netdev - Re: [PATCH v2] net: route: Fix vrf dst_entry ref count false increasing

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Date:   Sun, 5 May 2019 11:28:11 +0800
From:   linmiaohe <linmiaohe@...wei.com>
To:     David Ahern <dsahern@...il.com>, <davem@...emloft.net>,
        <kuznet@....inr.ac.ru>, <yoshfuji@...ux-ipv6.org>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     mousuanming <mousuanming@...wei.com>,
        Mingfangsen <mingfangsen@...wei.com>
Subject: Re: [PATCH v2] net: route: Fix vrf dst_entry ref count false
 increasing



On 2019/5/5 10:56, David Ahern wrote:
> On 5/4/19 8:11 PM, linmiaohe wrote:
>>
>>
>> On 2019/5/4 22:59, David Ahern wrote:
>>> On 5/4/19 7:13 AM, linmiaohe wrote:
>>>> From: Suanming.Mou <mousuanming@...wei.com>
>>>>
>>>> When config ip in default vrf same as the ip in specified
>>>> vrf, fib_lookup will return the route from table local
>>>> even if the in device is an enslaved l3mdev. Then the
>>>
>>> you need to move the local rule with a preference of 0 after the l3mdev
>>> rule.
>>>
>>>
>>
>> Move the local rule after l3mdev rule can get rid of this problem. And
>> even if this happend, we can delete the same ip address in default vrf
>> to fix it.
>> But I think maybe it's still a problem because other rule with default
>> vrf out device holds the specified vrf device. It looks unreasonable.
>>
>> Many Thanks.
>>
> 
> VRF is implemented using policy routing. If you do not move the local
> rule below the l3mdev rule, you are doing a lookup in the local table
> first, then vrf table, then main table. Doing the local table first can
> result in false hits - like the case of duplicate IP addresses in
> default VRF and a VRF. In short, it is just wrong.
> 
> Looking at the VRF documentation in the kernel tree I do see such a
> comment is missing, but I do mention in all of the VRF tutorials such as
> this one (see slide 79):
> 
> http://schd.ws/hosted_files/ossna2017/fe/vrf-tutorial-oss.pdf
> 
> .
> 

Thanks for your patience. As it's just like the case of duplicate
IP addresses in default VRF and a VRF and can be fix by hand, we
needn't this patch anymore.

Best regards.