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1 | /* |
1 | /* |
2 | * Copyright (C) 2001-2004 Jakub Jermar |
2 | * Copyright (C) 2001-2004 Jakub Jermar |
3 | * All rights reserved. |
3 | * All rights reserved. |
4 | * |
4 | * |
5 | * Redistribution and use in source and binary forms, with or without |
5 | * Redistribution and use in source and binary forms, with or without |
6 | * modification, are permitted provided that the following conditions |
6 | * modification, are permitted provided that the following conditions |
7 | * are met: |
7 | * are met: |
8 | * |
8 | * |
9 | * - Redistributions of source code must retain the above copyright |
9 | * - Redistributions of source code must retain the above copyright |
10 | * notice, this list of conditions and the following disclaimer. |
10 | * notice, this list of conditions and the following disclaimer. |
11 | * - Redistributions in binary form must reproduce the above copyright |
11 | * - Redistributions in binary form must reproduce the above copyright |
12 | * notice, this list of conditions and the following disclaimer in the |
12 | * notice, this list of conditions and the following disclaimer in the |
13 | * documentation and/or other materials provided with the distribution. |
13 | * documentation and/or other materials provided with the distribution. |
14 | * - The name of the author may not be used to endorse or promote products |
14 | * - The name of the author may not be used to endorse or promote products |
15 | * derived from this software without specific prior written permission. |
15 | * derived from this software without specific prior written permission. |
16 | * |
16 | * |
17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
27 | */ |
27 | */ |
28 | 28 | ||
29 | #include <synch/waitq.h> |
29 | #include <synch/waitq.h> |
30 | #include <synch/synch.h> |
30 | #include <synch/synch.h> |
31 | #include <synch/spinlock.h> |
31 | #include <synch/spinlock.h> |
32 | #include <proc/thread.h> |
32 | #include <proc/thread.h> |
33 | #include <proc/scheduler.h> |
33 | #include <proc/scheduler.h> |
34 | #include <arch/asm.h> |
34 | #include <arch/asm.h> |
35 | #include <arch/types.h> |
35 | #include <arch/types.h> |
36 | #include <time/timeout.h> |
36 | #include <time/timeout.h> |
37 | #include <arch.h> |
37 | #include <arch.h> |
38 | #include <context.h> |
38 | #include <context.h> |
39 | #include <list.h> |
39 | #include <list.h> |
40 | 40 | ||
41 | /** Initialize wait queue |
41 | /** Initialize wait queue |
42 | * |
42 | * |
43 | * Initialize wait queue. |
43 | * Initialize wait queue. |
44 | * |
44 | * |
45 | * @param wq Pointer to wait queue to be initialized. |
45 | * @param wq Pointer to wait queue to be initialized. |
46 | */ |
46 | */ |
47 | void waitq_initialize(waitq_t *wq) |
47 | void waitq_initialize(waitq_t *wq) |
48 | { |
48 | { |
49 | spinlock_initialize(&wq->lock); |
49 | spinlock_initialize(&wq->lock, "waitq_lock"); |
50 | list_initialize(&wq->head); |
50 | list_initialize(&wq->head); |
51 | wq->missed_wakeups = 0; |
51 | wq->missed_wakeups = 0; |
52 | } |
52 | } |
53 | 53 | ||
54 | /** Handle timeout during waitq_sleep_timeout() call |
54 | /** Handle timeout during waitq_sleep_timeout() call |
55 | * |
55 | * |
56 | * This routine is called when waitq_sleep_timeout() timeouts. |
56 | * This routine is called when waitq_sleep_timeout() timeouts. |
57 | * Interrupts are disabled. |
57 | * Interrupts are disabled. |
58 | * |
58 | * |
59 | * It is supposed to try to remove 'its' thread from the wait queue; |
