netdev - Re: [PATCH net 4/4] i40e: Revert "i40e: don't report link up for a VF who hasn't enabled queues"

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Message-ID: <20210129221851.20f6df9b@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Fri, 29 Jan 2021 22:18:51 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc:     Jacob Keller <jacob.e.keller@...el.com>,
        Tony Nguyen <anthony.l.nguyen@...el.com>,
        David Miller <davem@...emloft.net>,
        Aleksandr Loktionov <aleksandr.loktionov@...el.com>,
        Network Development <netdev@...r.kernel.org>,
        sassmann@...hat.com,
        Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>,
        Konrad Jankowski <konrad0.jankowski@...el.com>
Subject: Re: [PATCH net 4/4] i40e: Revert "i40e: don't report link up for a
 VF who hasn't enabled queues"

On Fri, 29 Jan 2021 21:00:02 -0500 Willem de Bruijn wrote:
> On Fri, Jan 29, 2021 at 7:09 PM Jacob Keller <jacob.e.keller@...el.com> wrote:
> > Yea this might re-introduce the issue described in that commit. However
> > I believe the bug in question was due to very old versions of VF
> > drivers, (including an ancient version of FreeBSD if I recall).
> >
> > Perhaps there is some better mechanism for handling this, but I think
> > reverting this is ok given that it causes problems in certain situations
> > where the link status wasn't reported properly.
> >
> > Maybe there is a solution for both cases? but I would worry less about
> > an issue with the incredibly old VFs because we know that the issue is
> > fixed in newer VF code and the real problem is that the VF driver is
> > incorrectly assuming link up means it is ready to send.
> >
> > Thus, I am comfortable with this revert: It simplifies the state for
> > both the PF and VF.
> >
> > I would be open to alternatives as long as the issue described here is
> > also fixed.
> >
> > Caveat: I was not involved in the decision to revert this and wasn't
> > aware of it until now, so I almost certainly have out of date information.  
> 
> That's reasonable. The original patch is over three years old.
> 
> If it is considered safe to revert now, I would just articulate that
> point in the commit.

Agreed. I'd call out that the original fix was a work around for
clearly buggy client drivers, and they had enough time to be fixed.