The [un]lock_system_sleep() APIs were originally introduced to mutually
exclude memory hotplug and hibernation.
Directly using mutex_lock(&pm_mutex) to achieve mutual exclusion with
suspend or hibernation code can lead to freezing failures. However, the
APIs [un]lock_system_sleep() can be safely used to achieve the same,
without causing freezing failures.
So, since it would be beneficial to modify all the existing users of
mutex_lock(&pm_mutex) (in all parts of the kernel), so that they use these
safe APIs intead, make these APIs generic by removing the restriction that
they work only when CONFIG_HIBERNATE_CALLBACKS is set. Moreover, that
restriction didn't buy us anything anyway.
v2: Rebased on top of the patchset posted at:
https://lkml.org/lkml/2011/12/6/334
Suggested-by: Tejun Heo <tj at kernel.org>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat at linux.vnet.ibm.com>
---
include/linux/suspend.h | 36 ++++++++++++++++--------------------
1 files changed, 16 insertions(+), 20 deletions(-)
diff --git a/include/linux/suspend.h b/include/linux/suspend.h
index 906d62c..95040cc 100644
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -332,6 +332,8 @@ 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
void save_processor_state(void);
void restore_processor_state(void);
@@ -352,6 +354,19 @@ extern bool events_check_enabled;
extern bool pm_wakeup_pending(void);
extern bool pm_get_wakeup_count(unsigned int *count);
extern bool pm_save_wakeup_count(unsigned int count);
+
+static inline void lock_system_sleep(void)
+{
+ freezer_do_not_count();
+ mutex_lock(&pm_mutex);
+}
+
+static inline void unlock_system_sleep(void)
+{
+ mutex_unlock(&pm_mutex);
+ freezer_count();
+}
+
#else /* !CONFIG_PM_SLEEP */
static inline int register_pm_notifier(struct notifier_block *nb)
@@ -367,30 +382,11 @@ 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; }
-#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) {}
-#else
-
-/* Let some subsystems like memory hotadd exclude hibernation */
-
-static inline void lock_system_sleep(void)
-{
- freezer_do_not_count();
- mutex_lock(&pm_mutex);
-}
-
-static inline void unlock_system_sleep(void)
-{
- mutex_unlock(&pm_mutex);
- freezer_count();
-}
-#endif
+#endif /* !CONFIG_PM_SLEEP */
#ifdef CONFIG_ARCH_SAVE_PAGE_KEYS
/*
