1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2010 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /*
28 * Copyright (c) 2012 by Delphix. All rights reserved.
29 */
30
31 #include <sys/thread.h>
32 #include <sys/proc.h>
33 #include <sys/debug.h>
34 #include <sys/cmn_err.h>
35 #include <sys/systm.h>
36 #include <sys/sobject.h>
37 #include <sys/sleepq.h>
38 #include <sys/cpuvar.h>
39 #include <sys/condvar.h>
40 #include <sys/condvar_impl.h>
41 #include <sys/schedctl.h>
42 #include <sys/procfs.h>
43 #include <sys/sdt.h>
44 #include <sys/callo.h>
45
46 /*
47 * CV_MAX_WAITERS is the maximum number of waiters we track; once
48 * the number becomes higher than that, we look at the sleepq to
49 * see whether there are *really* any waiters.
50 */
51 #define CV_MAX_WAITERS 1024 /* must be power of 2 */
52 #define CV_WAITERS_MASK (CV_MAX_WAITERS - 1)
53
54 /*
55 * Threads don't "own" condition variables.
56 */
57 /* ARGSUSED */
58 static kthread_t *
59 cv_owner(void *cvp)
60 {
61 return (NULL);
62 }
63
64 /*
65 * Unsleep a thread that's blocked on a condition variable.
66 */
67 static void
68 cv_unsleep(kthread_t *t)
69 {
70 condvar_impl_t *cvp = (condvar_impl_t *)t->t_wchan;
71 sleepq_head_t *sqh = SQHASH(cvp);
72
73 ASSERT(THREAD_LOCK_HELD(t));
74
75 if (cvp == NULL)
76 panic("cv_unsleep: thread %p not on sleepq %p",
77 (void *)t, (void *)sqh);
78 DTRACE_SCHED1(wakeup, kthread_t *, t);
79 sleepq_unsleep(t);
80 if (cvp->cv_waiters != CV_MAX_WAITERS)
81 cvp->cv_waiters--;
82 disp_lock_exit_high(&sqh->sq_lock);
83 CL_SETRUN(t);
84 }
85
86 /*
87 * Change the priority of a thread that's blocked on a condition variable.
88 */
89 static void
90 cv_change_pri(kthread_t *t, pri_t pri, pri_t *t_prip)
91 {
92 condvar_impl_t *cvp = (condvar_impl_t *)t->t_wchan;
93 sleepq_t *sqp = t->t_sleepq;
94
95 ASSERT(THREAD_LOCK_HELD(t));
96 ASSERT(&SQHASH(cvp)->sq_queue == sqp);
97
98 if (cvp == NULL)
99 panic("cv_change_pri: %p not on sleep queue", (void *)t);
100 sleepq_dequeue(t);
101 *t_prip = pri;
102 sleepq_insert(sqp, t);
103 }
104
105 /*
106 * The sobj_ops vector exports a set of functions needed when a thread
107 * is asleep on a synchronization object of this type.
108 */
109 static sobj_ops_t cv_sobj_ops = {
110 SOBJ_CV, cv_owner, cv_unsleep, cv_change_pri
111 };
112
113 /* ARGSUSED */
114 void
115 cv_init(kcondvar_t *cvp, char *name, kcv_type_t type, void *arg)
116 {
117 ((condvar_impl_t *)cvp)->cv_waiters = 0;
118 }
119
120 /*
121 * cv_destroy is not currently needed, but is part of the DDI.
122 * This is in case cv_init ever needs to allocate something for a cv.
123 */
124 /* ARGSUSED */
125 void
126 cv_destroy(kcondvar_t *cvp)
127 {
128 ASSERT((((condvar_impl_t *)cvp)->cv_waiters & CV_WAITERS_MASK) == 0);
129 }
130
131 /*
132 * The cv_block() function blocks a thread on a condition variable
133 * by putting it in a hashed sleep queue associated with the
134 * synchronization object.
135 *
136 * Threads are taken off the hashed sleep queues via calls to
137 * cv_signal(), cv_broadcast(), or cv_unsleep().
