root/include/linux/freezer.h

INCLUDED FROM

DEFINITIONS

1. frozen
2. freezing
3. try_to_freeze_unsafe
4. try_to_freeze
5. cgroup_freezing
6. freezer_do_not_count
7. freezer_count
8. freezer_count_unsafe
9. freezer_should_skip
10. freezable_schedule
11. freezable_schedule_unsafe
12. freezable_schedule_timeout
13. freezable_schedule_timeout_interruptible
14. freezable_schedule_timeout_killable
15. freezable_schedule_timeout_killable_unsafe
16. freezable_schedule_hrtimeout_range
17. frozen
18. freezing
19. __thaw_task
20. __refrigerator
21. freeze_processes
22. freeze_kernel_threads
23. thaw_processes
24. thaw_kernel_threads
25. try_to_freeze_nowarn
26. try_to_freeze
27. freezer_do_not_count
28. freezer_count
29. freezer_should_skip
30. set_freezable

/* Freezer declarations */

#ifndef FREEZER_H_INCLUDED
#define FREEZER_H_INCLUDED

#include <linux/debug_locks.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/atomic.h>

#ifdef CONFIG_FREEZER
extern atomic_t system_freezing_cnt;    /* nr of freezing conds in effect */
extern bool pm_freezing;                /* PM freezing in effect */
extern bool pm_nosig_freezing;          /* PM nosig freezing in effect */

/*
 * Timeout for stopping processes
 */
extern unsigned int freeze_timeout_msecs;

/*
 * Check if a process has been frozen
 */
static inline bool frozen(struct task_struct *p)
{
        return p->flags & PF_FROZEN;
}

extern bool freezing_slow_path(struct task_struct *p);

/*
 * Check if there is a request to freeze a process
 */
static inline bool freezing(struct task_struct *p)
{
        if (likely(!atomic_read(&system_freezing_cnt)))
                return false;
        return freezing_slow_path(p);
}

/* Takes and releases task alloc lock using task_lock() */
extern void __thaw_task(struct task_struct *t);

extern bool __refrigerator(bool check_kthr_stop);
extern int freeze_processes(void);
extern int freeze_kernel_threads(void);
extern void thaw_processes(void);
extern void thaw_kernel_threads(void);

/*
 * DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION
 * If try_to_freeze causes a lockdep warning it means the caller may deadlock
 */
static inline bool try_to_freeze_unsafe(void)
{
        might_sleep();
        if (likely(!freezing(current)))
                return false;
        return __refrigerator(false);
}

static inline bool try_to_freeze(void)
{
        if (!(current->flags & PF_NOFREEZE))
                debug_check_no_locks_held();
        return try_to_freeze_unsafe();
}

extern bool freeze_task(struct task_struct *p);
extern bool set_freezable(void);

#ifdef CONFIG_CGROUP_FREEZER
extern bool cgroup_freezing(struct task_struct *task);
#else /* !CONFIG_CGROUP_FREEZER */
static inline bool cgroup_freezing(struct task_struct *task)
{
        return false;
}
#endif /* !CONFIG_CGROUP_FREEZER */

/*
 * 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. 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.
 */


/**
 * freezer_do_not_count - tell freezer to ignore %current
 *
 * Tell freezers to ignore the current task when determining whether the
 * target frozen state is reached.  IOW, the current task will be
 * considered frozen enough by freezers.
 *
 * The caller shouldn't do anything which isn't allowed for a frozen task
 * until freezer_cont() is called.  Usually, freezer[_do_not]_count() pair
 * wrap a scheduling operation and nothing much else.
 */
static inline void freezer_do_not_count(void)
{
        current->flags |= PF_FREEZER_SKIP;
}

/**
 * freezer_count - tell freezer to stop ignoring %current
 *
 * Undo freezer_do_not_count().  It tells freezers that %current should be
 * considered again and tries to freeze if freezing condition is already in
 * effect.
 */
static inline void freezer_count(void)
{
        current->flags &= ~PF_FREEZER_SKIP;
        /*
         * If freezing is in progress, the following paired with smp_mb()
         * in freezer_should_skip() ensures that either we see %true
         * freezing() or freezer_should_skip() sees !PF_FREEZER_SKIP.
         */
        smp_mb();
        try_to_freeze();
}

/* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */
static inline void freezer_count_unsafe(void)
{
        current->flags &= ~PF_FREEZER_SKIP;
        smp_mb();
        try_to_freeze_unsafe();
}

/**
 * freezer_should_skip - whether to skip a task when determining frozen
 *                       state is reached
 * @p: task in quesion
 *
 * This function is used by freezers after establishing %true freezing() to
 * test whether a task should be skipped when determining the target frozen
 * state is reached.  IOW, if this function returns %true, @p is considered
 * frozen enough.
 */
static inline bool freezer_should_skip(struct task_struct *p)
{
        /*
         * The following smp_mb() paired with the one in freezer_count()
         * ensures that either freezer_count() sees %true freezing() or we
         * see cleared %PF_FREEZER_SKIP and return %false.  This makes it
         * impossible for a task to slip frozen state testing after
         * clearing %PF_FREEZER_SKIP.
         */
        smp_mb();
        return p->flags & PF_FREEZER_SKIP;
}

/*
 * These functions are intended to be used whenever you want allow a sleeping
 * task to be frozen. Note that neither return any clear indication of
 * whether a freeze event happened while in this function.
 */

