Line data Source code
1 : /* SPDX-License-Identifier: GPL-2.0 */
2 : #ifndef _LINUX_WAIT_BIT_H
3 : #define _LINUX_WAIT_BIT_H
4 :
5 : /*
6 : * Linux wait-bit related types and methods:
7 : */
8 : #include <linux/wait.h>
9 :
10 : struct wait_bit_key {
11 : void *flags;
12 : int bit_nr;
13 : unsigned long timeout;
14 : };
15 :
16 : struct wait_bit_queue_entry {
17 : struct wait_bit_key key;
18 : struct wait_queue_entry wq_entry;
19 : };
20 :
21 : #define __WAIT_BIT_KEY_INITIALIZER(word, bit) \
22 : { .flags = word, .bit_nr = bit, }
23 :
24 : typedef int wait_bit_action_f(struct wait_bit_key *key, int mode);
25 :
26 : void __wake_up_bit(struct wait_queue_head *wq_head, void *word, int bit);
27 : int __wait_on_bit(struct wait_queue_head *wq_head, struct wait_bit_queue_entry *wbq_entry, wait_bit_action_f *action, unsigned int mode);
28 : int __wait_on_bit_lock(struct wait_queue_head *wq_head, struct wait_bit_queue_entry *wbq_entry, wait_bit_action_f *action, unsigned int mode);
29 : void wake_up_bit(void *word, int bit);
30 : int out_of_line_wait_on_bit(void *word, int, wait_bit_action_f *action, unsigned int mode);
31 : int out_of_line_wait_on_bit_timeout(void *word, int, wait_bit_action_f *action, unsigned int mode, unsigned long timeout);
32 : int out_of_line_wait_on_bit_lock(void *word, int, wait_bit_action_f *action, unsigned int mode);
33 : struct wait_queue_head *bit_waitqueue(void *word, int bit);
34 : extern void __init wait_bit_init(void);
35 :
36 : int wake_bit_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync, void *key);
37 :
38 : #define DEFINE_WAIT_BIT(name, word, bit) \
39 : struct wait_bit_queue_entry name = { \
40 : .key = __WAIT_BIT_KEY_INITIALIZER(word, bit), \
41 : .wq_entry = { \
42 : .private = current, \
43 : .func = wake_bit_function, \
44 : .entry = \
45 : LIST_HEAD_INIT((name).wq_entry.entry), \
46 : }, \
47 : }
48 :
49 : extern int bit_wait(struct wait_bit_key *key, int mode);
50 : extern int bit_wait_io(struct wait_bit_key *key, int mode);
51 : extern int bit_wait_timeout(struct wait_bit_key *key, int mode);
52 : extern int bit_wait_io_timeout(struct wait_bit_key *key, int mode);
53 :
54 : /**
55 : * wait_on_bit - wait for a bit to be cleared
56 : * @word: the word being waited on, a kernel virtual address
57 : * @bit: the bit of the word being waited on
58 : * @mode: the task state to sleep in
59 : *
60 : * There is a standard hashed waitqueue table for generic use. This
61 : * is the part of the hashtable's accessor API that waits on a bit.
62 : * For instance, if one were to have waiters on a bitflag, one would
63 : * call wait_on_bit() in threads waiting for the bit to clear.
64 : * One uses wait_on_bit() where one is waiting for the bit to clear,
65 : * but has no intention of setting it.
66 : * Returned value will be zero if the bit was cleared, or non-zero
67 : * if the process received a signal and the mode permitted wakeup
68 : * on that signal.
69 : */
70 : static inline int
71 415 : wait_on_bit(unsigned long *word, int bit, unsigned mode)
72 : {
73 415 : might_sleep();
74 415 : if (!test_bit(bit, word))
75 : return 0;
76 0 : return out_of_line_wait_on_bit(word, bit,
77 : bit_wait,
78 : mode);
79 : }
80 :
81 : /**
82 : * wait_on_bit_io - wait for a bit to be cleared
83 : * @word: the word being waited on, a kernel virtual address
84 : * @bit: the bit of the word being waited on
85 : * @mode: the task state to sleep in
86 : *
87 : * Use the standard hashed waitqueue table to wait for a bit
88 : * to be cleared. This is similar to wait_on_bit(), but calls
89 : * io_schedule() instead of schedule() for the actual waiting.
90 : *
91 : * Returned value will be zero if the bit was cleared, or non-zero
92 : * if the process received a signal and the mode permitted wakeup
93 : * on that signal.
