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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>
This commit is contained in:
Bart Van Assche 2018-01-05 09:19:08 -08:00 committed by Rafael J. Wysocki
parent bdbc98abb3
commit 4bf236a333
2 changed files with 31 additions and 26 deletions
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28
include/linux/suspend.h
View File

@ -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 */

29
kernel/power/main.c
View File

@ -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);