[NET]: Inline net_device_stats

Network drivers which keep stats allocate their own stats structure
then write a get_stats() function to return them.  It would be nice if
this were done by default.

1) Add a new "stats" field to "struct net_device".
2) Add a new feature field to say "this driver uses the internal one"
3) Have a default "get_stats" which returns NULL if that feature not set.
4) Change callers to check result of get_stats call for NULL, not if
   ->get_stats is set.

This should not break backwards compatibility with older drivers, yet
allow modern drivers to shed some boilerplate code.

Lightly tested: works for a modified lguest network driver.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 18 insertions, 10 deletions

diff --git a/arch/s390/appldata/appldata_net_sum.c b/arch/s390/appldata/appldata_net_sum.c
index f64b8c867ae2..516b3ac9a9b5 100644
--- a/arch/s390/appldata/appldata_net_sum.c
+++ b/arch/s390/appldata/appldata_net_sum.c
@@ -108,10 +108,10 @@ static void appldata_get_net_sum_data(void *data)
         collisions = 0;
         read_lock(&dev_base_lock);
         for (dev = dev_base; dev != NULL; dev = dev->next) {
-                if (dev->get_stats == NULL) {
+                stats = dev->get_stats(dev);
+                if (stats == NULL) {
                         continue;
                 }
-                stats = dev->get_stats(dev);
                 rx_packets += stats->rx_packets;
                 tx_packets += stats->tx_packets;
                 rx_bytes   += stats->rx_bytes;
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 76d3504505bd..cea3783c92c5 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3640,9 +3640,8 @@ 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) {
-                if (slave->dev->get_stats) {
-                        sstats = slave->dev->get_stats(slave->dev);
-
+                sstats = slave->dev->get_stats(slave->dev);
+                if (sstats) {
                         stats->rx_packets += sstats->rx_packets;
                         stats->rx_bytes += sstats->rx_bytes;
                         stats->rx_errors += sstats->rx_errors;
diff --git a/drivers/parisc/led.c b/drivers/parisc/led.c
index d190c05d87ed..453e6829756c 100644
--- a/drivers/parisc/led.c
+++ b/drivers/parisc/led.c
@@ -372,9 +372,9 @@ static __inline__ int led_get_net_activity(void)
                 continue;
             if (LOOPBACK(in_dev->ifa_list->ifa_local))
                 continue;
-            if (!dev->get_stats) 
-                continue;
             stats = dev->get_stats(dev);
+            if (!stats)
+                continue;
             rx_total += stats->rx_packets;
             tx_total += stats->tx_packets;
         }
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 1a528548cd1d..71fc8ff4888b 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -323,6 +323,7 @@ struct net_device
 #define NETIF_F_VLAN_CHALLENGED 1024    /* Device cannot handle VLAN packets */
 #define NETIF_F_GSO             2048    /* Enable software GSO. */
 #define NETIF_F_LLTX            4096    /* LockLess TX */
+#define NETIF_F_INTERNAL_STATS  8192    /* Use stats structure in net_device */
 
         /* Segmentation offload features */
 #define NETIF_F_GSO_SHIFT       16
@@ -347,6 +348,7 @@ struct net_device
 
 
         struct net_device_stats* (*get_stats)(struct net_device *dev);
+        struct net_device_stats stats;
 
         /* List of functions to handle Wireless Extensions (instead of ioctl).
          * See <net/iw_handler.h> for details. Jean II */
diff --git a/net/core/dev.c b/net/core/dev.c
index 86dc9f693f66..fec8cf27f75d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -817,7 +817,6 @@ static int default_rebuild_header(struct sk_buff *skb)
         return 1;
 }
 
-
 /**
  *      dev_open        - prepare an interface for use.
  *      @dev:   device to open
@@ -2096,9 +2095,9 @@ void dev_seq_stop(struct seq_file *seq, void *v)
 
 static void dev_seq_printf_stats(struct seq_file *seq, struct net_device *dev)
 {
-        if (dev->get_stats) {
-                struct net_device_stats *stats = dev->get_stats(dev);
+        struct net_device_stats *stats = dev->get_stats(dev);
 
+        if (stats) {
                 seq_printf(seq, "%6s:%8lu %7lu %4lu %4lu %4lu %5lu %10lu %9lu "
                                 "%8lu %7lu %4lu %4lu %4lu %5lu %7lu %10lu\n",
                            dev->name, stats->rx_bytes, stats->rx_packets,
@@ -3282,6 +3281,13 @@ out:
         mutex_unlock(&net_todo_run_mutex);
 }
 
+static struct net_device_stats *maybe_internal_stats(struct net_device *dev)
+{
+        if (dev->features & NETIF_F_INTERNAL_STATS)
+                return &dev->stats;
+        return NULL;
+}
+
 /**
  *      alloc_netdev - allocate network device
  *      @sizeof_priv:   size of private data to allocate space for
@@ -3317,6 +3323,7 @@ struct net_device *alloc_netdev(int sizeof_priv, const char *name,
         if (sizeof_priv)
                 dev->priv = netdev_priv(dev);
 
+        dev->get_stats = maybe_internal_stats;
         setup(dev);
         strcpy(dev->name, name);
         return dev;