138 */
139 static void
140 cv_block(condvar_impl_t *cvp)
141 {
142 kthread_t *t = curthread;
143 klwp_t *lwp = ttolwp(t);
144 sleepq_head_t *sqh;
145
146 ASSERT(THREAD_LOCK_HELD(t));
147 ASSERT(t != CPU->cpu_idle_thread);
148 ASSERT(CPU_ON_INTR(CPU) == 0);
149 ASSERT(t->t_wchan0 == NULL && t->t_wchan == NULL);
150 ASSERT(t->t_state == TS_ONPROC);
151
152 t->t_schedflag &= ~TS_SIGNALLED;
153 CL_SLEEP(t); /* assign kernel priority */
154 t->t_wchan = (caddr_t)cvp;
155 t->t_sobj_ops = &cv_sobj_ops;
156 DTRACE_SCHED(sleep);
157
158 /*
159 * The check for t_intr is to avoid doing the
160 * account for an interrupt thread on the still-pinned
161 * lwp's statistics.
162 */
163 if (lwp != NULL && t->t_intr == NULL) {
164 lwp->lwp_ru.nvcsw++;
165 (void) new_mstate(t, LMS_SLEEP);
166 }
167
168 sqh = SQHASH(cvp);
169 disp_lock_enter_high(&sqh->sq_lock);
170 if (cvp->cv_waiters < CV_MAX_WAITERS)
171 cvp->cv_waiters++;
172 ASSERT(cvp->cv_waiters <= CV_MAX_WAITERS);
173 THREAD_SLEEP(t, &sqh->sq_lock);
174 sleepq_insert(&sqh->sq_queue, t);
175 /*
176 * THREAD_SLEEP() moves curthread->t_lockp to point to the
177 * lock sqh->sq_lock. This lock is later released by the caller
178 * when it calls thread_unlock() on curthread.
179 */
180 }
181
182 #define cv_block_sig(t, cvp) \
183 { (t)->t_flag |= T_WAKEABLE; cv_block(cvp); }
184
185 /*
186 * Block on the indicated condition variable and release the
187 * associated kmutex while blocked.
188 */
189 void
190 cv_wait(kcondvar_t *cvp, kmutex_t *mp)
191 {
192 if (panicstr)
193 return;
194 ASSERT(!quiesce_active);
195
196 ASSERT(curthread->t_schedflag & TS_DONT_SWAP);
197 thread_lock(curthread); /* lock the thread */
198 cv_block((condvar_impl_t *)cvp);
199 thread_unlock_nopreempt(curthread); /* unlock the waiters field */
200 mutex_exit(mp);
201 swtch();
202 mutex_enter(mp);
203 }
204
205 static void
206 cv_wakeup(void *arg)
207 {
208 kthread_t *t = arg;
209
210 /*
211 * This mutex is acquired and released in order to make sure that
212 * the wakeup does not happen before the block itself happens.
213 */
214 mutex_enter(&t->t_wait_mutex);
215 mutex_exit(&t->t_wait_mutex);
216 setrun(t);
217 }
218
219 /*
220 * Same as cv_wait except the thread will unblock at 'tim'
221 * (an absolute time) if it hasn't already unblocked.
222 *
223 * Returns the amount of time left from the original 'tim' value
224 * when it was unblocked.
225 */
226 clock_t
227 cv_timedwait(kcondvar_t *cvp, kmutex_t *mp, clock_t tim)
228 {
229 hrtime_t hrtim;
230 clock_t now = ddi_get_lbolt();
231
232 if (tim <= now)
233 return (-1);
234
235 hrtim = TICK_TO_NSEC(tim - now);
236 return (cv_timedwait_hires(cvp, mp, hrtim, nsec_per_tick, 0));
237 }
238
239 /*
240 * Same as cv_timedwait() except that the third argument is a relative
241 * timeout value, as opposed to an absolute one. There is also a fourth
242 * argument that specifies how accurately the timeout must be implemented.
