Re: [PATCH net v2 1/2] macvlan: introduce macvlan_dev_real_dev() helper function

[David Miller <davem@davemloft.net>]

From: Michal Kubecek <mkubecek@suse.cz>
Date: Thu, 14 Nov 2013 16:57:57 +0100

> On Thu, Nov 14, 2013 at 10:03:19AM -0500, Vlad Yasevich wrote:
>> On 11/14/2013 09:00 AM, Michal Kubecek wrote:
>> >+#if IS_ENABLED(CONFIG_MACVLAN)
>> >+static inline struct net_device *
>> >+macvlan_dev_real_dev(const struct net_device *dev)
>> >+{
>> >+	struct macvlan_dev *macvlan = netdev_priv(dev);
>> >+
>> >+	return macvlan->lowerdev;
>> >+}
>> >+#else
>> >+static inline struct net_device *
>> >+macvlan_dev_real_dev(const struct net_device *dev)
>> >+{
>> >+	return NULL;
>> >+}
>> >+#endif
>> >+
>> 
>> You may want to do the same here as was done for
>> vlan_dev_real_dev(). This function is not intended to be called
>> blindly and should always
>> be called after netif_is_macvlan().
> 
> I'm not sure. It makes sense from the developer point of view: if we
> find an inconsistency which must be caused by a bug in kernel code, do
> panic so that the bug is found and fixed as soon as possible. However,
> I remember a discussion where the point was that BUG() and BUG_ON()
> should only be used if there is no way to recover. From this point of
> view, WARN or WARN_ONCE might be better choice - but I'm not strictly
> opposed to BUG().

At least for the time being use BUG(), to be consistent with the same
way how VLAN handles this situation.

Thanks.