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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>
This commit is contained in:
Michael Brunner 2009-08-26 14:29:25 -07:00 committed by Linus Torvalds
parent 4ab6c08336
commit 0d288162f2
1 changed files with 8 additions and 1 deletions
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9
drivers/thermal/thermal_sys.c
View File

@ -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)