243 */
244 clock_t
245 cv_reltimedwait(kcondvar_t *cvp, kmutex_t *mp, clock_t delta, time_res_t res)
246 {
247 hrtime_t exp;
248
249 ASSERT(TIME_RES_VALID(res));
250
251 if (delta <= 0)
252 return (-1);
253
254 if ((exp = TICK_TO_NSEC(delta)) < 0)
255 exp = CY_INFINITY;
256
257 return (cv_timedwait_hires(cvp, mp, exp, time_res[res], 0));
258 }
259
260 clock_t
261 cv_timedwait_hires(kcondvar_t *cvp, kmutex_t *mp, hrtime_t tim,
262 hrtime_t res, int flag)
263 {
264 kthread_t *t = curthread;
265 callout_id_t id;
266 clock_t timeleft;
267 hrtime_t limit;
268 int signalled;
269
270 if (panicstr)
271 return (-1);
272 ASSERT(!quiesce_active);
273
274 limit = (flag & CALLOUT_FLAG_ABSOLUTE) ? gethrtime() : 0;
275 if (tim <= limit)
276 return (-1);
277 mutex_enter(&t->t_wait_mutex);
278 id = timeout_generic(CALLOUT_REALTIME, (void (*)(void *))cv_wakeup, t,
279 tim, res, flag);
280 thread_lock(t); /* lock the thread */
281 cv_block((condvar_impl_t *)cvp);
282 thread_unlock_nopreempt(t);
283 mutex_exit(&t->t_wait_mutex);
284 mutex_exit(mp);
285 swtch();
286 signalled = (t->t_schedflag & TS_SIGNALLED);
287 /*
288 * Get the time left. untimeout() returns -1 if the timeout has
289 * occured or the time remaining. If the time remaining is zero,
290 * the timeout has occured between when we were awoken and
291 * we called untimeout. We will treat this as if the timeout
292 * has occured and set timeleft to -1.
293 */
294 timeleft = untimeout_default(id, 0);
295 mutex_enter(mp);
296 if (timeleft <= 0) {
297 timeleft = -1;
298 if (signalled) /* avoid consuming the cv_signal() */
299 cv_signal(cvp);
300 }
301 return (timeleft);
302 }
303
304 int
305 cv_wait_sig(kcondvar_t *cvp, kmutex_t *mp)
306 {
307 kthread_t *t = curthread;
308 proc_t *p = ttoproc(t);
309 klwp_t *lwp = ttolwp(t);
310 int cancel_pending;
311 int rval = 1;
312 int signalled = 0;
313
314 if (panicstr)
315 return (rval);
316 ASSERT(!quiesce_active);
317
318 /*
319 * Threads in system processes don't process signals. This is
320 * true both for standard threads of system processes and for
321 * interrupt threads which have borrowed their pinned thread's LWP.
322 */
323 if (lwp == NULL || (p->p_flag & SSYS)) {
324 cv_wait(cvp, mp);
325 return (rval);
326 }
327 ASSERT(t->t_intr == NULL);
328
329 ASSERT(curthread->t_schedflag & TS_DONT_SWAP);
330 cancel_pending = schedctl_cancel_pending();
331 lwp->lwp_asleep = 1;
332 lwp->lwp_sysabort = 0;
333 thread_lock(t);
334 cv_block_sig(t, (condvar_impl_t *)cvp);
335 thread_unlock_nopreempt(t);
336 mutex_exit(mp);
337 if (ISSIG(t, JUSTLOOKING) || MUSTRETURN(p, t) || cancel_pending)
338 setrun(t);
339 /* ASSERT(no locks are held) */
340 swtch();
341 signalled = (t->t_schedflag & TS_SIGNALLED);
342 t->t_flag &= ~T_WAKEABLE;
343 mutex_enter(mp);
344 if (ISSIG_PENDING(t, lwp, p)) {
345 mutex_exit(mp);
346 if (issig(FORREAL))
347 rval = 0;
348 mutex_enter(mp);
349 }
350 if (lwp->lwp_sysabort || MUSTRETURN(p, t))
351 rval = 0;
352 if (rval != 0 && cancel_pending) {
353 schedctl_cancel_eintr();
354 rval = 0;
355 }
356 lwp->lwp_asleep = 0;
357 lwp->lwp_sysabort = 0;
358 if (rval == 0 && signalled) /* avoid consuming the cv_signal() */
359 cv_signal(cvp);
360 return (rval);
361 }
362
363 static clock_t
364 cv_timedwait_sig_hires(kcondvar_t *cvp, kmutex_t *mp, hrtime_t tim,
365 hrtime_t res, int flag)
366 {
367 kthread_t *t = curthread;
368 proc_t *p = ttoproc(t);
369 klwp_t *lwp = ttolwp(t);
370 int cancel_pending = 0;
371 callout_id_t id;
372 clock_t rval = 1;
373 hrtime_t limit;
374 int signalled = 0;
375
376 if (panicstr)
377 return (rval);
378 ASSERT(!quiesce_active);
379
380 /*
381 * Threads in system processes don't process signals. This is
382 * true both for standard threads of system processes and for
383 * interrupt threads which have borrowed their pinned thread's LWP.
