net: Enable 64-bit net device statistics on 32-bit architectures

Use struct rtnl_link_stats64 as the statistics structure.

On 32-bit architectures, insert 32 bits of padding after/before each
field of struct net_device_stats to make its layout compatible with
struct rtnl_link_stats64.  Add an anonymous union in net_device; move
stats into the union and add struct rtnl_link_stats64 stats64.

Add net_device_ops::ndo_get_stats64, implementations of which will
return a pointer to struct rtnl_link_stats64.  Drivers that implement
this operation must not update the structure asynchronously.

Change dev_get_stats() to call ndo_get_stats64 if available, and to
return a pointer to struct rtnl_link_stats64.  Change callers of
dev_get_stats() accordingly.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 56 insertions, 38 deletions

diff --git a/include/linux/if_link.h b/include/linux/if_link.h
index 85c812db5a3f..7fcad2e1be3d 100644
--- a/include/linux/if_link.h
+++ b/include/linux/if_link.h
@@ -4,7 +4,7 @@
 #include <linux/types.h>
 #include <linux/netlink.h>
 
-/* The struct should be in sync with struct net_device_stats */
+/* This struct should be in sync with struct rtnl_link_stats64 */
 struct rtnl_link_stats {
         __u32   rx_packets;             /* total packets received       */
         __u32   tx_packets;             /* total packets transmitted    */
@@ -37,6 +37,7 @@ struct rtnl_link_stats {
         __u32   tx_compressed;
 };
 
+/* The main device statistics structure */
 struct rtnl_link_stats64 {
         __u64   rx_packets;             /* total packets received       */
         __u64   tx_packets;             /* total packets transmitted    */
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index c319f28d699d..4fbccc5f609a 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -159,45 +159,49 @@ static inline bool dev_xmit_complete(int rc)
 #define MAX_HEADER (LL_MAX_HEADER + 48)
 #endif
 
-#endif  /*  __KERNEL__  */
-
 /*
- *      Network device statistics. Akin to the 2.0 ether stats but
- *      with byte counters.
+ *      Old network device statistics. Fields are native words
+ *      (unsigned long) so they can be read and written atomically.
+ *      Each field is padded to 64 bits for compatibility with
+ *      rtnl_link_stats64.
  */
 
