1 /*
2  * Copyright (c) 1995 John Birrell <jb@cimlogic.com.au>.
3  * Copyright (c) 2006 David Xu <yfxu@corp.netease.com>.
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 3. All advertising materials mentioning features or use of this software
15  *    must display the following acknowledgement:
16  *	This product includes software developed by John Birrell.
17  * 4. Neither the name of the author nor the names of any co-contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  * $DragonFly: src/lib/libthread_xu/thread/thr_mutex.c,v 1.15 2008/05/09 16:03:27 dillon Exp $
34  */
35 
36 #include "namespace.h"
37 #include <machine/tls.h>
38 
39 #include <errno.h>
40 #include <stdlib.h>
41 #include <string.h>
42 #include <sys/queue.h>
43 #include <pthread.h>
44 #include "un-namespace.h"
45 
46 #include "thr_private.h"
47 
48 #if defined(_PTHREADS_INVARIANTS)
49 #define MUTEX_INIT_LINK(m) 		do {		\
50 	(m)->m_qe.tqe_prev = NULL;			\
51 	(m)->m_qe.tqe_next = NULL;			\
52 } while (0)
53 #define MUTEX_ASSERT_IS_OWNED(m)	do {		\
54 	if ((m)->m_qe.tqe_prev == NULL)			\
55 		PANIC("mutex is not on list");		\
56 } while (0)
57 #define MUTEX_ASSERT_NOT_OWNED(m)	do {		\
58 	if (((m)->m_qe.tqe_prev != NULL) ||		\
59 	    ((m)->m_qe.tqe_next != NULL))		\
60 		PANIC("mutex is on list");		\
61 } while (0)
62 #define	THR_ASSERT_NOT_IN_SYNCQ(thr)	do {		\
63 	THR_ASSERT(((thr)->sflags & THR_FLAGS_IN_SYNCQ) == 0, \
64 	    "thread in syncq when it shouldn't be.");	\
65 } while (0);
66 #else
67 #define MUTEX_INIT_LINK(m)
68 #define MUTEX_ASSERT_IS_OWNED(m)
69 #define MUTEX_ASSERT_NOT_OWNED(m)
70 #define	THR_ASSERT_NOT_IN_SYNCQ(thr)
71 #endif
72 
73 #define THR_IN_MUTEXQ(thr)	(((thr)->sflags & THR_FLAGS_IN_SYNCQ) != 0)
74 #define	MUTEX_DESTROY(m) do {		\
75 	free(m);			\
76 } while (0)
77 
78 umtx_t	_mutex_static_lock;
79 
80 /*
81  * Prototypes
82  */
83 static int	mutex_self_trylock(pthread_mutex_t);
84 static int	mutex_self_lock(pthread_mutex_t,
85 			const struct timespec *abstime);
86 static int	mutex_unlock_common(pthread_mutex_t *);
87 
88 int __pthread_mutex_init(pthread_mutex_t *mutex,
89 	const pthread_mutexattr_t *mutex_attr);
90 int __pthread_mutex_trylock(pthread_mutex_t *mutex);
91 int __pthread_mutex_lock(pthread_mutex_t *mutex);
92 int __pthread_mutex_timedlock(pthread_mutex_t *mutex,
93 	const struct timespec *abs_timeout);
94 
95 static int
96 mutex_init(pthread_mutex_t *mutex,
97     const pthread_mutexattr_t *mutex_attr, int private)
98 {
99 	const struct pthread_mutex_attr *attr;
100 	struct pthread_mutex *pmutex;
101 
102 	if (mutex_attr == NULL) {
103 		attr = &_pthread_mutexattr_default;
104 	} else {
105 		attr = *mutex_attr;
106 		if (attr->m_type < PTHREAD_MUTEX_ERRORCHECK ||
107 		    attr->m_type >= MUTEX_TYPE_MAX)
108 			return (EINVAL);
109 		if (attr->m_protocol < PTHREAD_PRIO_NONE ||
110 		    attr->m_protocol > PTHREAD_PRIO_PROTECT)
111 			return (EINVAL);
112 	}
113 
