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PM / Sleep: Make [un]lock_system_sleep() generic 

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.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
This commit is contained in:
Srivatsa S. Bhat 2011-12-06 23:24:38 +01:00 committed by Rafael J. Wysocki
parent 33e638b907
commit 9b6fc5dc87
1 changed files with 16 additions and 20 deletions
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36
include/linux/suspend.h
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@ -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
/*