PM / sleep: Mark suspend/hibernation start and finish

Regardless of whether or not debug messages from the core system
suspend/hibernation code are enabled, it is useful to know when
system-wide transitions start and finish (or fail), so print "info"
messages at these points.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Mark Salyzyn <salyzyn@android.com>

kernel/power/hibernate.c

@@ -692,6 +692,7 @@ int hibernate(void)
 		goto Unlock;
 	}
 
+	pr_info("hibernation entry\n");
 	pm_prepare_console();
 	error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls);
 	if (error) {
@@ -762,6 +763,8 @@ int hibernate(void)
 	atomic_inc(&snapshot_device_available);
  Unlock:
 	unlock_system_sleep();
+	pr_info("hibernation exit\n");
+
 	return error;
 }
 
@@ -868,6 +871,7 @@ static int software_resume(void)
 		goto Unlock;
 	}
 
+	pr_info("resume from hibernation\n");
 	pm_prepare_console();
 	error = __pm_notifier_call_chain(PM_RESTORE_PREPARE, -1, &nr_calls);
 	if (error) {
@@ -884,6 +888,7 @@ static int software_resume(void)
  Finish:
 	__pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
 	pm_restore_console();
+	pr_info("resume from hibernation failed (%d)\n", error);
 	atomic_inc(&snapshot_device_available);
 	/* For success case, the suspend path will release the lock */
  Unlock:

kernel/power/suspend.c

@@ -584,6 +584,7 @@ int pm_suspend(suspend_state_t state)
 	if (state <= PM_SUSPEND_ON || state >= PM_SUSPEND_MAX)
 		return -EINVAL;
 
+	pr_info("PM: suspend entry (%s)\n", pm_states[state]);
 	error = enter_state(state);
 	if (error) {
 		suspend_stats.fail++;
@@ -591,6 +592,7 @@ int pm_suspend(suspend_state_t state)
 	} else {
 		suspend_stats.success++;
 	}
+	pr_info("PM: suspend exit\n");
 	return error;
 }
 EXPORT_SYMBOL(pm_suspend);