Hey,
On Thu, Apr 13, 2017 at 01:32:35PM +0530, Keerthy wrote:
> thermal_zone_device_check --> thermal_zone_device_update -->
> handle_thermal_trip --> handle_critical_trips --> orderly_poweroff
>
> The above sequence happens every 250/500 mS based on the configuration.
> The orderly_poweroff function is getting called every 250/500 mS.
> With a full fledged file system it takes at least 5-10 Seconds to
> power off gracefully.
>
> In that period due to the thermal_zone_device_check triggering
> periodically the thermal work queues bombard with
> orderly_poweroff calls multiple times eventually leading to
> failures in gracefully powering off the system.
>
> Make sure that orderly_poweroff is called only once.
>
> Reported-by: Nishanth Menon <nm@xxxxxx>
Was this reported by nm or found by you?
> Signed-off-by: Keerthy <j-keerthy@xxxxxx>
> ---
>
> Changes in v2:
>
> * Added a global mutex to serialize poweroff code sequence.
>
> drivers/thermal/thermal_core.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 11f0675..7462ae5 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -45,6 +45,7 @@
>
> static DEFINE_MUTEX(thermal_list_lock);
> static DEFINE_MUTEX(thermal_governor_lock);
> +static DEFINE_MUTEX(poweroff_lock);
>
> static atomic_t in_suspend;
>
> @@ -326,6 +327,7 @@ static void handle_critical_trips(struct thermal_zone_device *tz,
> int trip, enum thermal_trip_type trip_type)
> {
> int trip_temp;
> + static bool power_off_triggered;
>
> tz->ops->get_trip_temp(tz, trip, &trip_temp);
>
> @@ -338,11 +340,14 @@ static void handle_critical_trips(struct thermal_zone_device *tz,
> if (tz->ops->notify)
> tz->ops->notify(tz, trip, trip_type);
>
> - if (trip_type == THERMAL_TRIP_CRITICAL) {
> + if (trip_type == THERMAL_TRIP_CRITICAL && !power_off_triggered) {
> dev_emerg(&tz->device,
> "critical temperature reached(%d C),shutting down\n",
> tz->temperature / 1000);
> + mutex_lock(&poweroff_lock);
> orderly_poweroff(true);
> + power_off_triggered = true;
> + mutex_unlock(&poweroff_lock);
The above code does not fully prevent orderly_poweroff() to be called
only once, does it?
- thermal zone 0 goes all the way in the critical path, but gets
preempted between orderly_poweroff(true)l and power_off_triggered =
true;, i.e., preempted right before setting to true, therefore,
power_off_triggered still 0.
- thermal zone 1 also enters critical path, but will sleep at the
power_off_lock, right?
- then thermal zone 0 gets the CPU again, finishes the critical path,
unlocks poweroff_lock.
- thermal zone 1 is unblocked, and call again orderly_poweroff(true);
BR,
> }
> }
>
> @@ -1463,6 +1468,7 @@ static int __init thermal_init(void)
> {
> int result;
>
> + mutex_init(&poweroff_lock);
> result = thermal_register_governors();
> if (result)
> goto error;
> @@ -1497,6 +1503,7 @@ static int __init thermal_init(void)
> ida_destroy(&thermal_cdev_ida);
> mutex_destroy(&thermal_list_lock);
> mutex_destroy(&thermal_governor_lock);
> + mutex_destroy(&poweroff_lock);
> return result;
> }
>
> --
> 1.9.1
>
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