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: 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 */
62void
63cv_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 */
74void
75cv_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 */
94void
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	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 */
156void
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 */
211int
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	int lock_state, rval;
218
219	td = curthread;
220	lock_state = 0;
221#ifdef KTRACE
222	if (KTRPOINT(td, KTR_CSW))
223		ktrcsw(1, 0, cv_wmesg(cvp));
224#endif
225	CV_ASSERT(cvp, lock, td);
226	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
227	    "Waiting on \"%s\"", cvp->cv_description);
228	class = LOCK_CLASS(lock);
229
230	if (cold || panicstr) {
231		/*
232		 * After a panic, or during autoconfiguration, just give
233		 * interrupts a chance, then just return; don't run any other
234		 * procs or panic below, in case this is the idle process and
235		 * already asleep.
236		 */
237		return (0);
238	}
239
240	sleepq_lock(cvp);
241
242	cvp->cv_waiters++;
243	if (lock == &Giant.lock_object)
244		mtx_assert(&Giant, MA_OWNED);
245	DROP_GIANT();
246
247	sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR |
248	    SLEEPQ_INTERRUPTIBLE, 0);
249	if (lock != &Giant.lock_object) {
250		if (class->lc_flags & LC_SLEEPABLE)
251			sleepq_release(cvp);
252		WITNESS_SAVE(lock, lock_witness);
253		lock_state = class->lc_unlock(lock);
254		if (class->lc_flags & LC_SLEEPABLE)
255			sleepq_lock(cvp);
256	}
257	rval = sleepq_wait_sig(cvp, 0);
258
259#ifdef KTRACE
260	if (KTRPOINT(td, KTR_CSW))
261		ktrcsw(0, 0, cv_wmesg(cvp));
262#endif
263	PICKUP_GIANT();
264	if (lock != &Giant.lock_object) {
265		class->lc_lock(lock, lock_state);
266		WITNESS_RESTORE(lock, lock_witness);
267	}
268
269	return (rval);
270}
271
272/*
273 * Wait on a condition variable for at most timo/hz seconds.  Returns 0 if the
274 * process was resumed by cv_signal or cv_broadcast, EWOULDBLOCK if the timeout
275 * expires.
276 */
277int
278_cv_timedwait(struct cv *cvp, struct lock_object *lock, int timo)
279{
280	WITNESS_SAVE_DECL(lock_witness);
281	struct lock_class *class;
282	struct thread *td;
283	int lock_state, rval;
284
285	td = curthread;
286	lock_state = 0;
287#ifdef KTRACE
288	if (KTRPOINT(td, KTR_CSW))
289		ktrcsw(1, 0, cv_wmesg(cvp));
290#endif
291	CV_ASSERT(cvp, lock, td);
292	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
293	    "Waiting on \"%s\"", cvp->cv_description);
294	class = LOCK_CLASS(lock);
295
296	if (cold || panicstr) {
297		/*
298		 * After a panic, or during autoconfiguration, just give
299		 * interrupts a chance, then just return; don't run any other
300		 * thread or panic below, in case this is the idle process and
301		 * already asleep.
302		 */
303		return 0;
304	}
305
306	sleepq_lock(cvp);
307
308	cvp->cv_waiters++;
309	if (lock == &Giant.lock_object)
310		mtx_assert(&Giant, MA_OWNED);
311	DROP_GIANT();
312
313	sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
314	sleepq_set_timeout(cvp, timo);
315	if (lock != &Giant.lock_object) {
316		if (class->lc_flags & LC_SLEEPABLE)
317			sleepq_release(cvp);
318		WITNESS_SAVE(lock, lock_witness);
319		lock_state = class->lc_unlock(lock);
320		if (class->lc_flags & LC_SLEEPABLE)
321			sleepq_lock(cvp);
322	}
323	rval = sleepq_timedwait(cvp, 0);
324
325#ifdef KTRACE
326	if (KTRPOINT(td, KTR_CSW))
327		ktrcsw(0, 0, cv_wmesg(cvp));
328#endif
329	PICKUP_GIANT();
330	if (lock != &Giant.lock_object) {
331		class->lc_lock(lock, lock_state);
332		WITNESS_RESTORE(lock, lock_witness);
333	}
334
335	return (rval);
336}
337
338/*
339 * Wait on a condition variable for at most timo/hz seconds, allowing
340 * interruption by signals.  Returns 0 if the thread was resumed by cv_signal
341 * or cv_broadcast, EWOULDBLOCK if the timeout expires, and EINTR or ERESTART if
342 * a signal was caught.
