On 14/04/2021 07:52, Matti Vaittinen wrote:
> Thermal core contains a logic for safety shutdown. System is attempted to
> be powered off if temperature exceeds safety limits.
>
> Currently this can be also utilized by regulator subsystem as a final
> protection measure if PMICs report dangerous over-voltage, over-current or
> over-temperature and if per regulator counter measures fail or do not
> exist.
>
> Move this logic to kernel/reboot.c and export the functionality for other
> subsystems to use. Also replace the mutex with a spinlock to allow using
> the function from any context.
>
> Also the EMIF bus code has implemented a safety shut-down. EMIF does not
> attempt orderly_poweroff at all. Thus the EMIF code is not converted to use
> this new function.
>
> Signed-off-by: Matti Vaittinen <matti.vaittinen@xxxxxxxxxxxxxxxxx>
> ---
> Changelog
> v7:
> - new patch
>
> Please note - this patch has received only a minimal amount of testing.
> (The new API call was tested to shut-down my system at driver probe but
> no odd corner-cases have been tested).
>
> Any testing for thermal shutdown is appreciated.
> ---
> drivers/thermal/thermal_core.c | 63 ++-----------------------
> include/linux/reboot.h | 1 +
> kernel/reboot.c | 86 ++++++++++++++++++++++++++++++++++
Please send a patch implementing the reboot/shutdown and then another
one replacing the thermal shutdown code by a call to the new API.
> 3 files changed, 91 insertions(+), 59 deletions(-)
>
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 996c038f83a4..b1444845af38 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -36,10 +36,8 @@ static LIST_HEAD(thermal_governor_list);
>
> static DEFINE_MUTEX(thermal_list_lock);
> static DEFINE_MUTEX(thermal_governor_lock);
> -static DEFINE_MUTEX(poweroff_lock);
>
> static atomic_t in_suspend;
> -static bool power_off_triggered;
>
> static struct thermal_governor *def_governor;
>
> @@ -327,70 +325,18 @@ static void handle_non_critical_trips(struct thermal_zone_device *tz, int trip)
> 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 this is not scheduled.
> - */
> -static void thermal_emergency_poweroff(void)
> +void thermal_zone_device_critical(struct thermal_zone_device *tz)
> {
> - int poweroff_delay_ms = CONFIG_THERMAL_EMERGENCY_POWEROFF_DELAY_MS;
> /*
> * poweroff_delay_ms must be a carefully profiled positive value.
> - * Its a must for thermal_emergency_poweroff_work to be scheduled
> + * Its a must for forced_emergency_poweroff_work to be scheduled.
> */
> - if (poweroff_delay_ms <= 0)
> - return;
> - schedule_delayed_work(&thermal_emergency_poweroff_work,
> - msecs_to_jiffies(poweroff_delay_ms));
> -}
> + int poweroff_delay_ms = CONFIG_THERMAL_EMERGENCY_POWEROFF_DELAY_MS;
>
> -void thermal_zone_device_critical(struct thermal_zone_device *tz)
> -{
> dev_emerg(&tz->device, "%s: critical temperature reached, "
> "shutting down\n", tz->type);
>
> - 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;
> - }
> - mutex_unlock(&poweroff_lock);
> + hw_protection_shutdown("Temperature too high", poweroff_delay_ms);
> }
> EXPORT_SYMBOL(thermal_zone_device_critical);
>
> @@ -1549,7 +1495,6 @@ 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;
> }
> postcore_initcall(thermal_init);
> diff --git a/include/linux/reboot.h b/include/linux/reboot.h
> index 3734cd8f38a8..af907a3d68d1 100644
> --- a/include/linux/reboot.h
> +++ b/include/linux/reboot.h
> @@ -79,6 +79,7 @@ extern char poweroff_cmd[POWEROFF_CMD_PATH_LEN];
>
> extern void orderly_poweroff(bool force);
> extern void orderly_reboot(void);
> +void hw_protection_shutdown(const char *reason, int ms_until_forced);
>
> /*
> * Emergency restart, callable from an interrupt handler.
> diff --git a/kernel/reboot.c b/kernel/reboot.c
> index a6ad5eb2fa73..1b5fa6d213d4 100644
> --- a/kernel/reboot.c
> +++ b/kernel/reboot.c
> @@ -518,6 +518,92 @@ void orderly_reboot(void)
> }
> EXPORT_SYMBOL_GPL(orderly_reboot);
>
> +/**
> + * hw_failure_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 hw_failure_emergency_poweroff_func(struct work_struct *work)
> +{
> + /*
> + * We have reached here after the emergency 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, "Hardware protection timed-out. Trying forced poweroff\n");
> + kernel_power_off();
> +
> + /*
> + * Worst of the worst case trigger emergency restart
> + */
> + WARN(1,
> + "Hardware protection shutdown failed. Trying emergency restart\n");
> + emergency_restart();
> +}
> +
> +static DECLARE_DELAYED_WORK(hw_failure_emergency_poweroff_work,
> + hw_failure_emergency_poweroff_func);
> +
> +/**
> + * hw_failure_emergency_poweroff - Trigger an emergency system poweroff
> + *
> + * This may be called from any critical situation to trigger a system shutdown
> + * after a given period of time. If time is negative this is not scheduled.
> + */
> +static void hw_failure_emergency_poweroff(int poweroff_delay_ms)
> +{
> + if (poweroff_delay_ms <= 0)
> + return;
> + schedule_delayed_work(&hw_failure_emergency_poweroff_work,
> + msecs_to_jiffies(poweroff_delay_ms));
> +}
> +
> +static bool prot_power_off_triggered;
> +static DEFINE_SPINLOCK(poweroff_lock);
> +
> +/**
> + * hw_protection_shutdown - Trigger an emergency system poweroff
> + *
> + * @reason: Reason of emergency shutdown to be printed.
> + * @ms_until_forced: Time to wait for orderly shutdown before tiggering a
> + * forced shudown. Negative value disables the forced
> + * shutdown.
> + *
> + * Initiate an emergency system shutdown in order to protect hardware from
> + * further damage. Usage examples include a thermal protection or a voltage or
> + * current regulator failures.
> + * NOTE: The request is ignored if protection shutdown is already pending even
> + * if the previous request has given a large timeout for forced shutdown.
> + * Can be called from any context.
> + */
> +void hw_protection_shutdown(const char *reason, int ms_until_forced)
> +{
> + unsigned long flags;
> +
> + pr_emerg("HARDWARE PROTECTION shutdown (%s)\n", reason);
> +
> + spin_lock_irqsave(&poweroff_lock, flags);
> + if (prot_power_off_triggered) {
> + spin_unlock(&poweroff_lock);
Why not spin_unlock_irqrestore() ?
> + return;
> + }
> + prot_power_off_triggered = true;
> + spin_unlock_irqrestore(&poweroff_lock, flags);
Why not take the spin_lock definitively for all the procedure ?
eg.
{
...
pr_emerg( ... );
if (spin_trylock(&lock))
return;
hw_failure_emergency_poweroff(ms_until_forced);
orderly_poweroff(true);
}
No need of prot_power_off_triggered and the spin_lock can be declared
static inside the function.
> + /*
> + * Queue a backup emergency shutdown in the event of
> + * orderly_poweroff failure
> + */
> + hw_failure_emergency_poweroff(ms_until_forced);
> + orderly_poweroff(true);
> +}
> +EXPORT_SYMBOL_GPL(hw_protection_shutdown);
> +
> static int __init reboot_setup(char *str)
> {
> for (;;) {
>
--
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