On Tue, Aug 29, 2023 at 9:42 PM Fabio Estevam <festevam@xxxxxxxxx> wrote:
>
> From: Fabio Estevam <festevam@xxxxxxx>
>
> Introduce hw_protection_reboot() to trigger an emergency reboot.
>
> It is a counterpart of hw_protection_shutdown() with the difference
> that it will force a reboot instead of shutdown.
>
> The motivation for doing this is to allow the thermal subystem
> to trigger a reboot when the temperature reaches the critical
> temperature.
>
> Signed-off-by: Fabio Estevam <festevam@xxxxxxx>
> ---
> Changes since v4:
> - None
>
> include/linux/reboot.h | 1 +
> kernel/reboot.c | 34 ++++++++++++++++++++++++++++++++++
> 2 files changed, 35 insertions(+)
>
> diff --git a/include/linux/reboot.h b/include/linux/reboot.h
> index 2b6bb593be5b..4a319bc24f6a 100644
> --- a/include/linux/reboot.h
> +++ b/include/linux/reboot.h
> @@ -174,6 +174,7 @@ void ctrl_alt_del(void);
>
> extern void orderly_poweroff(bool force);
> extern void orderly_reboot(void);
> +void hw_protection_reboot(const char *reason, int ms_until_forced);
> void hw_protection_shutdown(const char *reason, int ms_until_forced);
>
> /*
> diff --git a/kernel/reboot.c b/kernel/reboot.c
> index 3bba88c7ffc6..05333ae8bc6b 100644
> --- a/kernel/reboot.c
> +++ b/kernel/reboot.c
> @@ -952,6 +952,40 @@ static void hw_failure_emergency_poweroff(int poweroff_delay_ms)
> msecs_to_jiffies(poweroff_delay_ms));
> }
>
> +/**
> + * hw_protection_reboot - Trigger an emergency system reboot
> + *
> + * @reason: Reason of emergency reboot to be printed.
> + * @ms_until_forced: Time to wait for orderly reboot before tiggering a
> + * forced reboot. Negative value disables the forced
> + * reboot.
> + *
> + * Initiate an emergency system reboot in order to protect hardware from
> + * further damage. Usage examples include a thermal protection.
> + *
> + * NOTE: The request is ignored if protection reboot is already pending even
> + * if the previous request has given a large timeout for forced reboot.
> + * Can be called from any context.
> + */
> +void hw_protection_reboot(const char *reason, int ms_until_forced)
Some code and kerneldoc comment duplication could be avoided by
changing hw_protection_shutdown() definition to take an additional
argument specifying the final action to carry out, so there would be
void __hw_protection_shutdown(const char *reason, int ms_until_forced,
bool reboot)
{
...
if (reboot)
orderly_reboot();
else
orderly_poweroff(true);
}
and both hw_protection_shutdown() and hw_protection_reboot() can be
defined as static inline wrappers around this.
> +{
> + static atomic_t allow_proceed = ATOMIC_INIT(1);
> +
> + pr_emerg("HARDWARE PROTECTION reboot (%s)\n", reason);
> +
> + /* Reboot should be initiated only once. */
> + if (!atomic_dec_and_test(&allow_proceed))
> + return;
> +
> + /*
> + * Queue a backup emergency reboot in the event of
> + * orderly_reboot failure
> + */
> + hw_failure_emergency_poweroff(ms_until_forced);
> + orderly_reboot();
> +}
> +EXPORT_SYMBOL_GPL(hw_protection_reboot);
> +
> /**
> * hw_protection_shutdown - Trigger an emergency system poweroff
> *
> --
> 2.34.1
>