343 */
344int
345_cv_timedwait_sig(struct cv *cvp, struct lock_object *lock, int timo)
346{
347	WITNESS_SAVE_DECL(lock_witness);
348	struct lock_class *class;
349	struct thread *td;
350	int lock_state, rval;
351
352	td = curthread;
353	lock_state = 0;
354#ifdef KTRACE
355	if (KTRPOINT(td, KTR_CSW))
356		ktrcsw(1, 0, cv_wmesg(cvp));
357#endif
358	CV_ASSERT(cvp, lock, td);
359	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
360	    "Waiting on \"%s\"", cvp->cv_description);
361	class = LOCK_CLASS(lock);
362
363	if (cold || panicstr) {
364		/*
365		 * After a panic, or during autoconfiguration, just give
366		 * interrupts a chance, then just return; don't run any other
367		 * thread or panic below, in case this is the idle process and
368		 * already asleep.
369		 */
370		return 0;
371	}
372
373	sleepq_lock(cvp);
374
375	cvp->cv_waiters++;
376	if (lock == &Giant.lock_object)
377		mtx_assert(&Giant, MA_OWNED);
378	DROP_GIANT();
379
380	sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR |
381	    SLEEPQ_INTERRUPTIBLE, 0);
382	sleepq_set_timeout(cvp, timo);
383	if (lock != &Giant.lock_object) {
384		if (class->lc_flags & LC_SLEEPABLE)
385			sleepq_release(cvp);
386		WITNESS_SAVE(lock, lock_witness);
387		lock_state = class->lc_unlock(lock);
388		if (class->lc_flags & LC_SLEEPABLE)
389			sleepq_lock(cvp);
390	}
391	rval = sleepq_timedwait_sig(cvp, 0);
392
393#ifdef KTRACE
394	if (KTRPOINT(td, KTR_CSW))
395		ktrcsw(0, 0, cv_wmesg(cvp));
396#endif
397	PICKUP_GIANT();
398	if (lock != &Giant.lock_object) {
399		class->lc_lock(lock, lock_state);
400		WITNESS_RESTORE(lock, lock_witness);
401	}
402
403	return (rval);
404}
405
406/*
407 * Signal a condition variable, wakes up one waiting thread.  Will also wakeup
408 * the swapper if the process is not in memory, so that it can bring the
409 * sleeping process in.  Note that this may also result in additional threads
410 * being made runnable.  Should be called with the same mutex as was passed to
411 * cv_wait held.
412 */
413void
414cv_signal(struct cv *cvp)
415{
416	int wakeup_swapper;
417
418	wakeup_swapper = 0;
419	sleepq_lock(cvp);
420	if (cvp->cv_waiters > 0) {
421		cvp->cv_waiters--;
422		wakeup_swapper = sleepq_signal(cvp, SLEEPQ_CONDVAR, 0, 0);
423	}
424	sleepq_release(cvp);
425	if (wakeup_swapper)
426		kick_proc0();
427}
428
429/*
430 * Broadcast a signal to a condition variable.  Wakes up all waiting threads.
431 * Should be called with the same mutex as was passed to cv_wait held.
432 */
433void
434cv_broadcastpri(struct cv *cvp, int pri)
435{
436	int wakeup_swapper;
437
438	/*
439	 * XXX sleepq_broadcast pri argument changed from -1 meaning
440	 * no pri to 0 meaning no pri.
441	 */
442	wakeup_swapper = 0;
443	if (pri == -1)
444		pri = 0;
445	sleepq_lock(cvp);
446	if (cvp->cv_waiters > 0) {
447		cvp->cv_waiters = 0;
448		wakeup_swapper = sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri, 0);
449	}
450	sleepq_release(cvp);
451	if (wakeup_swapper)
452		kick_proc0();
453}
454