384 */
385 if (lwp == NULL || (p->p_flag & SSYS))
386 return (cv_timedwait_hires(cvp, mp, tim, res, flag));
387 ASSERT(t->t_intr == NULL);
388
389 /*
390 * If tim is less than or equal to current hrtime, then the timeout
391 * has already occured. So just check to see if there is a signal
392 * pending. If so return 0 indicating that there is a signal pending.
393 * Else return -1 indicating that the timeout occured. No need to
394 * wait on anything.
395 */
396 limit = (flag & CALLOUT_FLAG_ABSOLUTE) ? gethrtime() : 0;
397 if (tim <= limit) {
398 lwp->lwp_asleep = 1;
399 lwp->lwp_sysabort = 0;
400 rval = -1;
401 goto out;
402 }
403
404 /*
405 * Set the timeout and wait.
406 */
407 cancel_pending = schedctl_cancel_pending();
408 mutex_enter(&t->t_wait_mutex);
409 id = timeout_generic(CALLOUT_REALTIME, (void (*)(void *))cv_wakeup, t,
410 tim, res, flag);
411 lwp->lwp_asleep = 1;
412 lwp->lwp_sysabort = 0;
413 thread_lock(t);
414 cv_block_sig(t, (condvar_impl_t *)cvp);
415 thread_unlock_nopreempt(t);
416 mutex_exit(&t->t_wait_mutex);
417 mutex_exit(mp);
418 if (ISSIG(t, JUSTLOOKING) || MUSTRETURN(p, t) || cancel_pending)
419 setrun(t);
420 /* ASSERT(no locks are held) */
421 swtch();
422 signalled = (t->t_schedflag & TS_SIGNALLED);
423 t->t_flag &= ~T_WAKEABLE;
424
425 /*
426 * Untimeout the thread. untimeout() returns -1 if the timeout has
427 * occured or the time remaining. If the time remaining is zero,
428 * the timeout has occured between when we were awoken and
429 * we called untimeout. We will treat this as if the timeout
430 * has occured and set rval to -1.
431 */
432 rval = untimeout_default(id, 0);
433 mutex_enter(mp);
434 if (rval <= 0)
435 rval = -1;
436
437 /*
438 * Check to see if a signal is pending. If so, regardless of whether
439 * or not we were awoken due to the signal, the signal is now pending
440 * and a return of 0 has the highest priority.
441 */
442 out:
443 if (ISSIG_PENDING(t, lwp, p)) {
444 mutex_exit(mp);
445 if (issig(FORREAL))
446 rval = 0;
447 mutex_enter(mp);
448 }
449 if (lwp->lwp_sysabort || MUSTRETURN(p, t))
450 rval = 0;
451 if (rval != 0 && cancel_pending) {
452 schedctl_cancel_eintr();
453 rval = 0;
454 }
455 lwp->lwp_asleep = 0;
456 lwp->lwp_sysabort = 0;
457 if (rval <= 0 && signalled) /* avoid consuming the cv_signal() */
458 cv_signal(cvp);
459 return (rval);
460 }
461
462 /*
463 * Returns:
464 * Function result in order of precedence:
465 * 0 if a signal was received
466 * -1 if timeout occured
467 * >0 if awakened via cv_signal() or cv_broadcast().
468 * (returns time remaining)
469 *
470 * cv_timedwait_sig() is now part of the DDI.
471 *
472 * This function is now just a wrapper for cv_timedwait_sig_hires().
473 */
474 clock_t
475 cv_timedwait_sig(kcondvar_t *cvp, kmutex_t *mp, clock_t tim)
476 {
477 hrtime_t hrtim;
478
479 hrtim = TICK_TO_NSEC(tim - ddi_get_lbolt());
480 return (cv_timedwait_sig_hires(cvp, mp, hrtim, nsec_per_tick, 0));
481 }
482
483 /*
484 * Wait until the specified time.
485 * If tim == -1, waits without timeout using cv_wait_sig_swap().
