1 /*-
2 * Copyright (c) 2000 Jake Burkholder <jake@freebsd.org>.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD: releng/10.2/sys/kern/kern_condvar.c 255745 2013-09-20 23:06:21Z davide $");
29
30 #include "opt_ktrace.h"
31
32 #include <sys/param.h>
33 #include <sys/systm.h>
34 #include <sys/lock.h>
35 #include <sys/mutex.h>
36 #include <sys/proc.h>
37 #include <sys/kernel.h>
38 #include <sys/ktr.h>
39 #include <sys/condvar.h>
40 #include <sys/sched.h>
41 #include <sys/signalvar.h>
42 #include <sys/sleepqueue.h>
43 #include <sys/resourcevar.h>
44 #ifdef KTRACE
45 #include <sys/uio.h>
46 #include <sys/ktrace.h>
47 #endif
48
49 /*
50 * Common sanity checks for cv_wait* functions.
51 */
52 #define CV_ASSERT(cvp, lock, td) do { \
53 KASSERT((td) != NULL, ("%s: td NULL", __func__)); \
54 KASSERT(TD_IS_RUNNING(td), ("%s: not TDS_RUNNING", __func__)); \
55 KASSERT((cvp) != NULL, ("%s: cvp NULL", __func__)); \
56 KASSERT((lock) != NULL, ("%s: lock NULL", __func__)); \
57 } while (0)
58
59 /*
60 * Initialize a condition variable. Must be called before use.
61 */
62 void
63 cv_init(struct cv *cvp, const char *desc)
64 {
65
66 cvp->cv_description = desc;
67 cvp->cv_waiters = 0;
68 }
69
70 /*
71 * Destroy a condition variable. The condition variable must be re-initialized
72 * in order to be re-used.
73 */
74 void
75 cv_destroy(struct cv *cvp)
76 {
77 #ifdef INVARIANTS
78 struct sleepqueue *sq;
79
80 sleepq_lock(cvp);
81 sq = sleepq_lookup(cvp);
82 sleepq_release(cvp);
83 KASSERT(sq == NULL, ("%s: associated sleep queue non-empty", __func__));
84 #endif
85 }
86
87 /*
88 * Wait on a condition variable. The current thread is placed on the condition
89 * variable's wait queue and suspended. A cv_signal or cv_broadcast on the same
90 * condition variable will resume the thread. The mutex is released before
91 * sleeping and will be held on return. It is recommended that the mutex be
92 * held when cv_signal or cv_broadcast are called.
93 */
94 void
95 _cv_wait(struct cv *cvp, struct lock_object *lock)
96 {
97 WITNESS_SAVE_DECL(lock_witness);
98 struct lock_class *class;
99 struct thread *td;
100 uintptr_t lock_state;
101
102 td = curthread;
103 lock_state = 0;
104 #ifdef KTRACE
105 if (KTRPOINT(td, KTR_CSW))
106 ktrcsw(1, 0, cv_wmesg(cvp));
107 #endif
108 CV_ASSERT(cvp, lock, td);
109 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
110 "Waiting on \"%s\"", cvp->cv_description);
111 class = LOCK_CLASS(lock);
112
113 if (cold || panicstr) {
114 /*
115 * During autoconfiguration, just give interrupts
116 * a chance, then just return. Don't run any other
117 * thread or panic below, in case this is the idle
118 * process and already asleep.
119 */
120 return;
121 }
122
123 sleepq_lock(cvp);
124
125 cvp->cv_waiters++;
126 if (lock == &Giant.lock_object)
127 mtx_assert(&Giant, MA_OWNED);
128 DROP_GIANT();
129
130 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
131 if (lock != &Giant.lock_object) {
132 if (class->lc_flags & LC_SLEEPABLE)
133 sleepq_release(cvp);
134 WITNESS_SAVE(lock, lock_witness);
135 lock_state = class->lc_unlock(lock);
136 if (class->lc_flags & LC_SLEEPABLE)
137 sleepq_lock(cvp);
138 }
139 sleepq_wait(cvp, 0);
140
141 #ifdef KTRACE
142 if (KTRPOINT(td, KTR_CSW))
143 ktrcsw(0, 0, cv_wmesg(cvp));
144 #endif
145 PICKUP_GIANT();
146 if (lock != &Giant.lock_object) {
147 class->lc_lock(lock, lock_state);
148 WITNESS_RESTORE(lock, lock_witness);
149 }
150 }
151
152 /*
153 * Wait on a condition variable. This function differs from cv_wait by
154 * not aquiring the mutex after condition variable was signaled.
155 */
156 void
157 _cv_wait_unlock(struct cv *cvp, struct lock_object *lock)
158 {
159 struct lock_class *class;
160 struct thread *td;
161
162 td = curthread;
163 #ifdef KTRACE
164 if (KTRPOINT(td, KTR_CSW))
165 ktrcsw(1, 0, cv_wmesg(cvp));
166 #endif
167 CV_ASSERT(cvp, lock, td);
168 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
169 "Waiting on \"%s\"", cvp->cv_description);
170 KASSERT(lock != &Giant.lock_object,
171 ("cv_wait_unlock cannot be used with Giant"));
172 class = LOCK_CLASS(lock);
173
174 if (cold || panicstr) {
175 /*
176 * During autoconfiguration, just give interrupts
177 * a chance, then just return. Don't run any other
178 * thread or panic below, in case this is the idle
179 * process and already asleep.
