| Message ID | 1492159933-4213-2-git-send-email-j-keerthy@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hey, On Fri, Apr 14, 2017 at 02:22:13PM +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 v4: > > * Updated documentation > * changed emergency_poweroff_func to thermal_emergency_poweroff_func > > Changes in v3: > > * Removed unnecessary mutex init. > * Added WARN messages instead of a simple warning message. > * Added Documentation. > > Documentation/thermal/sysfs-api.txt | 19 +++++++++++++++ > drivers/thermal/Kconfig | 13 +++++++++++ > drivers/thermal/thermal_core.c | 46 +++++++++++++++++++++++++++++++++++++ > 3 files changed, 78 insertions(+) > > diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt > index ef473dc..e73cc12 100644 > --- a/Documentation/thermal/sysfs-api.txt > +++ b/Documentation/thermal/sysfs-api.txt > @@ -582,3 +582,22 @@ 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. In case kernel_power_off() fails then finally > +emergency_restart() is called in the worst case. > + > +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..0dd5b85 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 Only now I realized that merging this may break the working orderly_poweroff() out there, because you are defaulting this to 0, no delay, therefore giving no time for orderly_poweroff() to finish. This is not good. I think using 0 delay as immediate power off is not good as we give no time for graceful shutdown, and by default. My suggestion here is to use 0 delay as no forced shutdown. Meaning, by default, this feature is disabled, and all other systems out there, despite DRA7 with arago over NFS, work as before. > + 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 8337c27..aed614d 100644 > --- a/drivers/thermal/thermal_core.c > +++ b/drivers/thermal/thermal_core.c > @@ -324,6 +324,47 @@ static void handle_non_critical_trips(struct thermal_zone_device *tz, > def_governor->throttle(tz, trip); > } > > +/** > + * thermal_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 thermal_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(thermal_emergency_poweroff_work, > + thermal_emergency_poweroff_func); > + > +/** > + * thermal_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(&thermal_emergency_poweroff_work, > + msecs_to_jiffies(CONFIG_THERMAL_EMERGENCY_POWEROFF_DELAY_MS)); So, please, only schedule if delay is greater than 0. Also I would prefer the config is set to a local variable.. > +} > + > static void handle_critical_trips(struct thermal_zone_device *tz, > int trip, enum thermal_trip_type trip_type) > { > @@ -346,6 +387,11 @@ 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 >
Hello again, On Fri, Apr 14, 2017 at 08:38:40AM -0700, Eduardo Valentin wrote: > Hey, > > On Fri, Apr 14, 2017 at 02:22:13PM +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 v4: > > > > * Updated documentation > > * changed emergency_poweroff_func to thermal_emergency_poweroff_func > > > > Changes in v3: > > > > * Removed unnecessary mutex init. > > * Added WARN messages instead of a simple warning message. > > * Added Documentation. > > > > Documentation/thermal/sysfs-api.txt | 19 +++++++++++++++ > > drivers/thermal/Kconfig | 13 +++++++++++ > > drivers/thermal/thermal_core.c | 46 +++++++++++++++++++++++++++++++++++++ > > 3 files changed, 78 insertions(+) > > > > diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt > > index ef473dc..e73cc12 100644 > > --- a/Documentation/thermal/sysfs-api.txt > > +++ b/Documentation/thermal/sysfs-api.txt > > @@ -582,3 +582,22 @@ 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. In case kernel_power_off() fails then finally > > +emergency_restart() is called in the worst case. > > + > > +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..0dd5b85 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 > > Only now I realized that merging this may break the working > orderly_poweroff() out there, because you are defaulting this to 0, no > delay, therefore giving no time for orderly_poweroff() to finish. This > is not good. > > I think using 0 delay as immediate power off is not good as we give no > time for graceful shutdown, and by default. My suggestion here > is to use 0 delay as no forced shutdown. Meaning, by default, this > feature is disabled, and all other systems out there, despite DRA7 with > arago over NFS, work as before. > > > + 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 8337c27..aed614d 100644 > > --- a/drivers/thermal/thermal_core.c > > +++ b/drivers/thermal/thermal_core.c > > @@ -324,6 +324,47 @@ static void handle_non_critical_trips(struct thermal_zone_device *tz, > > def_governor->throttle(tz, trip); > > } > > > > +/** > > + * thermal_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 thermal_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(thermal_emergency_poweroff_work, > > + thermal_emergency_poweroff_func); > > + > > +/** > > + * thermal_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(&thermal_emergency_poweroff_work, > > + msecs_to_jiffies(CONFIG_THERMAL_EMERGENCY_POWEROFF_DELAY_MS)); > > So, please, only schedule if delay is greater than 0. Please update documentation accordingly..
