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Date:   Tue, 27 Jun 2023 17:07:04 +0200
From:   Simon Horman <simon.horman@corigine.com>
To:     Vladimir Oltean <vladimir.oltean@nxp.com>
Cc:     netdev@vger.kernel.org, Andrew Lunn <andrew@lunn.ch>,
        Florian Fainelli <f.fainelli@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 net 2/2] net: dsa: tag_sja1105: always prefer source
 port information from INCL_SRCPT
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References: <20230627094207.3385231-1-vladimir.oltean@nxp.com>
 <20230627094207.3385231-3-vladimir.oltean@nxp.com>
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On Tue, Jun 27, 2023 at 12:42:07PM +0300, Vladimir Oltean wrote:
> Currently the sja1105 tagging protocol prefers using the source port
> information from the VLAN header if that is available, falling back to
> the INCL_SRCPT option if it isn't. The VLAN header is available for all
> frames except for META frames initiated by the switch (containing RX
> timestamps), and thus, the "if (is_link_local)" branch is practically
> dead.
> 
> The tag_8021q source port identification has become more loose
> ("imprecise") and will report a plausible rather than exact bridge port,
> when under a bridge (be it VLAN-aware or VLAN-unaware). But link-local
> traffic always needs to know the precise source port. With incorrect
> source port reporting, for example PTP traffic over 2 bridged ports will
> all be seen on sockets opened on the first such port, which is incorrect.
> 
> Now that the tagging protocol has been changed to make link-local frames
> always contain source port information, we can reverse the order of the
> checks so that we always give precedence to that information (which is
> always precise) in lieu of the tag_8021q VID which is only precise for a
> standalone port.
> 
> Fixes: d7f9787a763f ("net: dsa: tag_8021q: add support for imprecise RX based on the VBID")
> Fixes: 91495f21fcec ("net: dsa: tag_8021q: replace the SVL bridging with VLAN-unaware IVL bridging")
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> ---
> v1->v2: protect against malformed input packets ("vid" variable may be
> uninitialized)

Reviewed-by: Simon Horman <simon.horman@corigine.com>