On Mon, Sep 13, 2021 at 09:16:39AM +0200, Ondrej Mosnacek wrote:

Perhaps it would be a good idea to put a comment here to make it less
likely that this repeats in the future. Something like:

/* IMPORTANT: Only insert new entries right above this line, otherwise
you break ABI! */

Well, this statement is true for (almost) every UAPI-exposed enum, and
netlink is vast and relies on enums heavily.  I think it is already
mentioned somewhere in the documentation, and in the end it falls on the
shoulders of the maintainers—to pay additional attention to UAPI changes.