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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
5dd43ce2 IM |
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 | #define WAIT_ATOMIC_T_BIT_NR -1 | |
14 | unsigned long timeout; | |
15 | }; | |
16 | ||
17 | struct wait_bit_queue_entry { | |
18 | struct wait_bit_key key; | |
19 | struct wait_queue_entry wq_entry; | |
20 | }; | |
21 | ||
22 | #define __WAIT_BIT_KEY_INITIALIZER(word, bit) \ | |
23 | { .flags = word, .bit_nr = bit, } | |
24 | ||
25 | #define __WAIT_ATOMIC_T_KEY_INITIALIZER(p) \ | |
26 | { .flags = p, .bit_nr = WAIT_ATOMIC_T_BIT_NR, } | |
27 | ||
28 | typedef int wait_bit_action_f(struct wait_bit_key *key, int mode); | |
29 | void __wake_up_bit(struct wait_queue_head *wq_head, void *word, int bit); | |
30 | 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); | |
31 | 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); | |
32 | void wake_up_bit(void *word, int bit); | |
33 | void wake_up_atomic_t(atomic_t *p); | |
34 | int out_of_line_wait_on_bit(void *word, int, wait_bit_action_f *action, unsigned int mode); | |
35 | int out_of_line_wait_on_bit_timeout(void *word, int, wait_bit_action_f *action, unsigned int mode, unsigned long timeout); | |
36 | int out_of_line_wait_on_bit_lock(void *word, int, wait_bit_action_f *action, unsigned int mode); | |
37 | int out_of_line_wait_on_atomic_t(atomic_t *p, int (*)(atomic_t *), unsigned int mode); | |
38 | struct wait_queue_head *bit_waitqueue(void *word, int bit); | |
5822a454 | 39 | extern void __init wait_bit_init(void); |
5dd43ce2 IM |
40 | |
41 | int wake_bit_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync, void *key); | |
42 | ||
43 | #define DEFINE_WAIT_BIT(name, word, bit) \ | |
44 | struct wait_bit_queue_entry name = { \ | |
45 | .key = __WAIT_BIT_KEY_INITIALIZER(word, bit), \ | |
46 | .wq_entry = { \ | |
47 | .private = current, \ | |
48 | .func = wake_bit_function, \ | |
2055da97 IM |
49 | .entry = \ |
50 | LIST_HEAD_INIT((name).wq_entry.entry), \ | |
5dd43ce2 IM |
51 | }, \ |
52 | } | |
53 | ||
54 | extern int bit_wait(struct wait_bit_key *key, int bit); | |
55 | extern int bit_wait_io(struct wait_bit_key *key, int bit); | |
56 | extern int bit_wait_timeout(struct wait_bit_key *key, int bit); | |
57 | extern int bit_wait_io_timeout(struct wait_bit_key *key, int bit); | |
58 | ||
59 | /** | |
60 | * wait_on_bit - wait for a bit to be cleared | |
61 | * @word: the word being waited on, a kernel virtual address | |
62 | * @bit: the bit of the word being waited on | |
63 | * @mode: the task state to sleep in | |
64 | * | |
65 | * There is a standard hashed waitqueue table for generic use. This | |
66 | * is the part of the hashtable's accessor API that waits on a bit. | |
67 | * For instance, if one were to have waiters on a bitflag, one would | |
68 | * call wait_on_bit() in threads waiting for the bit to clear. | |
69 | * One uses wait_on_bit() where one is waiting for the bit to clear, | |
70 | * but has no intention of setting it. | |
71 | * Returned value will be zero if the bit was cleared, or non-zero | |
72 | * if the process received a signal and the mode permitted wakeup | |
73 | * on that signal. | |
74 | */ | |
75 | static inline int | |
76 | wait_on_bit(unsigned long *word, int bit, unsigned mode) | |
77 | { | |
78 | might_sleep(); | |
79 | if (!test_bit(bit, word)) | |
80 | return 0; | |
81 | return out_of_line_wait_on_bit(word, bit, | |
82 | bit_wait, | |
83 | mode); | |
84 | } | |
85 | ||
86 | /** | |
87 | * wait_on_bit_io - wait for a bit to be cleared | |
88 | * @word: the word being waited on, a kernel virtual address | |
89 | * @bit: the bit of the word being waited on | |
90 | * @mode: the task state to sleep in | |
91 | * | |
