432 lines
11 KiB
C
432 lines
11 KiB
C
/* $NetBSD: pthread_rwlock.c,v 1.18 2007/03/24 18:52:00 ad Exp $ */
|
|
|
|
/*-
|
|
* Copyright (c) 2002, 2006, 2007 The NetBSD Foundation, Inc.
|
|
* All rights reserved.
|
|
*
|
|
* This code is derived from software contributed to The NetBSD Foundation
|
|
* by Nathan J. Williams and Andrew Doran.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by the NetBSD
|
|
* Foundation, Inc. and its contributors.
|
|
* 4. Neither the name of The NetBSD Foundation nor the names of its
|
|
* contributors may be used to endorse or promote products derived
|
|
* from this software without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
|
|
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
|
|
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
|
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
|
|
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
* POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
|
|
#include <sys/cdefs.h>
|
|
__RCSID("$NetBSD: pthread_rwlock.c,v 1.18 2007/03/24 18:52:00 ad Exp $");
|
|
|
|
#include <errno.h>
|
|
|
|
#include "pthread.h"
|
|
#include "pthread_int.h"
|
|
|
|
__strong_alias(__libc_rwlock_init,pthread_rwlock_init)
|
|
__strong_alias(__libc_rwlock_rdlock,pthread_rwlock_rdlock)
|
|
__strong_alias(__libc_rwlock_wrlock,pthread_rwlock_wrlock)
|
|
__strong_alias(__libc_rwlock_tryrdlock,pthread_rwlock_tryrdlock)
|
|
__strong_alias(__libc_rwlock_trywrlock,pthread_rwlock_trywrlock)
|
|
__strong_alias(__libc_rwlock_unlock,pthread_rwlock_unlock)
|
|
__strong_alias(__libc_rwlock_destroy,pthread_rwlock_destroy)
|
|
|
|
int
|
|
pthread_rwlock_init(pthread_rwlock_t *rwlock,
|
|
const pthread_rwlockattr_t *attr)
|
|
{
|
|
#ifdef ERRORCHECK
|
|
if ((rwlock == NULL) ||
|
|
(attr && (attr->ptra_magic != _PT_RWLOCKATTR_MAGIC)))
|
|
return EINVAL;
|
|
#endif
|
|
rwlock->ptr_magic = _PT_RWLOCK_MAGIC;
|
|
pthread_lockinit(&rwlock->ptr_interlock);
|
|
PTQ_INIT(&rwlock->ptr_rblocked);
|
|
PTQ_INIT(&rwlock->ptr_wblocked);
|
|
rwlock->ptr_nreaders = 0;
|
|
rwlock->ptr_writer = NULL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
int
|
|
pthread_rwlock_destroy(pthread_rwlock_t *rwlock)
|
|
{
|
|
#ifdef ERRORCHECK
|
|
if ((rwlock == NULL) ||
|
|
(rwlock->ptr_magic != _PT_RWLOCK_MAGIC) ||
|
|
(!PTQ_EMPTY(&rwlock->ptr_rblocked)) ||
|
|
(!PTQ_EMPTY(&rwlock->ptr_wblocked)) ||
|
|
(rwlock->ptr_nreaders != 0) ||
|
|
(rwlock->ptr_writer != NULL))
|
|
return EINVAL;
|
|
#endif
|
|
rwlock->ptr_magic = _PT_RWLOCK_DEAD;
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
int
|
|
pthread_rwlock_rdlock(pthread_rwlock_t *rwlock)
|
|
{
|
|
pthread_t self;
|
|
#ifdef ERRORCHECK
|
|
if ((rwlock == NULL) || (rwlock->ptr_magic != _PT_RWLOCK_MAGIC))
|
|
return EINVAL;
|
|
#endif
|
|
self = pthread__self();
|
|
|
|
pthread_spinlock(self, &rwlock->ptr_interlock);
|
|
#ifdef ERRORCHECK
|
|
if (rwlock->ptr_writer == self) {
|
|
pthread_spinunlock(self, &rwlock->ptr_interlock);
|
|
return EDEADLK;
|
|
}
|
|
#endif
|
|
/*
|
|
* Don't get a readlock if there is a writer or if there are waiting
|
|
* writers; i.e. prefer writers to readers. This strategy is dictated
|
|
* by SUSv3.
