netdev - Re: [RFC net-next] ipv4: Don't promote secondaries when flushing addresses

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Message-ID: <20180607134416.qkmjavetihbdk4o6@unicorn.suse.cz>
Date:   Thu, 7 Jun 2018 15:44:16 +0200
From:   Michal Kubecek <mkubecek@...e.cz>
To:     netdev@...r.kernel.org
Cc:     Phil Sutter <phil@....cc>, Jakub Sitnicki <jkbs@...hat.com>
Subject: Re: [RFC net-next] ipv4: Don't promote secondaries when flushing
 addresses

On Thu, Jun 07, 2018 at 02:35:39PM +0200, Phil Sutter wrote:
> Yes, I agree with Michal. IIRC, flushing a specific primary along with
> all it's secondaries from an interface is not even supported by
> iproute2, so no need to optimize for that I guess. OTOH, if your
> solution allowed to get rid of that nasty loop in ipaddr_flush(), I owe
> you one extra beer at the next occasion. :)

I'm afraid it will have to stay as fallback for older kernels not
supporting flush requests. But there would be no need to actually use
it. If we know RTM_DELADDR request for zero address is guaranteed to
fail with current and older kernels, we could do

  - use RTM_DELADDR with IFA_F_FLUSH and zero address
  - if it fails, get the list and run the loop

If not, it could still be

  - use RTM_DELADDR with IFA_F_FLUSH and zero address
  - get the list of addresses (empty if first step worked)
  - run the loop

Michal Kubecek