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From: Marek Vasut <marex@denx.de>
To: David Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org, andrew@lunn.ch, f.fainelli@gmail.com,
	george.mccollister@gmail.com, Tristram.Ha@microchip.com,
	woojung.huh@microchip.com
Subject: Re: [PATCH 2/2] net: dsa: microchip: Add shared regmap mutex
Date: Sun, 13 Oct 2019 12:50:15 +0200
Message-ID: <018dad90-f6a4-328c-765e-8e5b66df27d6@denx.de> (raw)
In-Reply-To: <20191012.172140.1744793229621810305.davem@davemloft.net>

On 10/13/19 2:21 AM, David Miller wrote:
> From: David Miller <davem@davemloft.net>
> Date: Sat, 12 Oct 2019 17:20:55 -0700 (PDT)
> 
>> From: Marek Vasut <marex@denx.de>
>> Date: Thu, 10 Oct 2019 20:25:08 +0200
>>
>>> 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@denx.de>
>>
>> Applied.
> 
> Actually, both patches reverted.  Please test your changes properly:
> 
> ERROR: "ksz_regmap_unlock" [drivers/net/dsa/microchip/ksz8795_spi.ko] undefined!
> ERROR: "ksz_regmap_lock" [drivers/net/dsa/microchip/ksz8795_spi.ko] undefined!
> ERROR: "ksz_regmap_unlock" [drivers/net/dsa/microchip/ksz9477_spi.ko] undefined!
> ERROR: "ksz_regmap_lock" [drivers/net/dsa/microchip/ksz9477_spi.ko] undefined!
> ERROR: "ksz_regmap_unlock" [drivers/net/dsa/microchip/ksz9477_i2c.ko] undefined!
> ERROR: "ksz_regmap_lock" [drivers/net/dsa/microchip/ksz9477_i2c.ko] undefined!

So the test is to compile it as a module ?

-- 
Best regards,
Marek Vasut

  reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-10 18:25 [PATCH 1/2] net: dsa: microchip: Do not reinit mutexes on KSZ87xx Marek Vasut
2019-10-10 18:25 ` [PATCH 2/2] net: dsa: microchip: Add shared regmap mutex Marek Vasut
2019-10-13  0:20   ` David Miller
2019-10-13  0:21     ` David Miller
2019-10-13 10:50       ` Marek Vasut [this message]
2019-10-13 16:26         ` David Miller
2019-10-13  0:20 ` [PATCH 1/2] net: dsa: microchip: Do not reinit mutexes on KSZ87xx David Miller

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