92 | * Use the standard hashed waitqueue table to wait for a bit | |
93 | * to be cleared. This is similar to wait_on_bit(), but calls | |
94 | * io_schedule() instead of schedule() for the actual waiting. | |
95 | * | |
96 | * Returned value will be zero if the bit was cleared, or non-zero | |
97 | * if the process received a signal and the mode permitted wakeup | |
98 | * on that signal. | |
99 | */ | |
100 | static inline int | |
101 | wait_on_bit_io(unsigned long *word, int bit, unsigned mode) | |
102 | { | |
103 | might_sleep(); | |
104 | if (!test_bit(bit, word)) | |
105 | return 0; | |
106 | return out_of_line_wait_on_bit(word, bit, | |
107 | bit_wait_io, | |
108 | mode); | |
109 | } | |
110 | ||
111 | /** | |
112 | * wait_on_bit_timeout - wait for a bit to be cleared or a timeout elapses | |
113 | * @word: the word being waited on, a kernel virtual address | |
114 | * @bit: the bit of the word being waited on | |
115 | * @mode: the task state to sleep in | |
116 | * @timeout: timeout, in jiffies | |
117 | * | |
118 | * Use the standard hashed waitqueue table to wait for a bit | |
119 | * to be cleared. This is similar to wait_on_bit(), except also takes a | |
120 | * timeout parameter. | |
121 | * | |
122 | * Returned value will be zero if the bit was cleared before the | |
123 | * @timeout elapsed, or non-zero if the @timeout elapsed or process | |
124 | * received a signal and the mode permitted wakeup on that signal. | |
125 | */ | |
126 | static inline int | |
127 | wait_on_bit_timeout(unsigned long *word, int bit, unsigned mode, | |
128 | unsigned long timeout) | |
129 | { | |
130 | might_sleep(); | |
131 | if (!test_bit(bit, word)) | |
132 | return 0; | |
133 | return out_of_line_wait_on_bit_timeout(word, bit, | |
134 | bit_wait_timeout, | |
135 | mode, timeout); | |
136 | } | |
137 | ||
138 | /** | |
139 | * wait_on_bit_action - wait for a bit to be cleared | |
140 | * @word: the word being waited on, a kernel virtual address | |
141 | * @bit: the bit of the word being waited on | |
142 | * @action: the function used to sleep, which may take special actions | |
143 | * @mode: the task state to sleep in | |
144 | * | |
145 | * Use the standard hashed waitqueue table to wait for a bit | |
146 | * to be cleared, and allow the waiting action to be specified. | |
147 | * This is like wait_on_bit() but allows fine control of how the waiting | |
148 | * is done. | |
149 | * | |
150 | * Returned value will be zero if the bit was cleared, or non-zero | |
151 | * if the process received a signal and the mode permitted wakeup | |
152 | * on that signal. | |
153 | */ | |
154 | static inline int | |
155 | wait_on_bit_action(unsigned long *word, int bit, wait_bit_action_f *action, | |
156 | unsigned mode) | |
157 | { | |
158 | might_sleep(); | |
159 | if (!test_bit(bit, word)) | |
160 | return 0; | |
161 | return out_of_line_wait_on_bit(word, bit, action, mode); | |
162 | } | |
163 | ||
164 | /** | |
165 | * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it | |
166 | * @word: the word being waited on, a kernel virtual address | |
167 | * @bit: the bit of the word being waited on | |
168 | * @mode: the task state to sleep in | |
169 | * | |
170 | * There is a standard hashed waitqueue table for generic use. This | |
171 | * is the part of the hashtable's accessor API that waits on a bit | |
172 | * when one intends to set it, for instance, trying to lock bitflags. | |
173 | * For instance, if one were to have waiters trying to set bitflag | |
174 | * and waiting for it to clear before setting it, one would call | |
175 | * wait_on_bit() in threads waiting to be able to set the bit. | |
176 | * One uses wait_on_bit_lock() where one is waiting for the bit to | |
