linux-kernel - [PATCH v1 2/2] thermal: sysfs: Add sanity checks for trip temperature and hysteresis

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Message-ID: <7719509.EvYhyI6sBW@rjwysocki.net>
Date: Thu, 22 Aug 2024 21:48:57 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>, Zhang Rui <rui.zhang@...el.com>,
 Daniel Lezcano <daniel.lezcano@...aro.org>,
 Lukasz Luba <lukasz.luba@....com>,
 Peter Kästle <peter@...e.net>
Subject:
 [PATCH v1 2/2] thermal: sysfs: Add sanity checks for trip temperature and
 hysteresis

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Add sanity checks for new trip temperature and hysteresis values to
trip_point_temp_store() and trip_point_hyst_store() to prevent trip
point thresholds from falling below THERMAL_TEMP_INVALID.

However, still allow user space to pass THERMAL_TEMP_INVALID as the
new trip temperature value to invalidate the trip if necessary.

Fixes: be0a3600aa1e ("thermal: sysfs: Rework the handling of trip point updates")
Cc: 6.8+ <stable@...r.kernel.org> # 6.8+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/thermal/thermal_sysfs.c |   38 ++++++++++++++++++++++++++------------
 1 file changed, 26 insertions(+), 12 deletions(-)

Index: linux-pm/drivers/thermal/thermal_sysfs.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_sysfs.c
+++ linux-pm/drivers/thermal/thermal_sysfs.c
@@ -111,18 +111,25 @@ trip_point_temp_store(struct device *dev

 	mutex_lock(&tz->lock);

-	if (temp != trip->temperature) {
-		if (tz->ops.set_trip_temp) {
-			ret = tz->ops.set_trip_temp(tz, trip, temp);
-			if (ret)
-				goto unlock;
-		}
+	if (temp == trip->temperature)
+		goto unlock;

-		thermal_zone_set_trip_temp(tz, trip, temp);
+	if (temp != THERMAL_TEMP_INVALID &&
+	    temp <= trip->hysteresis + THERMAL_TEMP_INVALID) {
+		ret = -EINVAL;
+		goto unlock;
+	}

-		__thermal_zone_device_update(tz, THERMAL_TRIP_CHANGED);
+	if (tz->ops.set_trip_temp) {
+		ret = tz->ops.set_trip_temp(tz, trip, temp);
+		if (ret)
+			goto unlock;
 	}

+	thermal_zone_set_trip_temp(tz, trip, temp);
+
+	__thermal_zone_device_update(tz, THERMAL_TRIP_CHANGED);
+
 unlock:
 	mutex_unlock(&tz->lock);

@@ -152,15 +159,22 @@ trip_point_hyst_store(struct device *dev

 	mutex_lock(&tz->lock);

-	if (hyst != trip->hysteresis) {
-		thermal_zone_set_trip_hyst(tz, trip, hyst);
+	if (hyst == trip->hysteresis)
+		goto unlock;

-		__thermal_zone_device_update(tz, THERMAL_TRIP_CHANGED);
+	if (hyst + THERMAL_TEMP_INVALID >= trip->temperature) {
+		ret = -EINVAL;
+		goto unlock;
 	}

+	thermal_zone_set_trip_hyst(tz, trip, hyst);
+
+	__thermal_zone_device_update(tz, THERMAL_TRIP_CHANGED);
+
+unlock:
 	mutex_unlock(&tz->lock);

-	return count;
+	return ret ? ret : count;
 }

 static ssize_t