/* SPDX-License-Identifier: GPL-2.0 */ /* 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 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, u64 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> */ /* 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; \ }) #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_freezekillable_unsafe(wq, condition) \ wait_event_killable(wq, condition) #endif /* !CONFIG_FREEZER */ #endif /* FREEZER_H_INCLUDED */