114 	if ((pmutex = (pthread_mutex_t)
115 		malloc(sizeof(struct pthread_mutex))) == NULL)
116 		return (ENOMEM);
117 
118 	_thr_umtx_init(&pmutex->m_lock);
119 	pmutex->m_type = attr->m_type;
120 	pmutex->m_protocol = attr->m_protocol;
121 	TAILQ_INIT(&pmutex->m_queue);
122 	pmutex->m_owner = NULL;
123 	pmutex->m_flags = attr->m_flags | MUTEX_FLAGS_INITED;
124 	if (private)
125 		pmutex->m_flags |= MUTEX_FLAGS_PRIVATE;
126 	pmutex->m_count = 0;
127 	pmutex->m_refcount = 0;
128 	if (attr->m_protocol == PTHREAD_PRIO_PROTECT)
129 		pmutex->m_prio = attr->m_ceiling;
130 	else
131 		pmutex->m_prio = -1;
132 	pmutex->m_saved_prio = 0;
133 	MUTEX_INIT_LINK(pmutex);
134 	*mutex = pmutex;
135 	return (0);
136 }
137 
138 static int
139 init_static(struct pthread *thread, pthread_mutex_t *mutex)
140 {
141 	int ret;
142 
143 	THR_LOCK_ACQUIRE(thread, &_mutex_static_lock);
144 
145 	if (*mutex == NULL)
146 		ret = mutex_init(mutex, NULL, 0);
147 	else
148 		ret = 0;
149 
150 	THR_LOCK_RELEASE(thread, &_mutex_static_lock);
151 
152 	return (ret);
153 }
154 
155 static int
156 init_static_private(struct pthread *thread, pthread_mutex_t *mutex)
157 {
158 	int ret;
159 
160 	THR_LOCK_ACQUIRE(thread, &_mutex_static_lock);
161 
162 	if (*mutex == NULL)
163 		ret = mutex_init(mutex, NULL, 1);
164 	else
165 		ret = 0;
166 
167 	THR_LOCK_RELEASE(thread, &_mutex_static_lock);
168 
169 	return (ret);
170 }
171 
172 int
173 _pthread_mutex_init(pthread_mutex_t *mutex,
174     const pthread_mutexattr_t *mutex_attr)
175 {
176 	return mutex_init(mutex, mutex_attr, 1);
177 }
178 
179 int
180 __pthread_mutex_init(pthread_mutex_t *mutex,
181     const pthread_mutexattr_t *mutex_attr)
182 {
183 	return mutex_init(mutex, mutex_attr, 0);
184 }
185 
186 int
187 _mutex_reinit(pthread_mutex_t *mutex)
188 {
189 	_thr_umtx_init(&(*mutex)->m_lock);
190 	TAILQ_INIT(&(*mutex)->m_queue);
191 	MUTEX_INIT_LINK(*mutex);
192 	(*mutex)->m_owner = NULL;
193 	(*mutex)->m_count = 0;
194 	(*mutex)->m_refcount = 0;
195 	(*mutex)->m_prio = 0;
196 	(*mutex)->m_saved_prio = 0;
197 	return (0);
198 }
199 
200 void
201 _mutex_fork(struct pthread *curthread)
202 {
203 	struct pthread_mutex *m;
204 
205 	TAILQ_FOREACH(m, &curthread->mutexq, m_qe)
206 		m->m_lock = UMTX_LOCKED;
207 }
208 
209 int
210 _pthread_mutex_destroy(pthread_mutex_t *mutex)
211 {
212 	struct pthread *curthread = tls_get_curthread();
213 	pthread_mutex_t m;
214 	int ret = 0;
215 
216 	if (mutex == NULL)
217 		ret = EINVAL;
218 	else if (*mutex == NULL)
219 		ret = 0;
220 	else {
221 		/*
222 		 * Try to lock the mutex structure, we only need to
223 		 * try once, if failed, the mutex is in used.
224 		 */
225 		ret = THR_UMTX_TRYLOCK(curthread, &(*mutex)->m_lock);
226 		if (ret)
227 			return (ret);
228 
229 		/*
230 		 * Check mutex other fields to see if this mutex is
231 		 * in use. Mostly for prority mutex types, or there
232 		 * are condition variables referencing it.
