RE: [07/22] Cyclades PC300 driver: ioctl() fixes for mixed 64/32-bit systems

On Mon, 2012-01-30 at 11:44 +0000, David Laight wrote:

quoted

+struct pc300_net_stats {
+	u64 rx_packets;

...

quoted

+	u64 rx_compressed;
+	u64 tx_compressed;
+};
+
 typedef struct pc300stats {
 	int hw_type;
 	u32 line_on;
 	u32 line_off;
-	struct net_device_stats gen_stats;
+	/* Use this instead of net_device_stats, since passing
+	 * net_device_stats breaks 32-bit user processes on 
64-bit kernels,
+	 * and rtnetlink is unreasonably complicated just to get
+	 * some statistics.
+	 */
+	struct pc300_net_stats net_stats;
 	falc_t te_stats;
 } pc300stats_t;

Since 'struct net_device_stats' looks like a common structure,
maybe the 64bit version should be added in the same place??

[...]

It's called struct rtnl_link_stats64 and is already defined in
<linux/rtnetlink.h> (where it must remain).

This change doesn't seem to be a proper fix.  If the ioctl interface to
this driver uses struct net_device_stats (which I didn't realise,
otherwise I would have left that structure exported from
<linux/netdevice.h>) then it should continue doing so to maintain
compatibility.  And the driver will need a compat_ioctl for that.

If backward-compatibility is really not a concern for the driver then
this ioctl should be completely removed in favour of ethtool extended
stats.

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
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