/* Like schedule(), but should not block the freezer. */
static inline void freezable_schedule(void)
{
        freezer_do_not_count();
        schedule();
        freezer_count();
}

/* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */
static inline void freezable_schedule_unsafe(void)
{
        freezer_do_not_count();
        schedule();
        freezer_count_unsafe();
}

/*
 * Like freezable_schedule_timeout(), but should not block the freezer.  Do not
 * call this with locks held.
 */
static inline long freezable_schedule_timeout(long timeout)
{
        long __retval;
        freezer_do_not_count();
        __retval = schedule_timeout(timeout);
        freezer_count();
        return __retval;
}

/*
 * Like schedule_timeout_interruptible(), but should not block the freezer.  Do not
 * call this with locks held.
 */
static inline long freezable_schedule_timeout_interruptible(long timeout)
{
        long __retval;
        freezer_do_not_count();
        __retval = schedule_timeout_interruptible(timeout);
        freezer_count();
        return __retval;
}

/* Like schedule_timeout_killable(), but should not block the freezer. */
static inline long freezable_schedule_timeout_killable(long timeout)
{
        long __retval;
        freezer_do_not_count();
        __retval = schedule_timeout_killable(timeout);
        freezer_count();
        return __retval;
}

/* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */
static inline long freezable_schedule_timeout_killable_unsafe(long timeout)
{
        long __retval;
        freezer_do_not_count();
        __retval = schedule_timeout_killable(timeout);
        freezer_count_unsafe();
        return __retval;
}

/*
 * Like schedule_hrtimeout_range(), but should not block the freezer.  Do not
 * call this with locks held.
 */
static inline int freezable_schedule_hrtimeout_range(ktime_t *expires,
                unsigned long delta, const enum hrtimer_mode mode)
{
        int __retval;
        freezer_do_not_count();
        __retval = schedule_hrtimeout_range(expires, delta, mode);
        freezer_count();
        return __retval;
}

/*
 * Freezer-friendly wrappers around wait_event_interruptible(),
 * wait_event_killable() and wait_event_interruptible_timeout(), originally
 * defined in <linux/wait.h>
 */

#define wait_event_freezekillable(wq, condition)                        \
({                                                                      \
        int __retval;                                                   \
        freezer_do_not_count();                                         \
        __retval = wait_event_killable(wq, (condition));                \
        freezer_count();                                                \
        __retval;                                                       \
})

/* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */
#define wait_event_freezekillable_unsafe(wq, condition)                 \
({                                                                      \
        int __retval;                                                   \
        freezer_do_not_count();                                         \
        __retval = wait_event_killable(wq, (condition));                \
        freezer_count_unsafe();                                         \
        __retval;                                                       \
})

#define wait_event_freezable(wq, condition)                             \
({                                                                      \
        int __retval;                                                   \
        freezer_do_not_count();                                         \
        __retval = wait_event_interruptible(wq, (condition));           \
        freezer_count();                                                \
        __retval;                                                       \
})

#define wait_event_freezable_timeout(wq, condition, timeout)            \
({                                                                      \
        long __retval = timeout;                                        \
        freezer_do_not_count();                                         \
        __retval = wait_event_interruptible_timeout(wq, (condition),    \
                                __retval);                              \
        freezer_count();                                                \
        __retval;                                                       \
})

#define wait_event_freezable_exclusive(wq, condition)                   \
({                                                                      \
        int __retval;                                                   \
        freezer_do_not_count();                                         \
        __retval = wait_event_interruptible_exclusive(wq, condition);   \
        freezer_count();                                                \
        __retval;                                                       \
})


#else /* !CONFIG_FREEZER */
static inline bool frozen(struct task_struct *p) { return false; }
static inline bool freezing(struct task_struct *p) { return false; }
static inline void __thaw_task(struct task_struct *t) {}

static inline bool __refrigerator(bool check_kthr_stop) { return false; }
static inline int freeze_processes(void) { return -ENOSYS; }
static inline int freeze_kernel_threads(void) { return -ENOSYS; }
static inline void thaw_processes(void) {}
static inline void thaw_kernel_threads(void) {}

static inline bool try_to_freeze_nowarn(void) { return false; }
static inline bool try_to_freeze(void) { return false; }

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) {}

#define freezable_schedule()  schedule()

#define freezable_schedule_unsafe()  schedule()

#define freezable_schedule_timeout(timeout)  schedule_timeout(timeout)

#define freezable_schedule_timeout_interruptible(timeout)               \
        schedule_timeout_interruptible(timeout)

#define freezable_schedule_timeout_killable(timeout)                    \
        schedule_timeout_killable(timeout)

#define freezable_schedule_timeout_killable_unsafe(timeout)             \
        schedule_timeout_killable(timeout)

#define freezable_schedule_hrtimeout_range(expires, delta, mode)        \
        schedule_hrtimeout_range(expires, delta, mode)

#define wait_event_freezable(wq, condition)                             \
                wait_event_interruptible(wq, condition)

#define wait_event_freezable_timeout(wq, condition, timeout)            \
                wait_event_interruptible_timeout(wq, condition, timeout)

#define wait_event_freezable_exclusive(wq, condition)                   \
                wait_event_interruptible_exclusive(wq, condition)

#define wait_event_freezekillable(wq, condition)                \
                wait_event_killable(wq, condition)

#define wait_event_freezekillable_unsafe(wq, condition)                 \
                wait_event_killable(wq, condition)

#endif /* !CONFIG_FREEZER */

#endif  /* FREEZER_H_INCLUDED */