59 | * It is supposed to try to remove 'its' thread from the wait queue; |
60 | * it can eventually fail to achieve this goal when these two events |
60 | * it can eventually fail to achieve this goal when these two events |
61 | * overlap. In that case it behaves just as though there was no |
61 | * overlap. In that case it behaves just as though there was no |
62 | * timeout at all. |
62 | * timeout at all. |
63 | * |
63 | * |
64 | * @param data Pointer to the thread that called waitq_sleep_timeout(). |
64 | * @param data Pointer to the thread that called waitq_sleep_timeout(). |
65 | */ |
65 | */ |
66 | void waitq_interrupted_sleep(void *data) |
66 | void waitq_interrupted_sleep(void *data) |
67 | { |
67 | { |
68 | thread_t *t = (thread_t *) data; |
68 | thread_t *t = (thread_t *) data; |
69 | waitq_t *wq; |
69 | waitq_t *wq; |
70 | int do_wakeup = 0; |
70 | int do_wakeup = 0; |
71 | 71 | ||
72 | spinlock_lock(&threads_lock); |
72 | spinlock_lock(&threads_lock); |
73 | if (!list_member(&t->threads_link, &threads_head)) |
73 | if (!list_member(&t->threads_link, &threads_head)) |
74 | goto out; |
74 | goto out; |
75 | 75 | ||
76 | grab_locks: |
76 | grab_locks: |
77 | spinlock_lock(&t->lock); |
77 | spinlock_lock(&t->lock); |
78 | if (wq = t->sleep_queue) { |
78 | if (wq = t->sleep_queue) { |
79 | if (!spinlock_trylock(&wq->lock)) { |
79 | if (!spinlock_trylock(&wq->lock)) { |
80 | spinlock_unlock(&t->lock); |
80 | spinlock_unlock(&t->lock); |
81 | goto grab_locks; /* avoid deadlock */ |
81 | goto grab_locks; /* avoid deadlock */ |
82 | } |
82 | } |
83 | 83 | ||
84 | list_remove(&t->wq_link); |
84 | list_remove(&t->wq_link); |
85 | t->saved_context = t->sleep_timeout_context; |
85 | t->saved_context = t->sleep_timeout_context; |
86 | do_wakeup = 1; |
86 | do_wakeup = 1; |
87 | 87 | ||
88 | spinlock_unlock(&wq->lock); |
88 | spinlock_unlock(&wq->lock); |
89 | t->sleep_queue = NULL; |
89 | t->sleep_queue = NULL; |
90 | } |
90 | } |
91 | 91 | ||
92 | t->timeout_pending = 0; |
92 | t->timeout_pending = 0; |
93 | spinlock_unlock(&t->lock); |
93 | spinlock_unlock(&t->lock); |
94 | 94 | ||
95 | if (do_wakeup) thread_ready(t); |
95 | if (do_wakeup) thread_ready(t); |
96 | 96 | ||
97 | out: |
97 | out: |
98 | spinlock_unlock(&threads_lock); |
98 | spinlock_unlock(&threads_lock); |
99 | } |
99 | } |
100 | 100 | ||
101 | /** Sleep until either wakeup or timeout occurs |
101 | /** Sleep until either wakeup or timeout occurs |
102 | * |
102 | * |
103 | * This is a sleep implementation which allows itself to be |
103 | * This is a sleep implementation which allows itself to be |
104 | * interrupted from the sleep, restoring a failover context. |
104 | * interrupted from the sleep, restoring a failover context. |
105 | * |
105 | * |
106 | * Sleepers are organised in FIFO fashion in a structure called wait queue. |
106 | * Sleepers are organised in FIFO fashion in a structure called wait queue. |
107 | * |
107 | * |
108 | * This function is really basic in that other functions as waitq_sleep() |
108 | * This function is really basic in that other functions as waitq_sleep() |
109 | * and all the *_timeout() functions use it. |
109 | * and all the *_timeout() functions use it. |
110 | * |
110 | * |
111 | * @param wq Pointer to wait queue. |
111 | * @param wq Pointer to wait queue. |
112 | * @param usec Timeout in microseconds. |
112 | * @param usec Timeout in microseconds. |
113 | * @param nonblocking Blocking vs. non-blocking operation mode switch. |