Hey, On Fri, Apr 14, 2017 at 08:42:20AM -0700, Eduardo Valentin wrote: > Hello again, > > On Fri, Apr 14, 2017 at 08:38:40AM -0700, Eduardo Valentin wrote: > > Hey, > > > > On Fri, Apr 14, 2017 at 02:22:13PM +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 v4: > > > > > > * Updated documentation > > > * changed emergency_poweroff_func to thermal_emergency_poweroff_func > > > > > > Changes in v3: > > > > > > * Removed unnecessary mutex init. > > > * Added WARN messages instead of a simple warning message. > > > * Added Documentation. > > > > > > Documentation/thermal/sysfs-api.txt | 19 +++++++++++++++ > > > drivers/thermal/Kconfig | 13 +++++++++++ > > > drivers/thermal/thermal_core.c | 46 +++++++++++++++++++++++++++++++++++++ > > > 3 files changed, 78 insertions(+) > > > > > > diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt > > > index ef473dc..e73cc12 100644 > > > --- a/Documentation/thermal/sysfs-api.txt > > > +++ b/Documentation/thermal/sysfs-api.txt > > > @@ -582,3 +582,22 @@ 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. In case kernel_power_off() fails then finally > > > +emergency_restart() is called in the worst case. > > > + > > > +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..0dd5b85 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 > > > > Only now I realized that merging this may break the working > > orderly_poweroff() out there, because you are defaulting this to 0, no > > delay, therefore giving no time for orderly_poweroff() to finish. This > > is not good. > > > > I think using 0 delay as immediate power off is not good as we give no > > time for graceful shutdown, and by default. My suggestion here > > is to use 0 delay as no forced shutdown. Meaning, by default, this > > feature is disabled, and all other systems out there, despite DRA7 with > > arago over NFS, work as before. A better solution could be to have bool Kconfig, say THERMAL_EMERGENCY_POWEROFF, which would default to false. If one selects that option, you get the DELAY_MS configurable, and then you could get the 0 ms still as a valid entry, with the same semantics of immediate power off, no orderly_poweroff. I just want to avoid breaking everybody (or changing userland expectation) in honor of this change. > > > > > + 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 8337c27..aed614d 100644 > > > --- a/drivers/thermal/thermal_core.c > > > +++ b/drivers/thermal/thermal_core.c > > > @@ -324,6 +324,47 @@ static void handle_non_critical_trips(struct thermal_zone_device *tz, > > > def_governor->throttle(tz, trip); > > > } > > > > > > +/** > > > + * thermal_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 thermal_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(thermal_emergency_poweroff_work, > > > + thermal_emergency_poweroff_func); > > > + > > > +/** > > > + * thermal_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(&thermal_emergency_poweroff_work, > > > + msecs_to_jiffies(CONFIG_THERMAL_EMERGENCY_POWEROFF_DELAY_MS)); > > > > So, please, only schedule if delay is greater than 0. > > Please update documentation accordingly.. >
On Friday 14 April 2017 11:48 PM, Eduardo Valentin wrote: > Hey, > > On Fri, Apr 14, 2017 at 08:42:20AM -0700, Eduardo Valentin wrote: >> Hello again, >> >> On Fri, Apr 14, 2017 at 08:38:40AM -0700, Eduardo Valentin wrote: >>> Hey, >>> >>> On Fri, Apr 14, 2017 at 02:22:13PM +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 v4: >>>> >>>> * Updated documentation >>>> * changed emergency_poweroff_func to thermal_emergency_poweroff_func >>>> >>>> Changes in v3: >>>> >>>> * Removed unnecessary mutex init. >>>> * Added WARN messages instead of a simple warning message. >>>> * Added Documentation. >>>> >>>> Documentation/thermal/sysfs-api.txt | 19 +++++++++++++++ >>>> drivers/thermal/Kconfig | 13 +++++++++++ >>>> drivers/thermal/thermal_core.c | 46 +++++++++++++++++++++++++++++++++++++ >>>> 3 files changed, 78 