netdev - Re: [PATCH net v6] failover: allow name change on IFF

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Date:   Mon, 8 Apr 2019 13:56:28 -0700
From:   si-wei liu <si-wei.liu@...cle.com>
To:     "Samudrala, Sridhar" <sridhar.samudrala@...el.com>,
        Stephen Hemminger <stephen@...workplumber.org>,
        "Michael S. Tsirkin" <mst@...hat.com>
Cc:     davem@...emloft.net, kubakici@...pl, alexander.duyck@...il.com,
        jiri@...nulli.us, netdev@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, liran.alon@...cle.com,
        boris.ostrovsky@...cle.com, vijay.balakrishna@...cle.com
Subject: Re: [PATCH net v6] failover: allow name change on IFF_UP slave
 interfaces



On 4/6/2019 7:45 PM, Samudrala, Sridhar wrote:
>
> On 4/6/2019 12:21 AM, si-wei liu wrote:
>
>>>>
>>>> Stephen are you happy with this approach?
>>> I think it is the best solution for what you want to do.
>>
>> Since you're asking specifically, I tried what you suggested below.
>>
>>> Did you test with some things like Free Range Routing,
>>
>> Although there might be spurious warning (which is a check for sanity 
>> more than an error) while slave interface is up, slave rename had 
>> been handled quite well there, no matter which state slave is at.
>>
>> https://github.com/FRRouting/frr/blob/master/zebra/if_netlink.c#L97
>>
>> The FRR users are supposed to operate on failover master interface 
>> anyway. No one is expected to configure those passive interfaces for 
>> routing.
>>
>>> VPP
>> Nothing particular was seen for this one. The netlink usage there 
>> doesn't seem related to my change:
>> https://github.com/FDio/vpp/blob/master/src/vnet/devices/netlink.c
>>
>>> or other userspace
>>> control planes that consume netlink?
>> dhcpcd (https://github.com/kobolabs/dhcpcd/blob/kobo/if-linux.c#L761) 
>> was tested OK.
>>
>> In addition, the patch seems to play quite well with systemd-udev and 
>> dracut/initramfs-tools. No breakage, no weird error message was seen.
>>
>> What else do you suggest we should try/test with?
>
> Thanks Siwei for all the tests you are trying out. Did you notice that 
> any of these tests required the NETDEV_CHANGE notifier that you added?

No, that is not actually needed - none of NETDEV_CHANGE consumers checks 
for name change, although name change was reflected there already. I 
retested userspace applications above with NETDEV_CHANGE notifier 
removed, the results remainl same.

Thanks,
-Siwei

>
> -Sridhar