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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Linus Walleij <linus.walleij@linaro.org>,
        Guenter Roeck <linux@roeck-us.net>
Subject: [PATCH 4.9 245/271] hwmon: Deal with errors from the thermal subsystem
Date:   Tue, 28 Jan 2020 15:06:34 +0100
Message-Id: <20200128135910.760531414@linuxfoundation.org>
In-Reply-To: <20200128135852.449088278@linuxfoundation.org>
References: <20200128135852.449088278@linuxfoundation.org>
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From: Linus Walleij <linus.walleij@linaro.org>

commit 47c332deb8e89f6c59b0bb2615945c6e7fad1a60 upstream.

If the thermal subsystem returne -EPROBE_DEFER or any other error
when hwmon calls devm_thermal_zone_of_sensor_register(), this is
silently ignored.

I ran into this with an incorrectly defined thermal zone, making
it non-existing and thus this call failed with -EPROBE_DEFER
assuming it would appear later. The sensor was still added
which is incorrect: sensors must strictly be added after the
thermal zones, so deferred probe must be respected.

Fixes: d560168b5d0f ("hwmon: (core) New hwmon registration API")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/hwmon/hwmon.c |   21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -143,6 +143,7 @@ static int hwmon_thermal_add_sensor(stru
 				    struct hwmon_device *hwdev, int index)
 {
 	struct hwmon_thermal_data *tdata;
+	struct thermal_zone_device *tzd;
 
 	tdata = devm_kzalloc(dev, sizeof(*tdata), GFP_KERNEL);
 	if (!tdata)
@@ -151,8 +152,14 @@ static int hwmon_thermal_add_sensor(stru
 	tdata->hwdev = hwdev;
 	tdata->index = index;
 
-	devm_thermal_zone_of_sensor_register(&hwdev->dev, index, tdata,
-					     &hwmon_thermal_ops);
+	tzd = devm_thermal_zone_of_sensor_register(&hwdev->dev, index, tdata,
+						   &hwmon_thermal_ops);
+	/*
+	 * If CONFIG_THERMAL_OF is disabled, this returns -ENODEV,
+	 * so ignore that error but forward any other error.
+	 */
+	if (IS_ERR(tzd) && (PTR_ERR(tzd) != -ENODEV))
+		return PTR_ERR(tzd);
 
 	return 0;
 }
@@ -586,14 +593,20 @@ __hwmon_device_register(struct device *d
 				if (!chip->ops->is_visible(drvdata, hwmon_temp,
 							   hwmon_temp_input, j))
 					continue;
-				if (info[i]->config[j] & HWMON_T_INPUT)
-					hwmon_thermal_add_sensor(dev, hwdev, j);
+				if (info[i]->config[j] & HWMON_T_INPUT) {
+					err = hwmon_thermal_add_sensor(dev,
+								hwdev, j);
+					if (err)
+						goto free_device;
+				}
 			}
 		}
 	}
 
 	return hdev;
 
+free_device:
+	device_unregister(hdev);
 free_hwmon:
 	kfree(hwdev);
 ida_remove: