Re: [net-next] ipv6: Enable netlink notification for tentative addresses.

[David Miller <davem@davemloft.net>]

From: Ben Greear <greearb@candelatech.com>
Date: Wed, 25 Aug 2010 11:26:17 -0700

> By default, netlink messages are not sent when an IPv6 address
> is added if it is in tentative state.  This makes it harder
> for user-space applications to know the current state of the
> IPv6 addresses.  This patch adds an ipv6 sysctl that will
> allow tentative address notifications to be sent.  The sysctl
> is off by default.
> 
> Signed-off-by: Ben Greear <greearb@candelatech.com>

It's inconsistent to send two NEWADDR events for the same add.

I would advise that we unconditionally do the NEWADDR once,
when the tentative state address is added, and completely
elide the one we current send when it leaves tentative state.

Having a sysctl, and having it off by default, just means you haven't
actually fixes the problem.  Since it's only fixed if someone makes a
non-standard configuration change.

Otherwise what you're saying is that this is a very obscure thing for
very obscure applications, and it very nearly doesn't even matter
as a result.