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Date:   Sun, 11 Sep 2022 11:23:55 +0200
From:   netdev@kapio-technology.com
To:     Vladimir Oltean <olteanv@gmail.com>
Cc:     Ido Schimmel <idosch@nvidia.com>, davem@davemloft.net,
        kuba@kernel.org, netdev@vger.kernel.org,
        Florian Fainelli <f.fainelli@gmail.com>,
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        Paolo Abeni <pabeni@redhat.com>,
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        Hauke Mehrtens <hauke@hauke-m.de>,
        Woojung Huh <woojung.huh@microchip.com>,
        UNGLinuxDriver@microchip.com, Sean Wang <sean.wang@mediatek.com>,
        Landen Chao <Landen.Chao@mediatek.com>,
        DENG Qingfang <dqfext@gmail.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Claudiu Manoil <claudiu.manoil@nxp.com>,
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        Ivan Vecera <ivecera@redhat.com>,
        Roopa Prabhu <roopa@nvidia.com>,
        Nikolay Aleksandrov <razor@blackwall.org>,
        Shuah Khan <shuah@kernel.org>,
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        Daniel Borkmann <daniel@iogearbox.net>,
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        bridge@lists.linux-foundation.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v5 net-next 6/6] selftests: forwarding: add test of
 MAC-Auth Bypass to locked port tests
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On 2022-09-11 02:13, Vladimir Oltean wrote:
> On Fri, Sep 09, 2022 at 03:11:56PM +0200, netdev@kapio-technology.com 
> wrote:
>> > > > On Wed, Sep 07, 2022 at 11:10:07PM +0200, netdev@kapio-technology.com wrote:
>> > > > > I am at the blackhole driver implementation now, as I suppose that the
>> > > > > iproute2 command should work with the mv88e6xxx driver when adding blackhole
>> > > > > entries (with a added selftest)?
>> > > > > I decided to add the blackhole feature as new ops for drivers with functions
>> > > > > blackhole_fdb_add() and blackhole_fdb_del(). Do you agree with that approach?
>> > > >
>> > > > I assume you are talking about extending 'dsa_switch_ops'?
>> > >
>> > > Yes, that is the idea.
>> > >
>> > > > If so, it's up to the DSA maintainers to decide.
>> >
>> > What will be the usefulness of adding a blackhole FDB entry from user
>> > space?
>> 
>> With the software bridge it could be used to signal a untrusted host 
>> in
>> connection with a locked port entry attempt. I don't see so much use 
>> other
>> that test purposes with the driver though.
> 
> Not a huge selling point, to be honest. Can't the blackhole flag remain
> settable only in the device -> bridge direction, with user space just
> reading it?

That is possible, but it would of course not make sense to have 
selftests of the feature as that would not work unless there is a driver 
with this capability (now just mv88e6xxx).