233 		 */
234 		if (((*mutex)->m_owner != NULL) ||
235 		    (TAILQ_FIRST(&(*mutex)->m_queue) != NULL) ||
236 		    ((*mutex)->m_refcount != 0)) {
237 			THR_UMTX_UNLOCK(curthread, &(*mutex)->m_lock);
238 			ret = EBUSY;
239 		} else {
240 			/*
241 			 * Save a pointer to the mutex so it can be free'd
242 			 * and set the caller's pointer to NULL:
243 			 */
244 			m = *mutex;
245 			*mutex = NULL;
246 
247 			/* Unlock the mutex structure: */
248 			THR_UMTX_UNLOCK(curthread, &m->m_lock);
249 
250 			/*
251 			 * Free the memory allocated for the mutex
252 			 * structure:
253 			 */
254 			MUTEX_ASSERT_NOT_OWNED(m);
255 			MUTEX_DESTROY(m);
256 		}
257 	}
258 
259 	/* Return the completion status: */
260 	return (ret);
261 }
262 
263 static int
264 mutex_trylock_common(struct pthread *curthread, pthread_mutex_t *mutex)
265 {
266 	struct pthread_mutex *m;
267 	int ret;
268 
269 	m = *mutex;
270 	ret = THR_UMTX_TRYLOCK(curthread, &m->m_lock);
271 	if (ret == 0) {
272 		m->m_owner = curthread;
273 		/* Add to the list of owned mutexes: */
274 		MUTEX_ASSERT_NOT_OWNED(m);
275 		TAILQ_INSERT_TAIL(&curthread->mutexq,
276 		    m, m_qe);
277 	} else if (m->m_owner == curthread) {
278 		ret = mutex_self_trylock(m);
279 	} /* else {} */
280 
281 	return (ret);
282 }
283 
284 int
285 __pthread_mutex_trylock(pthread_mutex_t *m)
286 {
287 	struct pthread *curthread = tls_get_curthread();
288 	int ret;
289 
290 	if (__predict_false(m == NULL))
291 		return(EINVAL);
292 	/*
293 	 * If the mutex is statically initialized, perform the dynamic
294 	 * initialization:
295 	 */
296 	if (__predict_false(*m == NULL)) {
297 		ret = init_static(curthread, m);
298 		if (__predict_false(ret != 0))
299 			return (ret);
300 	}
301 	return (mutex_trylock_common(curthread, m));
302 }
303 
304 int
305 _pthread_mutex_trylock(pthread_mutex_t *m)
306 {
307 	struct pthread	*curthread = tls_get_curthread();
308 	int	ret = 0;
309 
310 	/*
311 	 * If the mutex is statically initialized, perform the dynamic
312 	 * initialization marking the mutex private (delete safe):
313 	 */
314 	if (__predict_false(*m == NULL)) {
315 		ret = init_static_private(curthread, m);
316 		if (__predict_false(ret != 0))
317 			return (ret);
318 	}
319 	return (mutex_trylock_common(curthread, m));
320 }
321 
322 static int
323 mutex_lock_common(struct pthread *curthread, pthread_mutex_t *mutex,
324 	const struct timespec * abstime)
325 {
326 	struct  timespec ts, ts2;
327 	struct  pthread_mutex *m;
328 	int	ret = 0;
329 
330 	m = *mutex;
331 	ret = THR_UMTX_TRYLOCK(curthread, &m->m_lock);
332 	if (ret == 0) {
333 		m->m_owner = curthread;
334 		/* Add to the list of owned mutexes: */
335 		MUTEX_ASSERT_NOT_OWNED(m);
336 		TAILQ_INSERT_TAIL(&curthread->mutexq,
337 		    m, m_qe);
338 	} else if (m->m_owner == curthread) {
339 		ret = mutex_self_lock(m, abstime);
340 	} else {
341 		if (abstime == NULL) {
342 			THR_UMTX_LOCK(curthread, &m->m_lock);
343 			ret = 0;
344 		} else if (__predict_false(
345 			abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
346 			abstime->tv_nsec >= 1000000000)) {
347 				ret = EINVAL;
348 		} else {
349 			clock_gettime(CLOCK_REALTIME, &ts);
350 			TIMESPEC_SUB(&ts2, abstime, &ts);
351 			ret = THR_UMTX_TIMEDLOCK(curthread,
352 				&m->m_lock, &ts2);
353 			/*
354 			 * Timed out wait is not restarted if
355 			 * it was interrupted, not worth to do it.
