Re: [PATCH] iio: gyro: adis16080: replace mlock with own lock

[Jonathan Cameron <jic23@kernel.org>]

On Thu, 19 Sep 2019 16:23:03 +0300
Alexandru Ardelean <alexandru.ardelean@analog.com> wrote:

> The lock is used to protect the buffer during reads. Though the spi
> routines have their own locks, it may be the case that the buffer needs to
> be protected before it's stored and passed to the IIO read hooks.
> 
> indio_dev's mlock was used before.
> This change replaces it with the driver's own lock.
> 
> 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 poke holes in it.

Thanks,

Jonathan

> ---
>  drivers/iio/gyro/adis16080.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/gyro/adis16080.c b/drivers/iio/gyro/adis16080.c
> index 236220d6de02..1b84b8e112fe 100644
> --- a/drivers/iio/gyro/adis16080.c
> +++ b/drivers/iio/gyro/adis16080.c
> @@ -38,10 +38,12 @@ struct adis16080_chip_info {
>   * @us:			actual spi_device to write data
>   * @info:		chip specific parameters
>   * @buf:		transmit or receive buffer
> + * @lock		lock to protect buffer during reads
>   **/
>  struct adis16080_state {
>  	struct spi_device		*us;
>  	const struct adis16080_chip_info *info;
> +	struct mutex			lock;
>  
>  	__be16 buf ____cacheline_aligned;
>  };
> @@ -82,9 +84,9 @@ static int adis16080_read_raw(struct iio_dev *indio_dev,
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
> -		mutex_lock(&indio_dev->mlock);
> +		mutex_lock(&st->lock);
>  		ret = adis16080_read_sample(indio_dev, chan->address, val);
> -		mutex_unlock(&indio_dev->mlock);
> +		mutex_unlock(&st->lock);
>  		return ret ? ret : IIO_VAL_INT;
>  	case IIO_CHAN_INFO_SCALE:
>  		switch (chan->type) {
> @@ -196,6 +198,8 @@ static int adis16080_probe(struct spi_device *spi)
>  	/* this is only used for removal purposes */
>  	spi_set_drvdata(spi, indio_dev);
>  
> +	mutex_init(&st->lock);
> +
>  	/* Allocate the comms buffers */
>  	st->us = spi;
>  	st->info = &adis16080_chip_info[id->driver_data];