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 1.14 2006/04/13 11:53:39 davidxu 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 || *mutex == NULL)
217 		ret = EINVAL;
218 	else {
219 		/*
220 		 * Try to lock the mutex structure, we only need to
221 		 * try once, if failed, the mutex is in used.
222 		 */
223 		ret = THR_UMTX_TRYLOCK(curthread, &(*mutex)->m_lock);
224 		if (ret)
225 			return (ret);
226 
227 		/*
228 		 * Check mutex other fields to see if this mutex is
229 		 * in use. Mostly for prority mutex types, or there
230 		 * are condition variables referencing it.
231 		 */
232 		if (((*mutex)->m_owner != NULL) ||
233 		    (TAILQ_FIRST(&(*mutex)->m_queue) != NULL) ||
234 		    ((*mutex)->m_refcount != 0)) {
235 			THR_UMTX_UNLOCK(curthread, &(*mutex)->m_lock);
236 			ret = EBUSY;
237 		} else {
238 			/*
239 			 * Save a pointer to the mutex so it can be free'd
240 			 * and set the caller's pointer to NULL:
241 			 */
242 			m = *mutex;
243 			*mutex = NULL;
244 
245 			/* Unlock the mutex structure: */
246 			THR_UMTX_UNLOCK(curthread, &m->m_lock);
247 
248 			/*
249 			 * Free the memory allocated for the mutex
250 			 * structure:
251 			 */
252 			MUTEX_ASSERT_NOT_OWNED(m);
253 			MUTEX_DESTROY(m);
254 		}
255 	}
256 
257 	/* Return the completion status: */
258 	return (ret);
259 }
260 
261 static int
262 mutex_trylock_common(struct pthread *curthread, pthread_mutex_t *mutex)
263 {
264 	struct pthread_mutex *m;
265 	int ret;
266 
267 	m = *mutex;
268 	ret = THR_UMTX_TRYLOCK(curthread, &m->m_lock);
269 	if (ret == 0) {
270 		m->m_owner = curthread;
271 		/* Add to the list of owned mutexes: */
272 		MUTEX_ASSERT_NOT_OWNED(m);
273 		TAILQ_INSERT_TAIL(&curthread->mutexq,
274 		    m, m_qe);
275 	} else if (m->m_owner == curthread) {
276 		ret = mutex_self_trylock(m);
277 	} /* else {} */
278 
279 	return (ret);
280 }
281 
282 int
283 __pthread_mutex_trylock(pthread_mutex_t *m)
284 {
285 	struct pthread *curthread = tls_get_curthread();
286 	int ret;
287 
288 	/*
289 	 * If the mutex is statically initialized, perform the dynamic
290 	 * initialization:
291 	 */
292 	if (__predict_false(*m == NULL)) {
293 		ret = init_static(curthread, m);
294 		if (__predict_false(ret != 0))
295 			return (ret);
296 	}
297 	return (mutex_trylock_common(curthread, m));
298 }
299 
300 int
301 _pthread_mutex_trylock(pthread_mutex_t *m)
302 {
303 	struct pthread	*curthread = tls_get_curthread();
304 	int	ret = 0;
305 
306 	/*
307 	 * If the mutex is statically initialized, perform the dynamic
308 	 * initialization marking the mutex private (delete safe):
309 	 */
310 	if (__predict_false(*m == NULL)) {
311 		ret = init_static_private(curthread, m);
312 		if (__predict_false(ret != 0))
313 			return (ret);
314 	}
315 	return (mutex_trylock_common(curthread, m));
316 }
317 
318 static int
319 mutex_lock_common(struct pthread *curthread, pthread_mutex_t *mutex,
320 	const struct timespec * abstime)
321 {
322 	struct  timespec ts, ts2;
323 	struct  pthread_mutex *m;
324 	int	ret = 0;
325 
326 	m = *mutex;
327 	ret = THR_UMTX_TRYLOCK(curthread, &m->m_lock);
328 	if (ret == 0) {
329 		m->m_owner = curthread;
330 		/* Add to the list of owned mutexes: */
331 		MUTEX_ASSERT_NOT_OWNED(m);
332 		TAILQ_INSERT_TAIL(&curthread->mutexq,
333 		    m, m_qe);
334 	} else if (m->m_owner == curthread) {
335 		ret = mutex_self_lock(m, abstime);
336 	} else {
337 		if (abstime == NULL) {
338 			THR_UMTX_LOCK(curthread, &m->m_lock);
339 			ret = 0;
340 		} else if (__predict_false(
341 			abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
342 			abstime->tv_nsec >= 1000000000)) {
343 				ret = EINVAL;
344 		} else {
345 			clock_gettime(CLOCK_REALTIME, &ts);
346 			TIMESPEC_SUB(&ts2, abstime, &ts);
347 			ret = THR_UMTX_TIMEDLOCK(curthread,
348 				&m->m_lock, &ts2);
349 			/*
350 			 * Timed out wait is not restarted if
351 			 * it was interrupted, not worth to do it.
