FAILED: patch "[PATCH] hwmon: chipcap2: synchronize ready IRQ state" failed to apply to 6.18-stable tree

FAILED: patch "[PATCH] hwmon: chipcap2: synchronize ready IRQ state" failed to apply to 6.18-stable tree

[Sasha Levin]

The patch below does not apply to the 6.18-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 <stable@vger.kernel.org>.

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-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x 8c02722be2caa6604a837b81faeaba78250eda4a
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261109200334-failed-6.18-8c02722be2ca@kernel.org' --subject-prefix 'PATCH 6.18.y' 'HEAD^..'

Thanks,
Sasha

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

From 8c02722be2caa6604a837b81faeaba78250eda4a Mon Sep 17 00:00:00 2001
From: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Date: Wed, 14 Oct 2026 19:34:10 +0200
Subject: [PATCH] hwmon: chipcap2: synchronize ready IRQ state

The ready IRQ handler can race with reinit_completion() in the enable
path. In particular, a handler from an earlier operation can complete
the completion after it is reset for a new operation.

Use irq_lock to serialize access to the completion and process_irqs.
Disable IRQ processing and synchronize any running handler before resetting
the completion for a new operation.

Fixes: 3af350929e75 ("hwmon: Add support for Amphenol ChipCap 2")
Cc: stable@vger.kernel.org
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://patch.msgid.link/20261014-chipcap2_locks-v3-11-27ebfc2c5b9e@gmail.com
[groeck: Dropped obsolete 'Assisted-by: tag]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/chipcap2.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/hwmon/chipcap2.c b/drivers/hwmon/chipcap2.c
index b3b725cc7224f..00f62a33d4637 100644
--- a/drivers/hwmon/chipcap2.c
+++ b/drivers/hwmon/chipcap2.c
@@ -123,6 +123,16 @@ static int cc2_enable(struct cc2_data *data)
 {
 	int ret;
 
+	if (data->irq_ready > 0) {
+		scoped_guard(mutex, &data->irq_lock)
+			data->process_irqs = false;
+
+		synchronize_irq(data->irq_ready);
+
+		scoped_guard(mutex, &data->irq_lock)
+			reinit_completion(&data->complete);
+	}
+
 	/* exclusive regulator, check in case a disable failed */
 	if (data->regulator_enabled) {
 		scoped_guard(mutex, &data->irq_lock)
@@ -130,9 +140,6 @@ static int cc2_enable(struct cc2_data *data)
 		return 0;
 	}
 
-	/* clear any pending completion */
-	try_wait_for_completion(&data->complete);
-
 	ret = regulator_enable(data->regulator);
 	if (ret < 0)
 		return ret;
@@ -162,6 +169,9 @@ static void cc2_disable(struct cc2_data *data)
 	scoped_guard(mutex, &data->irq_lock)
 		data->process_irqs = false;
 
+	if (data->irq_ready > 0)
+		synchronize_irq(data->irq_ready);
+
 	/* exclusive regulator, check in case an enable failed */
 	if (!data->regulator_enabled)
 		return;
@@ -510,8 +520,10 @@ static irqreturn_t cc2_ready_interrupt(int irq, void *data)
 {
 	struct cc2_data *cc2 = data;
 
-	if (cc2->process_irqs)
-		complete(&cc2->complete);
+	scoped_guard(mutex, &cc2->irq_lock) {
+		if (cc2->process_irqs)
+			complete(&cc2->complete);
+	}
 
 	return IRQ_HANDLED;
 }
-- 
2.53.0

[PATCH 6.18.y 1/3] hwmon: (chipcap2) Drop unnecessary include files

[Sasha Levin]

From: Guenter Roeck <linux@roeck-us.net>

[ Upstream commit 4c8d758d4ebff3780d09599f2c8db5d6af3ca2af ]

The driver does not perform any locking, does not execute or use any sleep
related functionality, and does not allocate memory. Drop the unnecessary
include files.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Stable-dep-of: 8c02722be2ca ("hwmon: chipcap2: synchronize ready IRQ state")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hwmon/chipcap2.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/hwmon/chipcap2.c b/drivers/hwmon/chipcap2.c
index 5f4b0fd535af8..a3d5d99bd57ea 100644
--- a/drivers/hwmon/chipcap2.c
+++ b/drivers/hwmon/chipcap2.c
@@ -82,7 +82,6 @@ struct cc2_data {
 	struct completion complete;
 	struct device *hwmon;
 	struct i2c_client *client;
-	struct mutex dev_access_lock; /* device access lock */
 	struct regulator *regulator;
 	const char *name;
 	int irq_ready;
@@ -570,8 +569,6 @@ static int cc2_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
 {
 	struct cc2_data *data = dev_get_drvdata(dev);
 
-	guard(mutex)(&data->dev_access_lock);
-
 	switch (type) {
 	case hwmon_temp:
 		return cc2_measurement(data, type, val);
@@ -612,8 +609,6 @@ static int cc2_write(struct device *dev, enum hwmon_sensor_types type, u32 attr,
 	if (val < 0 || val > CC2_RH_MAX)
 		return -EINVAL;
 
