linux-kernel - [PATCH v7 11/15] thermal: devfreq_cooling: work on a copy of device status

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Message-Id: <20200511111912.3001-12-lukasz.luba@arm.com>
Date:   Mon, 11 May 2020 12:19:08 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        dri-devel@...ts.freedesktop.org, linux-omap@...r.kernel.org,
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Subject: [PATCH v7 11/15] thermal: devfreq_cooling: work on a copy of device status

Devfreq framework can change the device status in the background. To
mitigate this situation make a copy of the status structure and use it
for internal calculations.

Signed-off-by: Lukasz Luba <lukasz.luba@....com>
---
 drivers/thermal/devfreq_cooling.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/thermal/devfreq_cooling.c b/drivers/thermal/devfreq_cooling.c
index 396f16bb6566..36ec6a48606c 100644
--- a/drivers/thermal/devfreq_cooling.c
+++ b/drivers/thermal/devfreq_cooling.c
@@ -348,14 +348,20 @@ static int devfreq_cooling_power2state(struct thermal_cooling_device *cdev,
 {
 	struct devfreq_cooling_device *dfc = cdev->devdata;
 	struct devfreq *df = dfc->devfreq;
-	struct devfreq_dev_status *status = &df->last_status;
-	unsigned long freq = status->current_frequency;
+	struct devfreq_dev_status status;
 	unsigned long busy_time;
+	unsigned long freq;
 	s32 dyn_power;
 	u32 static_power;
 	s32 est_power;
 	int i;
 
+	mutex_lock(&df->lock);
+	status = df->last_status;
+	mutex_unlock(&df->lock);
+
+	freq = status.current_frequency;
+
 	if (dfc->power_ops->get_real_power) {
 		/* Scale for resource utilization */
 		est_power = power * dfc->res_util;
@@ -367,8 +373,8 @@ static int devfreq_cooling_power2state(struct thermal_cooling_device *cdev,
 		dyn_power = dyn_power > 0 ? dyn_power : 0;
 
 		/* Scale dynamic power for utilization */
-		busy_time = status->busy_time ?: 1;
-		est_power = (dyn_power * status->total_time) / busy_time;
+		busy_time = status.busy_time ?: 1;
+		est_power = (dyn_power * status.total_time) / busy_time;
 	}
 
 	/*
-- 
2.17.1