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SubjectRe: [PATCH v2 1/3] PM suspend/hibernate: Call notifier after freezing processes
Date
On Sunday, June 21, 2015 01:20:32 PM Pali Rohár wrote:
> To prevent race conditions on userspace processes with I/O some taks must be
> called after processes are freezed. This patch adds new events which are
> delivered by pm_notifier_call_chain() after freezing processes when doing
> suspend or hibernate action.
>
> Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
> ---
> include/linux/suspend.h | 2 ++
> kernel/power/hibernate.c | 2 ++
> kernel/power/suspend.c | 4 +++-
> 3 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/suspend.h b/include/linux/suspend.h
> index 5efe743..bc743c8 100644
> --- a/include/linux/suspend.h
> +++ b/include/linux/suspend.h
> @@ -368,6 +368,8 @@ static inline bool hibernation_available(void) { return false; }
> #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_AFTER_FREEZE 0x0007 /* After hibernation freeze */
> +#define PM_SUSPEND_AFTER_FREEZE 0x0008 /* After suspend freeze */
>
> extern struct mutex pm_mutex;
>
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index 2329daa..184f7ee 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -671,6 +671,8 @@ int hibernate(void)
> if (error)
> goto Exit;
>
> + pm_notifier_call_chain(PM_HIBERNATION_AFTER_FREEZE);

Don't we need to check errors from these?

Also, if you're adding AFTER_FREEZE, it would be good to add BEFORE_THAW too
for symmetry.

> +
> lock_device_hotplug();
> /* Allocate memory management structures */
> error = create_basic_memory_bitmaps();
> diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
> index 8d7a1ef..ba2a945 100644
> --- a/kernel/power/suspend.c
> +++ b/kernel/power/suspend.c
> @@ -277,8 +277,10 @@ 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)
> + if (!error) {
> + pm_notifier_call_chain(PM_SUSPEND_AFTER_FREEZE);
> return 0;
> + }
>
> suspend_stats.failed_freeze++;
> dpm_save_failed_step(SUSPEND_FREEZE);
>

--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.


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