180 */
181 class->lc_unlock(lock);
182 return;
183 }
184
185 sleepq_lock(cvp);
186
187 cvp->cv_waiters++;
188 DROP_GIANT();
189
190 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
191 if (class->lc_flags & LC_SLEEPABLE)
192 sleepq_release(cvp);
193 class->lc_unlock(lock);
194 if (class->lc_flags & LC_SLEEPABLE)
195 sleepq_lock(cvp);
196 sleepq_wait(cvp, 0);
197
198 #ifdef KTRACE
199 if (KTRPOINT(td, KTR_CSW))
200 ktrcsw(0, 0, cv_wmesg(cvp));
201 #endif
202 PICKUP_GIANT();
203 }
204
205 /*
206 * Wait on a condition variable, allowing interruption by signals. Return 0 if
207 * the thread was resumed with cv_signal or cv_broadcast, EINTR or ERESTART if
208 * a signal was caught. If ERESTART is returned the system call should be
209 * restarted if possible.
210 */
211 int
212 _cv_wait_sig(struct cv *cvp, struct lock_object *lock)
213 {
214 WITNESS_SAVE_DECL(lock_witness);
215 struct lock_class *class;
216 struct thread *td;
217 uintptr_t lock_state;
218 int rval;
219
220 td = curthread;
221 lock_state = 0;
222 #ifdef KTRACE
223 if (KTRPOINT(td, KTR_CSW))
224 ktrcsw(1, 0, cv_wmesg(cvp));
225 #endif
226 CV_ASSERT(cvp, lock, td);
227 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
228 "Waiting on \"%s\"", cvp->cv_description);
229 class = LOCK_CLASS(lock);
230
231 if (cold || panicstr) {
232 /*
233 * After a panic, or during autoconfiguration, just give
234 * interrupts a chance, then just return; don't run any other
235 * procs or panic below, in case this is the idle process and
236 * already asleep.
237 */
238 return (0);
239 }
240
241 sleepq_lock(cvp);
242
243 cvp->cv_waiters++;
244 if (lock == &Giant.lock_object)
245 mtx_assert(&Giant, MA_OWNED);
246 DROP_GIANT();
247
248 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR |
249 SLEEPQ_INTERRUPTIBLE, 0);
250 if (lock != &Giant.lock_object) {
251 if (class->lc_flags & LC_SLEEPABLE)
252 sleepq_release(cvp);
253 WITNESS_SAVE(lock, lock_witness);
254 lock_state = class->lc_unlock(lock);
255 if (class->lc_flags & LC_SLEEPABLE)
256 sleepq_lock(cvp);
257 }
258 rval = sleepq_wait_sig(cvp, 0);
259
260 #ifdef KTRACE
261 if (KTRPOINT(td, KTR_CSW))
262 ktrcsw(0, 0, cv_wmesg(cvp));
263 #endif
264 PICKUP_GIANT();
265 if (lock != &Giant.lock_object) {
266 class->lc_lock(lock, lock_state);
267 WITNESS_RESTORE(lock, lock_witness);
268 }
269
270 return (rval);
271 }
272
273 /*
274 * Wait on a condition variable for (at most) the value specified in sbt
275 * argument. Returns 0 if the process was resumed by cv_signal or cv_broadcast,
276 * EWOULDBLOCK if the timeout expires.
277 */
278 int
279 _cv_timedwait_sbt(struct cv *cvp, struct lock_object *lock, sbintime_t sbt,
280 sbintime_t pr, int flags)
281 {
282 WITNESS_SAVE_DECL(lock_witness);
283 struct lock_class *class;
284 struct thread *td;
285 int lock_state, rval;
286
287 td = curthread;
288 lock_state = 0;
289 #ifdef KTRACE
290 if (KTRPOINT(td, KTR_CSW))
291 ktrcsw(1, 0, cv_wmesg(cvp));
292 #endif
293 CV_ASSERT(cvp, lock, td);
294 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
295 "Waiting on \"%s\"", cvp->cv_description);
296 class = LOCK_CLASS(lock);
297
298 if (cold || panicstr) {
299 /*
300 * After a panic, or during autoconfiguration, just give
301 * interrupts a chance, then just return; don't run any other
302 * thread or panic below, in case this is the idle process and
303 * already asleep.
