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From:   Long Li <longli@microsoft.com>
To:     Jakub Kicinski <kuba@kernel.org>,
        stephen <stephen@networkplumber.org>
CC:     "longli@linuxonhyperv.com" <longli@linuxonhyperv.com>,
        KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>,
        "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH net-next v4] hv_netvsc: Mark VF as slave before exposing
 it to user-mode
Thread-Topic: [PATCH net-next v4] hv_netvsc: Mark VF as slave before exposing
 it to user-mode
Thread-Index: AQHaEpbleF6H2i0O6EK5idFzE7vPXbBxP20AgAAPDICAAq7HgIAHmxUAgATOqoCAA5TaEA==
Date:   Tue, 21 Nov 2023 00:23:40 +0000
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References: <1699484212-24079-1-git-send-email-longli@linuxonhyperv.com>
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        <20231110120513.45ed505c@kernel.org>    <20231115081406.1bd9a4ed@hermes.local>
 <20231118093849.14e36043@kernel.org>
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> On Wed, 15 Nov 2023 08:14:06 -0800 Stephen Hemminger wrote:
> > Jakub is right that in an ideal world, this could all be managed by
> > userspace. But the management of network devices in Linux is a
> > dumpster fire! Every distro invents there own solution, last time I
> > counted there were six different tools claiming to be the "one network
> > device manager to rule them all". And that doesn't include all the
> > custom scripts and vendor appliances.
>=20
> To be clear, I thought Long Li was saying that the goal is work around ca=
ses where
> VF is probed before netvsc. That seems like something that can be prevent=
ed by
> the hypervisor.

Hi Jakub,

I think you misunderstood my response, here is the response again.

(quote)

The current workflow in the kernel looks like this:
1. VF net device is created and expose to user-mode 2. VF is bonded to NETV=
SC (if NETVSC exists on the system)

With the current kernel behavior, the user-mode can possibly see the VF aft=
er 1, and before 2 when VF is bonded. When this happens, the user-mode does=
n't know if the VF will be bonded in the future (it may never happen on sys=
tems without NETVSC). In this case, it doesn't know if it should configure =
the VF or not.

(end quote)

The problem is not that VF could be probed before netvsc. The problem is th=
at it's possible that VF is probed, exposed to user-mode earlier than netvs=
c has a chance to bond it.

Thanks,

Long