Re: [PATCH v3 2/3] PM: hibernate: add pm_hibernation_snapshot_done() helper

[Rafael J. Wysocki (Intel)]

On Thu, Jun 18, 2026 at 3:32 AM Haowen Tu <tuhaowen@xxxxxxxxxxxxx> wrote:
>
> Some subsystem resume callbacks do not receive the PM event and
> therefore cannot distinguish the PMSG_THAW phase after snapshot creation
> from the PMSG_RESTORE phase.
>
> Export pm_hibernation_snapshot_done() so a driver can query whether the
> hibernation snapshot has been created and is still available.  The
> helper only exposes the PM state; callers remain responsible for
> ensuring that any device-specific behavior is safe, including subsequent
> poweroff or shutdown handling.
>
> The helper returns !!in_suspend.  This variable is set before
> swsusp_arch_suspend(), cleared before the snapshot memory is released,
> and marked __nosavedata, so it remains clear on the restore path.
>
> Signed-off-by: Haowen Tu <tuhaowen@xxxxxxxxxxxxx>
> ---
> Changes in v3:
> - Split the in_suspend cleanup into a preceding patch.
> - Clarify that callers must account for poweroff/shutdown handling.
> - Drop extern from the new prototype.

Fine with me now, so

Acked-by: Rafael J. Wysocki (Intel) <rafael@xxxxxxxxxx>

and please feel free to route it along with the media patch.

> Changes in v2:
> - Rename pm_hibernation_storing_image() to
>   pm_hibernation_snapshot_done().
>
>  include/linux/suspend.h  |  2 ++
>  kernel/power/hibernate.c | 12 ++++++++++++
>  2 files changed, 14 insertions(+)
>
> diff --git a/include/linux/suspend.h b/include/linux/suspend.h
> index b02876f1ae38..2cebbec3e2f7 100644
> --- a/include/linux/suspend.h
> +++ b/include/linux/suspend.h
> @@ -393,6 +393,7 @@ extern void hibernation_set_ops(const struct platform_hibernation_ops *ops);
>  extern int hibernate(void);
>  extern bool system_entering_hibernation(void);
>  extern bool hibernation_available(void);
> +bool pm_hibernation_snapshot_done(void);
>  asmlinkage int swsusp_save(void);
>  extern struct pbe *restore_pblist;
>  int pfn_is_nosave(unsigned long pfn);
> @@ -412,6 +413,7 @@ static inline void hibernation_set_ops(const struct platform_hibernation_ops *op
>  static inline int hibernate(void) { return -ENOSYS; }
>  static inline bool system_entering_hibernation(void) { return false; }
>  static inline bool hibernation_available(void) { return false; }
> +static inline bool pm_hibernation_snapshot_done(void) { return false; }
>
>  static inline int hibernate_quiet_exec(int (*func)(void *data), void *data) {
>         return -ENOTSUPP;
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index 6d3e637c5a02..045d29f55011 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -113,6 +113,18 @@ bool hibernation_available(void)
>                 !secretmem_active() && !cxl_mem_active();
>  }
>
> +/**
> + * pm_hibernation_snapshot_done - check if a hibernation snapshot is available
> + *
> + * Return: %true if a hibernation snapshot has been taken and has not been
> + *         released yet.
> + */
> +bool pm_hibernation_snapshot_done(void)
> +{
> +       return !!in_suspend;
> +}
> +EXPORT_SYMBOL_GPL(pm_hibernation_snapshot_done);
> +
>  /**
>   * hibernation_set_ops - Set the global hibernate operations.
>   * @ops: Hibernation operations to use in subsequent hibernation transitions.
> --
> 2.20.1
>