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    Subject[PATCH 6.0 459/862] iio: adc: at91-sama5d2_adc: lock around oversampling and sample freq
    Date
    From: Claudiu Beznea <claudiu.beznea@microchip.com>

    [ Upstream commit 9780a23ed5a0a0a63683e078f576719a98d4fb70 ]

    .read_raw()/.write_raw() could be called asynchronously from user space
    or other in kernel drivers. Without locking on st->lock these could be
    called asynchronously while there is a conversion in progress. Read will
    be harmless but changing registers while conversion is in progress may
    lead to inconsistent results. Thus, to avoid this lock st->lock.

    Fixes: 27e177190891 ("iio:adc:at91_adc8xx: introduce new atmel adc driver")
    Fixes: 6794e23fa3fe ("iio: adc: at91-sama5d2_adc: add support for oversampling resolution")
    Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
    Link: https://lore.kernel.org/r/20220803102855.2191070-4-claudiu.beznea@microchip.com
    Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/iio/adc/at91-sama5d2_adc.c | 12 ++++++++----
    1 file changed, 8 insertions(+), 4 deletions(-)

    diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
    index 08d1f806c839..3734ddc82952 100644
    --- a/drivers/iio/adc/at91-sama5d2_adc.c
    +++ b/drivers/iio/adc/at91-sama5d2_adc.c
    @@ -1542,10 +1542,10 @@ static int at91_adc_read_info_raw(struct iio_dev *indio_dev,
    ret = at91_adc_read_position(st, chan->channel,
    &tmp_val);
    *val = tmp_val;
    - mutex_unlock(&st->lock);
    - iio_device_release_direct_mode(indio_dev);
    if (ret > 0)
    ret = at91_adc_adjust_val_osr(st, val);
    + mutex_unlock(&st->lock);
    + iio_device_release_direct_mode(indio_dev);

    return ret;
    }
    @@ -1558,10 +1558,10 @@ static int at91_adc_read_info_raw(struct iio_dev *indio_dev,
    ret = at91_adc_read_pressure(st, chan->channel,
    &tmp_val);
    *val = tmp_val;
    - mutex_unlock(&st->lock);
    - iio_device_release_direct_mode(indio_dev);
    if (ret > 0)
    ret = at91_adc_adjust_val_osr(st, val);
    + mutex_unlock(&st->lock);
    + iio_device_release_direct_mode(indio_dev);

    return ret;
    }
    @@ -1650,16 +1650,20 @@ static int at91_adc_write_raw(struct iio_dev *indio_dev,
    /* if no change, optimize out */
    if (val == st->oversampling_ratio)
    return 0;
    + mutex_lock(&st->lock);
    st->oversampling_ratio = val;
    /* update ratio */
    at91_adc_config_emr(st);
    + mutex_unlock(&st->lock);
    return 0;
    case IIO_CHAN_INFO_SAMP_FREQ:
    if (val < st->soc_info.min_sample_rate ||
    val > st->soc_info.max_sample_rate)
    return -EINVAL;

    + mutex_lock(&st->lock);
    at91_adc_setup_samp_freq(indio_dev, val);
    + mutex_unlock(&st->lock);
    return 0;
    default:
    return -EINVAL;
    --
    2.35.1


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