/* Freezer declarations */
#ifndef FREEZER_H_INCLUDED
#define FREEZER_H_INCLUDED
#include <linux/sched.h>
#include <linux/wait.h>
#ifdef CONFIG_FREEZER
/*
* 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);
}
static inline bool should_send_signal(struct task_struct *p)
{
return !(p->flags & PF_FREEZER_NOSIG);
}
/* Takes and releases task alloc lock using task_lock() */
extern int thaw_process(struct task_struct *p);
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;
}
extern bool freeze_task(struct task_struct *p, bool sig_only);
extern void cancel_freezing(struct task_struct *p);
#ifdef CONFIG_CGROUP_FREEZER
extern int cgroup_freezing_or_frozen(struct task_struct *task);
#else /* !CONFIG_CGROUP_FREEZER */
static inline int cgroup_freezing_or_frozen(struct task_struct *task)
{
return 0;
}
#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.
*/
/* Tell the freezer not to count the current task as freezable. */
static inline void freezer_do_not_count(void)
{
current->flags |= PF_FREEZER_SKIP;
}
/*
* Tell the freezer to count the current task as freezable again and try to
* freeze it.
*/
static inline void freezer_count(void)
{
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;
}
/*
* Tell the freezer that the current task should be frozen by it and that it
* should send a fake signal to the task to freeze it.
*/
static inline void set_freezable_with_signal(void)
{
current->flags &= ~(PF_NOFREEZE | PF_FREEZER_NOSIG);
}
/*
* These macros are intended to be used whenever you want allow a task that's
* sleeping in TASK_UNINTERRUPTIBLE or TASK_KILLABLE state 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. It may return immediately
* if it ends up racing with the freezer. Callers must be able to deal with
* spurious wakeups.
*/
#define freezable_schedule() \
({ \
freezer_do_not_count(); \
if (!try_to_freeze()) \
schedule(); \
freezer_count(); \
})
/*
* Like schedule_timeout_killable(), but should not block the freezer. It may
* end up returning immediately if it ends up racing with the freezer. Callers
* must be able to deal with the loose wakeup timing that can occur when the
* freezer races in. When that occurs, this function will return the timeout
* value instead of 0.
*/
#define freezable_schedule_timeout_killable(timeout) \
({ \
long __retval; \
freezer_do_not_count(); \
if (!try_to_freeze()) \
__retval = schedule_timeout_killable(timeout); \
else \
__retval = timeout; \
freezer_count(); \
__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(); \
if (!try_to_freeze()) \
__retval = wait_event_killable(wq, (condition)); \
else \
__retval = 0; \
freezer_count(); \
__retval; \
})
#define wait_event_freezable(wq, condition) \
({ \
int __retval; \
do { \
__retval = wait_event_interruptible(wq, \
(condition) || freezing(current)); \
if (__retval && !freezing(current)) \
break; \
else if (!(condition)) \
__retval = -ERESTARTSYS; \
} while (try_to_freeze()); \
__retval; \
})
#define wait_event_freezable_timeout(wq, condition, timeout) \
({ \
long __retval = timeout; \
do { \
__retval = wait_event_interruptible_timeout(wq, \
(condition) || freezing(current), \
__retval); \
} while (try_to_freeze()); \
__retval; \
})
#else /* !CONFIG_FREEZER */
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) {}
static inline void set_freezable_with_signal(void) {}
#define freezable_schedule() schedule()
#define freezable_schedule_timeout_killable(timeout) \
schedule_timeout_killable(timeout)
#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_freezekillable(wq, condition) \
wait_event_killable(wq, condition)
#endif /* !CONFIG_FREEZER */
#endif /* FREEZER_H_INCLUDED */
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