[dm-devel] [PATCH 1/3] PM suspend/hibernate: Call notifier after freezing processes

[Pali Rohár]

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 at 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);
+
 	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 b7d6b3a..1776938 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -268,8 +268,10 @@ 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);
-- 
1.7.9.5