[NET]: Catch buggy net drivers changing getstats op after registry.

include/linux/netdevice.h

@@ -469,6 +469,7 @@ struct net_device
 
 	/* class/net/name entry */
 	struct class_device	class_dev;
+	struct net_device_stats* (*last_stats)(struct net_device *);
 };
 
 #define SET_MODULE_OWNER(dev) do { } while (0)

net/core/dev.c

@@ -713,6 +713,19 @@ static int default_rebuild_header(struct sk_buff *skb)
 	return 1;
 }
 
+
+/*
+ * Some old buggy device drivers change get_stats after registering
+ * the device.  Try and trap them here.
+ * This can be elimnated when all devices are known fixed.
+ */
+static inline int get_stats_changed(struct net_device *dev)
+{
+	int changed = dev->last_stats != dev->get_stats;
+	dev->last_stats = dev->get_stats;
+	return changed;
+}
+
 /**
  *	dev_open	- prepare an interface for use.
  *	@dev:	device to open
@@ -736,6 +749,14 @@ int dev_open(struct net_device *dev)
 	if (dev->flags & IFF_UP)
 		return 0;
 
+	/*
+	 *	 Check for broken device drivers.
+	 */
+	if (get_stats_changed(dev) && net_ratelimit()) {
+		printk(KERN_ERR "%s: driver changed get_stats after register\n",
+		       dev->name);
+	}
+
 	/*
 	 *	Is it even present?
 	 */
@@ -752,6 +773,14 @@ int dev_open(struct net_device *dev)
 			clear_bit(__LINK_STATE_START, &dev->state);
 	}
 
+	/*
+	 * 	Check for more broken device drivers.
+	 */
+	if (get_stats_changed(dev) && net_ratelimit()) {
+		printk(KERN_ERR "%s: driver changed get_stats in open\n",
+		       dev->name);
+	}
+
  	/*
 	 *	If it went open OK then:
 	 */

net/core/net-sysfs.c

@@ -419,6 +419,7 @@ int netdev_register_sysfs(struct net_device *net)
 	}
 
 
+	net->last_stats = net->get_stats;
 	if (net->get_stats &&
 	    (ret = sysfs_create_group(&class_dev->kobj, &netstat_group)))
 		goto out_unreg;