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SubjectRe: [PATCH v2] iio: dac: ti-dac7612: Replace indio_dev->mlock with own device lock
On Wed, 16 Sep 2020 12:25:35 +0300
Alexandru Ardelean <alexandru.ardelean@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 from potential concurrent write
> accesses from userspace. The write operation requires an SPI write, then
> toggling of a GPIO, so the lock aims to protect the sanity of the entire
> sequence of operation.
>
> 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: Alexandru Ardelean <alexandru.ardelean@analog.com>

Applied to the togreg branch of iio.git and pushed out as testing for
the autobuilders to play with it.

Thanks,

Jonathan

> ---
> drivers/iio/dac/ti-dac7612.c | 14 ++++++++++++--
> 1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/dac/ti-dac7612.c b/drivers/iio/dac/ti-dac7612.c
> index 07c9f39d54f1..4c0f4b5e9ff4 100644
> --- a/drivers/iio/dac/ti-dac7612.c
> +++ b/drivers/iio/dac/ti-dac7612.c
> @@ -22,6 +22,14 @@ struct dac7612 {
> struct gpio_desc *loaddacs;
> uint16_t cache[2];
>
> + /*
> + * Lock to protect the state of the device from potential concurrent
> + * write accesses from userspace. The write operation requires an
> + * SPI write, then toggling of a GPIO, so the lock aims to protect
> + * the sanity of the entire sequence of operation.
> + */
> + struct mutex lock;
> +
> /*
> * DMA (thus cache coherency maintenance) requires the
> * transfer buffers to live in their own cache lines.
> @@ -101,9 +109,9 @@ static int dac7612_write_raw(struct iio_dev *iio_dev,
> if (val == priv->cache[chan->channel])
> return 0;
>
> - mutex_lock(&iio_dev->mlock);
> + mutex_lock(&priv->lock);
> ret = dac7612_cmd_single(priv, chan->channel, val);
> - mutex_unlock(&iio_dev->mlock);
> + mutex_unlock(&priv->lock);
>
> return ret;
> }
> @@ -145,6 +153,8 @@ static int dac7612_probe(struct spi_device *spi)
> iio_dev->num_channels = ARRAY_SIZE(priv->cache);
> iio_dev->name = spi_get_device_id(spi)->name;
>
> + mutex_init(&priv->lock);
> +
> for (i = 0; i < ARRAY_SIZE(priv->cache); i++) {
> ret = dac7612_cmd_single(priv, i, 0);
> if (ret)

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