linux-kernel - [PATCH 6/9] thermal/core: Protect hwmon accesses to thermal operations with thermal zone mutex

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Message-Id: <20221017130910.2307118-7-linux@roeck-us.net>
Date:   Mon, 17 Oct 2022 06:09:07 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     "Rafael J . Wysocki" <rafael@...nel.org>
Cc:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH 6/9] thermal/core: Protect hwmon accesses to thermal operations with thermal zone mutex

In preparation to protecting access to thermal operations against thermal
zone device removal, protect hwmon accesses to thermal zone operations
with the thermal zone mutex. After acquiring the mutex, ensure that the
thermal zone device is registered before proceeding.

Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
 drivers/thermal/thermal_hwmon.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/thermal/thermal_hwmon.c b/drivers/thermal/thermal_hwmon.c
index f53f4ceb6a5d..33bfbaed4236 100644
--- a/drivers/thermal/thermal_hwmon.c
+++ b/drivers/thermal/thermal_hwmon.c
@@ -77,11 +77,19 @@ temp_crit_show(struct device *dev, struct device_attribute *attr, char *buf)
 	int temperature;
 	int ret;
 
+	mutex_lock(&tz->lock);
+
+	if (!device_is_registered(&tz->device)) {
+		ret = -ENODEV;
+		goto unlock;
+	}
+
 	ret = tz->ops->get_crit_temp(tz, &temperature);
-	if (ret)
-		return ret;
 
-	return sprintf(buf, "%d\n", temperature);
+unlock:
+	mutex_unlock(&tz->lock);
+
+	return ret ? ret : sprintf(buf, "%d\n", temperature);
 }
 
 
-- 
2.36.2