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/* Freezer declarations */
#ifndef FREEZER_H_INCLUDED
#define FREEZER_H_INCLUDED
#include <linux/sched.h>
#ifdef CONFIG_PM
/*
* Check if a process has been frozen
*/
static inline int frozen(struct task_struct *p)
{
return p->flags & PF_FROZEN;
}
/*
* Check if there is a request to freeze a process
*/
static inline int freezing(struct task_struct *p)
{
return test_tsk_thread_flag(p, TIF_FREEZE);
}
/*
* Request that a process be frozen
*/
static inline void set_freeze_flag(struct task_struct *p)
{
set_tsk_thread_flag(p, TIF_FREEZE);
}
/*
* Sometimes we may need to cancel the previous 'freeze' request
*/
static inline void clear_freeze_flag(struct task_struct *p)
{
clear_tsk_thread_flag(p, TIF_FREEZE);
}
/*
* Wake up a frozen process
*
* task_lock() is taken to prevent the race with refrigerator() which may
* occur if the freezing of tasks fails. Namely, without the lock, if the
* freezing of tasks failed, thaw_tasks() might have run before a task in
* refrigerator() could call frozen_process(), in which case the task would be
* frozen and no one would thaw it.
*/
static inline int thaw_process(struct task_struct *p)
{
task_lock(p);
if (frozen(p)) {
p->flags &= ~PF_FROZEN;
task_unlock(p);
wake_up_process(p);
return 1;
}
clear_freeze_flag(p);
task_unlock(p);
return 0;
}
extern void refrigerator(void);
extern int freeze_processes(void);
extern void thaw_processes(void);
static inline int try_to_freeze(void)
{
if (freezing(current)) {
refrigerator();
return 1;
} else
return 0;
}
/*
* The PF_FREEZER_SKIP flag should be set by a vfork parent right before it
* calls wait_for_completion(&vfork) and reset right after it returns from this
* function. Next, the parent should call try_to_freeze() to freeze itself
* appropriately in case the child has exited before the freezing of tasks is
* complete. However, we don't want kernel threads to be frozen in unexpected
* places, so we allow them to block freeze_processes() instead or to set
* PF_NOFREEZE if needed and PF_FREEZER_SKIP is only set for userland vfork
* parents. Fortunately, in the ____call_usermodehelper() case the parent won't
* really block freeze_processes(), since ____call_usermodehelper() (the child)
* does a little before exec/exit and it can't be frozen before waking up the
* parent.
*/
/*
* If the current task is a user space one, tell the freezer not to count it as
* freezable.
*/
static inline void freezer_do_not_count(void)
{
if (current->mm)
current->flags |= PF_FREEZER_SKIP;
}
/*
* If the current task is a user space one, tell the freezer to count it as
* freezable again and try to freeze it.
*/
static inline void freezer_count(void)
{
if (current->mm) {
current->flags &= ~PF_FREEZER_SKIP;
try_to_freeze();
}
}
/*
* Check if the task should be counted as freezeable by the freezer
*/
static inline int freezer_should_skip(struct task_struct *p)
{
return !!(p->flags & PF_FREEZER_SKIP);
}
/*
* Tell the freezer that the current task should be frozen by it
*/
static inline void set_freezable(void)
{
current->flags &= ~PF_NOFREEZE;
}
#else
static inline int frozen(struct task_struct *p) { return 0; }
static inline int freezing(struct task_struct *p) { return 0; }
static inline void set_freeze_flag(struct task_struct *p) {}
static inline void clear_freeze_flag(struct task_struct *p) {}
static inline int thaw_process(struct task_struct *p) { return 1; }
static inline void refrigerator(void) {}
static inline int freeze_processes(void) { BUG(); return 0; }
static inline void thaw_processes(void) {}
static inline int try_to_freeze(void) { return 0; }
static inline void freezer_do_not_count(void) {}
static inline void freezer_count(void) {}
static inline int freezer_should_skip(struct task_struct *p) { return 0; }
static inline void set_freezable(void) {}
#endif
#endif /* FREEZER_H_INCLUDED */
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