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authorFrans Pop <elendil@planet.nl>2009-10-26 08:39:02 +0100
committerLen Brown <len.brown@intel.com>2009-11-05 18:18:10 -0500
commit3d8e3ad879441ae14c5957b933028daf39d252b0 (patch)
tree33f81135d8a8518e2507bc1db51b4adf29d60e41
parent7fb2616e249184e217f9818a7662596165710ea4 (diff)
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 <elendil@planet.nl> Acked-by: Zhang Rui <rui.zhang@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Len Brown <len.brown@intel.com>
-rw-r--r--Documentation/thermal/sysfs-api.txt1
-rw-r--r--drivers/thermal/thermal_sys.c6
2 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt
index a87dc277a5ca..cb3d15bc1aeb 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 6f8d8f971212..310e40ab00b6 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) {