kernel: remove fastcall in kernel/*
[linux-2.6.git] / kernel / wait.c
1 /*
2  * Generic waiting primitives.
3  *
4  * (C) 2004 William Irwin, Oracle
5  */
6 #include <linux/init.h>
7 #include <linux/module.h>
8 #include <linux/sched.h>
9 #include <linux/mm.h>
10 #include <linux/wait.h>
11 #include <linux/hash.h>
12
13 void init_waitqueue_head(wait_queue_head_t *q)
14 {
15         spin_lock_init(&q->lock);
16         INIT_LIST_HEAD(&q->task_list);
17 }
18
19 EXPORT_SYMBOL(init_waitqueue_head);
20
21 void add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait)
22 {
23         unsigned long flags;
24
25         wait->flags &= ~WQ_FLAG_EXCLUSIVE;
26         spin_lock_irqsave(&q->lock, flags);
27         __add_wait_queue(q, wait);
28         spin_unlock_irqrestore(&q->lock, flags);
29 }
30 EXPORT_SYMBOL(add_wait_queue);
31
32 void add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
33 {
34         unsigned long flags;
35
36         wait->flags |= WQ_FLAG_EXCLUSIVE;
37         spin_lock_irqsave(&q->lock, flags);
38         __add_wait_queue_tail(q, wait);
39         spin_unlock_irqrestore(&q->lock, flags);
40 }
41 EXPORT_SYMBOL(add_wait_queue_exclusive);
42
43 void remove_wait_queue(wait_queue_head_t *q, wait_queue_t *wait)
44 {
45         unsigned long flags;
46
47         spin_lock_irqsave(&q->lock, flags);
48         __remove_wait_queue(q, wait);
49         spin_unlock_irqrestore(&q->lock, flags);
50 }
51 EXPORT_SYMBOL(remove_wait_queue);
52
53
54 /*
55  * Note: we use "set_current_state()" _after_ the wait-queue add,
56  * because we need a memory barrier there on SMP, so that any
57  * wake-function that tests for the wait-queue being active
58  * will be guaranteed to see waitqueue addition _or_ subsequent
59  * tests in this thread will see the wakeup having taken place.
60  *
61  * The spin_unlock() itself is semi-permeable and only protects
62  * one way (it only protects stuff inside the critical region and
63  * stops them from bleeding out - it would still allow subsequent
64  * loads to move into the critical region).
65  */
66 void
67 prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state)
68 {
69         unsigned long flags;
70
71         wait->flags &= ~WQ_FLAG_EXCLUSIVE;
72         spin_lock_irqsave(&q->lock, flags);
73         if (list_empty(&wait->task_list))
74                 __add_wait_queue(q, wait);
75         /*
76          * don't alter the task state if this is just going to
77          * queue an async wait queue callback
78          */
79         if (is_sync_wait(wait))
80                 set_current_state(state);
81         spin_unlock_irqrestore(&q->lock, flags);
82 }
83 EXPORT_SYMBOL(prepare_to_wait);
84
85 void
86 prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state)
87 {
88         unsigned long flags;
89
90         wait->flags |= WQ_FLAG_EXCLUSIVE;
91         spin_lock_irqsave(&q->lock, flags);
92         if (list_empty(&wait->task_list))
93                 __add_wait_queue_tail(q, wait);
94         /*
95          * don't alter the task state if this is just going to
96          * queue an async wait queue callback
97          */
98         if (is_sync_wait(wait))
99                 set_current_state(state);
100         spin_unlock_irqrestore(&q->lock, flags);
101 }
102 EXPORT_SYMBOL(prepare_to_wait_exclusive);
103
104 void finish_wait(wait_queue_head_t *q, wait_queue_t *wait)
105 {
106         unsigned long flags;
107
108         __set_current_state(TASK_RUNNING);
109         /*
110          * We can check for list emptiness outside the lock
111          * IFF:
112          *  - we use the "careful" check that verifies both
113          *    the next and prev pointers, so that there cannot
114          *    be any half-pending updates in progress on other
115          *    CPU's that we haven't seen yet (and that might
116          *    still change the stack area.
117          * and
118          *  - all other users take the lock (ie we can only
119          *    have _one_ other CPU that looks at or modifies
120          *    the list).
