• Rafael J. Wysocki's avatar
    thermal/debugfs: Add missing count increment to thermal_debug_tz_trip_up() · b552f63c
    Rafael J. Wysocki authored
    The count field in struct trip_stats, representing the number of times
    the zone temperature was above the trip point, needs to be incremented
    in thermal_debug_tz_trip_up(), for two reasons.
    
    First, if a trip point is crossed on the way up for the first time,
    thermal_debug_update_temp() called from update_temperature() does
    not see it because it has not been added to trips_crossed[] array
    in the thermal zone's struct tz_debugfs object yet.  Therefore, when
    thermal_debug_tz_trip_up() is called after that, the trip point's
    count value is 0, and the attempt to divide by it during the average
    temperature computation leads to a divide error which causes the kernel
    to crash.  Setting the count to 1 before the division by incrementing it
    fixes this problem.
    
    Second, if a trip point is crossed on the way up, but it has been
    crossed on the way up already before, its count value needs to be
    incremented to make a record of the fact that the zone temperature is
    above the trip now.  Without doing that, if the mitigations applied
    after crossing the trip cause the zone temperature to drop below its
    threshold, the count will not be updated for this episode at all and
    the average temperature in the trip statistics record will be somewhat
    higher than it should be.
    
    Fixes: 7ef01f22 ("thermal/debugfs: Add thermal debugfs information for mitigation episodes")
    Cc :6.8+ <stable@vger.kernel.org> # 6.8+
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    b552f63c
thermal_debugfs.c 22.2 KB