netdev - Re: [PATCH net] hv_netvsc: Fix VF namespace also in netvsc

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Message-ID: <a96b1e00-70e3-46d8-a918-e4eb2e7443e8@redhat.com>
Date: Thu, 3 Oct 2024 11:34:49 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Haiyang Zhang <haiyangz@...rosoft.com>, linux-hyperv@...r.kernel.org,
 netdev@...r.kernel.org
Cc: kys@...rosoft.com, wei.liu@...nel.org, decui@...rosoft.com,
 edumazet@...gle.com, kuba@...nel.org, stephen@...workplumber.org,
 davem@...emloft.net, linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH net] hv_netvsc: Fix VF namespace also in netvsc_open

On 9/27/24 22:54, Haiyang Zhang wrote:
> The existing code moves VF to the same namespace as the synthetic device
> during netvsc_register_vf(). But, if the synthetic device is moved to a
> new namespace after the VF registration, the VF won't be moved together.
> 
> To make the behavior more consistent, add a namespace check to netvsc_open(),
> and move the VF if it is not in the same namespace.
> 
> Cc: stable@...r.kernel.org
> Fixes: c0a41b887ce6 ("hv_netvsc: move VF to same namespace as netvsc device")
> Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.com>

This looks strange to me. Skimming over the code it looks like that with 
VF you really don't mean a Virtual Function...

Looking at the blamed commit, it looks like that having both the 
synthetic and the "VF" device in different namespaces is an intended 
use-case. This change would make such scenario more difficult and could 
possibly break existing use-cases.

Why do you think it will be more consistent? If the user moved the 
synthetic device in another netns, possibly/likely the user intended to 
keep both devices separated.

Thanks,

Paolo