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("$FreeBSD$");
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: curthread 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 int lock_state;
101
102 td = curthread;
103 #ifdef KTRACE
104 if (KTRPOINT(td, KTR_CSW))
105 ktrcsw(1, 0);
106 #endif
107 CV_ASSERT(cvp, lock, td);
108 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
109 "Waiting on \"%s\"", cvp->cv_description);
110 WITNESS_SAVE(lock, lock_witness);
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 DROP_GIANT();
127
128 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
129 if (class->lc_flags & LC_SLEEPABLE)
130 sleepq_release(cvp);
131 lock_state = class->lc_unlock(lock);
132 if (class->lc_flags & LC_SLEEPABLE)
133 sleepq_lock(cvp);
134 sleepq_wait(cvp);
135
136 #ifdef KTRACE
137 if (KTRPOINT(td, KTR_CSW))
138 ktrcsw(0, 0);
139 #endif
140 PICKUP_GIANT();
141 class->lc_lock(lock, lock_state);
142 WITNESS_RESTORE(lock, lock_witness);
143 }
144
145 /*
146 * Wait on a condition variable. This function differs from cv_wait by
147 * not aquiring the mutex after condition variable was signaled.
148 */
149 void
150 _cv_wait_unlock(struct cv *cvp, struct lock_object *lock)
151 {
152 struct lock_class *class;
153 struct thread *td;
154
155 td = curthread;
156 #ifdef KTRACE
157 if (KTRPOINT(td, KTR_CSW))
158 ktrcsw(1, 0);
159 #endif
160 CV_ASSERT(cvp, lock, td);
161 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
162 "Waiting on \"%s\"", cvp->cv_description);
163 class = LOCK_CLASS(lock);
164
165 if (cold || panicstr) {
166 /*
167 * During autoconfiguration, just give interrupts
168 * a chance, then just return. Don't run any other
169 * thread or panic below, in case this is the idle
170 * process and already asleep.
171 */
172 class->lc_unlock(lock);
173 return;
174 }
175
176 sleepq_lock(cvp);
177
178 cvp->cv_waiters++;
179 DROP_GIANT();
180
181 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
182 if (class->lc_flags & LC_SLEEPABLE)
183 sleepq_release(cvp);
184 class->lc_unlock(lock);
185 if (class->lc_flags & LC_SLEEPABLE)
186 sleepq_lock(cvp);
187 sleepq_wait(cvp);
188
189 #ifdef KTRACE
190 if (KTRPOINT(td, KTR_CSW))
191 ktrcsw(0, 0);
192 #endif
193 PICKUP_GIANT();
194 }
195
196 /*
197 * Wait on a condition variable, allowing interruption by signals. Return 0 if
198 * the thread was resumed with cv_signal or cv_broadcast, EINTR or ERESTART if
199 * a signal was caught. If ERESTART is returned the system call should be
200 * restarted if possible.
201 */
202 int
203 _cv_wait_sig(struct cv *cvp, struct lock_object *lock)
204 {
205 WITNESS_SAVE_DECL(lock_witness);
206 struct lock_class *class;
207 struct thread *td;
208 struct proc *p;
209 int lock_state, rval;
210
211 td = curthread;
212 p = td->td_proc;
213 #ifdef KTRACE
214 if (KTRPOINT(td, KTR_CSW))
215 ktrcsw(1, 0);
216 #endif
217 CV_ASSERT(cvp, lock, td);
218 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
219 "Waiting on \"%s\"", cvp->cv_description);
220 WITNESS_SAVE(lock, lock_witness);
221 class = LOCK_CLASS(lock);
222
223 if (cold || panicstr) {
224 /*
225 * After a panic, or during autoconfiguration, just give
226 * interrupts a chance, then just return; don't run any other
227 * procs or panic below, in case this is the idle process and
228 * already asleep.
229 */
230 return (0);
231 }
232
233 sleepq_lock(cvp);
234
235 cvp->cv_waiters++;
236 DROP_GIANT();
237
238 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR |
239 SLEEPQ_INTERRUPTIBLE, 0);
240 if (class->lc_flags & LC_SLEEPABLE)
241 sleepq_release(cvp);
242 lock_state = class->lc_unlock(lock);
243 if (class->lc_flags & LC_SLEEPABLE)
244 sleepq_lock(cvp);
245 rval = sleepq_wait_sig(cvp);
246
247 #ifdef KTRACE
248 if (KTRPOINT(td, KTR_CSW))
249 ktrcsw(0, 0);
250 #endif
251 PICKUP_GIANT();
252 class->lc_lock(lock, lock_state);
253 WITNESS_RESTORE(lock, lock_witness);
254
255 return (rval);
256 }
257
258 /*
259 * Wait on a condition variable for at most timo/hz seconds. Returns 0 if the
260 * process was resumed by cv_signal or cv_broadcast, EWOULDBLOCK if the timeout
261 * expires.