-	guard(mutex)(&data->dev_access_lock);
-
 	switch (attr) {
 	case hwmon_humidity_min:
 		cmd = CC2_W_ALARM_L_ON;
@@ -726,8 +721,6 @@ static int cc2_probe(struct i2c_client *client)
 
 	i2c_set_clientdata(client, data);
 
-	mutex_init(&data->dev_access_lock);
-
 	data->client = client;
 
 	data->regulator = devm_regulator_get_exclusive(dev, "vdd");
-- 
2.53.0

[PATCH 6.18.y 2/3] hwmon: chipcap2: serialize access to the alarm indicators

[Sasha Levin]

From: Javier Carrasco <javier.carrasco.cruz@gmail.com>

[ Upstream commit bed5f0c075eb99442fca6a61c009a32752eceda2 ]

low_alarm and high_alarm are accessed from the threaded interrupt
handlers and from sysfs without any locking, which can lead to lost
alarms.

Add a mutex to serialize the access to the alarm indicators and to
process_irqs, which the handlers use to decide whether an interrupt
belongs to an ongoing operation.

Fixes: 3af350929e75 ("hwmon: Add support for Amphenol ChipCap 2")
Cc: stable@vger.kernel.org
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://patch.msgid.link/20261014-chipcap2_locks-v3-10-27ebfc2c5b9e@gmail.com
[groeck: Dropped obsolete 'Assisted-by: tag]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Stable-dep-of: 8c02722be2ca ("hwmon: chipcap2: synchronize ready IRQ state")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hwmon/chipcap2.c | 58 +++++++++++++++++++++++++---------------
 1 file changed, 37 insertions(+), 21 deletions(-)

diff --git a/drivers/hwmon/chipcap2.c b/drivers/hwmon/chipcap2.c
index a3d5d99bd57ea..49df66728ae9d 100644
--- a/drivers/hwmon/chipcap2.c
+++ b/drivers/hwmon/chipcap2.c
@@ -20,6 +20,7 @@
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
+#include <linux/mutex.h>
 #include <linux/module.h>
 #include <linux/unaligned.h>
 #include <linux/regulator/consumer.h>
@@ -88,6 +89,8 @@ struct cc2_data {
 	int irq_low;
 	int irq_high;
 	bool process_irqs;
+	/* protects process_irqs and the alarm indicators */
+	struct mutex irq_lock;
 	bool regulator_enabled;
 };
 
@@ -119,7 +122,8 @@ static int cc2_enable(struct cc2_data *data)
 
 	/* exclusive regulator, check in case a disable failed */
 	if (data->regulator_enabled) {
-		data->process_irqs = true;
+		scoped_guard(mutex, &data->irq_lock)
+			data->process_irqs = true;
 		return 0;
 	}
 
@@ -134,7 +138,8 @@ static int cc2_enable(struct cc2_data *data)
 
 	usleep_range(CC2_STARTUP_TIME_US, CC2_STARTUP_TIME_US + 125);
 
-	data->process_irqs = true;
+	scoped_guard(mutex, &data->irq_lock)
+		data->process_irqs = true;
 
 	return 0;
 }
@@ -151,7 +156,8 @@ static void cc2_disable(struct cc2_data *data)
 		synchronize_irq(data->irq_high);
 
 	/* ignore alarms triggered by voltage toggling when powering up */
-	data->process_irqs = false;
+	scoped_guard(mutex, &data->irq_lock)
+		data->process_irqs = false;
 
 	/* exclusive regulator, check in case an enable failed */
 	if (!data->regulator_enabled)
@@ -502,10 +508,12 @@ static irqreturn_t cc2_low_interrupt(int irq, void *data)
 {
 	struct cc2_data *cc2 = data;
 
-	if (cc2->process_irqs) {
-		hwmon_notify_event(cc2->hwmon, hwmon_humidity,
-				   hwmon_humidity_min_alarm, 0);
-		cc2->rh_alarm.low_alarm = true;
+	scoped_guard(mutex, &cc2->irq_lock) {
+		if (cc2->process_irqs) {
+			hwmon_notify_event(cc2->hwmon, hwmon_humidity,
+					   hwmon_humidity_min_alarm, 0);
+			cc2->rh_alarm.low_alarm = true;
+		}
 	}
 
 	return IRQ_HANDLED;
@@ -515,10 +523,12 @@ static irqreturn_t cc2_high_interrupt(int irq, void *data)
 {
 	struct cc2_data *cc2 = data;
 
