Merge tag 'm68k-for-v5.14-tag1' of git://git.kernel.org/pub/scm/linux/kernel/git...
[linux-2.6-microblaze.git] / kernel / sched / wait_bit.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * The implementation of the wait_bit*() and related waiting APIs:
4  */
5 #include "sched.h"
6
7 #define WAIT_TABLE_BITS 8
8 #define WAIT_TABLE_SIZE (1 << WAIT_TABLE_BITS)
9
10 static wait_queue_head_t bit_wait_table[WAIT_TABLE_SIZE] __cacheline_aligned;
11
12 wait_queue_head_t *bit_waitqueue(void *word, int bit)
13 {
14         const int shift = BITS_PER_LONG == 32 ? 5 : 6;
15         unsigned long val = (unsigned long)word << shift | bit;
16
17         return bit_wait_table + hash_long(val, WAIT_TABLE_BITS);
18 }
19 EXPORT_SYMBOL(bit_waitqueue);
20
21 int wake_bit_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync, void *arg)
22 {
23         struct wait_bit_key *key = arg;
24         struct wait_bit_queue_entry *wait_bit = container_of(wq_entry, struct wait_bit_queue_entry, wq_entry);
25
26         if (wait_bit->key.flags != key->flags ||
27                         wait_bit->key.bit_nr != key->bit_nr ||
28                         test_bit(key->bit_nr, key->flags))
29                 return 0;
30
31         return autoremove_wake_function(wq_entry, mode, sync, key);
32 }
33 EXPORT_SYMBOL(wake_bit_function);
34
35 /*
36  * To allow interruptible waiting and asynchronous (i.e. nonblocking)
37  * waiting, the actions of __wait_on_bit() and __wait_on_bit_lock() are
38  * permitted return codes. Nonzero return codes halt waiting and return.
39  */
40 int __sched
41 __wait_on_bit(struct wait_queue_head *wq_head, struct wait_bit_queue_entry *wbq_entry,
42               wait_bit_action_f *action, unsigned mode)
43 {
44         int ret = 0;
45
46         do {
47                 prepare_to_wait(wq_head, &wbq_entry->wq_entry, mode);
48                 if (test_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags))
49                         ret = (*action)(&wbq_entry->key, mode);
50         } while (test_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags) && !ret);
51
52         finish_wait(wq_head, &wbq_entry->wq_entry);
53
54         return ret;
55 }
56 EXPORT_SYMBOL(__wait_on_bit);
57
58 int __sched out_of_line_wait_on_bit(void *word, int bit,
59                                     wait_bit_action_f *action, unsigned mode)
60 {
61         struct wait_queue_head *wq_head = bit_waitqueue(word, bit);
62         DEFINE_WAIT_BIT(wq_entry, word, bit);
63
64         return __wait_on_bit(wq_head, &wq_entry, action, mode);
65 }
66 EXPORT_SYMBOL(out_of_line_wait_on_bit);
67
68 int __sched out_of_line_wait_on_bit_timeout(
69         void *word, int bit, wait_bit_action_f *action,
70         unsigned mode, unsigned long timeout)
71 {
72         struct wait_queue_head *wq_head = bit_waitqueue(word, bit);
73         DEFINE_WAIT_BIT(wq_entry, word, bit);
74
75         wq_entry.key.timeout = jiffies + timeout;
76
77         return __wait_on_bit(wq_head, &wq_entry, action, mode);
78 }
79 EXPORT_SYMBOL_GPL(out_of_line_wait_on_bit_timeout);
80
81 int __sched
82 __wait_on_bit_lock(struct wait_queue_head *wq_head, struct wait_bit_queue_entry *wbq_entry,
83                         wait_bit_action_f *action, unsigned mode)
84 {
85         int ret = 0;
86
87         for (;;) {
88                 prepare_to_wait_exclusive(wq_head, &wbq_entry->wq_entry, mode);
89                 if (test_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags)) {
90                         ret = action(&wbq_entry->key, mode);
91                         /*
92                          * See the comment in prepare_to_wait_event().
93                          * finish_wait() does not necessarily takes wwq_head->lock,
94                          * but test_and_set_bit() implies mb() which pairs with
95                          * smp_mb__after_atomic() before wake_up_page().
