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1 | /* Freezer declarations */ |
2 | |
3 | #ifndef FREEZER_H_INCLUDED |
4 | #define FREEZER_H_INCLUDED |
5 | |
6 | #include <linux/debug_locks.h> |
7 | #include <linux/sched.h> |
8 | #include <linux/wait.h> |
9 | #include <linux/atomic.h> |
10 | |
11 | #ifdef CONFIG_FREEZER |
12 | extern atomic_t system_freezing_cnt; /* nr of freezing conds in effect */ |
13 | extern bool pm_freezing; /* PM freezing in effect */ |
14 | extern bool pm_nosig_freezing; /* PM nosig freezing in effect */ |
15 | |
16 | /* |
17 | * Timeout for stopping processes |
18 | */ |
19 | extern unsigned int freeze_timeout_msecs; |
20 | |
21 | /* |
22 | * Check if a process has been frozen |
23 | */ |
24 | static inline bool frozen(struct task_struct *p) |
25 | { |
26 | return p->flags & PF_FROZEN; |
27 | } |
28 | |
29 | extern bool freezing_slow_path(struct task_struct *p); |
30 | |
31 | /* |
32 | * Check if there is a request to freeze a process |
33 | */ |
34 | static inline bool freezing(struct task_struct *p) |
35 | { |
36 | if (likely(!atomic_read(&system_freezing_cnt))) |
37 | return false; |
38 | return freezing_slow_path(p); |
39 | } |
40 | |
41 | /* Takes and releases task alloc lock using task_lock() */ |
42 | extern void __thaw_task(struct task_struct *t); |
43 | |
44 | extern bool __refrigerator(bool check_kthr_stop); |
45 | extern int freeze_processes(void); |
46 | extern int freeze_kernel_threads(void); |
47 | extern void thaw_processes(void); |
48 | extern void thaw_kernel_threads(void); |
49 | |
50 | /* |
51 | * DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION |
52 | * If try_to_freeze causes a lockdep warning it means the caller may deadlock |
53 | */ |
54 | static inline bool try_to_freeze_unsafe(void) |
55 | { |
56 | might_sleep(); |
57 | if (likely(!freezing(current))) |
58 | return false; |
59 | return __refrigerator(false); |
60 | } |
61 | |
62 | static inline bool try_to_freeze(void) |
63 | { |
64 | if (!(current->flags & PF_NOFREEZE)) |
65 | debug_check_no_locks_held(); |
66 | return try_to_freeze_unsafe(); |
67 | } |
68 | |
69 | extern bool freeze_task(struct task_struct *p); |
70 | extern bool set_freezable(void); |
71 | |
72 | #ifdef CONFIG_CGROUP_FREEZER |
73 | extern bool cgroup_freezing(struct task_struct *task); |
74 | #else /* !CONFIG_CGROUP_FREEZER */ |
75 | static inline bool cgroup_freezing(struct task_struct *task) |
76 | { |
77 | return false; |
78 | } |
79 | #endif /* !CONFIG_CGROUP_FREEZER */ |
80 | |
81 | /* |
82 | * The PF_FREEZER_SKIP flag should be set by a vfork parent right before it |
83 | * calls wait_for_completion(&vfork) and reset right after it returns from this |
84 | * function. Next, the parent should call try_to_freeze() to freeze itself |
85 | * appropriately in case the child has exited before the freezing of tasks is |
86 | * complete. However, we don't want kernel threads to be frozen in unexpected |
87 | * places, so we allow them to block freeze_processes() instead or to set |
88 | * PF_NOFREEZE if needed. Fortunately, in the ____call_usermodehelper() case the |
89 | * parent won't really block freeze_processes(), since ____call_usermodehelper() |
90 | * (the child) does a little before exec/exit and it can't be frozen before |
91 | * waking up the parent. |
92 | */ |
93 | |
94 | |
95 | /** |
96 | * freezer_do_not_count - tell freezer to ignore %current |
97 | * |
98 | * Tell freezers to ignore the current task when determining whether the |
99 | * target frozen state is reached. IOW, the current task will be |
100 | * considered frozen enough by freezers. |
101 | * |
102 | * The caller shouldn't do anything which isn't allowed for a frozen task |
103 | * until freezer_cont() is called. Usually, freezer[_do_not]_count() pair |
104 | * wrap a scheduling operation and nothing much else. |
105 | */ |
106 | static inline void freezer_do_not_count(void) |
107 | { |
108 | current->flags |= PF_FREEZER_SKIP; |
109 | } |
110 | |
111 | /** |
112 | * freezer_count - tell freezer to stop ignoring %current |
113 | * |
114 | * Undo freezer_do_not_count(). It tells freezers that %current should be |
115 | * considered again and tries to freeze if freezing condition is already in |
