Re: [Bonding-devel] 2.6.29 regression? Bonding tied to IPV6 in 29-rc5

Brian Haley
2009-02-17T21:50:33Z

Jay Vosburgh wrote:
> Brian Haley <brian.haley@hp.com> wrote:
>
>> Andrey Borzenkov wrote:
> [...]
>>> This hard dependency was apparently introduced by this commit:
>>>
>>> commit 305d552accae6afb859c493ebc7d98ca3371dae2
>>> Author: Brian Haley <brian.haley@hp.com>
>>> Date: Tue Nov 4 17:51:14 2008 -0800
>>>
>>> bonding: send IPv6 neighbor advertisement on failover
>> I initially had bonding IPv6 support as a Kconfig option, but it was
>> decided it would be cleaner if it just got built-in whenever CONFIG_IPV6
>> was set like SCTP, with the assumption you might want it.
>>
>> Is it a common configuration to not allow a module to load like you're
>> doing in modprobe.conf? I don't know how hard it would be to rip this
>> out into it's own bonding_ipv6.ko module, simply turning-off CONFIG_IPV6
>> seems better.
>
> I'm not sure either of those really helps. Distro kernels are
> built with CONFIG_IPV6 (and would have the CONFIG_BONDING_IPV6_DINGUS
> enabled as well), so the common case users would have it enabled, too.

I think that was one of the reasons too.

> Putting the ipv6 bits into a different module might not help,
> either, because the "core" bonding code would still have the call to the
> ipv6 functions. Unless there's some magic way to somehow know at
> runtime whether or not the ipv6 module is loaded, and only try to
> resolve those symbols if ipv6 is loaded. That seems complicated.

This separate bonding_ipv6 module would have to register itself with the
"core" one with a new proto_ops of some sort. Calls are made for the
appropriate method, for example bond_ops->send_gratuitous(bond). We'd
change the IPv4 code too. It's just a theory, does make things more
complicated.

> To answer your question, I have come across this (aliasing ipv6
> to nothing in modprobe.conf to disable IPv6) from time to time, but
> didn't think of it when the NA code was added to bonding.

So I guess I'll start hacking the above, unless someone has a better
suggestion.

-Brian