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 ca14ab407b33..8843f4e3f5e1 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 146dcfeb060e..afd42d717320 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 6f8e0778e565..790dd205bb5d 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) {