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

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Message-ID: <9448ae8f-c4e0-58a4-ff46-2f2951113d1e@oracle.com>
Date:   Tue, 5 Mar 2019 11:35:50 -0800
From:   si-wei liu <si-wei.liu@...cle.com>
To:     Stephen Hemminger <stephen@...workplumber.org>
Cc:     "Michael S. Tsirkin" <mst@...hat.com>,
        Sridhar Samudrala <sridhar.samudrala@...el.com>,
        Jakub Kicinski <kubakici@...pl>, Jiri Pirko <jiri@...nulli.us>,
        David Miller <davem@...emloft.net>,
        Netdev <netdev@...r.kernel.org>,
        virtualization@...ts.linux-foundation.org, liran.alon@...cle.com,
        boris.ostrovsky@...cle.com, vijay.balakrishna@...cle.com
Subject: Re: [RFC PATCH net-next] failover: allow name change on IFF_UP slave
 interfaces



On 3/5/2019 11:24 AM, Stephen Hemminger wrote:
> On Tue, 5 Mar 2019 11:19:32 -0800
> si-wei liu <si-wei.liu@...cle.com> wrote:
>
>>> I have a vague idea: would it work to *not* set
>>> IFF_UP on slave devices at all?
>> Hmm, I ever thought about this option, and it appears this solution is
>> more invasive than required to convert existing scripts, despite the
>> controversy of introducing internal netdev state to differentiate user
>> visible state. Either we disallow slave to be brought up by user, or to
>> not set IFF_UP flag but instead use the internal one, could end up with
>> substantial behavioral change that breaks scripts. Consider any admin
>> script that does `ip link set dev ... up' successfully just assumes the
>> link is up and subsequent operation can be done as usual. While it *may*
>> work for dracut (yet to be verified), I'm a bit concerned that there are
>> more scripts to be converted than those that don't follow volatile
>> failover slave names. It's technically doable, but may not worth the
>> effort (in terms of porting existing scripts/apps).
>>
>> Thanks
>> -Siwei
> Won't work for most devices.  Many devices turn off PHY and link layer
> if not IFF_UP
True, that's what I said about introducing internal state for those 
driver and other kernel component. Very invasive change indeed.

-Siwei