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iio: adc: ad_sigma_delta: do not use internal iio_dev lock 

commit 20228a1d5a upstream.

Drop 'mlock' usage by making use of iio_device_claim_direct_mode().
This change actually makes sure we cannot do a single conversion while
buffering is enable. Note there was a potential race in the previous
code since we were only acquiring the lock after checking if the bus is
enabled.

Fixes: af3008485e ("iio:adc: Add common code for ADI Sigma Delta devices")
Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: <Stable@vger.kernel.org> #No rush as race is very old.
Link: https://lore.kernel.org/r/20220920112821.975359-2-nuno.sa@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nuno Sá 2022-09-20 13:28:07 +02:00 committed by Greg Kroah-Hartman
parent 0cf939d003
commit c8b577fe8d
1 changed files with 4 additions and 4 deletions
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8
drivers/iio/adc/ad_sigma_delta.c
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@ -282,10 +282,10 @@ int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
unsigned int sample, raw_sample;
int ret = 0;
if (iio_buffer_enabled(indio_dev))
return -EBUSY;
ret = iio_device_claim_direct_mode(indio_dev);
if (ret)
return ret;
mutex_lock(&indio_dev->mlock);
ad_sigma_delta_set_channel(sigma_delta, chan->address);
spi_bus_lock(sigma_delta->spi->master);
@ -319,7 +319,7 @@ out:
ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);
sigma_delta->bus_locked = false;
spi_bus_unlock(sigma_delta->spi->master);
mutex_unlock(&indio_dev->mlock);
iio_device_release_direct_mode(indio_dev);
if (ret)
return ret;