insertions(+) >>>> >>>> diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt >>>> index ef473dc..e73cc12 100644 >>>> --- a/Documentation/thermal/sysfs-api.txt >>>> +++ b/Documentation/thermal/sysfs-api.txt >>>> @@ -582,3 +582,22 @@ 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. In case kernel_power_off() fails then finally >>>> +emergency_restart() is called in the worst case. >>>> + >>>> +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..0dd5b85 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 >>> >>> Only now I realized that merging this may break the working >>> orderly_poweroff() out there, because you are defaulting this to 0, no >>> delay, therefore giving no time for orderly_poweroff() to finish. This >>> is not good. >>> >>> I think using 0 delay as immediate power off is not good as we give no >>> time for graceful shutdown, and by default. My suggestion here >>> is to use 0 delay as no forced shutdown. Meaning, by default, this >>> feature is disabled, and all other systems out there, despite DRA7 with >>> arago over NFS, work as before. > > A better solution could be to have bool Kconfig, say > THERMAL_EMERGENCY_POWEROFF, which would default to false. If one selects > that option, you get the DELAY_MS configurable, and then you could get > the 0 ms still as a valid entry, with the same semantics of immediate > power off, no orderly_poweroff. > > I just want to avoid breaking everybody (or changing userland > expectation) in honor of this change. Sure. I have now used default value as no emergency shutdown. Any positive value is taken as the delay value. Sent a v5. > >>> >>>> + 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 8337c27..aed614d 100644 >>>> --- a/drivers/thermal/thermal_core.c >>>> +++ b/drivers/thermal/thermal_core.c >>>> @@ -324,6 +324,47 @@ static void handle_non_critical_trips(struct thermal_zone_device *tz, >>>> def_governor->throttle(tz, trip); >>>> } >>>> >>>> +/** >>>> + * thermal_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 thermal_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(thermal_emergency_poweroff_work, >>>> + thermal_emergency_poweroff_func); >>>> + >>>> +/** >>>> + * thermal_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(&thermal_emergency_poweroff_work, >>>> + msecs_to_jiffies(CONFIG_THERMAL_EMERGENCY_POWEROFF_DELAY_MS)); >>> >>> So, please, only schedule if delay is greater than 0. >> >> Please update documentation accordingly.. >> > > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt index ef473dc..e73cc12 100644 --- a/Documentation/thermal/sysfs-api.txt +++ b/Documentation/thermal/sysfs-api.txt @@ -582,3 +582,22 @@ 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. In case kernel_power_off() fails then finally +emergency_restart() is called in the worst case. + +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..0dd5b85 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 8337c27..aed614d 100644 --- a/drivers/thermal/thermal_core.c +++ b/drivers/thermal/thermal_core.c @@ -324,6 +324,47 @@ static void handle_non_critical_trips(struct thermal_zone_device *tz, def_governor->throttle(tz, trip); } +/** + * thermal_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 thermal_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(thermal_emergency_poweroff_work, + thermal_emergency_poweroff_func); + +/** + * thermal_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(&thermal_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 +387,11 @@ 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 v4: * Updated documentation * changed emergency_poweroff_func to thermal_emergency_poweroff_func Changes in v3: * Removed unnecessary mutex init. * Added WARN messages instead of a simple warning message. * Added Documentation. Documentation/thermal/sysfs-api.txt | 19 +++++++++++++++ drivers/thermal/Kconfig | 13 +++++++++++ drivers/thermal/thermal_core.c | 46 +++++++++++++++++++++++++++++++++++++ 3 files changed, 78 insertions(+)