262 */
263 int
264 _cv_timedwait(struct cv *cvp, struct lock_object *lock, int timo)
265 {
266 WITNESS_SAVE_DECL(lock_witness);
267 struct lock_class *class;
268 struct thread *td;
269 int lock_state, rval;
270
271 td = curthread;
272 rval = 0;
273 #ifdef KTRACE
274 if (KTRPOINT(td, KTR_CSW))
275 ktrcsw(1, 0);
276 #endif
277 CV_ASSERT(cvp, lock, td);
278 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
279 "Waiting on \"%s\"", cvp->cv_description);
280 WITNESS_SAVE(lock, lock_witness);
281 class = LOCK_CLASS(lock);
282
283 if (cold || panicstr) {
284 /*
285 * After a panic, or during autoconfiguration, just give
286 * interrupts a chance, then just return; don't run any other
287 * thread or panic below, in case this is the idle process and
288 * already asleep.
289 */
290 return 0;
291 }
292
293 sleepq_lock(cvp);
294
295 cvp->cv_waiters++;
296 DROP_GIANT();
297
298 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
299 sleepq_set_timeout(cvp, timo);
300 if (class->lc_flags & LC_SLEEPABLE)
301 sleepq_release(cvp);
302 lock_state = class->lc_unlock(lock);
303 if (class->lc_flags & LC_SLEEPABLE)
304 sleepq_lock(cvp);
305 rval = sleepq_timedwait(cvp);
306
307 #ifdef KTRACE
308 if (KTRPOINT(td, KTR_CSW))
309 ktrcsw(0, 0);
310 #endif
311 PICKUP_GIANT();
312 class->lc_lock(lock, lock_state);
313 WITNESS_RESTORE(lock, lock_witness);
314
315 return (rval);
316 }
317
318 /*
319 * Wait on a condition variable for at most timo/hz seconds, allowing
320 * interruption by signals. Returns 0 if the thread was resumed by cv_signal
321 * or cv_broadcast, EWOULDBLOCK if the timeout expires, and EINTR or ERESTART if
322 * a signal was caught.
323 */
324 int
325 _cv_timedwait_sig(struct cv *cvp, struct lock_object *lock, int timo)
326 {
327 WITNESS_SAVE_DECL(lock_witness);
328 struct lock_class *class;
329 struct thread *td;
330 struct proc *p;
331 int lock_state, rval;
332
333 td = curthread;
334 p = td->td_proc;
335 rval = 0;
336 #ifdef KTRACE
337 if (KTRPOINT(td, KTR_CSW))
338 ktrcsw(1, 0);
339 #endif
340 CV_ASSERT(cvp, lock, td);
341 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
342 "Waiting on \"%s\"", cvp->cv_description);
343 WITNESS_SAVE(lock, lock_witness);
344 class = LOCK_CLASS(lock);
345
346 if (cold || panicstr) {
347 /*
348 * After a panic, or during autoconfiguration, just give
349 * interrupts a chance, then just return; don't run any other
350 * thread or panic below, in case this is the idle process and
351 * already asleep.
352 */
353 return 0;
354 }
355
356 sleepq_lock(cvp);
357
358 cvp->cv_waiters++;
359 DROP_GIANT();
360
361 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR |
362 SLEEPQ_INTERRUPTIBLE, 0);
363 sleepq_set_timeout(cvp, timo);
364 if (class->lc_flags & LC_SLEEPABLE)
365 sleepq_release(cvp);
366 lock_state = class->lc_unlock(lock);
367 if (class->lc_flags & LC_SLEEPABLE)
368 sleepq_lock(cvp);
369 rval = sleepq_timedwait_sig(cvp);
370
371 #ifdef KTRACE
372 if (KTRPOINT(td, KTR_CSW))
373 ktrcsw(0, 0);
374 #endif
375 PICKUP_GIANT();
376 class->lc_lock(lock, lock_state);
377 WITNESS_RESTORE(lock, lock_witness);
378
379 return (rval);
380 }
381
382 /*
383 * Signal a condition variable, wakes up one waiting thread. Will also wakeup
384 * the swapper if the process is not in memory, so that it can bring the
385 * sleeping process in. Note that this may also result in additional threads
386 * being made runnable. Should be called with the same mutex as was passed to
387 * cv_wait held.
388 */
389 void
390 cv_signal(struct cv *cvp)
391 {
392 int wakeup_swapper;
393
394 wakeup_swapper = 0;
395 sleepq_lock(cvp);
396 if (cvp->cv_waiters > 0) {
397 cvp->cv_waiters--;
398 wakeup_swapper = sleepq_signal(cvp, SLEEPQ_CONDVAR, -1, 0);
399 }
400 sleepq_release(cvp);
401 if (wakeup_swapper)
402 kick_proc0();
403 }
404
405 /*
406 * Broadcast a signal to a condition variable. Wakes up all waiting threads.
407 * Should be called with the same mutex as was passed to cv_wait held.
408 */
409 void
410 cv_broadcastpri(struct cv *cvp, int pri)
411 {
412 int wakeup_swapper;
413
414 wakeup_swapper = 0;
415 sleepq_lock(cvp);
416 if (cvp->cv_waiters > 0) {
417 cvp->cv_waiters = 0;
418 wakeup_swapper = sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri, 0);
419 } else
420 sleepq_release(cvp);
421 if (wakeup_swapper)
422 kick_proc0();
423 }
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