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_acquire(bit, word)) |
75 | return 0; |
76 | return out_of_line_wait_on_bit(word, bit, |
77 | action: 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_acquire(bit, word)) |
100 | return 0; |
101 | return out_of_line_wait_on_bit(word, bit, |
102 | action: 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_acquire(bit, word)) |
127 | return 0; |
128 | return out_of_line_wait_on_bit_timeout(word, bit, |
129 | action: 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_acquire(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(nr: bit, addr: word)) |
183 | return 0; |
184 | return out_of_line_wait_on_bit_lock(word, bit, action: 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(nr: bit, addr: word)) |
207 | return 0; |
208 | return out_of_line_wait_on_bit_lock(word, bit, action: 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(nr: bit, addr: 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(nr: bit, addr: 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 */ |
339 | |