2017-03-13 18:09:36

by Simran Singhal

Subject: [PATCH v3] staging: adis16060_core: Use private driver lock instead of mlock

The IIO subsystem is redefining iio_dev->mlock to be used by
the IIO core only for protecting device operating mode changes.
ie. Changes between INDIO_DIRECT_MODE, INDIO_BUFFER_* modes.

In this driver, mlock was being used to protect hardware state
changes. Replace it with a lock in the devices global data.

Signed-off-by: simran singhal <[email protected]>
---

v3:
-Removed new lock to reuse the existing lock

drivers/staging/iio/gyro/adis16060_core.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/iio/gyro/adis16060_core.c b/drivers/staging/iio/gyro/adis16060_core.c
index c9d46e7..602ec53 100644
--- a/drivers/staging/iio/gyro/adis16060_core.c
+++ b/drivers/staging/iio/gyro/adis16060_core.c
@@ -83,11 +83,12 @@ static int adis16060_read_raw(struct iio_dev *indio_dev,
{
u16 tval = 0;
int ret;
+ struct adis16060_state *st = iio_priv(indio_dev);

switch (mask) {
case IIO_CHAN_INFO_RAW:
/* Take the iio_dev status lock */
- mutex_lock(&indio_dev->mlock);
+ mutex_lock(&st->buf_lock);
ret = adis16060_spi_write(indio_dev, chan->address);
if (ret < 0)
goto out_unlock;
@@ -96,7 +97,7 @@ static int adis16060_read_raw(struct iio_dev *indio_dev,
if (ret < 0)
goto out_unlock;

- mutex_unlock(&indio_dev->mlock);
+ mutex_unlock(&st->buf_lock);
*val = tval;
return IIO_VAL_INT;
case IIO_CHAN_INFO_OFFSET:
@@ -112,7 +113,7 @@ static int adis16060_read_raw(struct iio_dev *indio_dev,
return -EINVAL;

out_unlock:
- mutex_unlock(&indio_dev->mlock);
+ mutex_unlock(&st->buf_lock);
return ret;
}

--
2.7.4

2017-03-13 19:30:41

by Alison Schofield

Subject: Re: [Outreachy kernel] [PATCH v3] staging: adis16060_core: Use private driver lock instead of mlock

On Mon, Mar 13, 2017 at 11:41:30PM +0530, simran singhal wrote:
> The IIO subsystem is redefining iio_dev->mlock to be used by
> the IIO core only for protecting device operating mode changes.
> ie. Changes between INDIO_DIRECT_MODE, INDIO_BUFFER_* modes.
>
> In this driver, mlock was being used to protect hardware state
> changes. Replace it with a lock in the devices global data.
>
> Signed-off-by: simran singhal <[email protected]>
> ---
>
> v3:
> -Removed new lock to reuse the existing lock

Hi Simran,

Check Lars review comments about refactoring into a
write_then_read function protected by same buf_lock.

As it is now, it'll deadlock on buf_lock. It locks in
_read_raw and then calls _spi_write where an attempt
is made to grab the same lock.

alisons


>
> drivers/staging/iio/gyro/adis16060_core.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/staging/iio/gyro/adis16060_core.c b/drivers/staging/iio/gyro/adis16060_core.c
> index c9d46e7..602ec53 100644
> --- a/drivers/staging/iio/gyro/adis16060_core.c
> +++ b/drivers/staging/iio/gyro/adis16060_core.c
> @@ -83,11 +83,12 @@ static int adis16060_read_raw(struct iio_dev *indio_dev,
> {
> u16 tval = 0;
> int ret;
> + struct adis16060_state *st = iio_priv(indio_dev);
>
> switch (mask) {
> case IIO_CHAN_INFO_RAW:
> /* Take the iio_dev status lock */
> - mutex_lock(&indio_dev->mlock);
> + mutex_lock(&st->buf_lock);
> ret = adis16060_spi_write(indio_dev, chan->address);
> if (ret < 0)
> goto out_unlock;
> @@ -96,7 +97,7 @@ static int adis16060_read_raw(struct iio_dev *indio_dev,
> if (ret < 0)
> goto out_unlock;
>
> - mutex_unlock(&indio_dev->mlock);
> + mutex_unlock(&st->buf_lock);
> *val = tval;
> return IIO_VAL_INT;
> case IIO_CHAN_INFO_OFFSET:
> @@ -112,7 +113,7 @@ static int adis16060_read_raw(struct iio_dev *indio_dev,
> return -EINVAL;
>
> out_unlock:
> - mutex_unlock(&indio_dev->mlock);
> + mutex_unlock(&st->buf_lock);
> return ret;
> }
>
> --
> 2.7.4
>
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