[PATCHv2 1/1] thermal: sysfs: lock tz while on access to mode properties

[Eduardo Valentin <edubezval@gmail.com>]

Serialized calls to tz.ops in user facing
sysfs handler mode_show()  and mode_store().

Because several drivers do the following pattern:
.set_mode()
   ...
   local_data->mode = new_mode;
   thermal_zone_device_update(tz);

makes sense to simply do the thermal_zone_device_update()
in thermal core, after setting the new mode.

as .set_mode()  is now called always with tz->lock held.

Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: linux-acpi@vger.kernel.org
Cc: "Lee, Chun-Yi" <jlee@suse.com>
Cc: Darren Hart <dvhart@infradead.org>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Keerthy <j-keerthy@ti.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-omap@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
---
 drivers/acpi/thermal.c                             |  1 -
 drivers/platform/x86/acerhdf.c                     |  1 -
 drivers/thermal/imx_thermal.c                      |  1 -
 drivers/thermal/of-thermal.c                       |  5 -----
 drivers/thermal/thermal_sysfs.c                    | 14 +++++++++++---
 drivers/thermal/ti-soc-thermal/ti-thermal-common.c |  5 -----
 6 files changed, 11 insertions(+), 16 deletions(-)

diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c
index 82707f9..03c3460 100644
--- a/drivers/acpi/thermal.c
+++ b/drivers/acpi/thermal.c
@@ -581,7 +581,6 @@ static int thermal_set_mode(struct thermal_zone_device *thermal,
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 			"%s kernel ACPI thermal control\n",
 			tz->tz_enabled ? "Enable" : "Disable"));
-		acpi_thermal_check(tz);
 	}
 	return 0;
 }
diff --git a/drivers/platform/x86/acerhdf.c b/drivers/platform/x86/acerhdf.c
index 460fa67..aee33ba 100644
--- a/drivers/platform/x86/acerhdf.c
+++ b/drivers/platform/x86/acerhdf.c
@@ -405,7 +405,6 @@ static inline void acerhdf_enable_kernelmode(void)
 	kernelmode = 1;
 
 	thz_dev->polling_delay = interval*1000;
-	thermal_zone_device_update(thz_dev);
 	pr_notice("kernel mode fan control ON\n");
 }
 
diff --git a/drivers/thermal/imx_thermal.c b/drivers/thermal/imx_thermal.c
index c5547bd..a413eb6 100644
--- a/drivers/thermal/imx_thermal.c
+++ b/drivers/thermal/imx_thermal.c
@@ -246,7 +246,6 @@ static int imx_set_mode(struct thermal_zone_device *tz,
 	}
 
 	data->mode = mode;
-	thermal_zone_device_update(tz);
 
 	return 0;
 }
diff --git a/drivers/thermal/of-thermal.c b/drivers/thermal/of-thermal.c
index b8e509c..95c47da 100644
--- a/drivers/thermal/of-thermal.c
+++ b/drivers/thermal/of-thermal.c
@@ -282,17 +282,12 @@ static int of_thermal_set_mode(struct thermal_zone_device *tz,
 {
 	struct __thermal_zone *data = tz->devdata;
 
-	mutex_lock(&tz->lock);
-
 	if (mode == THERMAL_DEVICE_ENABLED)
 		tz->polling_delay = data->polling_delay;
 	else
 		tz->polling_delay = 0;
 
-	mutex_unlock(&tz->lock);
-
 	data->mode = mode;
-	thermal_zone_device_update(tz);
 
 	return 0;
 }
diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
index ee983ca..1e223d4 100644
--- a/drivers/thermal/thermal_sysfs.c
+++ b/drivers/thermal/thermal_sysfs.c
@@ -62,7 +62,9 @@ mode_show(struct device *dev, struct device_attribute *attr, char *buf)
 	if (!tz->ops->get_mode)
 		return -EPERM;
 
+	mutex_lock(&tz->lock);
 	result = tz->ops->get_mode(tz, &mode);
+	mutex_unlock(&tz->lock);
 	if (result)
 		return result;
 
@@ -75,17 +77,23 @@ mode_store(struct device *dev, struct device_attribute *attr,
 	   const char *buf, size_t count)
 {
 	struct thermal_zone_device *tz = to_thermal_zone(dev);
+	enum thermal_device_mode mode = THERMAL_DEVICE_DISABLED;
 	int result;
 
 	if (!tz->ops->set_mode)
 		return -EPERM;
 
 	if (!strncmp(buf, "enabled", sizeof("enabled") - 1))
-		result = tz->ops->set_mode(tz, THERMAL_DEVICE_ENABLED);
+		mode = THERMAL_DEVICE_ENABLED;
 	else if (!strncmp(buf, "disabled", sizeof("disabled") - 1))
-		result = tz->ops->set_mode(tz, THERMAL_DEVICE_DISABLED);
+		mode = THERMAL_DEVICE_DISABLED;
 	else
-		result = -EINVAL;
+		return -EINVAL;
+
+	mutex_lock(&tz->lock);
+	result = tz->ops->set_mode(tz, mode);
+	mutex_unlock(&tz->lock);
+	thermal_zone_device_update(tz);
 
 	if (result)
 		return result;
diff --git a/drivers/thermal/ti-soc-thermal/ti-thermal-common.c b/drivers/thermal/ti-soc-thermal/ti-thermal-common.c
index 15c0a9a..5dce053 100644
--- a/drivers/thermal/ti-soc-thermal/ti-thermal-common.c
+++ b/drivers/thermal/ti-soc-thermal/ti-thermal-common.c
@@ -193,19 +193,14 @@ static int ti_thermal_set_mode(struct thermal_zone_device *thermal,
 		return 0;
 	}
 
-	mutex_lock(&data->ti_thermal->lock);
-
 	if (mode == THERMAL_DEVICE_ENABLED)
 		data->ti_thermal->polling_delay = FAST_TEMP_MONITORING_RATE;
 	else
 		data->ti_thermal->polling_delay = 0;
 
-	mutex_unlock(&data->ti_thermal->lock);
-
 	data->mode = mode;
 	ti_bandgap_write_update_interval(bgp, data->sensor_id,
 					data->ti_thermal->polling_delay);
-	thermal_zone_device_update(data->ti_thermal);
 	dev_dbg(&thermal->device, "thermal polling set for duration=%d msec\n",
 		data->ti_thermal->polling_delay);
 
-- 
2.1.4