net: set name assign type for renamed devices

Based on a patch from David Herrmann.

This is the only place devices can be renamed.

v9: restore revers-christmas-tree order of local variables

Signed-off-by: Tom Gundersen <[e-mail]>
Reviewed-by: David Herrmann <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/core/dev.c

···
  */
 int dev_change_name(struct net_device *dev, const char *newname)
 {
+	unsigned char old_assign_type;
 	char oldname[IFNAMSIZ];
 	int err = 0;
 	int ret;
···
 		return err;
 	}
 
+	old_assign_type = dev->name_assign_type;
+	dev->name_assign_type = NET_NAME_RENAMED;
+
 rollback:
 	ret = device_rename(&dev->dev, dev->name);
 	if (ret) {
 		memcpy(dev->name, oldname, IFNAMSIZ);
+		dev->name_assign_type = old_assign_type;
 		write_seqcount_end(&devnet_rename_seq);
 		return ret;
 	}
···
 			write_seqcount_begin(&devnet_rename_seq);
 			memcpy(dev->name, oldname, IFNAMSIZ);
 			memcpy(oldname, newname, IFNAMSIZ);
+			dev->name_assign_type = old_assign_type;
+			old_assign_type = NET_NAME_RENAMED;
 			goto rollback;
 		} else {
 			pr_err("%s: name change rollback failed: %d\n",