304 */
305 return 0;
306 }
307
308 sleepq_lock(cvp);
309
310 cvp->cv_waiters++;
311 if (lock == &Giant.lock_object)
312 mtx_assert(&Giant, MA_OWNED);
313 DROP_GIANT();
314
315 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
316 sleepq_set_timeout_sbt(cvp, sbt, pr, flags);
317 if (lock != &Giant.lock_object) {
318 if (class->lc_flags & LC_SLEEPABLE)
319 sleepq_release(cvp);
320 WITNESS_SAVE(lock, lock_witness);
321 lock_state = class->lc_unlock(lock);
322 if (class->lc_flags & LC_SLEEPABLE)
323 sleepq_lock(cvp);
324 }
325 rval = sleepq_timedwait(cvp, 0);
326
327 #ifdef KTRACE
328 if (KTRPOINT(td, KTR_CSW))
329 ktrcsw(0, 0, cv_wmesg(cvp));
330 #endif
331 PICKUP_GIANT();
332 if (lock != &Giant.lock_object) {
333 class->lc_lock(lock, lock_state);
334 WITNESS_RESTORE(lock, lock_witness);
335 }
336
337 return (rval);
338 }
339
340 /*
341 * Wait on a condition variable for (at most) the value specified in sbt
342 * argument, allowing interruption by signals.
343 * Returns 0 if the thread was resumed by cv_signal or cv_broadcast,
344 * EWOULDBLOCK if the timeout expires, and EINTR or ERESTART if a signal
345 * was caught.
346 */
347 int
348 _cv_timedwait_sig_sbt(struct cv *cvp, struct lock_object *lock,
349 sbintime_t sbt, sbintime_t pr, int flags)
350 {
351 WITNESS_SAVE_DECL(lock_witness);
352 struct lock_class *class;
353 struct thread *td;
354 int lock_state, rval;
355
356 td = curthread;
357 lock_state = 0;
358 #ifdef KTRACE
359 if (KTRPOINT(td, KTR_CSW))
360 ktrcsw(1, 0, cv_wmesg(cvp));
361 #endif
362 CV_ASSERT(cvp, lock, td);
363 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
364 "Waiting on \"%s\"", cvp->cv_description);
365 class = LOCK_CLASS(lock);
366
367 if (cold || panicstr) {
368 /*
369 * After a panic, or during autoconfiguration, just give
370 * interrupts a chance, then just return; don't run any other
371 * thread or panic below, in case this is the idle process and
372 * already asleep.
373 */
374 return 0;
375 }
376
377 sleepq_lock(cvp);
378
379 cvp->cv_waiters++;
380 if (lock == &Giant.lock_object)
381 mtx_assert(&Giant, MA_OWNED);
382 DROP_GIANT();
383
384 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR |
385 SLEEPQ_INTERRUPTIBLE, 0);
386 sleepq_set_timeout_sbt(cvp, sbt, pr, flags);
387 if (lock != &Giant.lock_object) {
388 if (class->lc_flags & LC_SLEEPABLE)
389 sleepq_release(cvp);
390 WITNESS_SAVE(lock, lock_witness);
391 lock_state = class->lc_unlock(lock);
392 if (class->lc_flags & LC_SLEEPABLE)
393 sleepq_lock(cvp);
394 }
395 rval = sleepq_timedwait_sig(cvp, 0);
396
397 #ifdef KTRACE
398 if (KTRPOINT(td, KTR_CSW))
399 ktrcsw(0, 0, cv_wmesg(cvp));
400 #endif
401 PICKUP_GIANT();
402 if (lock != &Giant.lock_object) {
403 class->lc_lock(lock, lock_state);
404 WITNESS_RESTORE(lock, lock_witness);
405 }
406
407 return (rval);
408 }
409
410 /*
411 * Signal a condition variable, wakes up one waiting thread. Will also wakeup
412 * the swapper if the process is not in memory, so that it can bring the
413 * sleeping process in. Note that this may also result in additional threads
414 * being made runnable. Should be called with the same mutex as was passed to
415 * cv_wait held.
416 */
417 void
418 cv_signal(struct cv *cvp)
419 {
420 int wakeup_swapper;
421
422 wakeup_swapper = 0;
423 sleepq_lock(cvp);
424 if (cvp->cv_waiters > 0) {
425 cvp->cv_waiters--;
426 wakeup_swapper = sleepq_signal(cvp, SLEEPQ_CONDVAR, 0, 0);
427 }
428 sleepq_release(cvp);
429 if (wakeup_swapper)
430 kick_proc0();
431 }
432
433 /*
434 * Broadcast a signal to a condition variable. Wakes up all waiting threads.
435 * Should be called with the same mutex as was passed to cv_wait held.
436 */
437 void
438 cv_broadcastpri(struct cv *cvp, int pri)
439 {
440 int wakeup_swapper;
441
442 /*
443 * XXX sleepq_broadcast pri argument changed from -1 meaning
444 * no pri to 0 meaning no pri.
445 */
446 wakeup_swapper = 0;
447 if (pri == -1)
448 pri = 0;
449 sleepq_lock(cvp);
450 if (cvp->cv_waiters > 0) {
451 cvp->cv_waiters = 0;
452 wakeup_swapper = sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri, 0);
453 }
454 sleepq_release(cvp);
455 if (wakeup_swapper)
456 kick_proc0();
457 }
Cache object: c9f9e531be036dfd1ec00c9d8f8bd871
|