PM / hibernate: introduce system_in_hibernation

hulk inclusion
category: bugfix
bugzilla: 26326
CVE: NA

-------------------------------------------------
Introduce boolean function system_in_hibernation() returning
'true' when the system carrying out hibernation.

Some device drivers or syscore need such a function to check
if it is in the phase of hibernation.
Signed-off-by: NHongbo Yao <yaohongbo@huawei.com>
Reviewed-by: NHanjun Guo <guohanjun@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

include/linux/suspend.h

@@ -414,6 +414,7 @@ extern asmlinkage int swsusp_arch_resume(void);
 extern void hibernation_set_ops(const struct platform_hibernation_ops *ops);
 extern int hibernate(void);
 extern bool system_entering_hibernation(void);
+extern bool system_in_hibernation(void);
 extern bool hibernation_available(void);
 asmlinkage int swsusp_save(void);
 extern struct pbe *restore_pblist;
@@ -427,6 +428,7 @@ static inline void swsusp_unset_page_free(struct page *p) {}
 static inline void hibernation_set_ops(const struct platform_hibernation_ops *ops) {}
 static inline int hibernate(void) { return -ENOSYS; }
 static inline bool system_entering_hibernation(void) { return false; }
+static inline bool system_in_hibernation(void) { return false; }
 static inline bool hibernation_available(void) { return false; }
 #endif /* CONFIG_HIBERNATION */
 

kernel/power/hibernate.c

@@ -104,6 +104,15 @@ bool system_entering_hibernation(void)
 }
 EXPORT_SYMBOL(system_entering_hibernation);
 
+/* To let some devices or syscore know if system carrying out hibernation*/
+static bool carry_out_hibernation;
+
+bool system_in_hibernation(void)
+{
+	return carry_out_hibernation;
+}
+EXPORT_SYMBOL(system_in_hibernation);
+
 #ifdef CONFIG_PM_DEBUG
 static void hibernation_debug_sleep(void)
 {
@@ -711,6 +720,7 @@ int hibernate(void)
 	}
 
 	pr_info("hibernation entry\n");
+	carry_out_hibernation = true;
 	pm_prepare_console();
 	error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls);
 	if (error) {
@@ -781,6 +791,7 @@ int hibernate(void)
 	atomic_inc(&snapshot_device_available);
  Unlock:
 	unlock_system_sleep();
+	carry_out_hibernation = false;
 	pr_info("hibernation exit\n");
 
 	return error;