From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Subject: Re: [PATCH v2 1/3] PM suspend/hibernate: Call notifier after freezing processes
Date: Thu, 16 Jul 2015 03:02:03 +0200
Message-ID: <3729395.1oJCgMXcLU@vostro.rjw.lan>
References: <1428254419-7334-1-git-send-email-pali.rohar@gmail.com> <1434885634-19895-1-git-send-email-pali.rohar@gmail.com> <1434885634-19895-2-git-send-email-pali.rohar@gmail.com>
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To: Pali =?ISO-8859-1?Q?Roh=E1r?= <pali.rohar@gmail.com>
Cc: Alasdair Kergon <agk@redhat.com>, Mike Snitzer <snitzer@redhat.com>, Neil Brown <neilb@suse.de>, Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>, dm-devel@redhat.com, linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
List-Id: linux-raid.ids

On Sunday, June 21, 2015 01:20:32 PM Pali Roh=C3=A1r 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 d=
oing
> suspend or hibernate action.
>=20
> Signed-off-by: Pali Roh=C3=A1r <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(-)
>=20
> 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 free=
ze */
> +#define PM_SUSPEND_AFTER_FREEZE		0x0008 /* After suspend freeze */
> =20
>  extern struct mutex pm_mutex;
> =20
> 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;
> =20
> +	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_THA=
W too
for symmetry.

> +
>  	lock_device_hotplug();
>  	/* Allocate memory management structures */
>  	error =3D 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 =3D 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;
> +	}
> =20
>  	suspend_stats.failed_freeze++;
>  	dpm_save_failed_step(SUSPEND_FREEZE);
>=20

--=20
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.