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