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GCC Code Coverage Report

Directory:	./		Exec	Total	Coverage
File:	lib/librthread/rthread_rwlock.c	Lines:	69	105	65.7 %
Date:	2017-11-13	Branches:	26	76	34.2 %


/*	$OpenBSD: rthread_rwlock.c,v 1.10 2017/07/29 16:42:10 deraadt Exp $ */
/*
 * Copyright (c) 2004,2005 Ted Unangst <tedu@openbsd.org>
 * Copyright (c) 2012 Philip Guenther <guenther@openbsd.org>
 * All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
/*
 * rwlocks
 */

#include <assert.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>

#include <pthread.h>

#include "rthread.h"

static _atomic_lock_t rwlock_init_lock = _SPINLOCK_UNLOCKED;

int
pthread_rwlock_init(pthread_rwlock_t *lockp,
    const pthread_rwlockattr_t *attrp __unused)
{
	pthread_rwlock_t lock;

	lock = calloc(1, sizeof(*lock));
	if (!lock)
		return (errno);
	lock->lock = _SPINLOCK_UNLOCKED;
	TAILQ_INIT(&lock->writers);

	*lockp = lock;

	return (0);
}
DEF_STD(pthread_rwlock_init);

int
pthread_rwlock_destroy(pthread_rwlock_t *lockp)
{
	pthread_rwlock_t lock;

	assert(lockp);
	lock = *lockp;
	if (lock) {
		if (lock->readers || !TAILQ_EMPTY(&lock->writers)) {
#define MSG "pthread_rwlock_destroy on rwlock with waiters!\n"
			write(2, MSG, sizeof(MSG) - 1);
#undef MSG
			return (EBUSY);
		}
		free(lock);
	}
	*lockp = NULL;

	return (0);
}

static int
_rthread_rwlock_ensure_init(pthread_rwlock_t *lockp)
{
	int ret = 0;

	/*
	 * If the rwlock is statically initialized, perform the dynamic
	 * initialization.
	 */
	if (*lockp == NULL)
	{
		_spinlock(&rwlock_init_lock);
		if (*lockp == NULL)
			ret = pthread_rwlock_init(lockp, NULL);
		_spinunlock(&rwlock_init_lock);
	}
	return (ret);
}


static int
_rthread_rwlock_rdlock(pthread_rwlock_t *lockp, const struct timespec *abstime,
    int try)
{
	pthread_rwlock_t lock;
	pthread_t thread = pthread_self();
	int error;

	if ((error = _rthread_rwlock_ensure_init(lockp)))
		return (error);

	lock = *lockp;
	_rthread_debug(5, "%p: rwlock_rdlock %p\n", (void *)thread,
	    (void *)lock);
	_spinlock(&lock->lock);

	/* writers have precedence */
	if (lock->owner == NULL && TAILQ_EMPTY(&lock->writers))
		lock->readers++;
	else if (try)
		error = EBUSY;
	else if (lock->owner == thread)
		error = EDEADLK;
	else {
		do {
			if (__thrsleep(lock, CLOCK_REALTIME, abstime,
			    &lock->lock, NULL) == EWOULDBLOCK)
				return (ETIMEDOUT);
			_spinlock(&lock->lock);
		} while (lock->owner != NULL || !TAILQ_EMPTY(&lock->writers));
		lock->readers++;
	}
	_spinunlock(&lock->lock);

	return (error);
}

int
pthread_rwlock_rdlock(pthread_rwlock_t *lockp)
{
	return (_rthread_rwlock_rdlock(lockp, NULL, 0));
}

int
pthread_rwlock_tryrdlock(pthread_rwlock_t *lockp)
{
	return (_rthread_rwlock_rdlock(lockp, NULL, 1));
}

int
pthread_rwlock_timedrdlock(pthread_rwlock_t *lockp,
    const struct timespec *abstime)
{
	if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
	    abstime->tv_nsec > 1000000000)
		return (EINVAL);
	return (_rthread_rwlock_rdlock(lockp, abstime, 0));
}


static int
_rthread_rwlock_wrlock(pthread_rwlock_t *lockp, const struct timespec *abstime,
    int try)
{
	pthread_rwlock_t lock;
	pthread_t thread = pthread_self();
	int error;

	if ((error = _rthread_rwlock_ensure_init(lockp)))
		return (error);

	lock = *lockp;

