On 21/03/17 16:15, sayli karnik wrote:
> iio_dev->mlock should be used by the IIO core only for protecting
> device operating mode changes. ie. Changes between INDIO_DIRECT_MODE,
> INDIO_BUFFER_* modes.
> Replace mlock with a lock in the device's global data to protect
> hardware state changes. Declare a new lock to avoid deadlocks due to
> nested mutex locks.
>
> Signed-off-by: sayli karnik <karniksayli1995@xxxxxxxxx>
Talk me through the logic of which lock you have used where...
> ---
> Changes in v2:
> Declared a new lock for raw reads/writes
>
> drivers/staging/iio/meter/ade7758.h | 4 +++-
> drivers/staging/iio/meter/ade7758_core.c | 12 +++++++-----
> 2 files changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/staging/iio/meter/ade7758.h b/drivers/staging/iio/meter/ade7758.h
> index 6ae78d8..e45887e 100644
> --- a/drivers/staging/iio/meter/ade7758.h
> +++ b/drivers/staging/iio/meter/ade7758.h
> @@ -112,13 +112,15 @@
> * @tx: transmit buffer
> * @rx: receive buffer
> * @buf_lock: mutex to protect tx and rx
> + * @lock: mutex to protect raw reads and writes
> **/
> struct ade7758_state {
> struct spi_device *us;
> struct iio_trigger *trig;
> u8 *tx;
> u8 *rx;
> - struct mutex buf_lock;
> + struct mutex buf_lock; /* protect buffer reads/writes */
> + struct mutex lock; /* protect raw reads/writes */
> struct spi_transfer ring_xfer[4];
> struct spi_message ring_msg;
> /*
> diff --git a/drivers/staging/iio/meter/ade7758_core.c b/drivers/staging/iio/meter/ade7758_core.c
> index 99c89e6..0996d74 100644
> --- a/drivers/staging/iio/meter/ade7758_core.c
> +++ b/drivers/staging/iio/meter/ade7758_core.c
> @@ -522,13 +522,14 @@ static int ade7758_read_raw(struct iio_dev *indio_dev,
> int *val2,
> long mask)
> {
> + struct ade7758_state *st = iio_priv(indio_dev);
> int ret;
>
> switch (mask) {
> case IIO_CHAN_INFO_SAMP_FREQ:
> - mutex_lock(&indio_dev->mlock);
> + mutex_lock(&st->lock);
> ret = ade7758_read_samp_freq(&indio_dev->dev, val);
> - mutex_unlock(&indio_dev->mlock);
> + mutex_unlock(&st->lock);
> return ret;
> default:
> return -EINVAL;
> @@ -541,15 +542,16 @@ static int ade7758_write_raw(struct iio_dev *indio_dev,
> struct iio_chan_spec const *chan,
> int val, int val2, long mask)
> {
> + struct ade7758_state *st = iio_priv(indio_dev);
> int ret;
>
> switch (mask) {
> case IIO_CHAN_INFO_SAMP_FREQ:
> if (val2)
> return -EINVAL;
> - mutex_lock(&indio_dev->mlock);
> + mutex_lock(&st->buf_lock);
Why buf_lock here?
> ret = ade7758_write_samp_freq(&indio_dev->dev, val);
> - mutex_unlock(&indio_dev->mlock);
> + mutex_unlock(&st->buf_lock);
> return ret;
> default:
> return -EINVAL;
> @@ -855,7 +857,7 @@ static int ade7758_probe(struct spi_device *spi)
> }
> st->us = spi;
> mutex_init(&st->buf_lock);
> -
> + mutex_init(&st->lock);
> indio_dev->name = spi->dev.driver->name;
> indio_dev->dev.parent = &spi->dev;
> indio_dev->info = &ade7758_info;
>
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