From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeff Barnhill <0xeffeff@gmail.com>
Subject: Re: [PATCH net v5] net/ipv6: Add anycast addresses to a global hashtable
Date: Tue, 30 Oct 2018 07:10:58 -0400
Message-ID: <CAL6e_pfB=8RE6XFTVj6Bz2qHRstPciS6x3TdHggxwcJqcAtwVQ@mail.gmail.com>
References: <CAL6e_peP8_h43maaUGhfyybqmDfAfSOTdrHig0iXEN4DD2gYvQ@mail.gmail.com>
 <20181028015159.10636-1-0xeffeff@gmail.com> <20181029.203211.604037421868394185.davem@davemloft.net>
Mime-Version: 1.0
Content-Type: text/plain; charset="UTF-8"
Cc: netdev@vger.kernel.org, Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        yoshfuji@linux-ipv6.org
To: davem@davemloft.net
Return-path: <netdev-owner@vger.kernel.org>
Received: from mail-yw1-f67.google.com ([209.85.161.67]:36070 "EHLO
        mail-yw1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1727381AbeJ3UE1 (ORCPT
        <rfc822;netdev@vger.kernel.org>); Tue, 30 Oct 2018 16:04:27 -0400
Received: by mail-yw1-f67.google.com with SMTP id h21-v6so4455623ywa.3
        for <netdev@vger.kernel.org>; Tue, 30 Oct 2018 04:11:25 -0700 (PDT)
In-Reply-To: <20181029.203211.604037421868394185.davem@davemloft.net>
Sender: netdev-owner@vger.kernel.org
List-ID: <netdev.vger.kernel.org>

I originally started implementing it the way you suggested; however,
it seemed to complicate management of that structure because it isn't
currently using rcu.  Also, assuming that can be worked out, where
would I get the net from?  Would I need to store a copy in ifcaddr6,
or is there some way to access it during ipv6_chk_acast_addr()?  It
seems that if I don't add a copy of net, but instead access it through
aca_rt(?), then freeing the ifcaddr6 memory becomes problematic
(detaching it from idev, while read_rcu may still be accessing it).
On Mon, Oct 29, 2018 at 11:32 PM David Miller <davem@davemloft.net> wrote:
>
> From: Jeff Barnhill <0xeffeff@gmail.com>
> Date: Sun, 28 Oct 2018 01:51:59 +0000
>
> > +struct ipv6_ac_addrlist {
> > +     struct in6_addr         acal_addr;
> > +     possible_net_t          acal_pnet;
> > +     refcount_t              acal_users;
> > +     struct hlist_node       acal_lst; /* inet6_acaddr_lst */
> > +     struct rcu_head         rcu;
> > +};
>
> Please just add the hlist to ifcaddr6 instead of duplicating so much
> information and reference counters here.
>
> This seems to waste a lot of memory unnecessary and add lots of
> unnecessary object allocate/setup/destroy logic.