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Rev 1288 | Rev 1375 | ||
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Line 155... | Line 155... | ||
155 | out: |
155 | out: |
156 | spinlock_unlock(&threads_lock); |
156 | spinlock_unlock(&threads_lock); |
157 | interrupts_restore(ipl); |
157 | interrupts_restore(ipl); |
158 | } |
158 | } |
159 | 159 | ||
160 | - | ||
161 | /** Sleep until either wakeup, timeout or interruption occurs |
160 | /** Sleep until either wakeup, timeout or interruption occurs |
162 | * |
161 | * |
163 | * This is a sleep implementation which allows itself to be |
162 | * This is a sleep implementation which allows itself to be |
164 | * interrupted from the sleep, restoring a failover context. |
163 | * interrupted from the sleep, restoring a failover context. |
165 | * |
164 | * |
166 | * Sleepers are organised in FIFO fashion in a structure called wait queue. |
165 | * Sleepers are organised in a FIFO fashion in a structure called wait queue. |
167 | * |
166 | * |
168 | * This function is really basic in that other functions as waitq_sleep() |
167 | * This function is really basic in that other functions as waitq_sleep() |
169 | * and all the *_timeout() functions use it. |
168 | * and all the *_timeout() functions use it. |
170 | * |
169 | * |
171 | * @param wq Pointer to wait queue. |
170 | * @param wq Pointer to wait queue. |
Line 198... | Line 197... | ||
198 | * @li ESYNCH_OK_BLOCKED means that the sleep succeeded; the full sleep was |
197 | * @li ESYNCH_OK_BLOCKED means that the sleep succeeded; the full sleep was |
199 | * attempted. |
198 | * attempted. |
200 | */ |
199 | */ |
201 | int waitq_sleep_timeout(waitq_t *wq, __u32 usec, int nonblocking) |
200 | int waitq_sleep_timeout(waitq_t *wq, __u32 usec, int nonblocking) |
202 | { |
201 | { |
203 | volatile ipl_t ipl; /* must be live after context_restore() */ |
202 | ipl_t ipl; |
- | 203 | int rc; |
|
204 | 204 | ||
- | 205 | ipl = waitq_sleep_prepare(wq); |
|
- | 206 | rc = waitq_sleep_timeout_unsafe(wq, usec, nonblocking); |
|
- | 207 | waitq_sleep_finish(wq, rc, ipl); |
|
- | 208 | return rc; |
|
- | 209 | } |
|
- | 210 | ||
- | 211 | /** Prepare to sleep in a waitq. |
|
- | 212 | * |
|
- | 213 | * This function will return holding the lock of the wait queue |
|
- | 214 | * and interrupts disabled. |
|
- | 215 | * |
|
- | 216 | * @param wq Wait queue. |
|
- | 217 | * |
|
- | 218 | * @return Interrupt level as it existed on entry to this function. |
|
- | 219 | */ |
|
- | 220 | ipl_t waitq_sleep_prepare(waitq_t *wq) |
|
- | 221 | { |
|
- | 222 | ipl_t ipl; |
|
205 | 223 | ||
206 | restart: |
224 | restart: |
207 | ipl = interrupts_disable(); |
225 | ipl = interrupts_disable(); |
208 | 226 | ||
209 | /* |
227 | /* |
210 | * Busy waiting for a delayed timeout. |
228 | * Busy waiting for a delayed timeout. |
211 | * This is an important fix for the race condition between |
229 | * This is an important fix for the race condition between |
212 | * a delayed timeout and a next call to waitq_sleep_timeout(). |
230 | * a delayed timeout and a next call to waitq_sleep_timeout(). |
213 | * Simply, the thread is not allowed to go to sleep if |
231 | * Simply, the thread is not allowed to go to sleep if |
214 | * there are timeouts in progress. |
232 | * there are timeouts in progress. |
215 | */ |
233 | */ |
216 | spinlock_lock(&THREAD->lock); |
234 | spinlock_lock(&THREAD->lock); |
217 | if (THREAD->timeout_pending) { |
235 | if (THREAD->timeout_pending) { |
218 | spinlock_unlock(&THREAD->lock); |
236 | spinlock_unlock(&THREAD->lock); |
219 | interrupts_restore(ipl); |
237 | interrupts_restore(ipl); |
220 | goto restart; |
238 | goto restart; |
221 | } |
239 | } |
222 | spinlock_unlock(&THREAD->lock); |
240 | spinlock_unlock(&THREAD->lock); |
223 | 241 | ||
224 | spinlock_lock(&wq->lock); |
242 | spinlock_lock(&wq->lock); |
- | 243 | return ipl; |
|
- | 244 | } |
|
- | 245 | ||
- | 246 | /** Finish waiting in a wait queue. |
|
- | 247 | * |
|
- | 248 | * This function restores interrupts to the state that existed prior |
|
- | 249 | * to the call to waitq_sleep_prepare(). If necessary, the wait queue |
|