486 */
487 int
488 cv_timedwait_sig_hrtime(kcondvar_t *cvp, kmutex_t *mp, hrtime_t tim)
489 {
490 if (tim == -1) {
491 return (cv_wait_sig_swap(cvp, mp));
492 } else {
493 return (cv_timedwait_sig_hires(cvp, mp, tim, 1,
494 CALLOUT_FLAG_ABSOLUTE | CALLOUT_FLAG_ROUNDUP));
495 }
496 }
497
498 /*
499 * Same as cv_timedwait_sig() except that the third argument is a relative
500 * timeout value, as opposed to an absolute one. There is also a fourth
501 * argument that specifies how accurately the timeout must be implemented.
502 */
503 clock_t
504 cv_reltimedwait_sig(kcondvar_t *cvp, kmutex_t *mp, clock_t delta,
505 time_res_t res)
506 {
507 hrtime_t exp = 0;
508
509 ASSERT(TIME_RES_VALID(res));
510
511 if (delta > 0) {
512 if ((exp = TICK_TO_NSEC(delta)) < 0)
513 exp = CY_INFINITY;
514 }
515
516 return (cv_timedwait_sig_hires(cvp, mp, exp, time_res[res], 0));
517 }
518
519 /*
520 * Like cv_wait_sig_swap but allows the caller to indicate (with a
521 * non-NULL sigret) that they will take care of signalling the cv
522 * after wakeup, if necessary. This is a vile hack that should only
523 * be used when no other option is available; almost all callers
524 * should just use cv_wait_sig_swap (which takes care of the cv_signal
525 * stuff automatically) instead.
526 */
527 int
528 cv_wait_sig_swap_core(kcondvar_t *cvp, kmutex_t *mp, int *sigret)
529 {
530 kthread_t *t = curthread;
531 proc_t *p = ttoproc(t);
532 klwp_t *lwp = ttolwp(t);
533 int cancel_pending;
534 int rval = 1;
535 int signalled = 0;
536
537 if (panicstr)
538 return (rval);
539
540 /*
541 * Threads in system processes don't process signals. This is
542 * true both for standard threads of system processes and for
543 * interrupt threads which have borrowed their pinned thread's LWP.
544 */
545 if (lwp == NULL || (p->p_flag & SSYS)) {
546 cv_wait(cvp, mp);
547 return (rval);
548 }
549 ASSERT(t->t_intr == NULL);
550
551 cancel_pending = schedctl_cancel_pending();
552 lwp->lwp_asleep = 1;
553 lwp->lwp_sysabort = 0;
554 thread_lock(t);
555 t->t_kpri_req = 0; /* don't need kernel priority */
556 cv_block_sig(t, (condvar_impl_t *)cvp);
557 /* I can be swapped now */
558 curthread->t_schedflag &= ~TS_DONT_SWAP;
559 thread_unlock_nopreempt(t);
560 mutex_exit(mp);
561 if (ISSIG(t, JUSTLOOKING) || MUSTRETURN(p, t) || cancel_pending)
562 setrun(t);
563 /* ASSERT(no locks are held) */
564 swtch();
565 signalled = (t->t_schedflag & TS_SIGNALLED);
566 t->t_flag &= ~T_WAKEABLE;
567 /* TS_DONT_SWAP set by disp() */
568 ASSERT(curthread->t_schedflag & TS_DONT_SWAP);
569 mutex_enter(mp);
570 if (ISSIG_PENDING(t, lwp, p)) {
571 mutex_exit(mp);
572 if (issig(FORREAL))
573 rval = 0;
574 mutex_enter(mp);
575 }
576 if (lwp->lwp_sysabort || MUSTRETURN(p, t))
577 rval = 0;
578 if (rval != 0 && cancel_pending) {
579 schedctl_cancel_eintr();
580 rval = 0;
581 }
582 lwp->lwp_asleep = 0;
583 lwp->lwp_sysabort = 0;
584 if (rval == 0) {
585 if (sigret != NULL)
586 *sigret = signalled; /* just tell the caller */
587 else if (signalled)
588 cv_signal(cvp); /* avoid consuming the cv_signal() */
589 }
590 return (rval);
591 }
592
593 /*
594 * Same as cv_wait_sig but the thread can be swapped out while waiting.
595 * This should only be used when we know we aren't holding any locks.