116 | * effect. |
117 | */ |
118 | static inline void freezer_count(void) |
119 | { |
120 | current->flags &= ~PF_FREEZER_SKIP; |
121 | /* |
122 | * If freezing is in progress, the following paired with smp_mb() |
123 | * in freezer_should_skip() ensures that either we see %true |
124 | * freezing() or freezer_should_skip() sees !PF_FREEZER_SKIP. |
125 | */ |
126 | smp_mb(); |
127 | try_to_freeze(); |
128 | } |
129 | |
130 | /* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */ |
131 | static inline void freezer_count_unsafe(void) |
132 | { |
133 | current->flags &= ~PF_FREEZER_SKIP; |
134 | smp_mb(); |
135 | try_to_freeze_unsafe(); |
136 | } |
137 | |
138 | /** |
139 | * freezer_should_skip - whether to skip a task when determining frozen |
140 | * state is reached |
141 | * @p: task in quesion |
142 | * |
143 | * This function is used by freezers after establishing %true freezing() to |
144 | * test whether a task should be skipped when determining the target frozen |
145 | * state is reached. IOW, if this function returns %true, @p is considered |
146 | * frozen enough. |
147 | */ |
148 | static inline bool freezer_should_skip(struct task_struct *p) |
149 | { |
150 | /* |
151 | * The following smp_mb() paired with the one in freezer_count() |
152 | * ensures that either freezer_count() sees %true freezing() or we |
153 | * see cleared %PF_FREEZER_SKIP and return %false. This makes it |
154 | * impossible for a task to slip frozen state testing after |
155 | * clearing %PF_FREEZER_SKIP. |
156 | */ |
157 | smp_mb(); |
158 | return p->flags & PF_FREEZER_SKIP; |
159 | } |
160 | |
161 | /* |
162 | * These functions are intended to be used whenever you want allow a sleeping |
163 | * task to be frozen. Note that neither return any clear indication of |
164 | * whether a freeze event happened while in this function. |
165 | */ |
166 | |
167 | /* Like schedule(), but should not block the freezer. */ |
168 | static inline void freezable_schedule(void) |
169 | { |
170 | freezer_do_not_count(); |
171 | schedule(); |
172 | freezer_count(); |
173 | } |
174 | |
175 | /* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */ |
176 | static inline void freezable_schedule_unsafe(void) |
177 | { |
178 | freezer_do_not_count(); |
179 | schedule(); |
180 | freezer_count_unsafe(); |
181 | } |
182 | |
183 | /* |
184 | * Like freezable_schedule_timeout(), but should not block the freezer. Do not |
185 | * call this with locks held. |
186 | */ |
187 | static inline long freezable_schedule_timeout(long timeout) |
188 | { |
189 | long __retval; |
190 | freezer_do_not_count(); |
191 | __retval = schedule_timeout(timeout); |
192 | freezer_count(); |
193 | return __retval; |
194 | } |
195 | |
196 | /* |
197 | * Like schedule_timeout_interruptible(), but should not block the freezer. Do not |
198 | * call this with locks held. |
199 | */ |
200 | static inline long freezable_schedule_timeout_interruptible(long timeout) |
201 | { |
202 | long __retval; |
203 | freezer_do_not_count(); |
204 | __retval = schedule_timeout_interruptible(timeout); |
205 | freezer_count(); |
206 | return __retval; |
207 | } |
208 | |
209 | /* Like schedule_timeout_killable(), but should not block the freezer. */ |
210 | static inline long freezable_schedule_timeout_killable(long timeout) |
211 | { |
212 | long __retval; |
213 | freezer_do_not_count(); |
214 | __retval = schedule_timeout_killable(timeout); |
215 | freezer_count(); |
216 | return __retval; |
217 | } |
218 | |
219 | /* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */ |
220 | static inline long freezable_schedule_timeout_killable_unsafe(long timeout) |
221 | { |
222 | long __retval; |
223 | freezer_do_not_count(); |
224 | __retval = schedule_timeout_killable(timeout); |
225 | freezer_count_unsafe(); |
226 | return __retval; |
227 | } |
228 | |
229 | /* |
230 | * Like schedule_hrtimeout_range(), but should not block the freezer. Do not |
231 | * call this with locks held. |
232 | */ |
233 | static inline int freezable_schedule_hrtimeout_range(ktime_t *expires, |
234 | unsigned long delta, const enum hrtimer_mode mode) |
235 | { |
236 | int __retval; |
237 | freezer_do_not_count(); |