- | 250 | * lock is released. |
|
- | 251 | * |
|
- | 252 | * @param wq Wait queue. |
|
- | 253 | * @param rc Return code of waitq_sleep_timeout_unsafe(). |
|
- | 254 | * @param ipl Interrupt level returned by waitq_sleep_prepare(). |
|
- | 255 | */ |
|
- | 256 | void waitq_sleep_finish(waitq_t *wq, int rc, ipl_t ipl) |
|
- | 257 | { |
|
- | 258 | switch (rc) { |
|
- | 259 | case ESYNCH_WOULD_BLOCK: |
|
- | 260 | case ESYNCH_OK_ATOMIC: |
|
- | 261 | spinlock_unlock(&wq->lock); |
|
- | 262 | break; |
|
- | 263 | default: |
|
- | 264 | break; |
|
225 | 265 | } |
|
- | 266 | interrupts_restore(ipl); |
|
- | 267 | } |
|
- | 268 | ||
- | 269 | /** Internal implementation of waitq_sleep_timeout(). |
|
- | 270 | * |
|
- | 271 | * This function implements logic of sleeping in a wait queue. |
|
- | 272 | * This call must be preceeded by a call to waitq_sleep_prepare() |
|
- | 273 | * and followed by a call to waitq_slee_finish(). |
|
- | 274 | * |
|
- | 275 | * @param wq See waitq_sleep_timeout(). |
|
- | 276 | * @param usec See waitq_sleep_timeout(). |
|
- | 277 | * @param nonblocking See waitq_sleep_timeout(). |
|
- | 278 | * |
|
- | 279 | * @return See waitq_sleep_timeout(). |
|
- | 280 | */ |
|
- | 281 | int waitq_sleep_timeout_unsafe(waitq_t *wq, __u32 usec, int nonblocking) |
|
- | 282 | { |
|
226 | /* checks whether to go to sleep at all */ |
283 | /* checks whether to go to sleep at all */ |
227 | if (wq->missed_wakeups) { |
284 | if (wq->missed_wakeups) { |
228 | wq->missed_wakeups--; |
285 | wq->missed_wakeups--; |
229 | spinlock_unlock(&wq->lock); |
- | |
230 | interrupts_restore(ipl); |
- | |
231 | return ESYNCH_OK_ATOMIC; |
286 | return ESYNCH_OK_ATOMIC; |
232 | } |
287 | } |
233 | else { |
288 | else { |
234 | if (nonblocking && (usec == 0)) { |
289 | if (nonblocking && (usec == 0)) { |
235 | /* return immediatelly instead of going to sleep */ |
290 | /* return immediatelly instead of going to sleep */ |
236 | spinlock_unlock(&wq->lock); |
- | |
237 | interrupts_restore(ipl); |
- | |
238 | return ESYNCH_WOULD_BLOCK; |
291 | return ESYNCH_WOULD_BLOCK; |
239 | } |
292 | } |
240 | } |
293 | } |
241 | 294 | ||
242 | /* |
295 | /* |
Line 249... | Line 302... | ||
249 | * of this thread is ever interrupted. |
302 | * of this thread is ever interrupted. |
250 | */ |
303 | */ |
251 | if (!context_save(&THREAD->sleep_interruption_context)) { |
304 | if (!context_save(&THREAD->sleep_interruption_context)) { |
252 | /* Short emulation of scheduler() return code. */ |
305 | /* Short emulation of scheduler() return code. */ |
253 | spinlock_unlock(&THREAD->lock); |
306 | spinlock_unlock(&THREAD->lock); |
254 | interrupts_restore(ipl); |
- | |
255 | return ESYNCH_INTERRUPTED; |
307 | return ESYNCH_INTERRUPTED; |
256 | } |
308 | } |
257 | 309 | ||
258 | if (usec) { |
310 | if (usec) { |
259 | /* We use the timeout variant. */ |
311 | /* We use the timeout variant. */ |
260 | if (!context_save(&THREAD->sleep_timeout_context)) { |
312 | if (!context_save(&THREAD->sleep_timeout_context)) { |
261 | /* Short emulation of scheduler() return code. */ |
313 | /* Short emulation of scheduler() return code. */ |
262 | spinlock_unlock(&THREAD->lock); |
314 | spinlock_unlock(&THREAD->lock); |
263 | interrupts_restore(ipl); |
- | |
264 | return ESYNCH_TIMEOUT; |
315 | return ESYNCH_TIMEOUT; |
265 | } |
316 | } |
266 | THREAD->timeout_pending = true; |
317 | THREAD->timeout_pending = true; |
267 | timeout_register(&THREAD->sleep_timeout, (__u64) usec, waitq_timeouted_sleep, THREAD); |
318 | timeout_register(&THREAD->sleep_timeout, (__u64) usec, waitq_timeouted_sleep, THREAD); |
268 | } |
319 | } |
Line 276... | Line 327... | ||
276 | THREAD->sleep_queue = wq; |
327 | THREAD->sleep_queue = wq; |
277 | 328 | ||
278 | spinlock_unlock(&THREAD->lock); |
329 | spinlock_unlock(&THREAD->lock); |
279 | 330 | ||
280 | scheduler(); /* wq->lock is released in scheduler_separated_stack() */ |
331 | scheduler(); /* wq->lock is released in scheduler_separated_stack() */ |
281 | interrupts_restore(ipl); |
- | |
282 | 332 | ||
283 | return ESYNCH_OK_BLOCKED; |
333 | return ESYNCH_OK_BLOCKED; |
284 | } |
334 | } |
285 | 335 | ||
286 | 336 |