Re: [PATCH net] ipv6: set all.accept_dad to 0 by default

[Stefano Brivio <sbrivio@redhat.com>]

On Mon, 13 Nov 2017 14:21:52 +0000
Erik Kline <ek@google.com> wrote:

> Alternatively, if we really want to make all, default, and ifname
> useful perhaps we need to investigate a tristate option (for currently
> boolean values, at least).  -1 could mean no preference, for example.

I think this would make sense in general, but on the other hand it
would be quite a big change, and Nicolas' patch has the advantages of
being small, keeping the global flag functional, and restoring the
previous default behaviour out of the box when 'accept_dad' is disabled
by the user for a given interface.

Besides, this still wouldn't solve the case where flags are >= 0 and
conflicting -- there, it's still debatable whether we want a logical
OR or a logical AND.

In the end, I would prefer either Nicolas' patch, or to get rid of the
global 'accept_dad' flag altogether. Having a flag which does
absolutely nothing, which was the case before 35e015e1f577, doesn't
sound correct by any means.

-- 
Stefano