	_rthread_debug(5, "%p: rwlock_timedwrlock %p\n", (void *)thread,
	    (void *)lock);
	_spinlock(&lock->lock);
	if (lock->readers == 0 && lock->owner == NULL)
		lock->owner = thread;
	else if (try)
		error = EBUSY;
	else if (lock->owner == thread)
		error = EDEADLK;
	else {
		int do_wait;

		/* gotta block */
		TAILQ_INSERT_TAIL(&lock->writers, thread, waiting);
		do {
			do_wait = __thrsleep(thread, CLOCK_REALTIME, abstime,
			    &lock->lock, NULL) != EWOULDBLOCK;
			_spinlock(&lock->lock);
		} while (lock->owner != thread && do_wait);

		if (lock->owner != thread) {
			/* timed out, sigh */
			TAILQ_REMOVE(&lock->writers, thread, waiting);
			error = ETIMEDOUT;
		}
	}
	_spinunlock(&lock->lock);

	return (error);
}

int
pthread_rwlock_wrlock(pthread_rwlock_t *lockp)
{
	return (_rthread_rwlock_wrlock(lockp, NULL, 0));
}

int
pthread_rwlock_trywrlock(pthread_rwlock_t *lockp)
{
	return (_rthread_rwlock_wrlock(lockp, NULL, 1));
}

int
pthread_rwlock_timedwrlock(pthread_rwlock_t *lockp,
    const struct timespec *abstime)
{
	if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
	    abstime->tv_nsec > 1000000000)
		return (EINVAL);
	return (_rthread_rwlock_wrlock(lockp, abstime, 0));
}


int
pthread_rwlock_unlock(pthread_rwlock_t *lockp)
{
	pthread_rwlock_t lock;
	pthread_t thread = pthread_self();
	pthread_t next;
	int was_writer;

	lock = *lockp;

	_rthread_debug(5, "%p: rwlock_unlock %p\n", (void *)thread,
	    (void *)lock);
	_spinlock(&lock->lock);
	if (lock->owner != NULL) {
		assert(lock->owner == thread);
		was_writer = 1;
	} else {
		assert(lock->readers > 0);
		lock->readers--;
		if (lock->readers > 0)
			goto out;
		was_writer = 0;
	}

	lock->owner = next = TAILQ_FIRST(&lock->writers);
	if (next != NULL) {
		/* dequeue and wake first writer */
		TAILQ_REMOVE(&lock->writers, next, waiting);
		_spinunlock(&lock->lock);
		__thrwakeup(next, 1);
		return (0);
	}

	/* could there have been blocked readers?  wake them all */
	if (was_writer)
		__thrwakeup(lock, 0);
out:
	_spinunlock(&lock->lock);

	return (0);
}


Generated by: GCOVR (Version 3.3)

