linux-kernel - Re: [PATCH v4] PM: hibernate: Avoid missing wakeup events during hibernation

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Date:   Wed, 13 Dec 2023 14:45:53 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Chris Feng <chris.feng@...iatek.com>
Cc:     rafael@...nel.org, pavel@....cz, len.brown@...el.com,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...nel.org, hua.yang@...iatek.com, ting.wang@...iatek.com,
        liang.lu@...iatek.com, chetan.kumar@...iatek.com
Subject: Re: [PATCH v4] PM: hibernate: Avoid missing wakeup events during hibernation

On Wed, Dec 13, 2023 at 9:33 AM Chris Feng <chris.feng@...iatek.com> wrote:
>
> Wakeup events that occur in the hibernation process's
> hibernation_platform_enter() cannot wake up the system. Although the
> current hibernation framework will execute part of the recovery process
> after a wakeup event occurs, it ultimately performs a shutdown operation
> because the system does not check the return value of
> hibernation_platform_enter(). In short, if a wakeup event occurs before
> putting the system into the final low-power state, it will be missed.
>
> To solve this problem, check the return value of
> hibernation_platform_enter(). When it returns -EAGAIN or -EBUSY (indicate
> the occurrence of a wakeup event), execute the hibernation recovery
> process, discard the previously saved image, and ultimately return to the
> working state.
>
> Signed-off-by: Chris Feng <chris.feng@...iatek.com>
> ---
> [PATCH v2]:
>  - Optimize the "if" condition logic.
>  - Link to v1: https://lore.kernel.org/all/20231024091447.108072-1-chris.feng@mediatek.com
> [PATCH v3]:
>  - Use pr_info instead of pr_err.
>  - Fix undeclared function 'swsusp_unmark' build error.
>  - Refine commit and printing message.
>  - Change the subject.
>  - Link to v2: https://lore.kernel.org/all/20231120081516.55172-1-chris.feng@mediatek.com
> [PATCH v4]:
>  - Define an empty swsusp_unmark() function for scenarios where
>    CONFIG_SUSPEND is not defined.
>  - Link to v3: https://lore.kernel.org/all/20231204021155.10434-1-chris.feng@mediatek.com
> ---
>  kernel/power/hibernate.c | 10 ++++++++--
>  kernel/power/power.h     |  2 ++
>  2 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index dee341ae4ace..621326b3e679 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -642,9 +642,9 @@ int hibernation_platform_enter(void)
>   */
>  static void power_down(void)
>  {
> -#ifdef CONFIG_SUSPEND
>         int error;
>
> +#ifdef CONFIG_SUSPEND
>         if (hibernation_mode == HIBERNATION_SUSPEND) {
>                 error = suspend_devices_and_enter(mem_sleep_current);
>                 if (error) {
> @@ -667,7 +667,13 @@ static void power_down(void)
>                 kernel_restart(NULL);
>                 break;
>         case HIBERNATION_PLATFORM:
> -               hibernation_platform_enter();
> +               error = hibernation_platform_enter();
> +               if (error == -EAGAIN || error == -EBUSY) {
> +                       swsusp_unmark();
> +                       events_check_enabled = false;
> +                       pr_info("Hibernation process aborted due to detected wakeup event.\n");
> +                       return;
> +               }
>                 fallthrough;
>         case HIBERNATION_SHUTDOWN:
>                 if (kernel_can_power_off())
> diff --git a/kernel/power/power.h b/kernel/power/power.h
> index 17fd9aaaf084..8499a39c62f4 100644
> --- a/kernel/power/power.h
> +++ b/kernel/power/power.h
> @@ -175,6 +175,8 @@ extern int swsusp_write(unsigned int flags);
>  void swsusp_close(void);
>  #ifdef CONFIG_SUSPEND
>  extern int swsusp_unmark(void);
> +#else
> +static inline int swsusp_unmark(void) { return 0; }
>  #endif
>
>  struct __kernel_old_timeval;
> --

Applied as 6.8 material, but I have rephrased the pr_info() message
added by this patch.

Thanks!