246 lines
7.3 KiB
C++
246 lines
7.3 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/debug_locks.h>
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#include <linux/sched.h>
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#include <linux/wait.h>
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#include <linux/atomic.h>
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#ifdef CONFIG_FREEZER
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extern atomic_t system_freezing_cnt; /* nr of freezing conds in effect */
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extern bool pm_freezing; /* PM freezing in effect */
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extern bool pm_nosig_freezing; /* PM nosig freezing in effect */
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/*
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* Timeout for stopping processes
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*/
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extern unsigned int freeze_timeout_msecs;
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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 bool 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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extern bool freezing_slow_path(struct task_struct *p);
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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 bool freezing(struct task_struct *p)
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{
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if (likely(!atomic_read(&system_freezing_cnt)))
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return false;
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return freezing_slow_path(p);
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}
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/* Takes and releases task alloc lock using task_lock() */
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extern void __thaw_task(struct task_struct *t);
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extern bool __refrigerator(bool check_kthr_stop);
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extern int freeze_processes(void);
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extern int freeze_kernel_threads(void);
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extern void thaw_processes(void);
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extern void thaw_kernel_threads(void);
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static inline bool try_to_freeze(void)
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{
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if (!(current->flags & PF_NOFREEZE))
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debug_check_no_locks_held();
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might_sleep();
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if (likely(!freezing(current)))
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return false;
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return __refrigerator(false);
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}
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extern bool freeze_task(struct task_struct *p);
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extern bool set_freezable(void);
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#ifdef CONFIG_CGROUP_FREEZER
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extern bool cgroup_freezing(struct task_struct *task);
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#else /* !CONFIG_CGROUP_FREEZER */
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static inline bool cgroup_freezing(struct task_struct *task)
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{
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return false;
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}
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#endif /* !CONFIG_CGROUP_FREEZER */
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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. Fortunately, in the ____call_usermodehelper() case the
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* parent won't really block freeze_processes(), since ____call_usermodehelper()
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* (the child) does a little before exec/exit and it can't be frozen before
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* waking up the parent.
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*/
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/**
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* freezer_do_not_count - tell freezer to ignore %current
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*
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* Tell freezers to ignore the current task when determining whether the
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* target frozen state is reached. IOW, the current task will be
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* considered frozen enough by freezers.
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*
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* The caller shouldn't do anything which isn't allowed for a frozen task
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* until freezer_cont() is called. Usually, freezer[_do_not]_count() pair
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* wrap a scheduling operation and nothing much else.
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*/
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static inline void freezer_do_not_count(void)
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{
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current->flags |= PF_FREEZER_SKIP;
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}
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/**
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* freezer_count - tell freezer to stop ignoring %current
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*
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* Undo freezer_do_not_count(). It tells freezers that %current should be
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* considered again and tries to freeze if freezing condition is already in
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* effect.
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*/
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static inline void freezer_count(void)
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{
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current->flags &= ~PF_FREEZER_SKIP;
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/*
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* If freezing is in progress, the following paired with smp_mb()
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* in freezer_should_skip() ensures that either we see %true
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* freezing() or freezer_should_skip() sees !PF_FREEZER_SKIP.
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*/
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smp_mb();
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try_to_freeze();
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}
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/**
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* freezer_should_skip - whether to skip a task when determining frozen
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* state is reached
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* @p: task in quesion
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*
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* This function is used by freezers after establishing %true freezing() to
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* test whether a task should be skipped when determining the target frozen
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* state is reached. IOW, if this function returns %true, @p is considered
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* frozen enough.
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*/
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static inline bool freezer_should_skip(struct task_struct *p)
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{
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/*
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* The following smp_mb() paired with the one in freezer_count()
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* ensures that either freezer_count() sees %true freezing() or we
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* see cleared %PF_FREEZER_SKIP and return %false. This makes it
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* impossible for a task to slip frozen state testing after
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* clearing %PF_FREEZER_SKIP.
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*/
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smp_mb();
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return p->flags & PF_FREEZER_SKIP;
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}
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/*
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* These macros are intended to be used whenever you want allow a sleeping
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* task to be frozen. Note that neither return any clear indication of
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* whether a freeze event happened while in this function.
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*/
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/* Like schedule(), but should not block the freezer. */
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#define freezable_schedule() \
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({ \
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freezer_do_not_count(); \
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schedule(); \
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freezer_count(); \
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})
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/* Like schedule_timeout_killable(), but should not block the freezer. */
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#define freezable_schedule_timeout_killable(timeout) \
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({ \
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long __retval; \
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freezer_do_not_count(); \
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__retval = schedule_timeout_killable(timeout); \
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freezer_count(); \
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__retval; \
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})
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/*
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* Freezer-friendly wrappers around wait_event_interruptible(),
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* wait_event_killable() and wait_event_interruptible_timeout(), originally
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* defined in <linux/wait.h>
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*/
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#define wait_event_freezekillable(wq, condition) \
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({ \
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int __retval; \
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freezer_do_not_count(); \
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__retval = wait_event_killable(wq, (condition)); \
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freezer_count(); \
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__retval; \
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})
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#define wait_event_freezable(wq, condition) \
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({ \
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int __retval; \
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for (;;) { \
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__retval = wait_event_interruptible(wq, \
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(condition) || freezing(current)); \
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if (__retval || (condition)) \
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break; \
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try_to_freeze(); \
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} \
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__retval; \
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})
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#define wait_event_freezable_timeout(wq, condition, timeout) \
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({ \
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long __retval = timeout; \
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for (;;) { \
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__retval = wait_event_interruptible_timeout(wq, \
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(condition) || freezing(current), \
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__retval); \
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if (__retval <= 0 || (condition)) \
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break; \
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try_to_freeze(); \
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} \
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__retval; \
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})
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#else /* !CONFIG_FREEZER */
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static inline bool frozen(struct task_struct *p) { return false; }
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static inline bool freezing(struct task_struct *p) { return false; }
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static inline void __thaw_task(struct task_struct *t) {}
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static inline bool __refrigerator(bool check_kthr_stop) { return false; }
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static inline int freeze_processes(void) { return -ENOSYS; }
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static inline int freeze_kernel_threads(void) { return -ENOSYS; }
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static inline void thaw_processes(void) {}
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static inline void thaw_kernel_threads(void) {}
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static inline bool try_to_freeze_nowarn(void) { return false; }
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static inline bool try_to_freeze(void) { return false; }
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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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#define freezable_schedule() schedule()
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#define freezable_schedule_timeout_killable(timeout) \
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schedule_timeout_killable(timeout)
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#define wait_event_freezable(wq, condition) \
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wait_event_interruptible(wq, condition)
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#define wait_event_freezable_timeout(wq, condition, timeout) \
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wait_event_interruptible_timeout(wq, condition, timeout)
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#define wait_event_freezekillable(wq, condition) \
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wait_event_killable(wq, condition)
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#endif /* !CONFIG_FREEZER */
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#endif /* FREEZER_H_INCLUDED */
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