patch "iio: addac: stx104: Fix race condition when converting" added to char-misc-testing

patch "iio: addac: stx104: Fix race condition when converting" added to char-misc-testing

[gregkh]

This is a note to let you know that I've just added the patch titled

    iio: addac: stx104: Fix race condition when converting

to my char-misc git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-testing branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will be merged to the char-misc-next branch sometime soon,
after it passes testing, and the merge window is open.

If you have any questions about this process, please let me know.


From 4f9b80aefb9e2f542a49d9ec087cf5919730e1dd Mon Sep 17 00:00:00 2001
From: William Breathitt Gray <william.gray@linaro.org>
Date: Thu, 6 Apr 2023 10:40:11 -0400
Subject: iio: addac: stx104: Fix race condition when converting
 analog-to-digital

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/2ae5e40eed5006ca735e4c12181a9ff5ced65547.1680790580.git.william.gray@linaro.org
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 drivers/iio/addac/stx104.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/iio/addac/stx104.c b/drivers/iio/addac/stx104.c
index 4239aafe42fc..8730b79e921c 100644
--- a/drivers/iio/addac/stx104.c
+++ b/drivers/iio/addac/stx104.c
@@ -117,6 +117,8 @@ 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), &reg->achan);
 
@@ -127,6 +129,8 @@ static int stx104_read_raw(struct iio_dev *indio_dev,
 		while (ioread8(&reg->cir_asr) & BIT(7));
 
 		*val = ioread16(&reg->ssr_ad);
+
+		mutex_unlock(&priv->lock);
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_OFFSET:
 		/* get ADC bipolar/unipolar configuration */
-- 
2.40.0