[NET]: Add __dev_getfirstbyhwtype

Add __dev_getfirstbyhwtype for callers that don't want a reference but
some data from the device and thus need to take the rtnl anyway.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -582,6 +582,7 @@ extern int 			netdev_boot_setup_check(struct net_device *dev);
 extern unsigned long		netdev_boot_base(const char *prefix, int unit);
 extern struct net_device    *dev_getbyhwaddr(unsigned short type, char *hwaddr);
 extern struct net_device *dev_getfirstbyhwtype(unsigned short type);
+extern struct net_device *__dev_getfirstbyhwtype(unsigned short type);
 extern void		dev_add_pack(struct packet_type *pt);
 extern void		dev_remove_pack(struct packet_type *pt);
 extern void		__dev_remove_pack(struct packet_type *pt);

net/core/dev.c

@@ -576,17 +576,28 @@ struct net_device *dev_getbyhwaddr(unsigned short type, char *ha)
 
 EXPORT_SYMBOL(dev_getbyhwaddr);
 
-struct net_device *dev_getfirstbyhwtype(unsigned short type)
+struct net_device *__dev_getfirstbyhwtype(unsigned short type)
 {
 	struct net_device *dev;
 
-	rtnl_lock();
+	ASSERT_RTNL();
 	for (dev = dev_base; dev; dev = dev->next) {
-		if (dev->type == type) {
-			dev_hold(dev);
+		if (dev->type == type)
 			break;
-		}
 	}
+	return dev;
+}
+
+EXPORT_SYMBOL(__dev_getfirstbyhwtype);
+
+struct net_device *dev_getfirstbyhwtype(unsigned short type)
+{
+	struct net_device *dev;
+
+	rtnl_lock();
+	dev = __dev_getfirstbyhwtype(type);
+	if (dev)
+		dev_hold(dev);
 	rtnl_unlock();
 	return dev;
 }