113 | * @param nonblocking Blocking vs. non-blocking operation mode switch. |
114 | * |
114 | * |
115 | * If usec is greater than zero, regardless of the value of nonblocking, |
115 | * If usec is greater than zero, regardless of the value of nonblocking, |
116 | * the call will not return until either timeout or wakeup comes. |
116 | * the call will not return until either timeout or wakeup comes. |
117 | * |
117 | * |
118 | * If usec is zero and nonblocking is zero (false), the call |
118 | * If usec is zero and nonblocking is zero (false), the call |
119 | * will not return until wakeup comes. |
119 | * will not return until wakeup comes. |
120 | * |
120 | * |
121 | * If usec is zero and nonblocking is non-zero (true), the call will |
121 | * If usec is zero and nonblocking is non-zero (true), the call will |
122 | * immediately return, reporting either success or failure. |
122 | * immediately return, reporting either success or failure. |
123 | * |
123 | * |
124 | * @return Returns one of: ESYNCH_WOULD_BLOCK, ESYNCH_TIMEOUT, |
124 | * @return Returns one of: ESYNCH_WOULD_BLOCK, ESYNCH_TIMEOUT, |
125 | * ESYNCH_OK_ATOMIC, ESYNCH_OK_BLOCKED. |
125 | * ESYNCH_OK_ATOMIC, ESYNCH_OK_BLOCKED. |
126 | * |
126 | * |
127 | * ESYNCH_WOULD_BLOCK means that the sleep failed because at the time |
127 | * ESYNCH_WOULD_BLOCK means that the sleep failed because at the time |
128 | * of the call there was no pending wakeup. |
128 | * of the call there was no pending wakeup. |
129 | * |
129 | * |
130 | * ESYNCH_TIMEOUT means that the sleep timed out. |
130 | * ESYNCH_TIMEOUT means that the sleep timed out. |
131 | * |
131 | * |
132 | * ESYNCH_OK_ATOMIC means that the sleep succeeded and that there was |
132 | * ESYNCH_OK_ATOMIC means that the sleep succeeded and that there was |
133 | * a pending wakeup at the time of the call. The caller was not put |
133 | * a pending wakeup at the time of the call. The caller was not put |
134 | * asleep at all. |
134 | * asleep at all. |
135 | * |
135 | * |
136 | * ESYNCH_OK_BLOCKED means that the sleep succeeded; the full sleep was |
136 | * ESYNCH_OK_BLOCKED means that the sleep succeeded; the full sleep was |
137 | * attempted. |
137 | * attempted. |
138 | */ |
138 | */ |
139 | int waitq_sleep_timeout(waitq_t *wq, __u32 usec, int nonblocking) |
139 | int waitq_sleep_timeout(waitq_t *wq, __u32 usec, int nonblocking) |
140 | { |
140 | { |
141 | volatile ipl_t ipl; /* must be live after context_restore() */ |
141 | volatile ipl_t ipl; /* must be live after context_restore() */ |
142 | 142 | ||
143 | 143 | ||
144 | restart: |
144 | restart: |
145 | ipl = interrupts_disable(); |
145 | ipl = interrupts_disable(); |
146 | 146 | ||
147 | /* |
147 | /* |
148 | * Busy waiting for a delayed timeout. |
148 | * Busy waiting for a delayed timeout. |
149 | * This is an important fix for the race condition between |
149 | * This is an important fix for the race condition between |
150 | * a delayed timeout and a next call to waitq_sleep_timeout(). |
150 | * a delayed timeout and a next call to waitq_sleep_timeout(). |
151 | * Simply, the thread is not allowed to go to sleep if |
151 | * Simply, the thread is not allowed to go to sleep if |
152 | * there are timeouts in progress. |
152 | * there are timeouts in progress. |
153 | */ |
153 | */ |
154 | spinlock_lock(&THREAD->lock); |
154 | spinlock_lock(&THREAD->lock); |
155 | if (THREAD->timeout_pending) { |
155 | if (THREAD->timeout_pending) { |
156 | spinlock_unlock(&THREAD->lock); |
156 | spinlock_unlock(&THREAD->lock); |
