Re: [PATCH 3/5] iio: adc: npcm_adc: Replace indio_dev->mlock with own device lock

Jonathan Cameron
2021-02-21T16:39:54Z

On Mon, 28 Sep 2020 16:13:31 +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/npcm_adc.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/adc/npcm_adc.c b/drivers/iio/adc/npcm_adc.c
> index d9d105920001..f7bc0bb7f112 100644
> --- a/drivers/iio/adc/npcm_adc.c
> +++ b/drivers/iio/adc/npcm_adc.c
> @@ -25,6 +25,15 @@ struct npcm_adc {
> wait_queue_head_t wq;
> struct regulator *vref;
> struct reset_control *reset;
> + /*
> + * 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 event 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.
> + */
> + struct mutex lock;
> };
>
> /* ADC registers */
> @@ -135,9 +144,9 @@ static int npcm_adc_read_raw(struct iio_dev *indio_dev,
>
> switch (mask) {
> case IIO_CHAN_INFO_RAW:
> - mutex_lock(&indio_dev->mlock);
> + mutex_lock(&info->lock);
> ret = npcm_adc_read(info, val, chan->channel);
> - mutex_unlock(&indio_dev->mlock);
> + mutex_unlock(&info->lock);
> if (ret) {
> dev_err(info->dev, "NPCM ADC read failed\n");
> return ret;
> @@ -187,6 +196,8 @@ static int npcm_adc_probe(struct platform_device *pdev)
> return -ENOMEM;
> info = iio_priv(indio_dev);
>
> + mutex_init(&info->lock);
> +
> info->dev = &pdev->dev;
>
> info->regs = devm_platform_ioremap_resource(pdev, 0);