linux-kernel - [PATCH 4.14 49/55] thermal/drivers/hisi: Remove pointless lock

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Date:   Thu,  6 Dec 2018 15:39:23 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Daniel Lezcano <daniel.lezcano@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        Eduardo Valentin <edubezval@...il.com>,
        Rafael David Tinoco <rafael.tinoco@...aro.org>
Subject: [PATCH 4.14 49/55] thermal/drivers/hisi: Remove pointless lock

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Daniel Lezcano <daniel.lezcano@...aro.org>

commit 2d4fa7b4c6f8080ced2e8237c9f46fb1fc110d64 upstream.

The threaded interrupt inspect the sensors structure to look in the temp
threshold field, but this field is read-only in all the code, except in the
probe function before the threaded interrupt is set. In other words there
is not race window in the threaded interrupt when reading the field value.

Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
Reviewed-by: Leo Yan <leo.yan@...aro.org>
Signed-off-by: Eduardo Valentin <edubezval@...il.com>
Signed-off-by: Rafael David Tinoco <rafael.tinoco@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/thermal/hisi_thermal.c |    6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

--- a/drivers/thermal/hisi_thermal.c
+++ b/drivers/thermal/hisi_thermal.c
@@ -221,14 +221,10 @@ static irqreturn_t hisi_thermal_alarm_ir
 static irqreturn_t hisi_thermal_alarm_irq_thread(int irq, void *dev)
 {
 	struct hisi_thermal_data *data = dev;
-	struct hisi_thermal_sensor *sensor;
-
-	mutex_lock(&data->thermal_lock);
-	sensor = &data->sensors;
+	struct hisi_thermal_sensor *sensor = &data->sensors;
 
 	dev_crit(&data->pdev->dev, "THERMAL ALARM: T > %d\n",
 		 sensor->thres_temp);
-	mutex_unlock(&data->thermal_lock);
 
 	thermal_zone_device_update(data->sensors.tzd,
 				   THERMAL_EVENT_UNSPECIFIED);