From 3d8e3ad879441ae14c5957b933028daf39d252b0 Mon Sep 17 00:00:00 2001 From: Frans Pop Date: Mon, 26 Oct 2009 08:39:02 +0100 Subject: [PATCH] thermal: add sanity check for the passive attribute Values below 1000 milli-celsius don't make sense and can cause the system to go into a thermal heart attack: the actual temperature will always be lower and thus the system will be throttled down to its lowest setting. An additional problem is that values below 1000 will show as 0 in /proc/acpi/thermal/TZx/trip_points:passive. cat passive 0 echo -n 90 >passive bash: echo: write error: Invalid argument echo -n 90000 >passive cat passive 90000 Signed-off-by: Frans Pop Acked-by: Zhang Rui Signed-off-by: Andrew Morton Signed-off-by: Len Brown --- Documentation/thermal/sysfs-api.txt | 1 + drivers/thermal/thermal_sys.c | 6 ++++++ 2 files changed, 7 insertions(+) diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt index a87dc277a5c..cb3d15bc1ae 100644 --- a/Documentation/thermal/sysfs-api.txt +++ b/Documentation/thermal/sysfs-api.txt @@ -206,6 +206,7 @@ passive passive trip point for the zone. Activation is done by polling with an interval of 1 second. Unit: millidegrees Celsius + Valid values: 0 (disabled) or greater than 1000 RW, Optional ***************************** diff --git a/drivers/thermal/thermal_sys.c b/drivers/thermal/thermal_sys.c index 6f8d8f97121..310e40ab00b 100644 --- a/drivers/thermal/thermal_sys.c +++ b/drivers/thermal/thermal_sys.c @@ -225,6 +225,12 @@ passive_store(struct device *dev, struct device_attribute *attr, if (!sscanf(buf, "%d\n", &state)) return -EINVAL; + /* sanity check: values below 1000 millicelcius don't make sense + * and can cause the system to go into a thermal heart attack + */ + if (state && state < 1000) + return -EINVAL; + if (state && !tz->forced_passive) { mutex_lock(&thermal_list_lock); list_for_each_entry(cdev, &thermal_cdev_list, node) {