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Date:   Wed, 23 Feb 2022 09:05:02 -0800
From:   Stephen Hemminger <stephen@networkplumber.org>
To:     Jakub Kicinski <kuba@kernel.org>
Cc:     Guillaume Nault <gnault@redhat.com>,
        Kees Cook <keescook@chromium.org>,
        Eric Dumazet <edumazet@google.com>,
        "Ziyang Xuan (William)" <william.xuanziyang@huawei.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        David Miller <davem@davemloft.net>,
        netdev <netdev@vger.kernel.org>,
        Vasily Averin <vvs@virtuozzo.com>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net] net: vlan: allow vlan device MTU change follow real
 device from smaller to bigger
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On Wed, 23 Feb 2022 08:03:42 -0800
Jakub Kicinski <kuba@kernel.org> wrote:

> On Wed, 23 Feb 2022 12:26:18 +0100 Guillaume Nault wrote:
> > Do you mean something like:
> > 
> >   ip link set dev eth0 vlan-mtu-policy <policy-name>
> > 
> > that'd affect all existing (and future) vlans of eth0?  
> 
> I meant
> 
>   ip link set dev vlan0 mtu-policy blah
> 
> but also
> 
>   ip link set dev bond0 mtu-policy blah
> 
> and
> 
>   ip link set dev macsec0 mtu-policy blah2
>   ip link set dev vxlan0 mtu-policy blah2

Sorry, putting this in ip link is not the right place.
It belongs in sysctl (if at all); not convinced this is worth doing.