From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Ahern <dsahern@gmail.com>
Subject: Re: [PATCH net] ipv6: no need to return rt->dst.error if it is not
 null entry.
Date: Wed, 26 Jul 2017 13:00:26 -0600
Message-ID: <2d75317c-160c-01c2-5a5b-bc6111c099c6@gmail.com>
References: <1500562286-14312-1-git-send-email-liuhangbin@gmail.com>
 <CAPwn2JQHyj5gxqTFcJ-u9ABe544ivTBWskQfMgk2a2NirCF5rg@mail.gmail.com>
 <CAPwn2JTF+j84+Bv4Zn=pqju2tnMuuJrhTr9Un786-PZ0D6af3w@mail.gmail.com>
 <CAM_iQpUM6m=GvUU0OfwZAFsOGsf1UZmTjmuM9FH2P1iOZP=Svw@mail.gmail.com>
 <20170724030907.GC2938@leo.usersys.redhat.com>
 <CAM_iQpW4qj2N77QrCvt9jd6jhOGvyRye8eyBzzk+vXeUi_FaoQ@mail.gmail.com>
 <20170725000849.GD2938@leo.usersys.redhat.com>
 <01b1cd24-ab81-3276-f253-70eef20e550b@gmail.com>
 <20170725073202.GE2938@leo.usersys.redhat.com>
 <9e198c2a-c026-f4bd-f190-8d5a887efe7f@gmail.com>
 <CAJieiUgyHDksxVjoCSz9pxbDy-ZZR9uUWWZXdth0diSKAcvx4Q@mail.gmail.com>
 <64377a01-38df-6d43-16a4-401d426fb9b2@gmail.com>
 <CAJieiUi+Me_wXDz0A1oLH2LgBw9DsMoxctV56SjEwGpusFGt4Q@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Cc: Hangbin Liu <liuhangbin@gmail.com>,
        Cong Wang <xiyou.wangcong@gmail.com>,
        network dev <netdev@vger.kernel.org>
To: Roopa Prabhu <roopa@cumulusnetworks.com>
Return-path: <netdev-owner@vger.kernel.org>
Received: from mail-pg0-f67.google.com ([74.125.83.67]:38329 "EHLO
        mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1750930AbdGZTA2 (ORCPT
        <rfc822;netdev@vger.kernel.org>); Wed, 26 Jul 2017 15:00:28 -0400
Received: by mail-pg0-f67.google.com with SMTP id 125so4662994pgi.5
        for <netdev@vger.kernel.org>; Wed, 26 Jul 2017 12:00:28 -0700 (PDT)
In-Reply-To: <CAJieiUi+Me_wXDz0A1oLH2LgBw9DsMoxctV56SjEwGpusFGt4Q@mail.gmail.com>
Sender: netdev-owner@vger.kernel.org
List-ID: <netdev.vger.kernel.org>

On 7/26/17 12:55 PM, Roopa Prabhu wrote:
> On Wed, Jul 26, 2017 at 11:49 AM, David Ahern <dsahern@gmail.com> wrote:
>> On 7/26/17 12:27 PM, Roopa Prabhu wrote:
>>> agreed...so looks like the check in v3 should be
>>>
>>>
>>> +       if ( rt == net->ipv6.ip6_null_entry ||
>>> +            (rt->dst.error &&
>>> + #ifdef CONFIG_IPV6_MULTIPLE_TABLES
>>> +              rt != net->ipv6.ip6_prohibit_entry &&
>>> +              rt != net->ipv6.ip6_blk_hole_entry &&
>>> +#endif
>>> +             )) {
>>>                 err = rt->dst.error;
>>>                 ip6_rt_put(rt);
>>>                 goto errout;
>>>
>>
>> I don't think so. If I add a prohibit route and use the fibmatch
>> attribute, I want to see the route from the FIB that was matched.
> 
> 
> yes, exactly. wouldn't  'rt != net->ipv6.ip6_prohibit_entry' above let
> it fall through to the route fill code ?
> 
> ah...but i guess you are saying that they will have rt6_info's of
> their own and will not match. got it. ack.
> 

This:

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 4d30c96a819d..24de81c804c2 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3637,11 +3637,6 @@ static int inet6_rtm_getroute(struct sk_buff
*in_skb, struct nlmsghdr *nlh,
                dst = ip6_route_lookup(net, &fl6, 0);

        rt = container_of(dst, struct rt6_info, dst);
-       if (rt->dst.error) {
-               err = rt->dst.error;
-               ip6_rt_put(rt);
-               goto errout;
-       }

        if (rt == net->ipv6.ip6_null_entry) {
                err = rt->dst.error;

Puts back the original behavior. In that case, only rt == null_entry
drops to the error path which is correct. All other rt values will drop
to rt6_fill_node and return rt data.