linux-kernel - [PATCH v2 6/9] thermal/core: Protect hwmon accesses to thermal operations with thermal zone mutex

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Message-Id: <20221110152500.3032655-7-linux@roeck-us.net>
Date:   Thu, 10 Nov 2022 07:24:57 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     "Rafael J . Wysocki" <rafael@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     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 v2 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>
---
v2: Simplify error handling to avoid additional goto.
    Do not use ternary operator in modified code.

 drivers/thermal/thermal_hwmon.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/thermal/thermal_hwmon.c b/drivers/thermal/thermal_hwmon.c
index f53f4ceb6a5d..c594c42bea6d 100644
--- a/drivers/thermal/thermal_hwmon.c
+++ b/drivers/thermal/thermal_hwmon.c
@@ -77,7 +77,15 @@ temp_crit_show(struct device *dev, struct device_attribute *attr, char *buf)
 	int temperature;
 	int ret;
 
-	ret = tz->ops->get_crit_temp(tz, &temperature);
+	mutex_lock(&tz->lock);
+
+	if (device_is_registered(&tz->device))
+		ret = tz->ops->get_crit_temp(tz, &temperature);
+	else
+		ret = -ENODEV;
+
+	mutex_unlock(&tz->lock);
+
 	if (ret)
 		return ret;
 
-- 
2.36.2