netdev - Re: [PATCH net] ipv4: Avoid caching dsts when lookup skipped nh oif check

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Date:   Thu, 20 Apr 2017 15:39:43 +0100
From:   Robert Shearman <rshearma@...cade.com>
To:     David Ahern <dsa@...ulusnetworks.com>, <davem@...emloft.net>
CC:     <netdev@...r.kernel.org>
Subject: Re: [PATCH net] ipv4: Avoid caching dsts when lookup skipped nh oif
 check

On 20/04/17 15:21, David Ahern wrote:
> On 4/20/17 6:58 AM, Robert Shearman wrote:
>> David reported that doing the following:
>>
>>     ip li add red type vrf table 10
>>     ip link set dev eth1 vrf red
>>     ip addr add 127.0.0.1/8 dev red
>>     ip link set dev eth1 up
>>     ip li set red up
>>     ping -c1 -w1 -I red 127.0.0.1
>>     ip li del red
>>
>> results in a hang with this message:
>>
>>     unregister_netdevice: waiting for red to become free. Usage count = 1
>
> I think you misunderstood my comment. The above works fine today. There
> is no bug with refcnts.
>
> It breaks with your patches wanting to use a VRF device with the main
> table (254).

That doesn't seem to match with my experience. I can reproduce this on 
the net tree with the listed commands and the behaviour matches what I 
see in the code.

Thanks,
Rob