Line	Branch	Exec	Source
1			/* $OpenBSD: rthread_rwlock.c,v 1.10 2017/07/29 16:42:10 deraadt Exp $ */
2			/*
3			* Copyright (c) 2004,2005 Ted Unangst <tedu@openbsd.org>
4			* Copyright (c) 2012 Philip Guenther <guenther@openbsd.org>
5			* All Rights Reserved.
6			*
7			* Permission to use, copy, modify, and distribute this software for any
8			* purpose with or without fee is hereby granted, provided that the above
9			* copyright notice and this permission notice appear in all copies.
10			*
11			* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12			* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13			* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14			* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15			* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16			* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17			* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18			*/
19			/*
20			* rwlocks
21			*/
22
23			#include <assert.h>
24			#include <stdlib.h>
25			#include <unistd.h>
26			#include <errno.h>
27
28			#include <pthread.h>
29
30			#include "rthread.h"
31
32			static _atomic_lock_t rwlock_init_lock = _SPINLOCK_UNLOCKED;
33
34			int
35			pthread_rwlock_init(pthread_rwlock_t *lockp,
36			const pthread_rwlockattr_t *attrp __unused)
37			{
38			pthread_rwlock_t lock;
39
40		130	lock = calloc(1, sizeof(*lock));
41	✗✓	65	if (!lock)
42			return (errno);
43		65	lock->lock = _SPINLOCK_UNLOCKED;
44		65	TAILQ_INIT(&lock->writers);
45
46		65	*lockp = lock;
47
48		65	return (0);
49		65	}
50			DEF_STD(pthread_rwlock_init);
51
52			int
53			pthread_rwlock_destroy(pthread_rwlock_t *lockp)
54			{
55			pthread_rwlock_t lock;
56
57			assert(lockp);
58			lock = *lockp;
59			if (lock) {
60			if (lock->readers \|\| !TAILQ_EMPTY(&lock->writers)) {
61			#define MSG "pthread_rwlock_destroy on rwlock with waiters!\n"
62			write(2, MSG, sizeof(MSG) - 1);
63			#undef MSG
64			return (EBUSY);
65			}
66			free(lock);
67			}
68			*lockp = NULL;
69
70			return (0);
71			}
72
73			static int
74			_rthread_rwlock_ensure_init(pthread_rwlock_t *lockp)
75			{
76			int ret = 0;
77
78			/*
79			* If the rwlock is statically initialized, perform the dynamic
80			* initialization.
81			*/
82	✓✓	2710	if (*lockp == NULL)
83			{
84		44	_spinlock(&rwlock_init_lock);
85	✓✗	44	if (*lockp == NULL)
86		44	ret = pthread_rwlock_init(lockp, NULL);
87		44	_spinunlock(&rwlock_init_lock);
88		44	}
89		1355	return (ret);
90			}
91
92
93			static int
94			_rthread_rwlock_rdlock(pthread_rwlock_t lockp, const struct timespec abstime,
95			int try)
96			{
97			pthread_rwlock_t lock;
98		2512	pthread_t thread = pthread_self();
99			int error;
100
101	✗✓	1256	if ((error = _rthread_rwlock_ensure_init(lockp)))
102			return (error);
103
104		1256	lock = *lockp;
105		2512	_rthread_debug(5, "%p: rwlock_rdlock %p\n", (void *)thread,
106		1256	(void *)lock);
107		1256	_spinlock(&lock->lock);
108
109			/* writers have precedence */
110	✓✗✓✗	2512	if (lock->owner == NULL && TAILQ_EMPTY(&lock->writers))
111		1256	lock->readers++;
112			else if (try)
113			error = EBUSY;
114			else if (lock->owner == thread)
115			error = EDEADLK;
116			else {
117			do {
118			if (__thrsleep(lock, CLOCK_REALTIME, abstime,
119			&lock->lock, NULL) == EWOULDBLOCK)
120			return (ETIMEDOUT);
121			_spinlock(&lock->lock);
122			} while (lock->owner != NULL \|\| !TAILQ_EMPTY(&lock->writers));
123			lock->readers++;
124			}
125		1256	_spinunlock(&lock->lock);
126
127		1256	return (error);
128		1256	}
129
130			int