356 			 */
357 			if (ret == EINTR)
358 				ret = ETIMEDOUT;
359 		}
360 		if (ret == 0) {
361 			m->m_owner = curthread;
362 			/* Add to the list of owned mutexes: */
363 			MUTEX_ASSERT_NOT_OWNED(m);
364 			TAILQ_INSERT_TAIL(&curthread->mutexq,
365 			    m, m_qe);
366 		}
367 	}
368 	return (ret);
369 }
370 
371 int
372 __pthread_mutex_lock(pthread_mutex_t *m)
373 {
374 	struct pthread *curthread;
375 	int	ret;
376 
377 	if (__predict_false(m == NULL))
378 		return(EINVAL);
379 
380 	/*
381 	 * If the mutex is statically initialized, perform the dynamic
382 	 * initialization:
383 	 */
384 	curthread = tls_get_curthread();
385 	if (__predict_false(*m == NULL)) {
386 		ret = init_static(curthread, m);
387 		if (__predict_false(ret))
388 			return (ret);
389 	}
390 	return (mutex_lock_common(curthread, m, NULL));
391 }
392 
393 int
394 _pthread_mutex_lock(pthread_mutex_t *m)
395 {
396 	struct pthread *curthread;
397 	int	ret;
398 
399 	if (__predict_false(m == NULL))
400 		return(EINVAL);
401 
402 	/*
403 	 * If the mutex is statically initialized, perform the dynamic
404 	 * initialization marking it private (delete safe):
405 	 */
406 	curthread = tls_get_curthread();
407 	if (__predict_false(*m == NULL)) {
408 		ret = init_static_private(curthread, m);
409 		if (__predict_false(ret))
410 			return (ret);
411 	}
412 	return (mutex_lock_common(curthread, m, NULL));
413 }
414 
415 int
416 __pthread_mutex_timedlock(pthread_mutex_t *m,
417 	const struct timespec *abs_timeout)
418 {
419 	struct pthread *curthread;
420 	int	ret;
421 
422 	if (__predict_false(m == NULL))
423 		return(EINVAL);
424 
425 	/*
426 	 * If the mutex is statically initialized, perform the dynamic
427 	 * initialization:
428 	 */
429 	curthread = tls_get_curthread();
430 	if (__predict_false(*m == NULL)) {
431 		ret = init_static(curthread, m);
432 		if (__predict_false(ret))
433 			return (ret);
434 	}
435 	return (mutex_lock_common(curthread, m, abs_timeout));
436 }
437 
438 int
439 _pthread_mutex_timedlock(pthread_mutex_t *m,
440 	const struct timespec *abs_timeout)
441 {
442 	struct pthread *curthread;
443 	int	ret;
444 
445 	if (__predict_false(m == NULL))
446 		return(EINVAL);
447 
448 	curthread = tls_get_curthread();
449 
450 	/*
451 	 * If the mutex is statically initialized, perform the dynamic
452 	 * initialization marking it private (delete safe):
453 	 */
454 	if (__predict_false(*m == NULL)) {
455 		ret = init_static_private(curthread, m);
456 		if (__predict_false(ret))
457 			return (ret);
458 	}
459 	return (mutex_lock_common(curthread, m, abs_timeout));
460 }
461 
462 int
463 _pthread_mutex_unlock(pthread_mutex_t *m)
464 {
465 	if (__predict_false(m == NULL))
466 		return(EINVAL);
467 	return (mutex_unlock_common(m));
468 }
469 
470 static int
471 mutex_self_trylock(pthread_mutex_t m)
472 {
473 	int	ret;
474 
475 	switch (m->m_type) {
476 	/* case PTHREAD_MUTEX_DEFAULT: */
477 	case PTHREAD_MUTEX_ERRORCHECK:
478 	case PTHREAD_MUTEX_NORMAL:
479 		ret = EBUSY;
480 		break;
481 
482 	case PTHREAD_MUTEX_RECURSIVE:
483 		/* Increment the lock count: */
484 		if (m->m_count + 1 > 0) {
485 			m->m_count++;
486 			ret = 0;
487 		} else
488 			ret = EAGAIN;
489 		break;
490 
491 	default:
492 		/* Trap invalid mutex types; */
493 		ret = EINVAL;
494 	}
495 
496 	return (ret);
497 }
498 
499 static int
500 mutex_self_lock(pthread_mutex_t m, const struct timespec *abstime)
501 {
502 	struct timespec ts1, ts2;
503 	int ret;
504 
505 	switch (m->m_type) {
506 	/* case PTHREAD_MUTEX_DEFAULT: */
507 	case PTHREAD_MUTEX_ERRORCHECK:
508 		if (abstime) {
509 			clock_gettime(CLOCK_REALTIME, &ts1);
510 			TIMESPEC_SUB(&ts2, abstime, &ts1);
511 			__sys_nanosleep(&ts2, NULL);
512 			ret = ETIMEDOUT;
513 		} else {
514 			/*
515 			 * POSIX specifies that mutexes should return
516 			 * EDEADLK if a recursive lock is detected.
517 			 */
518 			ret = EDEADLK;
519 		}
520 		break;
521 
522 	case PTHREAD_MUTEX_NORMAL:
523 		/*
524 		 * What SS2 define as a 'normal' mutex.  Intentionally
525 		 * deadlock on attempts to get a lock you already own.