157 | interrupts_restore(ipl); |
157 | interrupts_restore(ipl); |
158 | goto restart; |
158 | goto restart; |
159 | } |
159 | } |
160 | spinlock_unlock(&THREAD->lock); |
160 | spinlock_unlock(&THREAD->lock); |
161 | 161 | ||
162 | spinlock_lock(&wq->lock); |
162 | spinlock_lock(&wq->lock); |
163 | 163 | ||
164 | /* checks whether to go to sleep at all */ |
164 | /* checks whether to go to sleep at all */ |
165 | if (wq->missed_wakeups) { |
165 | if (wq->missed_wakeups) { |
166 | wq->missed_wakeups--; |
166 | wq->missed_wakeups--; |
167 | spinlock_unlock(&wq->lock); |
167 | spinlock_unlock(&wq->lock); |
168 | interrupts_restore(ipl); |
168 | interrupts_restore(ipl); |
169 | return ESYNCH_OK_ATOMIC; |
169 | return ESYNCH_OK_ATOMIC; |
170 | } |
170 | } |
171 | else { |
171 | else { |
172 | if (nonblocking && (usec == 0)) { |
172 | if (nonblocking && (usec == 0)) { |
173 | /* return immediatelly instead of going to sleep */ |
173 | /* return immediatelly instead of going to sleep */ |
174 | spinlock_unlock(&wq->lock); |
174 | spinlock_unlock(&wq->lock); |
175 | interrupts_restore(ipl); |
175 | interrupts_restore(ipl); |
176 | return ESYNCH_WOULD_BLOCK; |
176 | return ESYNCH_WOULD_BLOCK; |
177 | } |
177 | } |
178 | } |
178 | } |
179 | 179 | ||
180 | 180 | ||
181 | /* |
181 | /* |
182 | * Now we are firmly decided to go to sleep. |
182 | * Now we are firmly decided to go to sleep. |
183 | */ |
183 | */ |
184 | spinlock_lock(&THREAD->lock); |
184 | spinlock_lock(&THREAD->lock); |
185 | if (usec) { |
185 | if (usec) { |
186 | /* We use the timeout variant. */ |
186 | /* We use the timeout variant. */ |
187 | if (!context_save(&THREAD->sleep_timeout_context)) { |
187 | if (!context_save(&THREAD->sleep_timeout_context)) { |
188 | /* |
188 | /* |
189 | * Short emulation of scheduler() return code. |
189 | * Short emulation of scheduler() return code. |
190 | */ |
190 | */ |
191 | before_thread_runs(); |
191 | before_thread_runs(); |
192 | spinlock_unlock(&THREAD->lock); |
192 | spinlock_unlock(&THREAD->lock); |
193 | interrupts_restore(ipl); |
193 | interrupts_restore(ipl); |
194 | return ESYNCH_TIMEOUT; |
194 | return ESYNCH_TIMEOUT; |
195 | } |
195 | } |
196 | THREAD->timeout_pending = 1; |
196 | THREAD->timeout_pending = 1; |
197 | timeout_register(&THREAD->sleep_timeout, (__u64) usec, waitq_interrupted_sleep, THREAD); |
197 | timeout_register(&THREAD->sleep_timeout, (__u64) usec, waitq_interrupted_sleep, THREAD); |
198 | } |
198 | } |
199 | 199 | ||
200 | list_append(&THREAD->wq_link, &wq->head); |
200 | list_append(&THREAD->wq_link, &wq->head); |
201 | 201 | ||
202 | /* |
202 | /* |
203 | * Suspend execution. |
203 | * Suspend execution. |
204 | */ |
204 | */ |
205 | THREAD->state = Sleeping; |
205 | THREAD->state = Sleeping; |
206 | THREAD->sleep_queue = wq; |
206 | THREAD->sleep_queue = wq; |
207 | 207 | ||
208 | spinlock_unlock(&THREAD->lock); |
208 | spinlock_unlock(&THREAD->lock); |
209 | 209 | ||
210 | scheduler(); /* wq->lock is released in scheduler_separated_stack() */ |
210 | scheduler(); /* wq->lock is released in scheduler_separated_stack() */ |
211 | interrupts_restore(ipl); |
211 | interrupts_restore(ipl); |
212 | 212 | ||
213 | return ESYNCH_OK_BLOCKED; |
213 | return ESYNCH_OK_BLOCKED; |
214 | } |
214 | } |
215 | 215 | ||
216 | 216 | ||
217 | /** Wake up first thread sleeping in a wait queue |
217 | /** Wake up first thread sleeping in a wait queue |
218 | * |
218 | * |
219 | * Wake up first thread sleeping in a wait queue. |
219 | * Wake up first thread sleeping in a wait queue. |
