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>

3 files changed, 22 insertions, 10 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index ca14ab4..8843f4e 100644
--- a/net/core/dev.c
+++ b/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);
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 146dcfe..afd42d7 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -270,7 +270,6 @@ 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) ||
@@ -278,7 +277,7 @@ static ssize_t netstat_show(const struct device *d,
 
 	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));
 	}
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 6f8e077..790dd20 100644
--- a/net/core/rtnetlink.c
+++ b/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) {