526 		 */
527 		ret = 0;
528 		if (abstime) {
529 			clock_gettime(CLOCK_REALTIME, &ts1);
530 			TIMESPEC_SUB(&ts2, abstime, &ts1);
531 			__sys_nanosleep(&ts2, NULL);
532 			ret = ETIMEDOUT;
533 		} else {
534 			ts1.tv_sec = 30;
535 			ts1.tv_nsec = 0;
536 			for (;;)
537 				__sys_nanosleep(&ts1, NULL);
538 		}
539 		break;
540 
541 	case PTHREAD_MUTEX_RECURSIVE:
542 		/* Increment the lock count: */
543 		if (m->m_count + 1 > 0) {
544 			m->m_count++;
545 			ret = 0;
546 		} else
547 			ret = EAGAIN;
548 		break;
549 
550 	default:
551 		/* Trap invalid mutex types; */
552 		ret = EINVAL;
553 	}
554 
555 	return (ret);
556 }
557 
558 static int
559 mutex_unlock_common(pthread_mutex_t *mutex)
560 {
561 	struct pthread *curthread = tls_get_curthread();
562 	struct pthread_mutex *m;
563 
564 	if (__predict_false((m = *mutex)== NULL))
565 		return (EINVAL);
566 	if (__predict_false(m->m_owner != curthread))
567 		return (EPERM);
568 
569 	if (__predict_false(
570 		m->m_type == PTHREAD_MUTEX_RECURSIVE &&
571 		m->m_count > 0)) {
572 		m->m_count--;
573 	} else {
574 		/*
575 		 * Clear the count in case this is a recursive mutex.
576 		 */
577 		m->m_count = 0;
578 		m->m_owner = NULL;
579 		/* Remove the mutex from the threads queue. */
580 		MUTEX_ASSERT_IS_OWNED(m);
581 		TAILQ_REMOVE(&curthread->mutexq, m, m_qe);
582 		MUTEX_INIT_LINK(m);
583 		/*
584 		 * Hand off the mutex to the next waiting thread.
585 		 */
586 		THR_UMTX_UNLOCK(curthread, &m->m_lock);
587 	}
588 	return (0);
589 }
590 
591 int
592 _mutex_cv_lock(pthread_mutex_t *m, int count)
593 {
594 	int	ret;
595 
596 	if ((ret = _pthread_mutex_lock(m)) == 0) {
597 		(*m)->m_refcount--;
598 		(*m)->m_count += count;
599 	}
600 	return (ret);
601 }
602 
603 int
604 _mutex_cv_unlock(pthread_mutex_t *mutex, int *count)
605 {
606 	struct pthread *curthread = tls_get_curthread();
607 	struct pthread_mutex *m;
608 
609 	if (__predict_false(mutex == NULL))
610 		return (EINVAL);
611 	if (__predict_false((m = *mutex) == NULL))
612 		return (EINVAL);
613 	if (__predict_false(m->m_owner != curthread))
614 		return (EPERM);
615 
616 	*count = m->m_count;
617 	m->m_count = 0;
618 	m->m_refcount++;
619 	m->m_owner = NULL;
620 	/* Remove the mutex from the threads queue. */
621 	MUTEX_ASSERT_IS_OWNED(m);
622 	TAILQ_REMOVE(&curthread->mutexq, m, m_qe);
623 	MUTEX_INIT_LINK(m);
624 	THR_UMTX_UNLOCK(curthread, &m->m_lock);
625 	return (0);
626 }
627 
628 void
629 _mutex_unlock_private(pthread_t pthread)
630 {
631 	struct pthread_mutex	*m, *m_next;
632 
633 	for (m = TAILQ_FIRST(&pthread->mutexq); m != NULL; m = m_next) {
634 		m_next = TAILQ_NEXT(m, m_qe);
635 		if ((m->m_flags & MUTEX_FLAGS_PRIVATE) != 0)
636 			_pthread_mutex_unlock(&m);
637 	}
638 }
639 
640 __strong_reference(__pthread_mutex_init, pthread_mutex_init);
641 __strong_reference(__pthread_mutex_lock, pthread_mutex_lock);
642 __strong_reference(__pthread_mutex_timedlock, pthread_mutex_timedlock);
643 __strong_reference(__pthread_mutex_trylock, pthread_mutex_trylock);
644 
645 /* Single underscore versions provided for libc internal usage: */
646 /* No difference between libc and application usage of these: */
647 __strong_reference(_pthread_mutex_destroy, pthread_mutex_destroy);
648 __strong_reference(_pthread_mutex_unlock, pthread_mutex_unlock);
649