On Wed, Dec 28, 2011 at 01:39:33PM -0500, David Miller wrote:

From: Neil Horman <nhorman@tuxdriver.com>
Date: Wed, 28 Dec 2011 10:19:28 -0500

quoted

Yeah, If the premise that the test never triggers is true (and it seems like
you've confirmed that), then theres no harm in removing it.  It still
seems like we might still need the test somewhere (maybe on a manual route add).
I've family in town, so I'm not able to look at this closely today, but I'd say this
is at least a harmless change right now.  Lets take this change, and I'll
re-read the RFC and look for appropriate code paths where we may need this
test in a few days.  Thanks Dave!

Acked-By: Neil Horman <nhorman@tuxdriver.com>

Thanks for reviewing Neil, I've applied this patch to net-next.

No problem, I got some time this afternoon, and I've reread the relevant section
of RFC 4429, and clearly I made a mistake in the above test, but I'm a little
confused over what the test should be.  The relevant language from the RFC is:

3.3 Modifications to RFC 2462 Stateless Address Autoconfiguration

   * (modifies section 5.5) A host MAY choose to configure a new address
        as an Optimistic Address.  A host that does not know the SLLAO
        of its router SHOULD NOT configure a new address as Optimistic.
        A router SHOULD NOT configure an Optimistic Address.

So my read of that is that, when we are adding a new address to the host, we
should not make the address optimistic if:

1) The interface is acting as a router - We catch this with the !forwarding
check in addrconf_prefix_rcv, although we should perhaps move that to a common
code path, as we won't catch that if we manually add an ipv6 address via
inet6_rtm_newaddr

2) If the interface has not recieved a router advertizement, and that
solicitation did not contain a source link layer option in it.

Clearly I misread the RFC the first time through and the test as it existed is
incorrect.  I'm wondering though if what we need is a way to lookup if we've
received a RA on the interface, and check to see if it has a source link layer
option attached to it.

Thoughts?
Neil

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