121          */
122         if (!list_empty_careful(&wait->task_list)) {
123                 spin_lock_irqsave(&q->lock, flags);
124                 list_del_init(&wait->task_list);
125                 spin_unlock_irqrestore(&q->lock, flags);
126         }
127 }
128 EXPORT_SYMBOL(finish_wait);
129
130 int autoremove_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key)
131 {
132         int ret = default_wake_function(wait, mode, sync, key);
133
134         if (ret)
135                 list_del_init(&wait->task_list);
136         return ret;
137 }
138 EXPORT_SYMBOL(autoremove_wake_function);
139
140 int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *arg)
141 {
142         struct wait_bit_key *key = arg;
143         struct wait_bit_queue *wait_bit
144                 = container_of(wait, struct wait_bit_queue, wait);
145
146         if (wait_bit->key.flags != key->flags ||
147                         wait_bit->key.bit_nr != key->bit_nr ||
148                         test_bit(key->bit_nr, key->flags))
149                 return 0;
150         else
151                 return autoremove_wake_function(wait, mode, sync, key);
152 }
153 EXPORT_SYMBOL(wake_bit_function);
154
155 /*
156  * To allow interruptible waiting and asynchronous (i.e. nonblocking)
157  * waiting, the actions of __wait_on_bit() and __wait_on_bit_lock() are
158  * permitted return codes. Nonzero return codes halt waiting and return.
159  */
160 int __sched
161 __wait_on_bit(wait_queue_head_t *wq, struct wait_bit_queue *q,
162                         int (*action)(void *), unsigned mode)
163 {
164         int ret = 0;
165
166         do {
167                 prepare_to_wait(wq, &q->wait, mode);
168                 if (test_bit(q->key.bit_nr, q->key.flags))
169                         ret = (*action)(q->key.flags);
170         } while (test_bit(q->key.bit_nr, q->key.flags) && !ret);
171         finish_wait(wq, &q->wait);
172         return ret;
173 }
174 EXPORT_SYMBOL(__wait_on_bit);
175
176 int __sched out_of_line_wait_on_bit(void *word, int bit,
177                                         int (*action)(void *), unsigned mode)
178 {
179         wait_queue_head_t *wq = bit_waitqueue(word, bit);
180         DEFINE_WAIT_BIT(wait, word, bit);
181
182         return __wait_on_bit(wq, &wait, action, mode);
183 }
184 EXPORT_SYMBOL(out_of_line_wait_on_bit);
185
186 int __sched
187 __wait_on_bit_lock(wait_queue_head_t *wq, struct wait_bit_queue *q,
188                         int (*action)(void *), unsigned mode)
189 {
190         int ret = 0;
191
192         do {
193                 prepare_to_wait_exclusive(wq, &q->wait, mode);
194                 if (test_bit(q->key.bit_nr, q->key.flags)) {
195                         if ((ret = (*action)(q->key.flags)))
196                                 break;
197                 }
198         } while (test_and_set_bit(q->key.bit_nr, q->key.flags));
199         finish_wait(wq, &q->wait);
200         return ret;
201 }
202 EXPORT_SYMBOL(__wait_on_bit_lock);
203
204 int __sched out_of_line_wait_on_bit_lock(void *word, int bit,
205                                         int (*action)(void *), unsigned mode)
206 {
207         wait_queue_head_t *wq = bit_waitqueue(word, bit);
208         DEFINE_WAIT_BIT(wait, word, bit);
209
210         return __wait_on_bit_lock(wq, &wait, action, mode);
211 }
212 EXPORT_SYMBOL(out_of_line_wait_on_bit_lock);
213
214 void __wake_up_bit(wait_queue_head_t *wq, void *word, int bit)
215 {
216         struct wait_bit_key key = __WAIT_BIT_KEY_INITIALIZER(word, bit);
217         if (waitqueue_active(wq))
218                 __wake_up(wq, TASK_NORMAL, 1, &key);
219 }
220 EXPORT_SYMBOL(__wake_up_bit);
221
222 /**
223  * wake_up_bit - wake up a waiter on a bit
224  * @word: the word being waited on, a kernel virtual address
225  * @bit: the bit of the word being waited on
226  *
227  * There is a standard hashed waitqueue table for generic use. This
228  * is the part of the hashtable's accessor API that wakes up waiters
229  * on a bit. For instance, if one were to have waiters on a bitflag,
230  * one would call wake_up_bit() after clearing the bit.
231  *
232  * In order for this to function properly, as it uses waitqueue_active()
233  * internally, some kind of memory barrier must be done prior to calling
234  * this. Typically, this will be smp_mb__after_clear_bit(), but in some
235  * cases where bitflags are manipulated non-atomically under a lock, one
236  * may need to use a less regular barrier, such fs/inode.c's smp_mb(),
237  * because spin_unlock() does not guarantee a memory barrier.
238  */
239 void wake_up_bit(void *word, int bit)
240 {
241         __wake_up_bit(bit_waitqueue(word, bit), word, bit);
242 }
243 EXPORT_SYMBOL(wake_up_bit);
244
245 wait_queue_head_t *bit_waitqueue(void *word, int bit)
246 {
247         const int shift = BITS_PER_LONG == 32 ? 5 : 6;
248         const struct zone *zone = page_zone(virt_to_page(word));
249         unsigned long val = (unsigned long)word << shift | bit;
250
251         return &zone->wait_table[hash_long(val, zone->wait_table_bits)];
252 }
253 EXPORT_SYMBOL(bit_waitqueue);