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