+#if BITS_PER_LONG == 64
+#define NET_DEVICE_STATS_DEFINE(name)   unsigned long name
+#elif defined(__LITTLE_ENDIAN)
+#define NET_DEVICE_STATS_DEFINE(name)   unsigned long name, pad_ ## name
+#else
+#define NET_DEVICE_STATS_DEFINE(name)   unsigned long pad_ ## name, name
+#endif
+
 struct net_device_stats {
-        unsigned long   rx_packets;             /* total packets received       */
-        unsigned long   tx_packets;             /* total packets transmitted    */
-        unsigned long   rx_bytes;               /* total bytes received         */
-        unsigned long   tx_bytes;               /* total bytes transmitted      */
-        unsigned long   rx_errors;              /* bad packets received         */
-        unsigned long   tx_errors;              /* packet transmit problems     */
-        unsigned long   rx_dropped;             /* no space in linux buffers    */
-        unsigned long   tx_dropped;             /* no space available in linux  */
-        unsigned long   multicast;              /* multicast packets received   */
-        unsigned long   collisions;
-
-        /* detailed rx_errors: */
-        unsigned long   rx_length_errors;
-        unsigned long   rx_over_errors;         /* receiver ring buff overflow  */
-        unsigned long   rx_crc_errors;          /* recved pkt with crc error    */
-        unsigned long   rx_frame_errors;        /* recv'd frame alignment error */
-        unsigned long   rx_fifo_errors;         /* recv'r fifo overrun          */
-        unsigned long   rx_missed_errors;       /* receiver missed packet       */
-
-        /* detailed tx_errors */
-        unsigned long   tx_aborted_errors;
-        unsigned long   tx_carrier_errors;
-        unsigned long   tx_fifo_errors;
-        unsigned long   tx_heartbeat_errors;
-        unsigned long   tx_window_errors;
-        
-        /* for cslip etc */
-        unsigned long   rx_compressed;
-        unsigned long   tx_compressed;
+        NET_DEVICE_STATS_DEFINE(rx_packets);
+        NET_DEVICE_STATS_DEFINE(tx_packets);
+        NET_DEVICE_STATS_DEFINE(rx_bytes);
+        NET_DEVICE_STATS_DEFINE(tx_bytes);
+        NET_DEVICE_STATS_DEFINE(rx_errors);
+        NET_DEVICE_STATS_DEFINE(tx_errors);
+        NET_DEVICE_STATS_DEFINE(rx_dropped);
+        NET_DEVICE_STATS_DEFINE(tx_dropped);
+        NET_DEVICE_STATS_DEFINE(multicast);
+        NET_DEVICE_STATS_DEFINE(collisions);
+        NET_DEVICE_STATS_DEFINE(rx_length_errors);
+        NET_DEVICE_STATS_DEFINE(rx_over_errors);
+        NET_DEVICE_STATS_DEFINE(rx_crc_errors);
+        NET_DEVICE_STATS_DEFINE(rx_frame_errors);
+        NET_DEVICE_STATS_DEFINE(rx_fifo_errors);
+        NET_DEVICE_STATS_DEFINE(rx_missed_errors);
+        NET_DEVICE_STATS_DEFINE(tx_aborted_errors);
+        NET_DEVICE_STATS_DEFINE(tx_carrier_errors);
+        NET_DEVICE_STATS_DEFINE(tx_fifo_errors);
+        NET_DEVICE_STATS_DEFINE(tx_heartbeat_errors);
+        NET_DEVICE_STATS_DEFINE(tx_window_errors);
+        NET_DEVICE_STATS_DEFINE(rx_compressed);
+        NET_DEVICE_STATS_DEFINE(tx_compressed);
 };
 
+#endif  /*  __KERNEL__  */
+
 
 /* Media selection options. */
 enum {
@@ -662,10 +666,19 @@ struct netdev_rx_queue {
  *      Callback uses when the transmitter has not made any progress
  *      for dev->watchdog ticks.
  *
+ * struct rtnl_link_stats64* (*ndo_get_stats64)(struct net_device *dev);
  * struct net_device_stats* (*ndo_get_stats)(struct net_device *dev);
  *      Called when a user wants to get the network device usage
- *      statistics. If not defined, the counters in dev->stats will
- *      be used.
+ *      statistics. Drivers must do one of the following:
+ *      1. Define @ndo_get_stats64 to update a rtnl_link_stats64 structure
+ *         (which should normally be dev->stats64) and return a ponter to
+ *         it. The structure must not be changed asynchronously.
+ *      2. Define @ndo_get_stats to update a net_device_stats64 structure
+ *         (which should normally be dev->stats) and return a pointer to
+ *         it. The structure may be changed asynchronously only if each
+ *         field is written atomically.
+ *      3. Update dev->stats asynchronously and atomically, and define
+ *         neither operation.
  *
  * void (*ndo_vlan_rx_register)(struct net_device *dev, struct vlan_group *grp);
  *      If device support VLAN receive accleration
@@ -720,6 +733,7 @@ struct net_device_ops {
                                                    struct neigh_parms *);
         void                    (*ndo_tx_timeout) (struct net_device *dev);
 
+        struct rtnl_link_stats64* (*ndo_get_stats64)(struct net_device *dev);
         struct net_device_stats* (*ndo_get_stats)(struct net_device *dev);
 
         void                    (*ndo_vlan_rx_register)(struct net_device *dev,
@@ -869,7 +883,10 @@ struct net_device {
         int                     ifindex;
         int                     iflink;
 
-        struct net_device_stats stats;
+        union {
+                struct rtnl_link_stats64 stats64;
+                struct net_device_stats stats;
+        };
 
 #ifdef CONFIG_WIRELESS_EXT
         /* List of functions to handle Wireless Extensions (instead of ioctl).
@@ -2121,7 +2138,7 @@ 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 const struct rtnl_link_stats64 *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;