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thermal/sysfs: Update instance->weight under tz lock

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User space can change the weight of a thermal instance via sysfs while the
.throttle() callback is running for a governor, because weight_store()
does not use the zone lock.

The IPA governor uses instance weight values for power calculations and
caches the sum of them as total_weight, so it gets confused when one of
them changes while its .throttle() callback is running.

To prevent that from happening, use thermal zone locking in
weight_store().

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Lukasz Luba 2023-12-20 23:17:51 +00:00 committed by Rafael J. Wysocki
parent e3ecd5716b
commit 879c9dc511
1 changed files with 4 additions and 0 deletions
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4
drivers/thermal/thermal_sysfs.c
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@ -936,7 +936,11 @@ ssize_t weight_store(struct device *dev, struct device_attribute *attr,
return ret;
instance = container_of(attr, struct thermal_instance, weight_attr);
/* Don't race with governors using the 'weight' value */
mutex_lock(&instance->tz->lock);
instance->weight = weight;
mutex_unlock(&instance->tz->lock);
return count;
}