|
|
*/
|
|
while ((rwlock->ptr_writer != NULL) ||
|
|
(!PTQ_EMPTY(&rwlock->ptr_wblocked))) {
|
|
PTQ_INSERT_TAIL(&rwlock->ptr_rblocked, self, pt_sleep);
|
|
self->pt_sleeponq = 1;
|
|
self->pt_sleepobj = &rwlock->ptr_rblocked;
|
|
(void)pthread__park(self, &rwlock->ptr_interlock,
|
|
&rwlock->ptr_rblocked, NULL, 0, &rwlock->ptr_rblocked);
|
|
}
|
|
|
|
rwlock->ptr_nreaders++;
|
|
pthread_spinunlock(self, &rwlock->ptr_interlock);
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
int
|
|
pthread_rwlock_tryrdlock(pthread_rwlock_t *rwlock)
|
|
{
|
|
pthread_t self;
|
|
#ifdef ERRORCHECK
|
|
if ((rwlock == NULL) || (rwlock->ptr_magic != _PT_RWLOCK_MAGIC))
|
|
return EINVAL;
|
|
#endif
|
|
self = pthread__self();
|
|
|
|
pthread_spinlock(self, &rwlock->ptr_interlock);
|
|
/*
|
|
* Don't get a readlock if there is a writer or if there are waiting
|
|
* writers; i.e. prefer writers to readers. This strategy is dictated
|
|
* by SUSv3.
|
|
*/
|
|
if ((rwlock->ptr_writer != NULL) ||
|
|
(!PTQ_EMPTY(&rwlock->ptr_wblocked))) {
|
|
pthread_spinunlock(self, &rwlock->ptr_interlock);
|
|
return EBUSY;
|
|
}
|
|
|
|
rwlock->ptr_nreaders++;
|
|
pthread_spinunlock(self, &rwlock->ptr_interlock);
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
int
|
|
pthread_rwlock_wrlock(pthread_rwlock_t *rwlock)
|
|
{
|
|
pthread_t self;
|
|
extern int pthread__started;
|
|
|
|
#ifdef ERRORCHECK
|
|
if ((rwlock == NULL) || (rwlock->ptr_magic != _PT_RWLOCK_MAGIC))
|
|
return EINVAL;
|
|
#endif
|
|
self = pthread__self();
|
|
|
|
pthread_spinlock(self, &rwlock->ptr_interlock);
|
|
#ifdef ERRORCHECK
|
|
if (rwlock->ptr_writer == self) {
|
|
pthread_spinunlock(self, &rwlock->ptr_interlock);
|
|
return EDEADLK;
|
|
}
|
|
#endif
|
|
/*
|
|
* Prefer writers to readers here; permit writers even if there are
|
|
* waiting readers.
|
|
*/
|
|
while ((rwlock->ptr_nreaders > 0) || (rwlock->ptr_writer != NULL)) {
|
|
#ifdef ERRORCHECK
|
|
if (pthread__started == 0) {
|
|
pthread_spinunlock(self, &rwlock->ptr_interlock);
|
|
return EDEADLK;
|
|
}
|
|
#endif
|
|
PTQ_INSERT_TAIL(&rwlock->ptr_wblocked, self, pt_sleep);
|
|
self->pt_sleeponq = 1;
|
|
self->pt_sleepobj = &rwlock->ptr_wblocked;
|
|
(void)pthread__park(self, &rwlock->ptr_interlock,
|
|
&rwlock->ptr_wblocked, NULL, 0, &rwlock->ptr_wblocked);
|
|
}
|
|
|
|
rwlock->ptr_writer = self;
|
|
pthread_spinunlock(self, &rwlock->ptr_interlock);
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
int
|
|
pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock)
|
|
{
|
|
pthread_t self;
|
|
#ifdef ERRORCHECK
|
|
if ((rwlock == NULL) || (rwlock->ptr_magic != _PT_RWLOCK_MAGIC))
|
|
return EINVAL;
|
|
#endif
|
|
self = pthread__self();
|
|
|
|
pthread_spinlock(self, &rwlock->ptr_interlock);
|
|
/*
|
|
* Prefer writers to readers here; permit writers even if there are
|
|
* waiting readers.
