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

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

[Alexandru Ardelean]

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>
---
 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];
-- 
2.20.1

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

[Jonathan Cameron]

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];