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7dfb7103 NC |
1 | /* Freezer declarations */ |
2 | ||
83144186 RW |
3 | #ifndef FREEZER_H_INCLUDED |
4 | #define FREEZER_H_INCLUDED | |
5 | ||
5c543eff RD |
6 | #include <linux/sched.h> |
7 | ||
7dfb7103 NC |
8 | #ifdef CONFIG_PM |
9 | /* | |
10 | * Check if a process has been frozen | |
11 | */ | |
12 | static 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 | */ | |
20 | static inline int freezing(struct task_struct *p) | |
21 | { | |
8a102eed | 22 | return test_tsk_thread_flag(p, TIF_FREEZE); |
7dfb7103 NC |
23 | } |
24 | ||
25 | /* | |
26 | * Request that a process be frozen | |
7dfb7103 NC |
27 | */ |
28 | static inline void freeze(struct task_struct *p) | |
29 | { | |
8a102eed | 30 | set_tsk_thread_flag(p, TIF_FREEZE); |
7dfb7103 NC |
31 | } |
32 | ||
33 | /* | |
34 | * Sometimes we may need to cancel the previous 'freeze' request | |
35 | */ | |
36 | static inline void do_not_freeze(struct task_struct *p) | |
37 | { | |
8a102eed | 38 | clear_tsk_thread_flag(p, TIF_FREEZE); |
7dfb7103 NC |
39 | } |
40 | ||
41 | /* | |
42 | * Wake up a frozen process | |
33e1c288 RW |
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. | |
7dfb7103 NC |
49 | */ |
50 | static inline int thaw_process(struct task_struct *p) | |
51 | { | |
33e1c288 | 52 | task_lock(p); |
7dfb7103 NC |
53 | if (frozen(p)) { |
54 | p->flags &= ~PF_FROZEN; | |
33e1c288 | 55 | task_unlock(p); |
7dfb7103 NC |
56 | wake_up_process(p); |
57 | return 1; | |
58 | } | |
33e1c288 RW |
59 | clear_tsk_thread_flag(p, TIF_FREEZE); |
60 | task_unlock(p); | |
7dfb7103 NC |
61 | return 0; |
62 | } | |
63 | ||
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64 | extern void refrigerator(void); |
65 | extern int freeze_processes(void); | |
a9b6f562 | 66 | extern void thaw_processes(void); |
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67 | |
68 | static inline int try_to_freeze(void) | |
69 | { | |
70 | if (freezing(current)) { | |
71 | refrigerator(); | |
72 | return 1; | |
73 | } else | |
74 | return 0; | |
75 | } | |
ff39593a | 76 | |
ba96a0c8 RW |
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 | */ | |
95 | static 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 | */ | |
105 | static 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 | */ | |
116 | static inline int freezer_should_skip(struct task_struct *p) | |
117 | { | |
118 | return !!(p->flags & PF_FREEZER_SKIP); | |
119 | } | |
ff39593a | 120 | |
83144186 RW |
121 | /* |
122 | * Tell the freezer that the current task should be frozen by it | |
123 | */ | |
124 | static inline void set_freezable(void) | |
125 | { | |
126 | current->flags &= ~PF_NOFREEZE; | |
127 | } | |
128 | ||
7dfb7103 NC |
129 | #else |
130 | static inline int frozen(struct task_struct *p) { return 0; } | |
131 | static inline int freezing(struct task_struct *p) { return 0; } | |
132 | static inline void freeze(struct task_struct *p) { BUG(); } | |
133 | static inline int thaw_process(struct task_struct *p) { return 1; } | |
7dfb7103 NC |
134 | |
135 | static inline void refrigerator(void) {} | |
136 | static inline int freeze_processes(void) { BUG(); return 0; } | |
137 | static inline void thaw_processes(void) {} | |
138 | ||
139 | static inline int try_to_freeze(void) { return 0; } | |
140 | ||
ba96a0c8 RW |
141 | static inline void freezer_do_not_count(void) {} |
142 | static inline void freezer_count(void) {} | |
143 | static inline int freezer_should_skip(struct task_struct *p) { return 0; } | |
83144186 | 144 | static inline void set_freezable(void) {} |
7dfb7103 | 145 | #endif |
83144186 RW |
146 | |
147 | #endif /* FREEZER_H_INCLUDED */ |