PM / sleep: Mechanism for aborting system suspends unconditionally

It sometimes may be necessary to abort a system suspend in
progress or wake up the system from suspend-to-idle even if the
pm_wakeup_event()/pm_stay_awake() mechanism is not enabled.

For this purpose, introduce a new global variable pm_abort_suspend
and make pm_wakeup_pending() check its value.  Also add routines
for manipulating that variable.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/power/wakeup.c

@@ -24,6 +24,9 @@
  */
 bool events_check_enabled __read_mostly;
 
+/* If set and the system is suspending, terminate the suspend. */
+static bool pm_abort_suspend __read_mostly;
+
 /*
  * Combined counters of registered wakeup events and wakeup events in progress.
  * They need to be modified together atomically, so it's better to use one
@@ -719,7 +722,18 @@ bool pm_wakeup_pending(void)
 		pm_print_active_wakeup_sources();
 	}
 
-	return ret;
+	return ret || pm_abort_suspend;
+}
+
+void pm_system_wakeup(void)
+{
+	pm_abort_suspend = true;
+	freeze_wake();
+}
+
+void pm_wakeup_clear(void)
+{
+	pm_abort_suspend = false;
 }
 
 /**

include/linux/suspend.h

@@ -371,6 +371,8 @@ extern int unregister_pm_notifier(struct notifier_block *nb);
 extern bool events_check_enabled;
 
 extern bool pm_wakeup_pending(void);
+extern void pm_system_wakeup(void);
+extern void pm_wakeup_clear(void);
 extern bool pm_get_wakeup_count(unsigned int *count, bool block);
 extern bool pm_save_wakeup_count(unsigned int count);
 extern void pm_wakep_autosleep_enabled(bool set);
@@ -418,6 +420,8 @@ static inline int unregister_pm_notifier(struct notifier_block *nb)
 #define pm_notifier(fn, pri)	do { (void)(fn); } while (0)
 
 static inline bool pm_wakeup_pending(void) { return false; }
+static inline void pm_system_wakeup(void) {}
+static inline void pm_wakeup_clear(void) {}
 
 static inline void lock_system_sleep(void) {}
 static inline void unlock_system_sleep(void) {}

kernel/power/process.c

@@ -129,6 +129,7 @@ int freeze_processes(void)
 	if (!pm_freezing)
 		atomic_inc(&system_freezing_cnt);
 
+	pm_wakeup_clear();
 	printk("Freezing user space processes ... ");
 	pm_freezing = true;
 	error = try_to_freeze_tasks(true);