linux-kernel - Re: [PATCH net-next 06/12] net: dsa: rzn1-a5psw: add Renesas RZ/N1 advanced 5 port switch driver

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Date:   Fri, 15 Apr 2022 12:02:14 +0100
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     Clément Léger <clement.leger@...tlin.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Magnus Damm <magnus.damm@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Herve Codina <herve.codina@...tlin.com>,
        Miquèl Raynal <miquel.raynal@...tlin.com>,
        Milan Stevanovic <milan.stevanovic@...com>,
        Jimmy Lalande <jimmy.lalande@...com>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org, netdev@...r.kernel.org,
        Jean-Pierre Geslin <jean-pierre.geslin@....se.com>,
        Phil Edworthy <phil.edworthy@...esas.com>
Subject: Re: [PATCH net-next 06/12] net: dsa: rzn1-a5psw: add Renesas RZ/N1
 advanced 5 port switch driver

On Fri, Apr 15, 2022 at 01:55:03PM +0300, Vladimir Oltean wrote:
> I meant that for a DSA switch driver is mandatory to call dsa_switch_shutdown()
> from your ->shutdown method, otherwise subtle things break, sorry for being unclear.
> 
> Please blindly copy-paste the odd pattern that all other DSA drivers use
> in ->shutdown and ->remove (with the platform_set_drvdata(dev, NULL) calls),
> like a normal person :)

Those platform_set_drvdata(, NULL) calls should be killed - the
driver model will set the driver data to NULL after ->remove has
been called - so having drivers also setting the driver data to
NULL is mere duplication.

The only case it would matter is if someone is looking up the device
and then accessing the driver data - and one would hope that's done
with appropriate locking or other guarantees (e.g. driver can never
be unbound once the driver data has been set.)

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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