| Message ID | 1492147105-26692-2-git-send-email-j-keerthy@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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@ti.com> > Signed-off-by: Keerthy <j-keerthy@ti.com> > --- > > 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 >
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. + +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 + * @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 + * + * 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; }
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@ti.com> Signed-off-by: Keerthy <j-keerthy@ti.com> --- 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(+)