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	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 */
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	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 */
278int
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 */
347int
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 */
417void
418cv_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 */
437void
438cv_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}
458