netdev - Re: [PATCH V2 2/2] net: dsa: microchip: Add shared regmap mutex

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Message-ID: <20191016120345.GC4780@lunn.ch>
Date:   Wed, 16 Oct 2019 14:03:45 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Marek Vasut <marex@...x.de>
Cc:     netdev@...r.kernel.org, "David S . Miller" <davem@...emloft.net>,
        Florian Fainelli <f.fainelli@...il.com>,
        George McCollister <george.mccollister@...il.com>,
        Tristram Ha <Tristram.Ha@...rochip.com>,
        Woojung Huh <woojung.huh@...rochip.com>
Subject: Re: [PATCH V2 2/2] net: dsa: microchip: Add shared regmap mutex

On Sun, Oct 13, 2019 at 09:32:38PM +0200, Marek Vasut wrote:
> The KSZ driver uses one regmap per register width (8/16/32), each with
> it's own lock, but accessing the same set of registers. In theory, it
> is possible to create a race condition between these regmaps, although
> the underlying bus (SPI or I2C) locking should assure nothing bad will
> really happen and the accesses would be correct.
> 
> To make the driver do the right thing, add one single shared mutex for
> all the regmaps used by the driver instead. This assures that even if
> some future hardware is on a bus which does not serialize the accesses
> the same way SPI or I2C does, nothing bad will happen.
> 
> Note that the status_mutex was unused and only initied, hence it was
> renamed and repurposed as the regmap mutex.
> 
> Signed-off-by: Marek Vasut <marex@...x.de>

Apart from the reverse Christmas tree:

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew