Hey,
On Fri, Apr 14, 2017 at 10:48:25AM +0530, Keerthy wrote:
> orderly_poweroff is triggered when a graceful shutdown
> of system is desired. This may be used in many critical states of the
> kernel such as when subsystems detects conditions such as critical
> temperature conditions. However, in certain conditions in system
> boot up sequences like those in the middle of driver probes being
> initiated, userspace will be unable to power off the system in a clean
> manner and leaves the system in a critical state. In cases like these,
> the /sbin/poweroff will return success (having forked off to attempt
> powering off the system. However, the system overall will fail to
> completely poweroff (since other modules will be probed) and the system
> is still functional with no userspace (since that would have shut itself
> off).
>
> However, there is no clean way of detecting such failure of userspace
> powering off the system. In such scenarios, it is necessary for a backup
> workqueue to be able to force a shutdown of the system when orderly
> shutdown is not successful after a configurable time period.
>
> Reported-by: Nishanth Menon <nm@xxxxxx>
> Signed-off-by: Keerthy <j-keerthy@xxxxxx>
> ---
>
> Changes in v3:
>
> * Removed unnecessary mutex init.
> * Added WARN messages instead of a simple warning message.
> * Added Documentation.
>
> Documentation/thermal/sysfs-api.txt | 18 +++++++++++++++
> drivers/thermal/Kconfig | 13 +++++++++++
> drivers/thermal/thermal_core.c | 45 +++++++++++++++++++++++++++++++++++++
> 3 files changed, 76 insertions(+)
Cool!
Just minor comments..
>
> diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt
> index ef473dc..94b707c 100644
> --- a/Documentation/thermal/sysfs-api.txt
> +++ b/Documentation/thermal/sysfs-api.txt
> @@ -582,3 +582,21 @@ platform data is provided, this uses the step_wise throttling policy.
> This function serves as an arbitrator to set the state of a cooling
> device. It sets the cooling device to the deepest cooling state if
> possible.
> +
> +6. thermal_emergency_poweroff:
> +
> +On an event of critical trip temperature crossing. Thermal framework
> +allows the system to shutdown gracefully by calling orderly_poweroff.
> +In the event of a failure of orderly_poweroff to shut down the system
> +we are in danger of keeping the system alive at undesirably high
> +temperatures. To mitigate this high risk scenario we program a work
> +queue to fire after a pre-determined number of seconds to start
> +an emergency shutdown of the device using the kernel_power_off
> +function.
> +
> +The delay should be carefully profiled so as to give adequate time for
> +orderly_poweroff. In case of failure of an orderly_poweroff the
> +emergency poweroff kicks in after the delay has elapsed and shuts down
> +the system.
Can you mark functions with () in the above, e.g., orderly_poweroff().
Also, you did not mention about the call to emergency_reset();
> +
> +If set to 0 emergency poweroff will happen immediately.
> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> index 9347401..971fd54 100644
> --- a/drivers/thermal/Kconfig
> +++ b/drivers/thermal/Kconfig
> @@ -15,6 +15,19 @@ menuconfig THERMAL
>
> if THERMAL
>
> +config THERMAL_EMERGENCY_POWEROFF_DELAY_MS
> + int "Emergency poweroff delay in milli-seconds"
> + depends on THERMAL
> + default 0
> + help
> + The number of milliseconds to delay before emergency
> + poweroff kicks in. The delay should be carefully profiled
> + so as to give adequate time for orderly_poweroff. In case
> + of failure of an orderly_poweroff the emergency poweroff
> + kicks in after the delay has elapsed and shuts down the system.
> +
> + If set to 0 poweroff will happen immediately.
> +
> config THERMAL_HWMON
> bool
> prompt "Expose thermal sensors as hwmon device"
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 9cad1ba..30098cd 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -323,6 +323,46 @@ static void handle_non_critical_trips(struct thermal_zone_device *tz,
> def_governor->throttle(tz, trip);
> }
>
> +/**
> + * emergency_poweroff_func - emergency poweroff work after a known delay
s/emergency_poweroff_func/thermal_emergency_poweroff_func/g
> + * @work: work_struct associated with the emergency poweroff function
> + *
> + * This function is called in very critical situations to force
> + * a kernel poweroff after a configurable timeout value.
> + */
> +static void emergency_poweroff_func(struct work_struct *work)
> +{
> + /*
> + * We have reached here after the emergency thermal shutdown
> + * Waiting period has expired. This means orderly_poweroff has
> + * not been able to shut off the system for some reason.
> + * Try to shut down the system immediately using kernel_power_off
> + * if populated
> + */
> + WARN(1, "Attempting kernel_power_off: Temperature too high\n");
> + kernel_power_off();
> +
> + /*
> + * Worst of the worst case trigger emergency restart
> + */
> + WARN(1, "Attempting emergency_restart: Temperature too high\n");
> + emergency_restart();
> +}
> +
> +static DECLARE_DELAYED_WORK(emergency_poweroff_work, emergency_poweroff_func);
> +
> +/**
> + * emergency_poweroff - Trigger an emergency system poweroff
s/emergency_poweroff/thermal_emergency_poweroff/g
> + *
> + * This may be called from any critical situation to trigger a system shutdown
> + * after a known period of time. By default the delay is 0 millisecond
> + */
> +void thermal_emergency_poweroff(void)
> +{
> + schedule_delayed_work(&emergency_poweroff_work,
> + msecs_to_jiffies(CONFIG_THERMAL_EMERGENCY_POWEROFF_DELAY_MS));
> +}
> +
> static void handle_critical_trips(struct thermal_zone_device *tz,
> int trip, enum thermal_trip_type trip_type)
> {
> @@ -346,6 +386,11 @@ static void handle_critical_trips(struct thermal_zone_device *tz,
> tz->temperature / 1000);
> mutex_lock(&poweroff_lock);
> if (!power_off_triggered) {
> + /*
> + * Queue a backup emergency shutdown in the event of
> + * orderly_poweroff failure
> + */
> + thermal_emergency_poweroff();
> orderly_poweroff(true);
> power_off_triggered = true;
> }
> --
> 1.9.1
>
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