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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 | #include <linux/atomic.h> |
9 | |
10 | #ifdef CONFIG_FREEZER |
11 | extern atomic_t system_freezing_cnt; /* nr of freezing conds in effect */ |
12 | extern bool pm_freezing; /* PM freezing in effect */ |
13 | extern bool pm_nosig_freezing; /* PM nosig freezing in effect */ |
14 | |
15 | /* |
16 | * Timeout for stopping processes |
17 | */ |
18 | extern unsigned int freeze_timeout_msecs; |
19 | |
20 | /* |
21 | * Check if a process has been frozen |
22 | */ |
23 | static inline bool frozen(struct task_struct *p) |
24 | { |
25 | return p->flags & PF_FROZEN; |
26 | } |
27 | |
28 | extern bool freezing_slow_path(struct task_struct *p); |
29 | |
30 | /* |
31 | * Check if there is a request to freeze a process |
32 | */ |
33 | static inline bool freezing(struct task_struct *p) |
34 | { |
35 | if (likely(!atomic_read(&system_freezing_cnt))) |
36 | return false; |
37 | return freezing_slow_path(p); |
38 | } |
39 | |
40 | /* Takes and releases task alloc lock using task_lock() */ |
41 | extern void __thaw_task(struct task_struct *t); |
42 | |
43 | extern bool __refrigerator(bool check_kthr_stop); |
44 | extern int freeze_processes(void); |
45 | extern int freeze_kernel_threads(void); |
46 | extern void thaw_processes(void); |
47 | extern void thaw_kernel_threads(void); |
48 | |
49 | static inline bool try_to_freeze(void) |
50 | { |
51 | might_sleep(); |
52 | if (likely(!freezing(current))) |
53 | return false; |
54 | return __refrigerator(false); |
55 | } |
56 | |
57 | extern bool freeze_task(struct task_struct *p); |
58 | extern bool set_freezable(void); |
59 | |
60 | #ifdef CONFIG_CGROUP_FREEZER |
61 | extern bool cgroup_freezing(struct task_struct *task); |
62 | #else /* !CONFIG_CGROUP_FREEZER */ |
63 | static inline bool cgroup_freezing(struct task_struct *task) |
64 | { |
65 | return false; |
66 | } |
67 | #endif /* !CONFIG_CGROUP_FREEZER */ |
68 | |
69 | /* |
70 | * The PF_FREEZER_SKIP flag should be set by a vfork parent right before it |
71 | * calls wait_for_completion(&vfork) and reset right after it returns from this |
72 | * function. Next, the parent should call try_to_freeze() to freeze itself |
73 | * appropriately in case the child has exited before the freezing of tasks is |
74 | * complete. However, we don't want kernel threads to be frozen in unexpected |
75 | * places, so we allow them to block freeze_processes() instead or to set |
76 | * PF_NOFREEZE if needed. Fortunately, in the ____call_usermodehelper() case the |
77 | * parent won't really block freeze_processes(), since ____call_usermodehelper() |
78 | * (the child) does a little before exec/exit and it can't be frozen before |
79 | * waking up the parent. |
80 | */ |
81 | |
82 | |
83 | /** |
84 | * freezer_do_not_count - tell freezer to ignore %current |
85 | * |
86 | * Tell freezers to ignore the current task when determining whether the |
87 | * target frozen state is reached. IOW, the current task will be |
88 | * considered frozen enough by freezers. |
89 | * |
90 | * The caller shouldn't do anything which isn't allowed for a frozen task |
91 | * until freezer_cont() is called. Usually, freezer[_do_not]_count() pair |
92 | * wrap a scheduling operation and nothing much else. |
93 | */ |
94 | static inline void freezer_do_not_count(void) |
95 | { |
96 | current->flags |= PF_FREEZER_SKIP; |
97 | } |
98 | |
99 | /** |
100 | * freezer_count - tell freezer to stop ignoring %current |
101 | * |
102 | * Undo freezer_do_not_count(). It tells freezers that %current should be |
103 | * considered again and tries to freeze if freezing condition is already in |
104 | * effect. |
105 | */ |
106 | static inline void freezer_count(void) |
107 | { |
108 | current->flags &= ~PF_FREEZER_SKIP; |
109 | /* |
110 | * If freezing is in progress, the following paired with smp_mb() |
111 | * in freezer_should_skip() ensures that either we see %true |
112 | * freezing() or freezer_should_skip() sees !PF_FREEZER_SKIP. |
113 | */ |
114 | smp_mb(); |
115 | try_to_freeze(); |
116 | } |
117 | |
118 | /** |
119 | * freezer_should_skip - whether to skip a task when determining frozen |
120 | * state is reached |
121 | * @p: task in quesion |
122 | * |
123 | * This function is used by freezers after establishing %true freezing() to |
