PM / sleep: Make lock/unlock_system_sleep() available to kernel modules

Since pm_mutex is not exported using lock/unlock_system_sleep() from
inside a kernel module causes a "pm_mutex undefined" linker error.
Hence move lock/unlock_system_sleep() into kernel/power/main.c and
export these.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

include/linux/suspend.h

@@ -443,32 +443,8 @@ extern bool pm_save_wakeup_count(unsigned int count);
 extern void pm_wakep_autosleep_enabled(bool set);
 extern void pm_print_active_wakeup_sources(void);
 
-static inline void lock_system_sleep(void)
-{
-	current->flags |= PF_FREEZER_SKIP;
-	mutex_lock(&pm_mutex);
-}
-
-static inline void unlock_system_sleep(void)
-{
-	/*
-	 * Don't use freezer_count() because we don't want the call to
-	 * try_to_freeze() here.
-	 *
-	 * Reason:
-	 * Fundamentally, we just don't need it, because freezing condition
-	 * doesn't come into effect until we release the pm_mutex lock,
-	 * since the freezer always works with pm_mutex held.
-	 *
-	 * More importantly, in the case of hibernation,
-	 * unlock_system_sleep() gets called in snapshot_read() and
-	 * snapshot_write() when the freezing condition is still in effect.
-	 * Which means, if we use try_to_freeze() here, it would make them
-	 * enter the refrigerator, thus causing hibernation to lockup.
-	 */
-	current->flags &= ~PF_FREEZER_SKIP;
-	mutex_unlock(&pm_mutex);
-}
+extern void lock_system_sleep(void);
+extern void unlock_system_sleep(void);
 
 #else /* !CONFIG_PM_SLEEP */
 

kernel/power/main.c

@@ -22,6 +22,35 @@ DEFINE_MUTEX(pm_mutex);
 
 #ifdef CONFIG_PM_SLEEP
 
+void lock_system_sleep(void)
+{
+	current->flags |= PF_FREEZER_SKIP;
+	mutex_lock(&pm_mutex);
+}
+EXPORT_SYMBOL_GPL(lock_system_sleep);
+
+void unlock_system_sleep(void)
+{
+	/*
+	 * Don't use freezer_count() because we don't want the call to
+	 * try_to_freeze() here.
+	 *
+	 * Reason:
+	 * Fundamentally, we just don't need it, because freezing condition
+	 * doesn't come into effect until we release the pm_mutex lock,
+	 * since the freezer always works with pm_mutex held.
+	 *
+	 * More importantly, in the case of hibernation,
+	 * unlock_system_sleep() gets called in snapshot_read() and
+	 * snapshot_write() when the freezing condition is still in effect.
+	 * Which means, if we use try_to_freeze() here, it would make them
+	 * enter the refrigerator, thus causing hibernation to lockup.
+	 */
+	current->flags &= ~PF_FREEZER_SKIP;
+	mutex_unlock(&pm_mutex);
+}
+EXPORT_SYMBOL_GPL(unlock_system_sleep);
+
 /* Routines for PM-transition notifications */
 
 static BLOCKING_NOTIFIER_HEAD(pm_chain_head);