94 : */
95 : static inline int
96 802 : wait_on_bit_io(unsigned long *word, int bit, unsigned mode)
97 : {
98 802 : might_sleep();
99 802 : if (!test_bit(bit, word))
100 : return 0;
101 801 : return out_of_line_wait_on_bit(word, bit,
102 : bit_wait_io,
103 : mode);
104 : }
105 :
106 : /**
107 : * wait_on_bit_timeout - wait for a bit to be cleared or a timeout elapses
108 : * @word: the word being waited on, a kernel virtual address
109 : * @bit: the bit of the word being waited on
110 : * @mode: the task state to sleep in
111 : * @timeout: timeout, in jiffies
112 : *
113 : * Use the standard hashed waitqueue table to wait for a bit
114 : * to be cleared. This is similar to wait_on_bit(), except also takes a
115 : * timeout parameter.
116 : *
117 : * Returned value will be zero if the bit was cleared before the
118 : * @timeout elapsed, or non-zero if the @timeout elapsed or process
119 : * received a signal and the mode permitted wakeup on that signal.
120 : */
121 : static inline int
122 : wait_on_bit_timeout(unsigned long *word, int bit, unsigned mode,
123 : unsigned long timeout)
124 : {
125 : might_sleep();
126 : if (!test_bit(bit, word))
127 : return 0;
128 : return out_of_line_wait_on_bit_timeout(word, bit,
129 : bit_wait_timeout,
130 : mode, timeout);
131 : }
132 :
133 : /**
134 : * wait_on_bit_action - wait for a bit to be cleared
135 : * @word: the word being waited on, a kernel virtual address
136 : * @bit: the bit of the word being waited on
137 : * @action: the function used to sleep, which may take special actions
138 : * @mode: the task state to sleep in
139 : *
140 : * Use the standard hashed waitqueue table to wait for a bit
141 : * to be cleared, and allow the waiting action to be specified.
142 : * This is like wait_on_bit() but allows fine control of how the waiting
143 : * is done.
144 : *
145 : * Returned value will be zero if the bit was cleared, or non-zero
146 : * if the process received a signal and the mode permitted wakeup
147 : * on that signal.
148 : */
149 : static inline int
150 : wait_on_bit_action(unsigned long *word, int bit, wait_bit_action_f *action,
151 : unsigned mode)
152 : {
153 : might_sleep();
154 : if (!test_bit(bit, word))
155 : return 0;
156 : return out_of_line_wait_on_bit(word, bit, action, mode);
157 : }
158 :
159 : /**
160 : * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
161 : * @word: the word being waited on, a kernel virtual address
162 : * @bit: the bit of the word being waited on
163 : * @mode: the task state to sleep in
164 : *
165 : * There is a standard hashed waitqueue table for generic use. This
166 : * is the part of the hashtable's accessor API that waits on a bit
167 : * when one intends to set it, for instance, trying to lock bitflags.
168 : * For instance, if one were to have waiters trying to set bitflag
169 : * and waiting for it to clear before setting it, one would call
170 : * wait_on_bit() in threads waiting to be able to set the bit.
171 : * One uses wait_on_bit_lock() where one is waiting for the bit to
172 : * clear with the intention of setting it, and when done, clearing it.
173 : *
174 : * Returns zero if the bit was (eventually) found to be clear and was
175 : * set. Returns non-zero if a signal was delivered to the process and
176 : * the @mode allows that signal to wake the process.
177 : */
178 : static inline int
179 : wait_on_bit_lock(unsigned long *word, int bit, unsigned mode)
180 : {
181 : might_sleep();
182 : if (!test_and_set_bit(bit, word))
183 : return 0;
184 : return out_of_line_wait_on_bit_lock(word, bit, bit_wait, mode);
185 : }
186 :
187 : /**
188 : * wait_on_bit_lock_io - wait for a bit to be cleared, when wanting to set it
189 : * @word: the word being waited on, a kernel virtual address
190 : * @bit: the bit of the word being waited on
191 : * @mode: the task state to sleep in
192 : *
193 : * Use the standard hashed waitqueue table to wait for a bit
194 : * to be cleared and then to atomically set it. This is similar
195 : * to wait_on_bit(), but calls io_schedule() instead of schedule()
196 : * for the actual waiting.
197 : *
198 : * Returns zero if the bit was (eventually) found to be clear and was
199 : * set. Returns non-zero if a signal was delivered to the process and
200 : * the @mode allows that signal to wake the process.
201 : */
202 : static inline int
203 0 : wait_on_bit_lock_io(unsigned long *word, int bit, unsigned mode)
204 : {
205 0 : might_sleep();
206 0 : if (!test_and_set_bit(bit, word))
207 : return 0;
208 0 : return out_of_line_wait_on_bit_lock(word, bit, bit_wait_io, mode);
209 : }
210 :
211 : /**
212 : * wait_on_bit_lock_action - wait for a bit to be cleared, when wanting to set it
213 : * @word: the word being waited on, a kernel virtual address
214 : * @bit: the bit of the word being waited on
215 : * @action: the function used to sleep, which may take special actions
216 : * @mode: the task state to sleep in
217 : *
218 : * Use the standard hashed waitqueue table to wait for a bit
219 : * to be cleared and then to set it, and allow the waiting action
220 : * to be specified.
