (attr == NULL)
 		goto nla_put_failure;
 
-	stats = dev->get_stats(dev);
+	stats = dev_get_stats(dev);
 	copy_rtnl_link_stats(nla_data(attr), stats);
 
 	if (dev->rtnl_link_ops) {