596 */
597 int
598 cv_wait_sig_swap(kcondvar_t *cvp, kmutex_t *mp)
599 {
600 return (cv_wait_sig_swap_core(cvp, mp, NULL));
601 }
602
603 void
604 cv_signal(kcondvar_t *cvp)
605 {
606 condvar_impl_t *cp = (condvar_impl_t *)cvp;
607
608 /* make sure the cv_waiters field looks sane */
609 ASSERT(cp->cv_waiters <= CV_MAX_WAITERS);
610 if (cp->cv_waiters > 0) {
611 sleepq_head_t *sqh = SQHASH(cp);
612 disp_lock_enter(&sqh->sq_lock);
613 ASSERT(CPU_ON_INTR(CPU) == 0);
614 if (cp->cv_waiters & CV_WAITERS_MASK) {
615 kthread_t *t;
616 cp->cv_waiters--;
617 t = sleepq_wakeone_chan(&sqh->sq_queue, cp);
618 /*
619 * If cv_waiters is non-zero (and less than
620 * CV_MAX_WAITERS) there should be a thread
621 * in the queue.
622 */
623 ASSERT(t != NULL);
624 } else if (sleepq_wakeone_chan(&sqh->sq_queue, cp) == NULL) {
625 cp->cv_waiters = 0;
626 }
627 disp_lock_exit(&sqh->sq_lock);
628 }
629 }
630
631 void
632 cv_broadcast(kcondvar_t *cvp)
633 {
634 condvar_impl_t *cp = (condvar_impl_t *)cvp;
635
636 /* make sure the cv_waiters field looks sane */
637 ASSERT(cp->cv_waiters <= CV_MAX_WAITERS);
638 if (cp->cv_waiters > 0) {
639 sleepq_head_t *sqh = SQHASH(cp);
640 disp_lock_enter(&sqh->sq_lock);
641 ASSERT(CPU_ON_INTR(CPU) == 0);
642 sleepq_wakeall_chan(&sqh->sq_queue, cp);
643 cp->cv_waiters = 0;
644 disp_lock_exit(&sqh->sq_lock);
645 }
646 }
647
648 /*
649 * Same as cv_wait(), but wakes up (after wakeup_time milliseconds) to check
650 * for requests to stop, like cv_wait_sig() but without dealing with signals.
651 * This is a horrible kludge. It is evil. It is vile. It is swill.
652 * If your code has to call this function then your code is the same.
653 */
654 void
655 cv_wait_stop(kcondvar_t *cvp, kmutex_t *mp, int wakeup_time)
656 {
657 kthread_t *t = curthread;
658 klwp_t *lwp = ttolwp(t);
659 proc_t *p = ttoproc(t);
660 callout_id_t id;
661 clock_t tim;
662
663 if (panicstr)
664 return;
665
666 /*
667 * Threads in system processes don't process signals. This is
668 * true both for standard threads of system processes and for
669 * interrupt threads which have borrowed their pinned thread's LWP.
670 */
671 if (lwp == NULL || (p->p_flag & SSYS)) {
672 cv_wait(cvp, mp);
673 return;
674 }
675 ASSERT(t->t_intr == NULL);
676
677 /*
678 * Wakeup in wakeup_time milliseconds, i.e., human time.
679 */
680 tim = ddi_get_lbolt() + MSEC_TO_TICK(wakeup_time);
681 mutex_enter(&t->t_wait_mutex);
682 id = realtime_timeout_default((void (*)(void *))cv_wakeup, t,
683 tim - ddi_get_lbolt());
684 thread_lock(t); /* lock the thread */
685 cv_block((condvar_impl_t *)cvp);
686 thread_unlock_nopreempt(t);
687 mutex_exit(&t->t_wait_mutex);
688 mutex_exit(mp);
689 /* ASSERT(no locks are held); */
690 swtch();
691 (void) untimeout_default(id, 0);
692
693 /*
694 * Check for reasons to stop, if lwp_nostop is not true.
695 * See issig_forreal() for explanations of the various stops.
696 */
697 mutex_enter(&p->p_lock);
698 while (lwp->lwp_nostop == 0 && !(p->p_flag & SEXITLWPS)) {
699 /*
700 * Hold the lwp here for watchpoint manipulation.
701 */
702 if (t->t_proc_flag & TP_PAUSE) {
703 stop(PR_SUSPENDED, SUSPEND_PAUSE);
704 continue;
705 }
706 /*
707 * System checkpoint.
