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 > Signed-off-by: Keerthy > --- > > 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 >