220 | * This is the SMP- and IRQ-safe wrapper meant for |
220 | * This is the SMP- and IRQ-safe wrapper meant for |
221 | * general use. |
221 | * general use. |
222 | * |
222 | * |
223 | * Besides its 'normal' wakeup operation, it attempts |
223 | * Besides its 'normal' wakeup operation, it attempts |
224 | * to unregister possible timeout. |
224 | * to unregister possible timeout. |
225 | * |
225 | * |
226 | * @param wq Pointer to wait queue. |
226 | * @param wq Pointer to wait queue. |
227 | * @param all If this is non-zero, all sleeping threads |
227 | * @param all If this is non-zero, all sleeping threads |
228 | * will be woken up and missed count will be zeroed. |
228 | * will be woken up and missed count will be zeroed. |
229 | */ |
229 | */ |
230 | void waitq_wakeup(waitq_t *wq, int all) |
230 | void waitq_wakeup(waitq_t *wq, int all) |
231 | { |
231 | { |
232 | ipl_t ipl; |
232 | ipl_t ipl; |
233 | 233 | ||
234 | ipl = interrupts_disable(); |
234 | ipl = interrupts_disable(); |
235 | spinlock_lock(&wq->lock); |
235 | spinlock_lock(&wq->lock); |
236 | 236 | ||
237 | _waitq_wakeup_unsafe(wq, all); |
237 | _waitq_wakeup_unsafe(wq, all); |
238 | 238 | ||
239 | spinlock_unlock(&wq->lock); |
239 | spinlock_unlock(&wq->lock); |
240 | interrupts_restore(ipl); |
240 | interrupts_restore(ipl); |
241 | } |
241 | } |
242 | 242 | ||
243 | /** Internal SMP- and IRQ-unsafe version of waitq_wakeup() |
243 | /** Internal SMP- and IRQ-unsafe version of waitq_wakeup() |
244 | * |
244 | * |
245 | * This is the internal SMP- and IRQ-unsafe version |
245 | * This is the internal SMP- and IRQ-unsafe version |
246 | * of waitq_wakeup(). It assumes wq->lock is already |
246 | * of waitq_wakeup(). It assumes wq->lock is already |
247 | * locked and interrupts are already disabled. |
247 | * locked and interrupts are already disabled. |
248 | * |
248 | * |
249 | * @param wq Pointer to wait queue. |
249 | * @param wq Pointer to wait queue. |
250 | * @param all If this is non-zero, all sleeping threads |
250 | * @param all If this is non-zero, all sleeping threads |
251 | * will be woken up and missed count will be zeroed. |
251 | * will be woken up and missed count will be zeroed. |
252 | */ |
252 | */ |
253 | void _waitq_wakeup_unsafe(waitq_t *wq, int all) |
253 | void _waitq_wakeup_unsafe(waitq_t *wq, int all) |
254 | { |
254 | { |
255 | thread_t *t; |
255 | thread_t *t; |
256 | 256 | ||
257 | loop: |
257 | loop: |
258 | if (list_empty(&wq->head)) { |
258 | if (list_empty(&wq->head)) { |
259 | wq->missed_wakeups++; |
259 | wq->missed_wakeups++; |
260 | if (all) wq->missed_wakeups = 0; |
260 | if (all) wq->missed_wakeups = 0; |
261 | return; |
261 | return; |
262 | } |
262 | } |
263 | 263 | ||
264 | t = list_get_instance(wq->head.next, thread_t, wq_link); |
264 | t = list_get_instance(wq->head.next, thread_t, wq_link); |
265 | 265 | ||
266 | list_remove(&t->wq_link); |
266 | list_remove(&t->wq_link); |
267 | spinlock_lock(&t->lock); |
267 | spinlock_lock(&t->lock); |
268 | if (t->timeout_pending && timeout_unregister(&t->sleep_timeout)) |
268 | if (t->timeout_pending && timeout_unregister(&t->sleep_timeout)) |
269 | t->timeout_pending = 0; |
269 | t->timeout_pending = 0; |
270 | t->sleep_queue = NULL; |
270 | t->sleep_queue = NULL; |
271 | spinlock_unlock(&t->lock); |
271 | spinlock_unlock(&t->lock); |
272 | 272 | ||
273 | thread_ready(t); |
273 | thread_ready(t); |
274 | 274 | ||
275 | if (all) goto loop; |
275 | if (all) goto loop; |
276 | } |
276 | } |
277 | 277 |