netdev - RE: [PATCH 1/1] ipv6 addrconf:fix preferred lifetime state-changing behavior while valid

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Date:	Sun, 29 Dec 2013 05:57:18 +0000
From:	"Asano, Yasushi" <yasushi.asano@...fujitsu.com>
To:	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	"yazzep@...il.com" <yazzep@...il.com>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH 1/1] ipv6 addrconf:fix preferred lifetime state-changing
 behavior while valid_lft is infinity

> Ditto, I do think we cannot remove this flag unconditionally.
> 
> Actually, I don't think it is the correct way to remove the IFA_F_PERMANENT
> here at all. We break the interaction with prefix routes and won't remove
> them
> at the time of address deletion any more. This is definitely a no-go, sorry.
> 
> The prefix was added by hand and should get removed immediately if a user
> removes the address (well actually it is an error we set up a prefix route
> in
> the first place, but it is how things are now).
> 
> IMHO, the changes need to be made in addrconf_verify so that the route does
> get marked as deprecated. Please check the places where we mark an interface
> address as deprecated.
> 
> Thanks,
> 
>   Hannes

Sorry about not getting back to you sooner.
I have been thinking and testing about the correct way of fixing the problem.
I understand it's not the correct way to remove the IFA_F_PERMANENT. 
I agree with you that the changes need to be made in addrconf_verify.
and I think the changes also need to be made in inet6_fill_ifaddr
so that the "preferred" is set INFINITY_LIFE_TIME unconditionally while 
ifa->flags is IFA_F_PERMANENT.
It means, "preferred" is set to INFINITY_LIFE_TIME when I set preferred_lft a value 
not zero or infinity, while valid_lft is infinity(0xffffffff)
I am going to send a new patch soon.
Your kind consideration of this matter would be sincerely appreciated.

Yasushi