[PATCH v2 1/3] Introduce helper functions

["Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>]

Introduce helper functions used to prevent cpu hotplug (online operation) from
running in parallel with suspend or hibernate.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
---

 include/linux/suspend.h |   21 +++++++++++++++++++--
 1 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/include/linux/suspend.h b/include/linux/suspend.h
index 6bbcef2..89a5d27 100644
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -276,7 +276,24 @@ static inline bool system_entering_hibernation(void) { return false; }
 #define PM_RESTORE_PREPARE	0x0005 /* Going to restore a saved image */
 #define PM_POST_RESTORE		0x0006 /* Restore failed */
 
+extern struct mutex pm_mutex;
+
 #ifdef CONFIG_PM_SLEEP
+
+/*
+ * Allow operations like CPU online to exclude suspend and hibernation
+ */
+static inline int trylock_pm_sleep(void)
+{
+	return mutex_trylock(&pm_mutex);
+}
+
+static inline void unlock_pm_sleep(void)
+{
+	mutex_unlock(&pm_mutex);
+}
+
 void save_processor_state(void);
 void restore_processor_state(void);
 
@@ -298,6 +315,8 @@ extern bool pm_get_wakeup_count(unsigned int *count);
 extern bool pm_save_wakeup_count(unsigned int count);
 #else /* !CONFIG_PM_SLEEP */
 
+static inline int trylock_pm_sleep(void) { return 1; }
+static inline void unlock_pm_sleep(void) {}
 static inline int register_pm_notifier(struct notifier_block *nb)
 {
 	return 0;
@@ -313,8 +332,6 @@ static inline int unregister_pm_notifier(struct notifier_block *nb)
 static inline bool pm_wakeup_pending(void) { return false; }
 #endif /* !CONFIG_PM_SLEEP */
 
-extern struct mutex pm_mutex;
-
 #ifndef CONFIG_HIBERNATE_CALLBACKS
 static inline void lock_system_sleep(void) {}
 static inline void unlock_system_sleep(void) {}