net: Print the module name as part of the watchdog message

As suggested by Dave:

This patch adds a function to get the driver name from a struct net_device,
and consequently uses this in the watchdog timeout handler to print as 
part of the message. 

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -1645,6 +1645,8 @@ extern void dev_seq_stop(struct seq_file *seq, void *v);
 extern int netdev_class_create_file(struct class_attribute *class_attr);
 extern void netdev_class_remove_file(struct class_attribute *class_attr);
 
+extern char *netdev_drivername(struct net_device *dev, char *buffer, int len);
+
 extern void linkwatch_run_queue(void);
 
 extern int netdev_compute_features(unsigned long all, unsigned long one);

net/core/dev.c

@@ -4686,6 +4686,26 @@ static int __net_init netdev_init(struct net *net)
 	return -ENOMEM;
 }
 
+char *netdev_drivername(struct net_device *dev, char *buffer, int len)
+{
+	struct device_driver *driver;
+	struct device *parent;
+
+	if (len <= 0 || !buffer)
+		return buffer;
+	buffer[0] = 0;
+
+	parent = dev->dev.parent;
+
+	if (!parent)
+		return buffer;
+
+	driver = parent->driver;
+	if (driver && driver->name)
+		strlcpy(buffer, driver->name, len);
+	return buffer;
+}
+
 static void __net_exit netdev_exit(struct net *net)
 {
 	kfree(net->dev_name_head);

net/sched/sch_generic.c

@@ -212,9 +212,9 @@ static void dev_watchdog(unsigned long arg)
 			if (some_queue_stopped &&
 			    time_after(jiffies, (dev->trans_start +
 						 dev->watchdog_timeo))) {
-				printk(KERN_INFO "NETDEV WATCHDOG: %s: "
-				       "transmit timed out\n",
-				       dev->name);
+				char drivername[64];
+				printk(KERN_INFO "NETDEV WATCHDOG: %s (%s): transmit timed out\n",
+				       dev->name, netdev_drivername(dev, drivername, 64));
 				dev->tx_timeout(dev);
 				WARN_ON_ONCE(1);
 			}