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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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