Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/* Freezer declarations */
2
3#ifndef FREEZER_H_INCLUDED
4#define FREEZER_H_INCLUDED
5
6#include <linux/sched.h>
7
8#ifdef CONFIG_PM_SLEEP
9/*
10 * Check if a process has been frozen
11 */
12static inline int frozen(struct task_struct *p)
13{
14 return p->flags & PF_FROZEN;
15}
16
17/*
18 * Check if there is a request to freeze a process
19 */
20static inline int freezing(struct task_struct *p)
21{
22 return test_tsk_thread_flag(p, TIF_FREEZE);
23}
24
25/*
26 * Request that a process be frozen
27 */
28static inline void set_freeze_flag(struct task_struct *p)
29{
30 set_tsk_thread_flag(p, TIF_FREEZE);
31}
32
33/*
34 * Sometimes we may need to cancel the previous 'freeze' request
35 */
36static inline void clear_freeze_flag(struct task_struct *p)
37{
38 clear_tsk_thread_flag(p, TIF_FREEZE);
39}
40
41/*
42 * Wake up a frozen process
43 *
44 * task_lock() is taken to prevent the race with refrigerator() which may
45 * occur if the freezing of tasks fails. Namely, without the lock, if the
46 * freezing of tasks failed, thaw_tasks() might have run before a task in
47 * refrigerator() could call frozen_process(), in which case the task would be
48 * frozen and no one would thaw it.
49 */
50static inline int thaw_process(struct task_struct *p)
51{
52 task_lock(p);
53 if (frozen(p)) {
54 p->flags &= ~PF_FROZEN;
55 task_unlock(p);
56 wake_up_process(p);
57 return 1;
58 }
59 clear_freeze_flag(p);
60 task_unlock(p);
61 return 0;
62}
63
64extern void refrigerator(void);
65extern int freeze_processes(void);
66extern void thaw_processes(void);
67
68static inline int try_to_freeze(void)
69{
70 if (freezing(current)) {
71 refrigerator();
72 return 1;
73 } else
74 return 0;
75}
76
77/*
78 * The PF_FREEZER_SKIP flag should be set by a vfork parent right before it
79 * calls wait_for_completion(&vfork) and reset right after it returns from this
80 * function. Next, the parent should call try_to_freeze() to freeze itself
81 * appropriately in case the child has exited before the freezing of tasks is
82 * complete. However, we don't want kernel threads to be frozen in unexpected
83 * places, so we allow them to block freeze_processes() instead or to set
84 * PF_NOFREEZE if needed and PF_FREEZER_SKIP is only set for userland vfork
85 * parents. Fortunately, in the ____call_usermodehelper() case the parent won't
86 * really block freeze_processes(), since ____call_usermodehelper() (the child)
87 * does a little before exec/exit and it can't be frozen before waking up the
88 * parent.
89 */
90
91/*
92 * If the current task is a user space one, tell the freezer not to count it as
93 * freezable.
94 */
95static inline void freezer_do_not_count(void)
96{
97 if (current->mm)
98 current->flags |= PF_FREEZER_SKIP;
99}
100
101/*
102 * If the current task is a user space one, tell the freezer to count it as
103 * freezable again and try to freeze it.
104 */
105static inline void freezer_count(void)
106{
107 if (current->mm) {
108 current->flags &= ~PF_FREEZER_SKIP;
109 try_to_freeze();
110 }
111}
112
113/*
114 * Check if the task should be counted as freezeable by the freezer
115 */
116static inline int freezer_should_skip(struct task_struct *p)
117{
118 return !!(p->flags & PF_FREEZER_SKIP);
119}
120
121/*
122 * Tell the freezer that the current task should be frozen by it
123 */
124static inline void set_freezable(void)
125{
126 current->flags &= ~PF_NOFREEZE;
127}
128
129#else /* !CONFIG_PM_SLEEP */
130static inline int frozen(struct task_struct *p) { return 0; }
131static inline int freezing(struct task_struct *p) { return 0; }
132static inline void set_freeze_flag(struct task_struct *p) {}
133static inline void clear_freeze_flag(struct task_struct *p) {}
134static inline int thaw_process(struct task_struct *p) { return 1; }
135
136static inline void refrigerator(void) {}
137static inline int freeze_processes(void) { BUG(); return 0; }
138static inline void thaw_processes(void) {}
139
140static inline int try_to_freeze(void) { return 0; }
141
142static inline void freezer_do_not_count(void) {}
143static inline void freezer_count(void) {}
144static inline int freezer_should_skip(struct task_struct *p) { return 0; }
145static inline void set_freezable(void) {}
146#endif /* !CONFIG_PM_SLEEP */
147
148#endif /* FREEZER_H_INCLUDED */