-	if (cc2->process_irqs) {
-		hwmon_notify_event(cc2->hwmon, hwmon_humidity,
-				   hwmon_humidity_max_alarm, 0);
-		cc2->rh_alarm.high_alarm = true;
+	scoped_guard(mutex, &cc2->irq_lock) {
+		if (cc2->process_irqs) {
+			hwmon_notify_event(cc2->hwmon, hwmon_humidity,
+					   hwmon_humidity_max_alarm, 0);
+			cc2->rh_alarm.high_alarm = true;
+		}
 	}
 
 	return IRQ_HANDLED;
@@ -534,11 +544,13 @@ static int cc2_humidity_min_alarm_status(struct cc2_data *data, long *val)
 	if (ret < 0)
 		return ret;
 
-	if (data->rh_alarm.low_alarm) {
-		*val = (measurement < min_hyst) ? 1 : 0;
-		data->rh_alarm.low_alarm = *val;
-	} else {
-		*val = 0;
+	scoped_guard(mutex, &data->irq_lock) {
+		if (data->rh_alarm.low_alarm) {
+			*val = (measurement < min_hyst) ? 1 : 0;
+			data->rh_alarm.low_alarm = *val;
+		} else {
+			*val = 0;
+		}
 	}
 
 	return 0;
@@ -554,11 +566,13 @@ static int cc2_humidity_max_alarm_status(struct cc2_data *data, long *val)
 	if (ret < 0)
 		return ret;
 
-	if (data->rh_alarm.high_alarm) {
-		*val = (measurement > max_hyst) ? 1 : 0;
-		data->rh_alarm.high_alarm = *val;
-	} else {
-		*val = 0;
+	scoped_guard(mutex, &data->irq_lock) {
+		if (data->rh_alarm.high_alarm) {
+			*val = (measurement > max_hyst) ? 1 : 0;
+			data->rh_alarm.high_alarm = *val;
+		} else {
+			*val = 0;
+		}
 	}
 
 	return 0;
@@ -721,6 +735,8 @@ static int cc2_probe(struct i2c_client *client)
 
 	i2c_set_clientdata(client, data);
 
+	mutex_init(&data->irq_lock);
+
 	data->client = client;
 
 	data->regulator = devm_regulator_get_exclusive(dev, "vdd");
-- 
2.53.0

[PATCH 6.18.y 3/3] hwmon: chipcap2: synchronize ready IRQ state

[Sasha Levin]

From: Javier Carrasco <javier.carrasco.cruz@gmail.com>

[ Upstream commit 8c02722be2caa6604a837b81faeaba78250eda4a ]

The ready IRQ handler can race with reinit_completion() in the enable
path. In particular, a handler from an earlier operation can complete
the completion after it is reset for a new operation.

Use irq_lock to serialize access to the completion and process_irqs.
Disable IRQ processing and synchronize any running handler before resetting
the completion for a new operation.

Fixes: 3af350929e75 ("hwmon: Add support for Amphenol ChipCap 2")
Cc: stable@vger.kernel.org
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://patch.msgid.link/20261014-chipcap2_locks-v3-11-27ebfc2c5b9e@gmail.com
[groeck: Dropped obsolete 'Assisted-by: tag]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hwmon/chipcap2.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/hwmon/chipcap2.c b/drivers/hwmon/chipcap2.c
index 49df66728ae9d..3eee0e41e1e4f 100644
--- a/drivers/hwmon/chipcap2.c
+++ b/drivers/hwmon/chipcap2.c
@@ -120,6 +120,16 @@ static int cc2_enable(struct cc2_data *data)
 {
 	int ret;
 
+	if (data->irq_ready > 0) {
+		scoped_guard(mutex, &data->irq_lock)
+			data->process_irqs = false;
+
+		synchronize_irq(data->irq_ready);
+
+		scoped_guard(mutex, &data->irq_lock)
+			reinit_completion(&data->complete);
+	}
+
 	/* exclusive regulator, check in case a disable failed */
 	if (data->regulator_enabled) {
 		scoped_guard(mutex, &data->irq_lock)
@@ -127,9 +137,6 @@ static int cc2_enable(struct cc2_data *data)
 		return 0;
 	}
 
-	/* clear any pending completion */
-	try_wait_for_completion(&data->complete);
-
 	ret = regulator_enable(data->regulator);
 	if (ret < 0)
 		return ret;
@@ -159,6 +166,9 @@ static void cc2_disable(struct cc2_data *data)
 	scoped_guard(mutex, &data->irq_lock)
 		data->process_irqs = false;
 
+	if (data->irq_ready > 0)
+		synchronize_irq(data->irq_ready);
+
 	/* exclusive regulator, check in case an enable failed */
 	if (!data->regulator_enabled)
 		return;
@@ -498,8 +508,10 @@ static irqreturn_t cc2_ready_interrupt(int irq, void *data)
 {
 	struct cc2_data *cc2 = data;
 
-	if (cc2->process_irqs)
-		complete(&cc2->complete);
+	scoped_guard(mutex, &cc2->irq_lock) {
+		if (cc2->process_irqs)
+			complete(&cc2->complete);
+	}
 
 	return IRQ_HANDLED;
 }
-- 
2.53.0