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_FREEZER
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 static inline bool should_send_signal(struct task_struct *p)
43 {
44 return !(p->flags & PF_FREEZER_NOSIG);
45 }
46
47 /* Takes and releases task alloc lock using task_lock() */
48 extern int thaw_process(struct task_struct *p);
49
50 extern void refrigerator(void);
51 extern int freeze_processes(void);
52 extern void thaw_processes(void);
53
54 static inline int try_to_freeze(void)
55 {
56 if (freezing(current)) {
57 refrigerator();
58 return 1;
59 } else
60 return 0;
61 }
62
63 extern bool freeze_task(struct task_struct *p, bool sig_only);
64 extern void cancel_freezing(struct task_struct *p);
65
66 #ifdef CONFIG_CGROUP_FREEZER
67 extern int cgroup_frozen(struct task_struct *task);
68 #else /* !CONFIG_CGROUP_FREEZER */
69 static inline int cgroup_frozen(struct task_struct *task) { return 0; }
70 #endif /* !CONFIG_CGROUP_FREEZER */
71
72 /*
73 * The PF_FREEZER_SKIP flag should be set by a vfork parent right before it
74 * calls wait_for_completion(&vfork) and reset right after it returns from this
75 * function. Next, the parent should call try_to_freeze() to freeze itself
76 * appropriately in case the child has exited before the freezing of tasks is
77 * complete. However, we don't want kernel threads to be frozen in unexpected
78 * places, so we allow them to block freeze_processes() instead or to set
79 * PF_NOFREEZE if needed and PF_FREEZER_SKIP is only set for userland vfork
80 * parents. Fortunately, in the ____call_usermodehelper() case the parent won't
81 * really block freeze_processes(), since ____call_usermodehelper() (the child)
82 * does a little before exec/exit and it can't be frozen before waking up the
83 * parent.
84 */
85
86 /*
87 * If the current task is a user space one, tell the freezer not to count it as
88 * freezable.
89 */
90 static inline void freezer_do_not_count(void)
91 {
92 if (current->mm)
93 current->flags |= PF_FREEZER_SKIP;
94 }
95
96 /*
97 * If the current task is a user space one, tell the freezer to count it as
98 * freezable again and try to freeze it.
99 */
100 static inline void freezer_count(void)
101 {
102 if (current->mm) {
103 current->flags &= ~PF_FREEZER_SKIP;
104 try_to_freeze();
105 }
106 }
107
108 /*
109 * Check if the task should be counted as freezeable by the freezer
110 */
111 static inline int freezer_should_skip(struct task_struct *p)
112 {
113 return !!(p->flags & PF_FREEZER_SKIP);
114 }
115
116 /*
117 * Tell the freezer that the current task should be frozen by it
118 */
119 static inline void set_freezable(void)
120 {
121 current->flags &= ~PF_NOFREEZE;
122 }
123
124 /*
125 * Tell the freezer that the current task should be frozen by it and that it
126 * should send a fake signal to the task to freeze it.
127 */
128 static inline void set_freezable_with_signal(void)
129 {
130 current->flags &= ~(PF_NOFREEZE | PF_FREEZER_NOSIG);
131 }
132
133 /*
134 * Freezer-friendly wrappers around wait_event_interruptible() and
135 * wait_event_interruptible_timeout(), originally defined in <linux/wait.h>
136 */
137
138 #define wait_event_freezable(wq, condition) \
139 ({ \
140 int __retval; \
141 do { \
142 __retval = wait_event_interruptible(wq, \
143 (condition) || freezing(current)); \
144 if (__retval && !freezing(current)) \
145 break; \
146 else if (!(condition)) \
147 __retval = -ERESTARTSYS; \
148 } while (try_to_freeze()); \
149 __retval; \
150 })
151
152
153 #define wait_event_freezable_timeout(wq, condition, timeout) \
154 ({ \
155 long __retval = timeout; \
156 do { \
157 __retval = wait_event_interruptible_timeout(wq, \
158 (condition) || freezing(current), \
159 __retval); \
160 } while (try_to_freeze()); \
161 __retval; \
162 })
163 #else /* !CONFIG_FREEZER */
164 static inline int frozen(struct task_struct *p) { return 0; }
165 static inline int freezing(struct task_struct *p) { return 0; }
166 static inline void set_freeze_flag(struct task_struct *p) {}
167 static inline void clear_freeze_flag(struct task_struct *p) {}
168 static inline int thaw_process(struct task_struct *p) { return 1; }
169
170 static inline void refrigerator(void) {}
171 static inline int freeze_processes(void) { BUG(); return 0; }
172 static inline void thaw_processes(void) {}
173
174 static inline int try_to_freeze(void) { return 0; }
175
176 static inline void freezer_do_not_count(void) {}
177 static inline void freezer_count(void) {}
178 static inline int freezer_should_skip(struct task_struct *p) { return 0; }
179 static inline void set_freezable(void) {}
180 static inline void set_freezable_with_signal(void) {}
181
182 #define wait_event_freezable(wq, condition) \
183 wait_event_interruptible(wq, condition)
184
185 #define wait_event_freezable_timeout(wq, condition, timeout) \
186 wait_event_interruptible_timeout(wq, condition, timeout)
187
188 #endif /* !CONFIG_FREEZER */
189
190 #endif /* FREEZER_H_INCLUDED */
191
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