[PATCH 6.18.y 1/2] hwmon: chipcap2: fix IRQ teardown ordering

[Sasha Levin <sashal@kernel.org>]

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

[ Upstream commit d2a66c515d7730fd453485ffb306c412f1f46d72 ]

The threaded IRQs are currently requested before the hwmon device
is registered. Since devres releases resources in reverse order,
the hwmon device is unregistered before the IRQs are freed during
driver teardown. An IRQ may therefore still run after the hwmon
device has been released and access the stale data->hwmon pointer.

Separate IRQ discovery from IRQ registration so that the IRQ numbers
and alarm visibility flags are initialized before registering the
hwmon device while the IRQs are released before the hwmon device
during devres cleanup.

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-v3-5-27ebfc2c5b9e@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Reuse the existing IRQ helpers for discovery and ready IRQ registration,
and request alarm IRQs directly from probe after hwmon registration. This
keeps the number of helper functions unchanged. Omit the unrelated label
property read because label support is absent.

Stable-dep-of: 4724ac5556ce ("hwmon: chipcap2: disable device after hwmon teardown")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hwmon/chipcap2.c | 69 ++++++++++++++++++++--------------------
 1 file changed, 35 insertions(+), 34 deletions(-)

diff --git a/drivers/hwmon/chipcap2.c b/drivers/hwmon/chipcap2.c
index 5f4b0fd535af8..8ba706ecd4012 100644
--- a/drivers/hwmon/chipcap2.c
+++ b/drivers/hwmon/chipcap2.c
@@ -636,60 +636,41 @@ static int cc2_write(struct device *dev, enum hwmon_sensor_types type, u32 attr,
 	}
 }
 
-static int cc2_request_ready_irq(struct cc2_data *data, struct device *dev)
+static int cc2_request_data_ready(struct cc2_data *data, struct device *dev)
 {
 	int ret = 0;
 
-	data->irq_ready = fwnode_irq_get_byname(dev_fwnode(dev), "ready");
-	if (data->irq_ready == -EPROBE_DEFER)
-		return data->irq_ready;
-	if (data->irq_ready > 0) {
-		init_completion(&data->complete);
+	if (data->irq_ready > 0)
 		ret = devm_request_threaded_irq(dev, data->irq_ready, NULL,
 						cc2_ready_interrupt,
 						IRQF_ONESHOT |
 						IRQF_TRIGGER_RISING,
 						dev_name(dev), data);
-	}
 
 	return ret;
 }
 
-static int cc2_request_alarm_irqs(struct cc2_data *data, struct device *dev)
+static int cc2_get_irqs(struct cc2_data *data, struct device *dev)
 {
-	int ret = 0;
+	data->irq_ready = fwnode_irq_get_byname(dev_fwnode(dev), "ready");
+	if (data->irq_ready == -EPROBE_DEFER)
+		return data->irq_ready;
+	if (data->irq_ready > 0)
+		init_completion(&data->complete);
 
 	data->irq_low = fwnode_irq_get_byname(dev_fwnode(dev), "low");
 	if (data->irq_low == -EPROBE_DEFER)
 		return data->irq_low;
-	if (data->irq_low > 0) {
-		ret = devm_request_threaded_irq(dev, data->irq_low, NULL,
-						cc2_low_interrupt,
-						IRQF_ONESHOT |
-						IRQF_TRIGGER_RISING,
-						dev_name(dev), data);
-		if (ret)
-			return ret;
-
+	if (data->irq_low > 0)
 		data->rh_alarm.low_alarm_visible = true;
-	}
 
 	data->irq_high = fwnode_irq_get_byname(dev_fwnode(dev), "high");
 	if (data->irq_high == -EPROBE_DEFER)
 		return data->irq_high;
-	if (data->irq_high > 0) {
-		ret = devm_request_threaded_irq(dev, data->irq_high, NULL,
-						cc2_high_interrupt,
-						IRQF_ONESHOT |
-						IRQF_TRIGGER_RISING,
-						dev_name(dev), data);
-		if (ret)
-			return ret;
-
+	if (data->irq_high > 0)
 		data->rh_alarm.high_alarm_visible = true;
-	}
 
-	return ret;
+	return 0;
 }
 
 static const struct hwmon_channel_info *cc2_info[] = {
@@ -735,13 +716,13 @@ static int cc2_probe(struct i2c_client *client)
 		return dev_err_probe(dev, PTR_ERR(data->regulator),
 				     "Failed to get regulator\n");
 
-	ret = cc2_request_ready_irq(data, dev);
+	ret = cc2_get_irqs(data, dev);
 	if (ret)
-		return dev_err_probe(dev, ret, "Failed to request ready irq\n");
+		return dev_err_probe(dev, ret, "Failed to get IRQs\n");
 
-	ret = cc2_request_alarm_irqs(data, dev);
+	ret = cc2_request_data_ready(data, dev);
 	if (ret)
-		return dev_err_probe(dev, ret, "Failed to request alarm irqs\n");
+		return dev_err_probe(dev, ret, "Failed to request ready irq\n");
 
 	data->hwmon = devm_hwmon_device_register_with_info(dev, client->name,
 							   data, &cc2_chip_info,
@@ -750,6 +731,26 @@ static int cc2_probe(struct i2c_client *client)
 		return dev_err_probe(dev, PTR_ERR(data->hwmon),
 				     "Failed to register hwmon device\n");
 
+	if (data->irq_low > 0) {
+		ret = devm_request_threaded_irq(dev, data->irq_low, NULL,
+						cc2_low_interrupt,
+						IRQF_ONESHOT |
+						IRQF_TRIGGER_RISING,
+						dev_name(dev), data);
+		if (ret)
+			return dev_err_probe(dev, ret, "Failed to request alarm irqs\n");
+	}
+
+	if (data->irq_high > 0) {
+		ret = devm_request_threaded_irq(dev, data->irq_high, NULL,
+						cc2_high_interrupt,
+						IRQF_ONESHOT |
+						IRQF_TRIGGER_RISING,
+						dev_name(dev), data);
+		if (ret)
+			return dev_err_probe(dev, ret, "Failed to request alarm irqs\n");
+	}
+
 	return 0;
 }
 
-- 
2.53.0