708 */
709 if (t->t_proc_flag & TP_CHKPT) {
710 stop(PR_CHECKPOINT, 0);
711 continue;
712 }
713 /*
714 * Honor fork1(), watchpoint activity (remapping a page),
715 * and lwp_suspend() requests.
716 */
717 if ((p->p_flag & (SHOLDFORK1|SHOLDWATCH)) ||
718 (t->t_proc_flag & TP_HOLDLWP)) {
719 stop(PR_SUSPENDED, SUSPEND_NORMAL);
720 continue;
721 }
722 /*
723 * Honor /proc requested stop.
724 */
725 if (t->t_proc_flag & TP_PRSTOP) {
726 stop(PR_REQUESTED, 0);
727 }
728 /*
729 * If some lwp in the process has already stopped
730 * showing PR_JOBCONTROL, stop in sympathy with it.
731 */
732 if (p->p_stopsig && t != p->p_agenttp) {
733 stop(PR_JOBCONTROL, p->p_stopsig);
734 continue;
735 }
736 break;
737 }
738 mutex_exit(&p->p_lock);
739 mutex_enter(mp);
740 }
741
742 /*
743 * Like cv_timedwait_sig(), but takes an absolute hires future time
744 * rather than a future time in clock ticks. Will not return showing
745 * that a timeout occurred until the future time is passed.
746 * If 'when' is a NULL pointer, no timeout will occur.
747 * Returns:
748 * Function result in order of precedence:
749 * 0 if a signal was received
750 * -1 if timeout occured
751 * >0 if awakened via cv_signal() or cv_broadcast()
752 * or by a spurious wakeup.
753 * (might return time remaining)
754 * As a special test, if someone abruptly resets the system time
755 * (but not through adjtime(2); drifting of the clock is allowed and
756 * expected [see timespectohz_adj()]), then we force a return of -1
757 * so the caller can return a premature timeout to the calling process
758 * so it can reevaluate the situation in light of the new system time.
759 * (The system clock has been reset if timecheck != timechanged.)
760 *
761 * Generally, cv_timedwait_sig_hrtime() should be used instead of this
762 * routine. It waits based on hrtime rather than wall-clock time and therefore
763 * does not need to deal with the time changing.
764 */
765 int
766 cv_waituntil_sig(kcondvar_t *cvp, kmutex_t *mp,
767 timestruc_t *when, int timecheck)
768 {
769 timestruc_t now;
770 timestruc_t delta;
771 hrtime_t interval;
772 int rval;
773
774 if (when == NULL)
775 return (cv_wait_sig_swap(cvp, mp));
776
777 gethrestime(&now);
778 delta = *when;
779 timespecsub(&delta, &now);
780 if (delta.tv_sec < 0 || (delta.tv_sec == 0 && delta.tv_nsec == 0)) {
781 /*
782 * We have already reached the absolute future time.
783 * Call cv_timedwait_sig() just to check for signals.
784 * We will return immediately with either 0 or -1.
785 */
786 rval = cv_timedwait_sig_hires(cvp, mp, 0, 1, 0);
787 } else {
788 if (timecheck == timechanged) {
789 /*
790 * Make sure that the interval is atleast one tick.
791 * This is to prevent a user from flooding the system
792 * with very small, high resolution timers.
793 */
794 interval = ts2hrt(&delta);
795 if (interval < nsec_per_tick)
796 interval = nsec_per_tick;
797 rval = cv_timedwait_sig_hires(cvp, mp, interval, 1,
798 CALLOUT_FLAG_HRESTIME);
799 } else {
800 /*
801 * Someone reset the system time;
802 * just force an immediate timeout.
803 */
804 rval = -1;
805 }
806 if (rval == -1 && timecheck == timechanged) {
807 /*
808 * Even though cv_timedwait_sig() returned showing a
809 * timeout, the future time may not have passed yet.
810 * If not, change rval to indicate a normal wakeup.
811 */
812 gethrestime(&now);
813 delta = *when;
814 timespecsub(&delta, &now);
815 if (delta.tv_sec > 0 || (delta.tv_sec == 0 &&
816 delta.tv_nsec > 0))
817 rval = 1;
818 }
819 }
820 return (rval);
821 }