131			pthread_rwlock_rdlock(pthread_rwlock_t *lockp)
132			{
133		2512	return (_rthread_rwlock_rdlock(lockp, NULL, 0));
134			}
135
136			int
137			pthread_rwlock_tryrdlock(pthread_rwlock_t *lockp)
138			{
139			return (_rthread_rwlock_rdlock(lockp, NULL, 1));
140			}
141
142			int
143			pthread_rwlock_timedrdlock(pthread_rwlock_t *lockp,
144			const struct timespec *abstime)
145			{
146			if (abstime == NULL \|\| abstime->tv_sec < 0 \|\| abstime->tv_nsec < 0 \|\|
147			abstime->tv_nsec > 1000000000)
148			return (EINVAL);
149			return (_rthread_rwlock_rdlock(lockp, abstime, 0));
150			}
151
152
153			static int
154			_rthread_rwlock_wrlock(pthread_rwlock_t lockp, const struct timespec abstime,
155			int try)
156			{
157			pthread_rwlock_t lock;
158		198	pthread_t thread = pthread_self();
159			int error;
160
161	✗✓	99	if ((error = _rthread_rwlock_ensure_init(lockp)))
162			return (error);
163
164		99	lock = *lockp;
165
166		198	_rthread_debug(5, "%p: rwlock_timedwrlock %p\n", (void *)thread,
167		99	(void *)lock);
168		99	_spinlock(&lock->lock);
169	✓✓✓✗	194	if (lock->readers == 0 && lock->owner == NULL)
170		95	lock->owner = thread;
171	✗✓	4	else if (try)
172			error = EBUSY;
173	✗✓	4	else if (lock->owner == thread)
174			error = EDEADLK;
175			else {
176			int do_wait;
177
178			/* gotta block */
179		4	TAILQ_INSERT_TAIL(&lock->writers, thread, waiting);
180		4	do {
181		4	do_wait = __thrsleep(thread, CLOCK_REALTIME, abstime,
182		8	&lock->lock, NULL) != EWOULDBLOCK;
183		4	_spinlock(&lock->lock);
184	✗✓	4	} while (lock->owner != thread && do_wait);
185
186	✗✓	4	if (lock->owner != thread) {
187			/* timed out, sigh */
188			TAILQ_REMOVE(&lock->writers, thread, waiting);
189			error = ETIMEDOUT;
190			}
191			}
192		99	_spinunlock(&lock->lock);
193
194		99	return (error);
195		99	}
196
197			int
198			pthread_rwlock_wrlock(pthread_rwlock_t *lockp)
199			{
200		198	return (_rthread_rwlock_wrlock(lockp, NULL, 0));
201			}
202
203			int
204			pthread_rwlock_trywrlock(pthread_rwlock_t *lockp)
205			{
206			return (_rthread_rwlock_wrlock(lockp, NULL, 1));
207			}
208
209			int
210			pthread_rwlock_timedwrlock(pthread_rwlock_t *lockp,
211			const struct timespec *abstime)
212			{
213			if (abstime == NULL \|\| abstime->tv_sec < 0 \|\| abstime->tv_nsec < 0 \|\|
214			abstime->tv_nsec > 1000000000)
215			return (EINVAL);
216			return (_rthread_rwlock_wrlock(lockp, abstime, 0));
217			}
218
219
220			int
221			pthread_rwlock_unlock(pthread_rwlock_t *lockp)
222			{
223			pthread_rwlock_t lock;
224		2674	pthread_t thread = pthread_self();
225			pthread_t next;
226			int was_writer;
227
228		1337	lock = *lockp;
229
230		2674	_rthread_debug(5, "%p: rwlock_unlock %p\n", (void *)thread,
231		1337	(void *)lock);
232		1337	_spinlock(&lock->lock);
233	✓✓	1337	if (lock->owner != NULL) {
234	✗✓	81	assert(lock->owner == thread);
235			was_writer = 1;
236		81	} else {
237	✗✓	1256	assert(lock->readers > 0);
238		1256	lock->readers--;
239	✓✓	1256	if (lock->readers > 0)
240			goto out;
241			was_writer = 0;
242			}
243
244		770	lock->owner = next = TAILQ_FIRST(&lock->writers);
245	✓✓	770	if (next != NULL) {
246			/* dequeue and wake first writer */
247	✗✓	12	TAILQ_REMOVE(&lock->writers, next, waiting);
248		4	_spinunlock(&lock->lock);
249		4	__thrwakeup(next, 1);
250		4	return (0);
251			}
252
253			/* could there have been blocked readers? wake them all */
254	✓✓	766	if (was_writer)
255		81	__thrwakeup(lock, 0);
256			out:
257		1333	_spinunlock(&lock->lock);
258
259		1333	return (0);
260		1337	}