linux-kernel - [PATCH v2 4/9] thermal/core: Move parameter validation from __thermal_zone_get_temp to thermal_zone_get

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Date:   Thu, 10 Nov 2022 07:24:55 -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 4/9] thermal/core: Move parameter validation from __thermal_zone_get_temp to thermal_zone_get_temp

All callers of __thermal_zone_get_temp() already validated the
thermal zone parameters. Move validation to thermal_zone_get_temp()
where it is actually needed. Also add kernel documentation for
__thermal_zone_get_temp(), listing the requirement that the
function must be called with validated parameters and with thermal
device mutex held.

Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
v2: Add note about added kernel documentation to description .
    Use IS_ERR_OR_NULL instead of manually coding it.

 drivers/thermal/thermal_helpers.c | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/thermal/thermal_helpers.c b/drivers/thermal/thermal_helpers.c
index fca0b23570f9..321f8020082d 100644
--- a/drivers/thermal/thermal_helpers.c
+++ b/drivers/thermal/thermal_helpers.c
@@ -64,6 +64,20 @@ get_thermal_instance(struct thermal_zone_device *tz,
 }
 EXPORT_SYMBOL(get_thermal_instance);
 
+/**
+ * __thermal_zone_get_temp() - returns the temperature of a thermal zone
+ * @tz: a valid pointer to a struct thermal_zone_device
+ * @temp: a valid pointer to where to store the resulting temperature.
+ *
+ * When a valid thermal zone reference is passed, it will fetch its
+ * temperature and fill @temp.
+ *
+ * Both tz and tz->ops must be valid pointers when calling this function,
+ * and the tz->ops->get_temp callback must be provided.
+ * The function must be called under tz->lock.
+ *
+ * Return: On success returns 0, an error code otherwise
+ */
 int __thermal_zone_get_temp(struct thermal_zone_device *tz, int *temp)
 {
 	int ret = -EINVAL;
@@ -73,9 +87,6 @@ int __thermal_zone_get_temp(struct thermal_zone_device *tz, int *temp)
 
 	lockdep_assert_held(&tz->lock);
 
-	if (!tz || IS_ERR(tz) || !tz->ops->get_temp)
-		return -EINVAL;
-
 	ret = tz->ops->get_temp(tz, temp);
 
 	if (IS_ENABLED(CONFIG_THERMAL_EMULATION) && tz->emul_temperature) {
@@ -114,13 +125,22 @@ int thermal_zone_get_temp(struct thermal_zone_device *tz, int *temp)
 {
 	int ret;
 
+	if (IS_ERR_OR_NULL(tz))
+		return -EINVAL;
+
 	mutex_lock(&tz->lock);
 
+	if (!tz->ops->get_temp) {
+		ret = -EINVAL;
+		goto unlock;
+	}
+
 	if (device_is_registered(&tz->device))
 		ret = __thermal_zone_get_temp(tz, temp);
 	else
 		ret = -ENODEV;
 
+unlock:
 	mutex_unlock(&tz->lock);
 
 	return ret;
-- 
2.36.2