238 | __retval = schedule_hrtimeout_range(expires, delta, mode); |
239 | freezer_count(); |
240 | return __retval; |
241 | } |
242 | |
243 | /* |
244 | * Freezer-friendly wrappers around wait_event_interruptible(), |
245 | * wait_event_killable() and wait_event_interruptible_timeout(), originally |
246 | * defined in <linux/wait.h> |
247 | */ |
248 | |
249 | #define wait_event_freezekillable(wq, condition) \ |
250 | ({ \ |
251 | int __retval; \ |
252 | freezer_do_not_count(); \ |
253 | __retval = wait_event_killable(wq, (condition)); \ |
254 | freezer_count(); \ |
255 | __retval; \ |
256 | }) |
257 | |
258 | /* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */ |
259 | #define wait_event_freezekillable_unsafe(wq, condition) \ |
260 | ({ \ |
261 | int __retval; \ |
262 | freezer_do_not_count(); \ |
263 | __retval = wait_event_killable(wq, (condition)); \ |
264 | freezer_count_unsafe(); \ |
265 | __retval; \ |
266 | }) |
267 | |
268 | #define wait_event_freezable(wq, condition) \ |
269 | ({ \ |
270 | int __retval; \ |
271 | freezer_do_not_count(); \ |
272 | __retval = wait_event_interruptible(wq, (condition)); \ |
273 | freezer_count(); \ |
274 | __retval; \ |
275 | }) |
276 | |
277 | #define wait_event_freezable_timeout(wq, condition, timeout) \ |
278 | ({ \ |
279 | long __retval = timeout; \ |
280 | freezer_do_not_count(); \ |
281 | __retval = wait_event_interruptible_timeout(wq, (condition), \ |
282 | __retval); \ |
283 | freezer_count(); \ |
284 | __retval; \ |
285 | }) |
286 | |
287 | #define wait_event_freezable_exclusive(wq, condition) \ |
288 | ({ \ |
289 | int __retval; \ |
290 | freezer_do_not_count(); \ |
291 | __retval = wait_event_interruptible_exclusive(wq, condition); \ |
292 | freezer_count(); \ |
293 | __retval; \ |
294 | }) |
295 | |
296 | |
297 | #else /* !CONFIG_FREEZER */ |
298 | static inline bool frozen(struct task_struct *p) { return false; } |
299 | static inline bool freezing(struct task_struct *p) { return false; } |
300 | static inline void __thaw_task(struct task_struct *t) {} |
301 | |
302 | static inline bool __refrigerator(bool check_kthr_stop) { return false; } |
303 | static inline int freeze_processes(void) { return -ENOSYS; } |
304 | static inline int freeze_kernel_threads(void) { return -ENOSYS; } |
305 | static inline void thaw_processes(void) {} |
306 | static inline void thaw_kernel_threads(void) {} |
307 | |
308 | static inline bool try_to_freeze_nowarn(void) { return false; } |
309 | static inline bool try_to_freeze(void) { return false; } |
310 | |
311 | static inline void freezer_do_not_count(void) {} |
312 | static inline void freezer_count(void) {} |
313 | static inline int freezer_should_skip(struct task_struct *p) { return 0; } |
314 | static inline void set_freezable(void) {} |
315 | |
316 | #define freezable_schedule() schedule() |
317 | |
318 | #define freezable_schedule_unsafe() schedule() |
319 | |
320 | #define freezable_schedule_timeout(timeout) schedule_timeout(timeout) |
321 | |
322 | #define freezable_schedule_timeout_interruptible(timeout) \ |
323 | schedule_timeout_interruptible(timeout) |
324 | |
325 | #define freezable_schedule_timeout_killable(timeout) \ |
326 | schedule_timeout_killable(timeout) |
327 | |
328 | #define freezable_schedule_timeout_killable_unsafe(timeout) \ |
329 | schedule_timeout_killable(timeout) |
330 | |
331 | #define freezable_schedule_hrtimeout_range(expires, delta, mode) \ |
332 | schedule_hrtimeout_range(expires, delta, mode) |
333 | |
334 | #define wait_event_freezable(wq, condition) \ |
335 | wait_event_interruptible(wq, condition) |
336 | |
337 | #define wait_event_freezable_timeout(wq, condition, timeout) \ |
338 | wait_event_interruptible_timeout(wq, condition, timeout) |
339 | |
340 | #define wait_event_freezable_exclusive(wq, condition) \ |
341 | wait_event_interruptible_exclusive(wq, condition) |
342 | |
343 | #define wait_event_freezekillable(wq, condition) \ |
344 | wait_event_killable(wq, condition) |
345 | |
346 | #define wait_event_freezekillable_unsafe(wq, condition) \ |
347 | wait_event_killable(wq, condition) |
348 | |
349 | #endif /* !CONFIG_FREEZER */ |
350 | |
351 | #endif /* FREEZER_H_INCLUDED */ |
352 |
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