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FAILED: patch "[PATCH] iio: dac: ad5686: acquire lock when doing powerdown control" failed to apply to 5.15-stable tree

PATCH New [email protected] 2 participants 2 messages Jun 4

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Stable branch IIO Analog Devices IIO drivers
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author maintainer
#0 lore raw

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 5237c3175cae5ab05f18878cec3301a04403859e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026060458-baked-charter-80ae@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 5237c3175cae5ab05f18878cec3301a04403859e Mon Sep 17 00:00:00 2001
From: Rodrigo Alencar <[email protected]>
Date: Tue, 5 May 2026 13:35:04 +0100
Subject: [PATCH] iio: dac: ad5686: acquire lock when doing powerdown control

Protect access of pwr_down_mode and pwr_down_mask fields with existing mutex lock. Each channel exposes their own attributes for controlling powerdown modes and powerdown state. This fixes potential race conditions as those the write functions perform non-atomic read-modify-write operations to those pwr_down_* fields. This issue exists since the ad5686 driver was first introduced.

Fixes c2f37c8dcadc ("iio: dac: New driver for AD5686R, AD5685R, AD5684R Digital to analog converters")
Signed-off-by Rodrigo Alencar <[email protected]>
Cc <[email protected]>
Signed-off-by Jonathan Cameron <[email protected]>
drivers/iio/dac/ad5686.c +8 -0
index 27878a6318ff..2e443fcfeb39 100644
@@ -30,6 +30,8 @@ static int ad5686_get_powerdown_mode(struct iio_dev *indio_dev,
 {
 	struct ad5686_state *st = iio_priv(indio_dev);
 
+	guard(mutex)(&st->lock);
+
 	return ((st->pwr_down_mode >> (chan->channel * 2)) & 0x3) - 1;
 }
 

@@ -39,6 +41,8 @@ static int ad5686_set_powerdown_mode(struct iio_dev *indio_dev,
 {
 	struct ad5686_state *st = iio_priv(indio_dev);
 
+	guard(mutex)(&st->lock);
+
 	st->pwr_down_mode &= ~(0x3 << (chan->channel * 2));
 	st->pwr_down_mode |= ((mode + 1) << (chan->channel * 2));
 

@@ -57,6 +61,8 @@ static ssize_t ad5686_read_dac_powerdown(struct iio_dev *indio_dev,
 {
 	struct ad5686_state *st = iio_priv(indio_dev);
 
+	guard(mutex)(&st->lock);
+
 	return sysfs_emit(buf, "%d\n", !!(st->pwr_down_mask &
 				       (0x3 << (chan->channel * 2))));
 }

@@ -77,6 +83,8 @@ static ssize_t ad5686_write_dac_powerdown(struct iio_dev *indio_dev,
 	if (ret)
 		return ret;
 
+	guard(mutex)(&st->lock);
+
 	if (readin)
 		st->pwr_down_mask |= (0x3 << (chan->channel * 2));
 	else
maintainer
#1 lore raw

PATCH 1/1 iio: dac: ad5686: acquire lock when doing powerdown control

From: Rodrigo Alencar <[email protected]>

[ Upstream commit 5237c3175cae5ab05f18878cec3301a04403859e ]

Protect access of pwr_down_mode and pwr_down_mask fields with existing mutex lock. Each channel exposes their own attributes for controlling powerdown modes and powerdown state. This fixes potential race conditions as those the write functions perform non-atomic read-modify-write operations to those pwr_down_* fields. This issue exists since the ad5686 driver was first introduced.

Fixes c2f37c8dcadc ("iio: dac: New driver for AD5686R, AD5685R, AD5684R Digital to analog converters")
Signed-off-by Rodrigo Alencar <[email protected]>
Cc <[email protected]>
Signed-off-by Jonathan Cameron <[email protected]>
Signed-off-by Sasha Levin <[email protected]>
---
 drivers/iio/dac/ad5686.c | 8 ++++++++
 1 file changed, 8 insertions(+)
drivers/iio/dac/ad5686.c +8 -0
index be705f8148cc39..b6e239821980bf 100644
@@ -30,6 +30,8 @@ static int ad5686_get_powerdown_mode(struct iio_dev *indio_dev,
 {
 	struct ad5686_state *st = iio_priv(indio_dev);
 
+	guard(mutex)(&st->lock);
+
 	return ((st->pwr_down_mode >> (chan->channel * 2)) & 0x3) - 1;
 }
 

@@ -39,6 +41,8 @@ static int ad5686_set_powerdown_mode(struct iio_dev *indio_dev,
 {
 	struct ad5686_state *st = iio_priv(indio_dev);
 
+	guard(mutex)(&st->lock);
+
 	st->pwr_down_mode &= ~(0x3 << (chan->channel * 2));
 	st->pwr_down_mode |= ((mode + 1) << (chan->channel * 2));
 

@@ -57,6 +61,8 @@ static ssize_t ad5686_read_dac_powerdown(struct iio_dev *indio_dev,
 {
 	struct ad5686_state *st = iio_priv(indio_dev);
 
+	guard(mutex)(&st->lock);
+
 	return sysfs_emit(buf, "%d\n", !!(st->pwr_down_mask &
 				       (0x3 << (chan->channel * 2))));
 }

@@ -77,6 +83,8 @@ static ssize_t ad5686_write_dac_powerdown(struct iio_dev *indio_dev,
 	if (ret)
 		return ret;
 
+	guard(mutex)(&st->lock);
+
 	if (readin)
 		st->pwr_down_mask |= (0x3 << (chan->channel * 2));
 	else
Signature · 1 line
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