221 : * This is like wait_on_bit() but allows fine control of how the waiting
222 : * is done.
223 : *
224 : * Returns zero if the bit was (eventually) found to be clear and was
225 : * set. Returns non-zero if a signal was delivered to the process and
226 : * the @mode allows that signal to wake the process.
227 : */
228 : static inline int
229 : wait_on_bit_lock_action(unsigned long *word, int bit, wait_bit_action_f *action,
230 : unsigned mode)
231 : {
232 : might_sleep();
233 : if (!test_and_set_bit(bit, word))
234 : return 0;
235 : return out_of_line_wait_on_bit_lock(word, bit, action, mode);
236 : }
237 :
238 : extern void init_wait_var_entry(struct wait_bit_queue_entry *wbq_entry, void *var, int flags);
239 : extern void wake_up_var(void *var);
240 : extern wait_queue_head_t *__var_waitqueue(void *p);
241 :
242 : #define ___wait_var_event(var, condition, state, exclusive, ret, cmd) \
243 : ({ \
244 : __label__ __out; \
245 : struct wait_queue_head *__wq_head = __var_waitqueue(var); \
246 : struct wait_bit_queue_entry __wbq_entry; \
247 : long __ret = ret; /* explicit shadow */ \
248 : \
249 : init_wait_var_entry(&__wbq_entry, var, \
250 : exclusive ? WQ_FLAG_EXCLUSIVE : 0); \
251 : for (;;) { \
252 : long __int = prepare_to_wait_event(__wq_head, \
253 : &__wbq_entry.wq_entry, \
254 : state); \
255 : if (condition) \
256 : break; \
257 : \
258 : if (___wait_is_interruptible(state) && __int) { \
259 : __ret = __int; \
260 : goto __out; \
261 : } \
262 : \
263 : cmd; \
264 : } \
265 : finish_wait(__wq_head, &__wbq_entry.wq_entry); \
266 : __out: __ret; \
267 : })
268 :
269 : #define __wait_var_event(var, condition) \
270 : ___wait_var_event(var, condition, TASK_UNINTERRUPTIBLE, 0, 0, \
271 : schedule())
272 :
273 : #define wait_var_event(var, condition) \
274 : do { \
275 : might_sleep(); \
276 : if (condition) \
277 : break; \
278 : __wait_var_event(var, condition); \
279 : } while (0)
280 :
281 : #define __wait_var_event_killable(var, condition) \
282 : ___wait_var_event(var, condition, TASK_KILLABLE, 0, 0, \
283 : schedule())
284 :
285 : #define wait_var_event_killable(var, condition) \
286 : ({ \
287 : int __ret = 0; \
288 : might_sleep(); \
289 : if (!(condition)) \
290 : __ret = __wait_var_event_killable(var, condition); \
291 : __ret; \
292 : })
293 :
294 : #define __wait_var_event_timeout(var, condition, timeout) \
295 : ___wait_var_event(var, ___wait_cond_timeout(condition), \
296 : TASK_UNINTERRUPTIBLE, 0, timeout, \
297 : __ret = schedule_timeout(__ret))
298 :
299 : #define wait_var_event_timeout(var, condition, timeout) \
300 : ({ \
301 : long __ret = timeout; \
302 : might_sleep(); \
303 : if (!___wait_cond_timeout(condition)) \
304 : __ret = __wait_var_event_timeout(var, condition, timeout); \
305 : __ret; \
306 : })
307 :
308 : #define __wait_var_event_interruptible(var, condition) \
309 : ___wait_var_event(var, condition, TASK_INTERRUPTIBLE, 0, 0, \
310 : schedule())
311 :
312 : #define wait_var_event_interruptible(var, condition) \
313 : ({ \
314 : int __ret = 0; \
315 : might_sleep(); \
316 : if (!(condition)) \
317 : __ret = __wait_var_event_interruptible(var, condition); \
318 : __ret; \
319 : })
320 :
321 : /**
322 : * clear_and_wake_up_bit - clear a bit and wake up anyone waiting on that bit
323 : *
324 : * @bit: the bit of the word being waited on
325 : * @word: the word being waited on, a kernel virtual address
326 : *
327 : * You can use this helper if bitflags are manipulated atomically rather than
328 : * non-atomically under a lock.
329 : */
330 : static inline void clear_and_wake_up_bit(int bit, void *word)
331 : {
332 : clear_bit_unlock(bit, word);
333 : /* See wake_up_bit() for which memory barrier you need to use. */
334 : smp_mb__after_atomic();
335 : wake_up_bit(word, bit);
336 : }
337 :
338 : #endif /* _LINUX_WAIT_BIT_H */
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