Re: [RFC alternate] ipv6: addrconf: clean up device type handling

[Hannes Frederic Sowa <hannes@stressinduktion.org>]

On Mi, 2014-07-30 at 17:58 +0200, David Lamparter wrote:
> This realigns addrconf support for the various lower-layer device types,
> and removes a little bit of duplicate code.
> 
> For GRE devices, this includes a semantic change in that there is now a
> ff00::/8 route installed on address autogeneration.  This was previously
> missing and broke any kind of IPv6 multicast - unless another address
> was configured from userspace (which then added the missing ff00::/8).
> 
> Fixes: aee80b54b235 (ipv6: generate link local address for GRE tunnel)
> Signed-off-by: David Lamparter <equinox@diac24.net>
> Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
> Cc: Stephen Hemminger <stephen@networkplumber.org>
> Cc: Jiri Pirko <jiri@resnulli.us>
> ---
> 
> This is an alternate version, yanking the switch() down and removing
> dev_config/gre_config duplication.  I have no idea what rationale is behind
> prefix_route - the result is a fe80::/64 route, but no address, which is not a
> functioning configuration.  Jiri, you touched this just a few weeks ago, can
> you comment?  (The "XXX: why is GRE special?")

Sure, it is valid. You can still use global addresses to talk to link
local addresses on the same link, even from another interface.

I prefer this patch.

Thanks,
Hannes