[RFC 1/2] PM: Add suspend and hibernate notifications for after freeze
Mario Limonciello
superm1 at kernel.org
Fri May 2 16:37:23 UTC 2025
On 5/1/2025 4:17 PM, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello at amd.com>
>
> Suspend and hibernate notifications are available specifically when
> the sequence starts and finishes. However there are no notifications
> during the process when tasks have been frozen.
>
> Introduce two new events `PM_SUSPEND_POST_FREEZE` and
> `PM_HIBERNATE_POST_FREEZE` that drivers can subscribe to and take
> different actions specifically knowing userspace is frozen.
>
> Suggested-by: Alex Deucher <alexander.deucher at amd.com>
> Signed-off-by: Mario Limonciello <mario.limonciello at amd.com>
> ---
> Documentation/driver-api/pm/notifiers.rst | 19 ++++++++++++++++---
> include/linux/suspend.h | 14 ++++++++------
> kernel/power/hibernate.c | 9 +++++++--
> kernel/power/suspend.c | 13 +++++++++----
> 4 files changed, 40 insertions(+), 15 deletions(-)
>
> diff --git a/Documentation/driver-api/pm/notifiers.rst b/Documentation/driver-api/pm/notifiers.rst
> index 186435c43b77e..6a1912fbee214 100644
> --- a/Documentation/driver-api/pm/notifiers.rst
> +++ b/Documentation/driver-api/pm/notifiers.rst
> @@ -32,6 +32,18 @@ will be called upon the following events by the PM core:
> additional work is done between the notifiers and the invocation of PM
> callbacks for the "freeze" transition.
>
> +``PM_HIBERNATION_POST_FREEZE``
> + The system is going to hibernate and tasks have just been frozen.
> +
> +``PM_SUSPEND_PREPARE``
> + The system is going to suspend, tasks will be frozen immediately. This
> + is different from ``PM_HIBERNATION_PREPARE`` above, because in this case
> + additional work is done between the notifiers and the invocation of PM
> + callbacks for the "freeze" transition.
I accidentally created this section ``PM_SUSPEND_PREPARE`` (there
already is one for PM_SUSPEND_PREPARE that is totally fine).
If conceptually the rest of the patch makes sense I will drop this section.
> +
> +``PM_SUSPEND_POST_FREEZE``
> + The system is going to suspend and tasks have just been frozen.
Looking again, I think this is better put between (the correct)
PM_SUSPEND_PREPARE and PM_POST_SUSPEND.
If conceptually the rest of the patch makes sense I will move it to that
section.
> +
> ``PM_POST_HIBERNATION``
> The system memory state has been restored from a hibernation image or an
> error occurred during hibernation. Device restore callbacks have been
> @@ -54,9 +66,10 @@ will be called upon the following events by the PM core:
> resume callbacks have been executed and tasks have been thawed.
>
> It is generally assumed that whatever the notifiers do for
> -``PM_HIBERNATION_PREPARE``, should be undone for ``PM_POST_HIBERNATION``.
> -Analogously, operations carried out for ``PM_SUSPEND_PREPARE`` should be
> -reversed for ``PM_POST_SUSPEND``.
> +``PM_HIBERNATION_PREPARE`` and ``PM_HIBERNATION_POST_FREEZE``, should be undone
> +for ``PM_POST_HIBERNATION``.
> +Analogously, operations carried out for ``PM_SUSPEND_PREPARE`` and ``PM_SUSPEND_POST_FREEZE``
> +should be reversed for ``PM_POST_SUSPEND``.
>
> Moreover, if one of the notifiers fails for the ``PM_HIBERNATION_PREPARE`` or
> ``PM_SUSPEND_PREPARE`` event, the notifiers that have already succeeded for that
> diff --git a/include/linux/suspend.h b/include/linux/suspend.h
> index da6ebca3ff774..704e6579b0df6 100644
> --- a/include/linux/suspend.h
> +++ b/include/linux/suspend.h
> @@ -422,12 +422,14 @@ static inline int is_hibernate_resume_dev(dev_t dev) { return 0; }
> #endif
>
> /* Hibernation and suspend events */
> -#define PM_HIBERNATION_PREPARE 0x0001 /* Going to hibernate */
> -#define PM_POST_HIBERNATION 0x0002 /* Hibernation finished */
> -#define PM_SUSPEND_PREPARE 0x0003 /* Going to suspend the system */
> -#define PM_POST_SUSPEND 0x0004 /* Suspend finished */
> -#define PM_RESTORE_PREPARE 0x0005 /* Going to restore a saved image */
> -#define PM_POST_RESTORE 0x0006 /* Restore failed */
> +#define PM_HIBERNATION_PREPARE 0x0001 /* Going to hibernate */
> +#define PM_HIBERNATION_POST_FREEZE 0x0002 /* Prepared for hibernation and tasks have been frozen */
> +#define PM_POST_HIBERNATION 0x0003 /* Hibernation finished */
> +#define PM_SUSPEND_PREPARE 0x0004 /* Going to suspend the system */
> +#define PM_SUSPEND_POST_FREEZE 0x0005 /* Prepared and tasks have been frozen */
> +#define PM_POST_SUSPEND 0x0006 /* Suspend finished */
> +#define PM_RESTORE_PREPARE 0x0007 /* Going to restore a saved image */
> +#define PM_POST_RESTORE 0x0008 /* Restore failed */
>
> extern struct mutex system_transition_mutex;
>
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index f0db9d1896e80..f896056ad2e5d 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -783,11 +783,15 @@ int hibernate(void)
> if (error)
> goto Exit;
>
> + error = pm_notifier_call_chain_robust(PM_HIBERNATION_POST_FREEZE, PM_POST_HIBERNATION);
> + if (error)
> + goto Thaw;
> +
> lock_device_hotplug();
> /* Allocate memory management structures */
> error = create_basic_memory_bitmaps();
> if (error)
> - goto Thaw;
> + goto Unlock_hotplug;
>
> error = hibernation_snapshot(hibernation_mode == HIBERNATION_PLATFORM);
> if (error || freezer_test_done)
> @@ -833,8 +837,9 @@ int hibernate(void)
>
> Free_bitmaps:
> free_basic_memory_bitmaps();
> - Thaw:
> + Unlock_hotplug:
> unlock_device_hotplug();
> + Thaw:
> if (snapshot_test) {
> pm_pr_dbg("Checking hibernation image\n");
> error = swsusp_check(false);
> diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
> index 8eaec4ab121d4..bc6654e8cdc80 100644
> --- a/kernel/power/suspend.c
> +++ b/kernel/power/suspend.c
> @@ -377,13 +377,18 @@ static int suspend_prepare(suspend_state_t state)
> trace_suspend_resume(TPS("freeze_processes"), 0, true);
> error = suspend_freeze_processes();
> trace_suspend_resume(TPS("freeze_processes"), 0, false);
> - if (!error)
> - return 0;
> + if (error)
> + goto Restore;
> + error = pm_notifier_call_chain_robust(PM_SUSPEND_POST_FREEZE, PM_POST_SUSPEND);
> + if (error)
> + goto Thaw;
>
> - dpm_save_failed_step(SUSPEND_FREEZE);
> - pm_notifier_call_chain(PM_POST_SUSPEND);
> + return 0;
> + Thaw:
> + suspend_thaw_processes();
> Restore:
> pm_restore_console();
> + dpm_save_failed_step(SUSPEND_FREEZE);
> return error;
> }
>
More information about the amd-gfx
mailing list