Subject: Re: [PATCH net-next] rtnetlink: add support for protodown reason

From: Stephen Hemminger <[email-masked]>
Date: Mon, 27 Jul 2020 13:47:03 -0700

On Mon, 27 Jul 2020 12:21:17 -0700
Roopa Prabhu <[email-masked]> wrote:

> -	       + nla_total_size(1)  /* IFLA_PROTO_DOWN */
> +	       + rtnl_proto_down_size(dev)  /* proto down */

Changing the size of a netlink field is an ABI change in the kernel.
This has the potential to break existing programs.

Wouldn't it be safer to add a new link attribute for the reason
rather than overloading the existing attribute?