352 			 */
353 			if (ret == EINTR)
354 				ret = ETIMEDOUT;
355 		}
356 		if (ret == 0) {
357 			m->m_owner = curthread;
358 			/* Add to the list of owned mutexes: */
359 			MUTEX_ASSERT_NOT_OWNED(m);
360 			TAILQ_INSERT_TAIL(&curthread->mutexq,
361 			    m, m_qe);
362 		}
363 	}
364 	return (ret);
365 }
366 
367 int
368 __pthread_mutex_lock(pthread_mutex_t *m)
369 {
370 	struct pthread *curthread;
371 	int	ret;
372 
373 	_thr_check_init();
374 
375 	curthread = tls_get_curthread();
376 
377 	/*
378 	 * If the mutex is statically initialized, perform the dynamic
379 	 * initialization:
380 	 */
381 	if (__predict_false(*m == NULL)) {
382 		ret = init_static(curthread, m);
383 		if (__predict_false(ret))
384 			return (ret);
385 	}
386 	return (mutex_lock_common(curthread, m, NULL));
387 }
388 
389 int
390 _pthread_mutex_lock(pthread_mutex_t *m)
391 {
392 	struct pthread *curthread;
393 	int	ret;
394 
395 	_thr_check_init();
396 
397 	curthread = tls_get_curthread();
398 
399 	/*
400 	 * If the mutex is statically initialized, perform the dynamic
401 	 * initialization marking it private (delete safe):
402 	 */
403 	if (__predict_false(*m == NULL)) {
404 		ret = init_static_private(curthread, m);
405 		if (__predict_false(ret))
406 			return (ret);
407 	}
408 	return (mutex_lock_common(curthread, m, NULL));
409 }
410 
411 int
412 __pthread_mutex_timedlock(pthread_mutex_t *m,
413 	const struct timespec *abs_timeout)
414 {
415 	struct pthread *curthread;
416 	int	ret;
417 
418 	_thr_check_init();
419 
420 	curthread = tls_get_curthread();
421 
422 	/*
423 	 * If the mutex is statically initialized, perform the dynamic
424 	 * initialization:
425 	 */
426 	if (__predict_false(*m == NULL)) {
427 		ret = init_static(curthread, m);
428 		if (__predict_false(ret))
429 			return (ret);
430 	}
431 	return (mutex_lock_common(curthread, m, abs_timeout));
432 }
433 
434 int
435 _pthread_mutex_timedlock(pthread_mutex_t *m,
436 	const struct timespec *abs_timeout)
437 {
438 	struct pthread *curthread;
439 	int	ret;
440 
441 	_thr_check_init();
442 
443 	curthread = tls_get_curthread();
444 
445 	/*
446 	 * If the mutex is statically initialized, perform the dynamic
447 	 * initialization marking it private (delete safe):
448 	 */
449 	if (__predict_false(*m == NULL)) {
450 		ret = init_static_private(curthread, m);
451 		if (__predict_false(ret))
452 			return (ret);
453 	}
454 	return (mutex_lock_common(curthread, m, abs_timeout));
455 }
456 
457 int
458 _pthread_mutex_unlock(pthread_mutex_t *m)
459 {
460 	return (mutex_unlock_common(m));
461 }
462 
463 static int
464 mutex_self_trylock(pthread_mutex_t m)
465 {
466 	int	ret;
467 
468 	switch (m->m_type) {
469 	/* case PTHREAD_MUTEX_DEFAULT: */
470 	case PTHREAD_MUTEX_ERRORCHECK:
471 	case PTHREAD_MUTEX_NORMAL:
472 		ret = EBUSY;
473 		break;
474 
475 	case PTHREAD_MUTEX_RECURSIVE:
476 		/* Increment the lock count: */
477 		if (m->m_count + 1 > 0) {
478 			m->m_count++;
479 			ret = 0;
480 		} else
481 			ret = EAGAIN;
482 		break;
483 
484 	default:
485 		/* Trap invalid mutex types; */
486 		ret = EINVAL;
487 	}
488 
489 	return (ret);
490 }
491 
492 static int
493 mutex_self_lock(pthread_mutex_t m, const struct timespec *abstime)
494 {
495 	struct timespec ts1, ts2;
496 	int ret;
497 
498 	switch (m->m_type) {
499 	/* case PTHREAD_MUTEX_DEFAULT: */
500 	case PTHREAD_MUTEX_ERRORCHECK:
501 		if (abstime) {
502 			clock_gettime(CLOCK_REALTIME, &ts1);
503 			TIMESPEC_SUB(&ts2, abstime, &ts1);
504 			__sys_nanosleep(&ts2, NULL);
505 			ret = ETIMEDOUT;
506 		} else {
507 			/*
508 			 * POSIX specifies that mutexes should return
509 			 * EDEADLK if a recursive lock is detected.
