linux-kernel - Re: [PATCH v8 net-next 05/12] net: dsa: propagate the locked flag down through the DSA layer

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Message-ID: <20221020153636.ceqk67hmut3govsp@skbuf>
Date:   Thu, 20 Oct 2022 18:36:36 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     Ido Schimmel <idosch@...dia.com>
Cc:     "Hans J. Schultz" <netdev@...io-technology.com>,
        davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Kurt Kanzenbach <kurt@...utronix.de>,
        Hauke Mehrtens <hauke@...ke-m.de>,
        Woojung Huh <woojung.huh@...rochip.com>,
        UNGLinuxDriver@...rochip.com, Sean Wang <sean.wang@...iatek.com>,
        Landen Chao <Landen.Chao@...iatek.com>,
        DENG Qingfang <dqfext@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Ivan Vecera <ivecera@...hat.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <razor@...ckwall.org>,
        Shuah Khan <shuah@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Christian Marangi <ansuelsmth@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Yuwei Wang <wangyuweihx@...il.com>,
        Petr Machata <petrm@...dia.com>,
        Florent Fourcot <florent.fourcot@...irst.fr>,
        Hans Schultz <schultz.hans@...il.com>,
        Joachim Wiberg <troglobit@...il.com>,
        Amit Cohen <amcohen@...dia.com>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        bridge@...ts.linux-foundation.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v8 net-next 05/12] net: dsa: propagate the locked flag
 down through the DSA layer

On Thu, Oct 20, 2022 at 06:23:37PM +0300, Ido Schimmel wrote:
> 3. Miss. FDB entry not found. Here I was thinking to always tell the
> packet to go to the software data path so that it will trigger the
> creation of the "locked" entry if MAB is enabled. If MAB is not enabled,
> it will simply be dropped by the bridge. We can't control it per port in
> hardware, which is why the BR_PORT_MAB flag is not consulted.

Ah, ok, this is the part I was missing, so you can't control an FDB miss
to generate a learn frame only on some ports. But in principle, it still
is the BR_PORT_MAB flag the one which requires these frames to be generated,
not BR_PORT_LOCKED. You can have all ports LOCKED but not MAB, and no
learn frames will be necessary to be sent to the CPU. Only EAPOL, which
is link-local multicast, will reach software for further processing and
unlock the port for a certain MAC DA.