Re: [PATCH 2/5] iio: adc: palmas_gpadc: Replace indio_dev->mlock with own device lock

From: Jonathan Cameron <jic23@kernel.org>
To: Mircea Caprioru <mircea.caprioru@analog.com>
Cc: <Michael.Hennerich@analog.com>, <alexandru.ardelean@analog.com>,
	<lars@metafoo.de>, <gregkh@linuxfoundation.org>,
	<linux-kernel@vger.kernel.org>, <linux-iio@vger.kernel.org>,
	Sergiu Cuciurean <sergiu.cuciurean@analog.com>
Subject: Re: [PATCH 2/5] iio: adc: palmas_gpadc: Replace indio_dev->mlock with own device lock
Date: Sun, 21 Feb 2021 16:38:26 +0000	[thread overview]
Message-ID: <20210221163826.10ba97be@archlinux> (raw)
In-Reply-To: <20200928131333.36646-2-mircea.caprioru@analog.com>

On Mon, 28 Sep 2020 16:13:30 +0300
Mircea Caprioru <mircea.caprioru@analog.com> wrote:

> From: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
> 
> As part of the general cleanup of indio_dev->mlock, this change replaces
> it with a local lock on the device's state structure.
> 
> This is part of a bigger cleanup.
> Link: https://lore.kernel.org/linux-iio/CA+U=Dsoo6YABe5ODLp+eFNPGFDjk5ZeQEceGkqjxXcVEhLWubw@mail.gmail.com/
> 
> Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
> Signed-off-by: Mircea Caprioru <mircea.caprioru@analog.com>
Applied,

Thanks,

Jonathan

> ---
>  drivers/iio/adc/palmas_gpadc.c | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/adc/palmas_gpadc.c b/drivers/iio/adc/palmas_gpadc.c
> index 889b88768b63..14874f11614d 100644
> --- a/drivers/iio/adc/palmas_gpadc.c
> +++ b/drivers/iio/adc/palmas_gpadc.c
> @@ -90,6 +90,12 @@ static struct palmas_gpadc_info palmas_gpadc_info[] = {
>   *			3: 800 uA
>   * @extended_delay:	enable the gpadc extended delay mode
>   * @auto_conversion_period:	define the auto_conversion_period
> + * @lock:	Lock to protect the device state during a potential concurrent
> + *		read access from userspace. Reading a raw value requires a sequence
> + *		of register writes, then a wait for a completion callback,
> + *		and finally a register read, during which userspace could issue
> + *		another read request. This lock protects a read access from
> + *		ocurring before another one has finished.
>   *
>   * This is the palmas_gpadc structure to store run-time information
>   * and pointers for this driver instance.
> @@ -110,6 +116,7 @@ struct palmas_gpadc {
>  	bool				wakeup1_enable;
>  	bool				wakeup2_enable;
>  	int				auto_conversion_period;
> +	struct mutex			lock;
>  };
>  
>  /*
> @@ -388,7 +395,7 @@ static int palmas_gpadc_read_raw(struct iio_dev *indio_dev,
>  	if (adc_chan > PALMAS_ADC_CH_MAX)
>  		return -EINVAL;
>  
> -	mutex_lock(&indio_dev->mlock);
> +	mutex_lock(&adc->lock);
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
> @@ -414,12 +421,12 @@ static int palmas_gpadc_read_raw(struct iio_dev *indio_dev,
>  		goto out;
>  	}
>  
> -	mutex_unlock(&indio_dev->mlock);
> +	mutex_unlock(&adc->lock);
>  	return ret;
>  
>  out:
>  	palmas_gpadc_read_done(adc, adc_chan);
> -	mutex_unlock(&indio_dev->mlock);
> +	mutex_unlock(&adc->lock);
>  
>  	return ret;
>  }
> @@ -516,6 +523,9 @@ static int palmas_gpadc_probe(struct platform_device *pdev)
>  	adc->dev = &pdev->dev;
>  	adc->palmas = dev_get_drvdata(pdev->dev.parent);
>  	adc->adc_info = palmas_gpadc_info;
> +
> +	mutex_init(&adc->lock);
> +
>  	init_completion(&adc->conv_completion);
>  	dev_set_drvdata(&pdev->dev, indio_dev);
>