510 			 */
511 			ret = EDEADLK;
512 		}
513 		break;
514 
515 	case PTHREAD_MUTEX_NORMAL:
516 		/*
517 		 * What SS2 define as a 'normal' mutex.  Intentionally
518 		 * deadlock on attempts to get a lock you already own.
519 		 */
520 		ret = 0;
521 		if (abstime) {
522 			clock_gettime(CLOCK_REALTIME, &ts1);
523 			TIMESPEC_SUB(&ts2, abstime, &ts1);
524 			__sys_nanosleep(&ts2, NULL);
525 			ret = ETIMEDOUT;
526 		} else {
527 			ts1.tv_sec = 30;
528 			ts1.tv_nsec = 0;
529 			for (;;)
530 				__sys_nanosleep(&ts1, NULL);
531 		}
532 		break;
533 
534 	case PTHREAD_MUTEX_RECURSIVE:
535 		/* Increment the lock count: */
536 		if (m->m_count + 1 > 0) {
537 			m->m_count++;
538 			ret = 0;
539 		} else
540 			ret = EAGAIN;
541 		break;
542 
543 	default:
544 		/* Trap invalid mutex types; */
545 		ret = EINVAL;
546 	}
547 
548 	return (ret);
549 }
550 
551 static int
552 mutex_unlock_common(pthread_mutex_t *mutex)
553 {
554 	struct pthread *curthread = tls_get_curthread();
555 	struct pthread_mutex *m;
556 
557 	if (__predict_false((m = *mutex)== NULL))
558 		return (EINVAL);
559 
560 	if (__predict_false(m->m_owner != curthread))
561 		return (EPERM);
562 
563 	if (__predict_false(
564 		m->m_type == PTHREAD_MUTEX_RECURSIVE &&
565 		m->m_count > 0)) {
566 		m->m_count--;
567 	} else {
568 		/*
569 		 * Clear the count in case this is a recursive mutex.
570 		 */
571 		m->m_count = 0;
572 		m->m_owner = NULL;
573 		/* Remove the mutex from the threads queue. */
574 		MUTEX_ASSERT_IS_OWNED(m);
575 		TAILQ_REMOVE(&curthread->mutexq, m, m_qe);
576 		MUTEX_INIT_LINK(m);
577 		/*
578 		 * Hand off the mutex to the next waiting thread.
579 		 */
580 		THR_UMTX_UNLOCK(curthread, &m->m_lock);
581 	}
582 	return (0);
583 }
584 
585 int
586 _mutex_cv_lock(pthread_mutex_t *m, int count)
587 {
588 	int	ret;
589 
590 	if ((ret = _pthread_mutex_lock(m)) == 0) {
591 		(*m)->m_refcount--;
592 		(*m)->m_count += count;
593 	}
594 	return (ret);
595 }
596 
597 int
598 _mutex_cv_unlock(pthread_mutex_t *mutex, int *count)
599 {
600 	struct pthread *curthread = tls_get_curthread();
601 	struct pthread_mutex *m;
602 
603 	if (__predict_false((m = *mutex)== NULL))
604 		return (EINVAL);
605 
606 	if (__predict_false(m->m_owner != curthread))
607 		return (EPERM);
608 
609 	*count = m->m_count;
610 	m->m_count = 0;
611 	m->m_refcount++;
612 	m->m_owner = NULL;
613 	/* Remove the mutex from the threads queue. */
614 	MUTEX_ASSERT_IS_OWNED(m);
615 	TAILQ_REMOVE(&curthread->mutexq, m, m_qe);
616 	MUTEX_INIT_LINK(m);
617 	THR_UMTX_UNLOCK(curthread, &m->m_lock);
618 	return (0);
619 }
620 
621 void
622 _mutex_unlock_private(pthread_t pthread)
623 {
624 	struct pthread_mutex	*m, *m_next;
625 
626 	for (m = TAILQ_FIRST(&pthread->mutexq); m != NULL; m = m_next) {
627 		m_next = TAILQ_NEXT(m, m_qe);
628 		if ((m->m_flags & MUTEX_FLAGS_PRIVATE) != 0)
629 			_pthread_mutex_unlock(&m);
630 	}
631 }
632 
633 __strong_reference(__pthread_mutex_init, pthread_mutex_init);
634 __strong_reference(__pthread_mutex_lock, pthread_mutex_lock);
635 __strong_reference(__pthread_mutex_timedlock, pthread_mutex_timedlock);
636 __strong_reference(__pthread_mutex_trylock, pthread_mutex_trylock);
637 
638 /* Single underscore versions provided for libc internal usage: */
639 /* No difference between libc and application usage of these: */
640 __strong_reference(_pthread_mutex_destroy, pthread_mutex_destroy);
641 __strong_reference(_pthread_mutex_unlock, pthread_mutex_unlock);
642