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 wait_on_bit(unsigned long *word, int bit, unsigned mode)
72 {
73 might_sleep();
74 if (!test_bit(bit, word))
75 return 0;
76 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 wait_on_bit_io(unsigned long *word, int bit, unsigned mode)
97 {
98 might_sleep();
99 if (!test_bit(bit, word))
100 return 0;
101 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 wait_on_bit_lock_io(unsigned long *word, int bit, unsigned mode)
204 {
205 might_sleep();
206 if (!test_and_set_bit(bit, word))
207 return 0;
208 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 */