Re: [PATCH 12/15] iio: fyro: itg3200_core: do not use internal iio_dev lock

From: Jonathan Cameron <jic23@kernel.org>
To: "Nuno Sá" <nuno.sa@analog.com>
Cc: <linux-arm-kernel@lists.infradead.org>,
	<linux-rockchip@lists.infradead.org>,
	<linux-amlogic@lists.infradead.org>, <linux-imx@nxp.com>,
	<linux-iio@vger.kernel.org>, Chunyan Zhang <zhang.lyra@gmail.com>,
	Michael Hennerich <Michael.Hennerich@analog.com>,
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Cixi Geng <cixi.geng1@unisoc.com>,
	Kevin Hilman <khilman@baylibre.com>,
	Vladimir Zapolskiy <vz@mleia.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Alexandru Ardelean <aardelean@deviqon.com>,
	"Fabio Estevam" <festevam@gmail.com>,
	Andriy Tryshnivskyy <andriy.tryshnivskyy@opensynergy.com>,
	Haibo Chen <haibo.chen@nxp.com>,
	"Shawn Guo" <shawnguo@kernel.org>,
	Hans de Goede <hdegoede@redhat.com>,
	Miquel Raynal <miquel.raynal@bootlin.com>,
	Jerome Brunet <jbrunet@baylibre.com>,
	"Heiko Stuebner" <heiko@sntech.de>,
	Florian Boor <florian.boor@kernelconcepts.de>,
	Ciprian Regus <ciprian.regus@analog.com>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Andy Shevchenko <andy.shevchenko@gmail.com>,
	Neil Armstrong <narmstrong@baylibre.com>,
	"Baolin Wang" <baolin.wang@linux.alibaba.com>,
	Jyoti Bhayana <jbhayana@google.com>, Chen-Yu Tsai <wens@csie.org>,
	Orson Zhai <orsonzhai@gmail.com>
Subject: Re: [PATCH 12/15] iio: fyro: itg3200_core: do not use internal iio_dev lock
Date: Sat, 24 Sep 2022 16:43:07 +0100	[thread overview]
Message-ID: <20220924164307.7c821708@jic23-huawei> (raw)
In-Reply-To: <20220920112821.975359-13-nuno.sa@analog.com>

On Tue, 20 Sep 2022 13:28:18 +0200
Nuno Sá <nuno.sa@analog.com> wrote:

> The iio_device lock is only meant for internal use. Hence define a
> device local lock to protect against concurrent accesses.
> 
> Signed-off-by: Nuno Sá <nuno.sa@analog.com>
> ---
>  drivers/iio/gyro/itg3200_core.c  | 9 ++++++---
>  include/linux/iio/gyro/itg3200.h | 2 ++
>  2 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/gyro/itg3200_core.c b/drivers/iio/gyro/itg3200_core.c
> index 0491c64e1b32..358aa8ac0c6b 100644
> --- a/drivers/iio/gyro/itg3200_core.c
> +++ b/drivers/iio/gyro/itg3200_core.c
> @@ -18,6 +18,7 @@
>  #include <linux/slab.h>
>  #include <linux/stat.h>
>  #include <linux/module.h>
> +#include <linux/mutex.h>
>  #include <linux/delay.h>
>  
>  #include <linux/iio/iio.h>
> @@ -131,6 +132,7 @@ static int itg3200_write_raw(struct iio_dev *indio_dev,
>  			     int val2,
>  			     long mask)
>  {
> +	struct itg3200 *st = iio_priv(indio_dev);
>  	int ret;
>  	u8 t;
>  
> @@ -139,11 +141,11 @@ static int itg3200_write_raw(struct iio_dev *indio_dev,
>  		if (val == 0 || val2 != 0)
>  			return -EINVAL;
>  
> -		mutex_lock(&indio_dev->mlock);
> +		mutex_lock(&st->lock);
>  
>  		ret = itg3200_read_reg_8(indio_dev, ITG3200_REG_DLPF, &t);
>  		if (ret) {
> -			mutex_unlock(&indio_dev->mlock);
> +			mutex_unlock(&st->lock);
>  			return ret;
>  		}
>  		t = ((t & ITG3200_DLPF_CFG_MASK) ? 1000u : 8000u) / val - 1;
> @@ -152,7 +154,7 @@ static int itg3200_write_raw(struct iio_dev *indio_dev,
>  					  ITG3200_REG_SAMPLE_RATE_DIV,
>  					  t);
>  
> -		mutex_unlock(&indio_dev->mlock);
> +		mutex_unlock(&st->lock);
>  		return ret;
>  
>  	default:
> @@ -307,6 +309,7 @@ static int itg3200_probe(struct i2c_client *client,
>  		return -ENOMEM;
>  
>  	st = iio_priv(indio_dev);
> +	mutex_init(&st->lock);
>  
>  	ret = iio_read_mount_matrix(&client->dev, &st->orientation);
>  	if (ret)
> diff --git a/include/linux/iio/gyro/itg3200.h b/include/linux/iio/gyro/itg3200.h
> index a602fe7b84fa..74b6d1cadc86 100644
> --- a/include/linux/iio/gyro/itg3200.h
> +++ b/include/linux/iio/gyro/itg3200.h
> @@ -102,6 +102,8 @@ struct itg3200 {
>  	struct i2c_client	*i2c;
>  	struct iio_trigger	*trig;
>  	struct iio_mount_matrix orientation;
> +	/* lock to protect against multiple access to the device */
> +	struct mutex		lock;
>  };
>  
>  enum ITG3200_SCAN_INDEX {