Re: [PATCH RFC net-next] net: Allow name change of IFF_UP interfaces

On Thu, 10 Aug 2017 10:55:01 -0600
David Ahern [off-list ref] wrote:

On 8/10/17 10:48 AM, David Miller wrote:

quoted

From: Andrew Lunn <andrew@lunn.ch>
Date: Thu, 10 Aug 2017 18:27:22 +0200
  

quoted

On Thu, Aug 10, 2017 at 05:24:55PM +0200, Vitaly Kuznetsov wrote:  

quoted

Andrew Lunn [off-list ref] writes:
 

quoted

quoted

We are - rtnetlink_event() does the job. We, however, don't have a
special IFLA_EVENT_* for name change and end up with IFLA_EVENT_NONE.  

What is in this event? Old and new name? Just the new name?  

Basically, it's everything we know about the interface - type, index,
name, mtu, qdisc, ... - see rtnl_fill_ifinfo(). Back to your question -
it's only the new name.  

So the program needs to keep track of ifindex to know which interface
has changed name. Doable.

I still expect this has the potential to break something. You probably
should be asking on linux-api for the API experts opinion.  

But a greater point is that nobody is monitoring device renames
explicitly right now.  

Just to throw in an example:
  https://github.com/kobolabs/dhcpcd/blob/kobo/if-linux.c#L761

Learned of its use from a recent regression:
https://bugzilla.kernel.org/show_bug.cgi?id=196355

Quagga is another example of what might break. Especially with all the new
forks..