4.19-stable review patch. If anyone has any objections, please let me know.
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From: William Breathitt Gray william.gray@linaro.org
[ Upstream commit 4f9b80aefb9e2f542a49d9ec087cf5919730e1dd ]
The ADC conversion procedure requires several device I/O operations performed in a particular sequence. If stx104_read_raw() is called concurrently, the ADC conversion procedure could be clobbered. Prevent such a race condition by utilizing a mutex.
Fixes: 4075a283ae83 ("iio: stx104: Add IIO support for the ADC channels") Signed-off-by: William Breathitt Gray william.gray@linaro.org Link: https://lore.kernel.org/r/2ae5e40eed5006ca735e4c12181a9ff5ced65547.168079058... Cc: Stable@vger.kernel.org Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/iio/adc/stx104.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/iio/adc/stx104.c b/drivers/iio/adc/stx104.c index 78e87d1aaaefb..49aeb76212fd0 100644 --- a/drivers/iio/adc/stx104.c +++ b/drivers/iio/adc/stx104.c @@ -125,6 +125,8 @@ static int stx104_read_raw(struct iio_dev *indio_dev, return IIO_VAL_INT; }
+ mutex_lock(&priv->lock); + /* select ADC channel */ iowrite8(chan->channel | (chan->channel << 4), ®->achan);
@@ -135,6 +137,8 @@ static int stx104_read_raw(struct iio_dev *indio_dev, while (ioread8(®->cir_asr) & BIT(7));
*val = ioread16(®->ssr_ad); + + mutex_unlock(&priv->lock); return IIO_VAL_INT; case IIO_CHAN_INFO_OFFSET: /* get ADC bipolar/unipolar configuration */