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From:   Kurt Kanzenbach <kurt@linutronix.de>
To:     Vladimir Oltean <vladimir.oltean@nxp.com>, netdev@vger.kernel.org
Cc:     Florian Fainelli <f.fainelli@gmail.com>,
        Andrew Lunn <andrew@lunn.ch>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        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>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        George McCollister <george.mccollister@gmail.com>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        Oleksij Rempel <linux@rempel-privat.de>,
        Michael Grzeschik <m.grzeschik@pengutronix.de>,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org,
        Lino Sanfilippo <LinoSanfilippo@gmx.de>
Subject: Re: [RFC PATCH net 3/5] net: dsa: hellcreek: be compatible with
 masters which unregister on shutdown
In-Reply-To: <20210912120932.993440-4-vladimir.oltean@nxp.com>
References: <20210912120932.993440-1-vladimir.oltean@nxp.com>
 <20210912120932.993440-4-vladimir.oltean@nxp.com>
Date:   Tue, 14 Sep 2021 10:08:26 +0200
Message-ID: <874kan1sw5.fsf@kurt>
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On Sun Sep 12 2021, Vladimir Oltean wrote:
> Since commit 2f1e8ea726e9 ("net: dsa: link interfaces with the DSA
> master to get rid of lockdep warnings"), DSA gained a requirement which
> it did not fulfill, which is to unlink itself from the DSA master at
> shutdown time.
>
> Since the hellcreek driver was introduced after the bad commit, it has
> never worked with DSA masters which decide to unregister their
> net_device on shutdown, effectively hanging the reboot process.
>
> Hellcreek is a platform device driver, so we probably cannot have the
> oddities of ->shutdown and ->remove getting both called for the exact
> same struct device. But to be in line with the pattern from the other
> device drivers which are on slow buses, implement the same "if this then
> not that" pattern of either running the ->shutdown or the ->remove hook.
> The driver's current ->remove implementation makes that very easy
> because it already zeroes out its device_drvdata on ->remove.
>
> Fixes: e4b27ebc780f ("net: dsa: Add DSA driver for Hirschmann Hellcreek switches")
> Link: https://lore.kernel.org/netdev/20210909095324.12978-1-LinoSanfilippo@gmx.de/
> Reported-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>

Acked-by: Kurt Kanzenbach <kurt@linutronix.de>

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