177 | * clear with the intention of setting it, and when done, clearing it. | |
178 | * | |
179 | * Returns zero if the bit was (eventually) found to be clear and was | |
180 | * set. Returns non-zero if a signal was delivered to the process and | |
181 | * the @mode allows that signal to wake the process. | |
182 | */ | |
183 | static inline int | |
184 | wait_on_bit_lock(unsigned long *word, int bit, unsigned mode) | |
185 | { | |
186 | might_sleep(); | |
187 | if (!test_and_set_bit(bit, word)) | |
188 | return 0; | |
189 | return out_of_line_wait_on_bit_lock(word, bit, bit_wait, mode); | |
190 | } | |
191 | ||
192 | /** | |
193 | * wait_on_bit_lock_io - wait for a bit to be cleared, when wanting to set it | |
194 | * @word: the word being waited on, a kernel virtual address | |
195 | * @bit: the bit of the word being waited on | |
196 | * @mode: the task state to sleep in | |
197 | * | |
198 | * Use the standard hashed waitqueue table to wait for a bit | |
199 | * to be cleared and then to atomically set it. This is similar | |
200 | * to wait_on_bit(), but calls io_schedule() instead of schedule() | |
201 | * for the actual waiting. | |
202 | * | |
203 | * Returns zero if the bit was (eventually) found to be clear and was | |
204 | * set. Returns non-zero if a signal was delivered to the process and | |
205 | * the @mode allows that signal to wake the process. | |
206 | */ | |
207 | static inline int | |
208 | wait_on_bit_lock_io(unsigned long *word, int bit, unsigned mode) | |
209 | { | |
210 | might_sleep(); | |
211 | if (!test_and_set_bit(bit, word)) | |
212 | return 0; | |
213 | return out_of_line_wait_on_bit_lock(word, bit, bit_wait_io, mode); | |
214 | } | |
215 | ||
216 | /** | |
217 | * wait_on_bit_lock_action - wait for a bit to be cleared, when wanting to set it | |
218 | * @word: the word being waited on, a kernel virtual address | |
219 | * @bit: the bit of the word being waited on | |
220 | * @action: the function used to sleep, which may take special actions | |
221 | * @mode: the task state to sleep in | |
222 | * | |
223 | * Use the standard hashed waitqueue table to wait for a bit | |
224 | * to be cleared and then to set it, and allow the waiting action | |
225 | * to be specified. | |
226 | * This is like wait_on_bit() but allows fine control of how the waiting | |
227 | * is done. | |
228 | * | |
229 | * Returns zero if the bit was (eventually) found to be clear and was | |
230 | * set. Returns non-zero if a signal was delivered to the process and | |
231 | * the @mode allows that signal to wake the process. | |
232 | */ | |
233 | static inline int | |
234 | wait_on_bit_lock_action(unsigned long *word, int bit, wait_bit_action_f *action, | |
235 | unsigned mode) | |
236 | { | |
237 | might_sleep(); | |
238 | if (!test_and_set_bit(bit, word)) | |
239 | return 0; | |
240 | return out_of_line_wait_on_bit_lock(word, bit, action, mode); | |
241 | } | |
242 | ||
243 | /** | |
244 | * wait_on_atomic_t - Wait for an atomic_t to become 0 | |
245 | * @val: The atomic value being waited on, a kernel virtual address | |
246 | * @action: the function used to sleep, which may take special actions | |
247 | * @mode: the task state to sleep in | |
248 | * | |
249 | * Wait for an atomic_t to become 0. We abuse the bit-wait waitqueue table for | |
250 | * the purpose of getting a waitqueue, but we set the key to a bit number | |
251 | * outside of the target 'word'. | |
252 | */ | |
253 | static inline | |
254 | int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode) | |
255 | { | |
256 | might_sleep(); | |
257 | if (atomic_read(val) == 0) | |
258 | return 0; | |
259 | return out_of_line_wait_on_atomic_t(val, action, mode); | |
260 | } | |
261 | ||
262 | #endif /* _LINUX_WAIT_BIT_H */ |