124 | * test whether a task should be skipped when determining the target frozen |
125 | * state is reached. IOW, if this function returns %true, @p is considered |
126 | * frozen enough. |
127 | */ |
128 | static inline bool freezer_should_skip(struct task_struct *p) |
129 | { |
130 | /* |
131 | * The following smp_mb() paired with the one in freezer_count() |
132 | * ensures that either freezer_count() sees %true freezing() or we |
133 | * see cleared %PF_FREEZER_SKIP and return %false. This makes it |
134 | * impossible for a task to slip frozen state testing after |
135 | * clearing %PF_FREEZER_SKIP. |
136 | */ |
137 | smp_mb(); |
138 | return p->flags & PF_FREEZER_SKIP; |
139 | } |
140 | |
141 | /* |
142 | * These macros are intended to be used whenever you want allow a sleeping |
143 | * task to be frozen. Note that neither return any clear indication of |
144 | * whether a freeze event happened while in this function. |
145 | */ |
146 | |
147 | /* Like schedule(), but should not block the freezer. */ |
148 | #define freezable_schedule() \ |
149 | ({ \ |
150 | freezer_do_not_count(); \ |
151 | schedule(); \ |
152 | freezer_count(); \ |
153 | }) |
154 | |
155 | /* Like schedule_timeout_killable(), but should not block the freezer. */ |
156 | #define freezable_schedule_timeout_killable(timeout) \ |
157 | ({ \ |
158 | long __retval; \ |
159 | freezer_do_not_count(); \ |
160 | __retval = schedule_timeout_killable(timeout); \ |
161 | freezer_count(); \ |
162 | __retval; \ |
163 | }) |
164 | |
165 | /* |
166 | * Freezer-friendly wrappers around wait_event_interruptible(), |
167 | * wait_event_killable() and wait_event_interruptible_timeout(), originally |
168 | * defined in <linux/wait.h> |
169 | */ |
170 | |
171 | #define wait_event_freezekillable(wq, condition) \ |
172 | ({ \ |
173 | int __retval; \ |
174 | freezer_do_not_count(); \ |
175 | __retval = wait_event_killable(wq, (condition)); \ |
176 | freezer_count(); \ |
177 | __retval; \ |
178 | }) |
179 | |
180 | #define wait_event_freezable(wq, condition) \ |
181 | ({ \ |
182 | int __retval; \ |
183 | for (;;) { \ |
184 | __retval = wait_event_interruptible(wq, \ |
185 | (condition) || freezing(current)); \ |
186 | if (__retval || (condition)) \ |
187 | break; \ |
188 | try_to_freeze(); \ |
189 | } \ |
190 | __retval; \ |
191 | }) |
192 | |
193 | #define wait_event_freezable_timeout(wq, condition, timeout) \ |
194 | ({ \ |
195 | long __retval = timeout; \ |
196 | for (;;) { \ |
197 | __retval = wait_event_interruptible_timeout(wq, \ |
198 | (condition) || freezing(current), \ |
199 | __retval); \ |
200 | if (__retval <= 0 || (condition)) \ |
201 | break; \ |
202 | try_to_freeze(); \ |
203 | } \ |
204 | __retval; \ |
205 | }) |
206 | |
207 | #else /* !CONFIG_FREEZER */ |
208 | static inline bool frozen(struct task_struct *p) { return false; } |
209 | static inline bool freezing(struct task_struct *p) { return false; } |
210 | static inline void __thaw_task(struct task_struct *t) {} |
211 | |
212 | static inline bool __refrigerator(bool check_kthr_stop) { return false; } |
213 | static inline int freeze_processes(void) { return -ENOSYS; } |
214 | static inline int freeze_kernel_threads(void) { return -ENOSYS; } |
215 | static inline void thaw_processes(void) {} |
216 | static inline void thaw_kernel_threads(void) {} |
217 | |
218 | static inline bool try_to_freeze_nowarn(void) { return false; } |
219 | static inline bool try_to_freeze(void) { return false; } |
220 | |
221 | static inline void freezer_do_not_count(void) {} |
222 | static inline void freezer_count(void) {} |
223 | static inline int freezer_should_skip(struct task_struct *p) { return 0; } |
224 | static inline void set_freezable(void) {} |
225 | |
226 | #define freezable_schedule() schedule() |
227 | |
228 | #define freezable_schedule_timeout_killable(timeout) \ |
229 | schedule_timeout_killable(timeout) |
230 | |
231 | #define wait_event_freezable(wq, condition) \ |
232 | wait_event_interruptible(wq, condition) |
233 | |
234 | #define wait_event_freezable_timeout(wq, condition, timeout) \ |
235 | wait_event_interruptible_timeout(wq, condition, timeout) |
236 | |
237 | #define wait_event_freezekillable(wq, condition) \ |
238 | wait_event_killable(wq, condition) |
239 | |
240 | #endif /* !CONFIG_FREEZER */ |
241 | |
242 | #endif /* FREEZER_H_INCLUDED */ |
243 |
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