1 /* Freezer declarations */
2
3 #ifndef FREEZER_H_INCLUDED
4 #define FREEZER_H_INCLUDED
5
6 #include <linux/sched.h>
7 #include <linux/wait.h>
8
9 #ifdef CONFIG_PM_SLEEP
10 /*
11 * Check if a process has been frozen
12 */
13 static inline int frozen(struct task_struct *p)
14 {
15 return p->flags & PF_FROZEN;
16 }
17
18 /*
19 * Check if there is a request to freeze a process
20 */
21 static inline int freezing(struct task_struct *p)
22 {
23 return test_tsk_thread_flag(p, TIF_FREEZE);
24 }
25
26 /*
27 * Request that a process be frozen
28 */
29 static inline void set_freeze_flag(struct task_struct *p)
30 {
31 set_tsk_thread_flag(p, TIF_FREEZE);
32 }
33
34 /*
35 * Sometimes we may need to cancel the previous 'freeze' request
36 */
37 static inline void clear_freeze_flag(struct task_struct *p)
38 {
39 clear_tsk_thread_flag(p, TIF_FREEZE);
40 }
41
42 /*
43 * Wake up a frozen process
44 *
45 * task_lock() is taken to prevent the race with refrigerator() which may
46 * occur if the freezing of tasks fails. Namely, without the lock, if the
47 * freezing of tasks failed, thaw_tasks() might have run before a task in
48 * refrigerator() could call frozen_process(), in which case the task would be
49 * frozen and no one would thaw it.
50 */
51 static inline int thaw_process(struct task_struct *p)
52 {
53 task_lock(p);
54 if (frozen(p)) {
55 p->flags &= ~PF_FROZEN;
56 task_unlock(p);
57 wake_up_process(p);
58 return 1;
59 }
60 clear_freeze_flag(p);
61 task_unlock(p);
62 return 0;
63 }
64
65 extern void refrigerator(void);
66 extern int freeze_processes(void);
67 extern void thaw_processes(void);
68
69 static inline int try_to_freeze(void)
70 {
71 if (freezing(current)) {
72 refrigerator();
73 return 1;
74 } else
75 return 0;
76 }
77
78 /*
79 * The PF_FREEZER_SKIP flag should be set by a vfork parent right before it
80 * calls wait_for_completion(&vfork) and reset right after it returns from this
81 * function. Next, the parent should call try_to_freeze() to freeze itself
82 * appropriately in case the child has exited before the freezing of tasks is
83 * complete. However, we don't want kernel threads to be frozen in unexpected
84 * places, so we allow them to block freeze_processes() instead or to set
85 * PF_NOFREEZE if needed and PF_FREEZER_SKIP is only set for userland vfork
86 * parents. Fortunately, in the ____call_usermodehelper() case the parent won't
87 * really block freeze_processes(), since ____call_usermodehelper() (the child)
88 * does a little before exec/exit and it can't be frozen before waking up the
89 * parent.
90 */
91
92 /*
93 * If the current task is a user space one, tell the freezer not to count it as
94 * freezable.
95 */
96 static inline void freezer_do_not_count(void)
97 {
98 if (current->mm)
99 current->flags |= PF_FREEZER_SKIP;
100 }
101
102 /*
103 * If the current task is a user space one, tell the freezer to count it as
104 * freezable again and try to freeze it.
105 */
106 static inline void freezer_count(void)
107 {
108 if (current->mm) {
109 current->flags &= ~PF_FREEZER_SKIP;
110 try_to_freeze();
111 }
112 }
113
114 /*
115 * Check if the task should be counted as freezeable by the freezer
116 */
117 static inline int freezer_should_skip(struct task_struct *p)
118 {
119 return !!(p->flags & PF_FREEZER_SKIP);
120 }
121
122 /*
123 * Tell the freezer that the current task should be frozen by it
124 */
125 static inline void set_freezable(void)
126 {
127 current->flags &= ~PF_NOFREEZE;
128 }
129
130 /*
131 * Freezer-friendly wrappers around wait_event_interruptible() and
132 * wait_event_interruptible_timeout(), originally defined in <linux/wait.h>
133 */
134
135 #define wait_event_freezable(wq, condition) \
136 ({ \
137 int __retval; \
138 do { \
139 __retval = wait_event_interruptible(wq, \
140 (condition) || freezing(current)); \
141 if (__retval && !freezing(current)) \
142 break; \
143 else if (!(condition)) \
144 __retval = -ERESTARTSYS; \
145 } while (try_to_freeze()); \
146 __retval; \
147 })
148
149
150 #define wait_event_freezable_timeout(wq, condition, timeout) \
151 ({ \
152 long __retval = timeout; \
153 do { \
154 __retval = wait_event_interruptible_timeout(wq, \
155 (condition) || freezing(current), \
156 __retval); \
157 } while (try_to_freeze()); \
158 __retval; \
159 })
160 #else /* !CONFIG_PM_SLEEP */
161 static inline int frozen(struct task_struct *p) { return 0; }
162 static inline int freezing(struct task_struct *p) { return 0; }
163 static inline void set_freeze_flag(struct task_struct *p) {}
164 static inline void clear_freeze_flag(struct task_struct *p) {}
165 static inline int thaw_process(struct task_struct *p) { return 1; }
166
167 static inline void refrigerator(void) {}
168 static inline int freeze_processes(void) { BUG(); return 0; }
169 static inline void thaw_processes(void) {}
170
171 static inline int try_to_freeze(void) { return 0; }
172
173 static inline void freezer_do_not_count(void) {}
174 static inline void freezer_count(void) {}
175 static inline int freezer_should_skip(struct task_struct *p) { return 0; }
176 static inline void set_freezable(void) {}
177
178 #define wait_event_freezable(wq, condition) \
179 wait_event_interruptible(wq, condition)
180
181 #define wait_event_freezable_timeout(wq, condition, timeout) \
182 wait_event_interruptible_timeout(wq, condition, timeout)
183
184 #endif /* !CONFIG_PM_SLEEP */
185
186 #endif /* FREEZER_H_INCLUDED */
187
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