96                          */
97                         if (ret)
98                                 finish_wait(wq_head, &wbq_entry->wq_entry);
99                 }
100                 if (!test_and_set_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags)) {
101                         if (!ret)
102                                 finish_wait(wq_head, &wbq_entry->wq_entry);
103                         return 0;
104                 } else if (ret) {
105                         return ret;
106                 }
107         }
108 }
109 EXPORT_SYMBOL(__wait_on_bit_lock);
110
111 int __sched out_of_line_wait_on_bit_lock(void *word, int bit,
112                                          wait_bit_action_f *action, unsigned mode)
113 {
114         struct wait_queue_head *wq_head = bit_waitqueue(word, bit);
115         DEFINE_WAIT_BIT(wq_entry, word, bit);
116
117         return __wait_on_bit_lock(wq_head, &wq_entry, action, mode);
118 }
119 EXPORT_SYMBOL(out_of_line_wait_on_bit_lock);
120
121 void __wake_up_bit(struct wait_queue_head *wq_head, void *word, int bit)
122 {
123         struct wait_bit_key key = __WAIT_BIT_KEY_INITIALIZER(word, bit);
124
125         if (waitqueue_active(wq_head))
126                 __wake_up(wq_head, TASK_NORMAL, 1, &key);
127 }
128 EXPORT_SYMBOL(__wake_up_bit);
129
130 /**
131  * wake_up_bit - wake up a waiter on a bit
132  * @word: the word being waited on, a kernel virtual address
133  * @bit: the bit of the word being waited on
134  *
135  * There is a standard hashed waitqueue table for generic use. This
136  * is the part of the hashtable's accessor API that wakes up waiters
137  * on a bit. For instance, if one were to have waiters on a bitflag,
138  * one would call wake_up_bit() after clearing the bit.
139  *
140  * In order for this to function properly, as it uses waitqueue_active()
141  * internally, some kind of memory barrier must be done prior to calling
142  * this. Typically, this will be smp_mb__after_atomic(), but in some
143  * cases where bitflags are manipulated non-atomically under a lock, one
144  * may need to use a less regular barrier, such fs/inode.c's smp_mb(),
145  * because spin_unlock() does not guarantee a memory barrier.
146  */
147 void wake_up_bit(void *word, int bit)
148 {
149         __wake_up_bit(bit_waitqueue(word, bit), word, bit);
150 }
151 EXPORT_SYMBOL(wake_up_bit);
152
153 wait_queue_head_t *__var_waitqueue(void *p)
154 {
155         return bit_wait_table + hash_ptr(p, WAIT_TABLE_BITS);
156 }
157 EXPORT_SYMBOL(__var_waitqueue);
158
159 static int
160 var_wake_function(struct wait_queue_entry *wq_entry, unsigned int mode,
161                   int sync, void *arg)
162 {
163         struct wait_bit_key *key = arg;
164         struct wait_bit_queue_entry *wbq_entry =
165                 container_of(wq_entry, struct wait_bit_queue_entry, wq_entry);
166
167         if (wbq_entry->key.flags != key->flags ||
168             wbq_entry->key.bit_nr != key->bit_nr)
169                 return 0;
170
171         return autoremove_wake_function(wq_entry, mode, sync, key);
172 }
173
174 void init_wait_var_entry(struct wait_bit_queue_entry *wbq_entry, void *var, int flags)
175 {
176         *wbq_entry = (struct wait_bit_queue_entry){
177                 .key = {
178                         .flags  = (var),
179                         .bit_nr = -1,
180                 },
181                 .wq_entry = {
182                         .flags   = flags,
183                         .private = current,
184                         .func    = var_wake_function,
185                         .entry   = LIST_HEAD_INIT(wbq_entry->wq_entry.entry),
186                 },
187         };
188 }
189 EXPORT_SYMBOL(init_wait_var_entry);
190
191 void wake_up_var(void *var)
192 {
193         __wake_up_bit(__var_waitqueue(var), var, -1);
194 }
195 EXPORT_SYMBOL(wake_up_var);
196
197 __sched int bit_wait(struct wait_bit_key *word, int mode)
198 {
199         schedule();
200         if (signal_pending_state(mode, current))
201                 return -EINTR;
202
203         return 0;
204 }
205 EXPORT_SYMBOL(bit_wait);
206
207 __sched int bit_wait_io(struct wait_bit_key *word, int mode)
208 {
209         io_schedule();
210         if (signal_pending_state(mode, current))
211                 return -EINTR;
212
213         return 0;
214 }
215 EXPORT_SYMBOL(bit_wait_io);
216
217 __sched int bit_wait_timeout(struct wait_bit_key *word, int mode)
218 {
219         unsigned long now = READ_ONCE(jiffies);
220
221         if (time_after_eq(now, word->timeout))
222                 return -EAGAIN;
223         schedule_timeout(word->timeout - now);
224         if (signal_pending_state(mode, current))
225                 return -EINTR;
226
227         return 0;
228 }
229 EXPORT_SYMBOL_GPL(bit_wait_timeout);
230
231 __sched int bit_wait_io_timeout(struct wait_bit_key *word, int mode)
232 {
233         unsigned long now = READ_ONCE(jiffies);
234
235         if (time_after_eq(now, word->timeout))
236                 return -EAGAIN;
237         io_schedule_timeout(word->timeout - now);
238         if (signal_pending_state(mode, current))
239                 return -EINTR;
240
241         return 0;
242 }
243 EXPORT_SYMBOL_GPL(bit_wait_io_timeout);
244
245 void __init wait_bit_init(void)
246 {
247         int i;
248
249         for (i = 0; i < WAIT_TABLE_SIZE; i++)
250                 init_waitqueue_head(bit_wait_table + i);
251 }