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/* 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 */
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