Commit 0d288162 authored Aug 26, 2009 by Michael Brunner Committed by Linus Torvalds Aug 26, 2009

thermal_sys: check get_temp return value



The return value of the get_temp function is not checked when doing a
thermal zone update.  This may lead to a critical shutdown if get_temp
fails and the content of the temp variable is incorrectly set higher than
the critical trip point.

This has been observed on a system with incorrect ACPI implementation
where the corresponding methods were not serialized and therefore
sometimes triggered ACPI errors (AE_ALREADY_EXISTS).  The following
critical shutdowns indicated a temperature of 2097 C, which was obviously
wrong.

The patch adds a return value check that jumps over all trip point
evaluations printing a warning if get_temp fails.  The trip points are
evaluated again on the next polling interval with successful get_temp
execution.

Signed-off-by: Michael Brunner <mibru@gmx.de>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 4ab6c083

drivers/thermal/thermal_sys.c

+8 −1

Original line number	Diff line number	Diff line
		@@ -953,7 +953,12 @@ void thermal_zone_device_update(struct thermal_zone_device *tz)

		mutex_lock(&tz->lock);

		tz->ops->get_temp(tz, &temp);
		if (tz->ops->get_temp(tz, &temp)) {
		/* get_temp failed - retry it later */
		printk(KERN_WARNING PREFIX "failed to read out thermal zone "
		"%d\n", tz->id);
		goto leave;
		}

		for (count = 0; count < tz->trips; count++) {
		tz->ops->get_trip_type(tz, count, &trip_type);
		@@ -1005,6 +1010,8 @@ void thermal_zone_device_update(struct thermal_zone_device *tz)
		THERMAL_TRIPS_NONE);

		tz->last_temperature = temp;

		leave:
		if (tz->passive)
		thermal_zone_device_set_polling(tz, tz->passive_delay);
		else if (tz->polling_delay)