|
|
*/
|
|
if ((rwlock->ptr_nreaders > 0) || (rwlock->ptr_writer != NULL)) {
|
|
pthread_spinunlock(self, &rwlock->ptr_interlock);
|
|
return EBUSY;
|
|
}
|
|
|
|
rwlock->ptr_writer = self;
|
|
pthread_spinunlock(self, &rwlock->ptr_interlock);
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
struct pthread_rwlock__waitarg {
|
|
pthread_t ptw_thread;
|
|
pthread_rwlock_t *ptw_rwlock;
|
|
struct pthread_queue_t *ptw_queue;
|
|
};
|
|
|
|
int
|
|
pthread_rwlock_timedrdlock(pthread_rwlock_t *rwlock,
|
|
const struct timespec *abs_timeout)
|
|
{
|
|
pthread_t self;
|
|
int retval;
|
|
|
|
#ifdef ERRORCHECK
|
|
if ((rwlock == NULL) || (rwlock->ptr_magic != _PT_RWLOCK_MAGIC))
|
|
return EINVAL;
|
|
if (abs_timeout == NULL)
|
|
return EINVAL;
|
|
#endif
|
|
if ((abs_timeout->tv_nsec >= 1000000000) ||
|
|
(abs_timeout->tv_nsec < 0) ||
|
|
(abs_timeout->tv_sec < 0))
|
|
return EINVAL;
|
|
|
|
self = pthread__self();
|
|
pthread_spinlock(self, &rwlock->ptr_interlock);
|
|
#ifdef ERRORCHECK
|
|
if (rwlock->ptr_writer == self) {
|
|
pthread_spinunlock(self, &rwlock->ptr_interlock);
|
|
return EDEADLK;
|
|
}
|
|
#endif
|
|
/*
|
|
* Don't get a readlock if there is a writer or if there are waiting
|
|
* writers; i.e. prefer writers to readers. This strategy is dictated
|
|
* by SUSv3.
|
|
*/
|
|
retval = 0;
|
|
while ((retval == 0) && ((rwlock->ptr_writer != NULL) ||
|
|
(!PTQ_EMPTY(&rwlock->ptr_wblocked)))) {
|
|
PTQ_INSERT_TAIL(&rwlock->ptr_rblocked, self, pt_sleep);
|
|
self->pt_sleeponq = 1;
|
|
self->pt_sleepobj = &rwlock->ptr_rblocked;
|
|
retval = pthread__park(self, &rwlock->ptr_interlock,
|
|
&rwlock->ptr_rblocked, abs_timeout, 0,
|
|
&rwlock->ptr_rblocked);
|
|
}
|
|
|
|
/* One last chance to get the lock, in case it was released between
|
|
the alarm firing and when this thread got rescheduled, or in case
|
|
a signal handler kept it busy */
|
|
if ((rwlock->ptr_writer == NULL) &&
|
|
(PTQ_EMPTY(&rwlock->ptr_wblocked))) {
|
|
rwlock->ptr_nreaders++;
|
|
retval = 0;
|
|
}
|
|
pthread_spinunlock(self, &rwlock->ptr_interlock);
|
|
|
|
return retval;
|
|
}
|
|
|
|
|
|
int
|
|
pthread_rwlock_timedwrlock(pthread_rwlock_t *rwlock,
|
|
const struct timespec *abs_timeout)
|
|
{
|
|
pthread_t self;
|
|
int retval;
|
|
extern int pthread__started;
|
|
|
|
#ifdef ERRORCHECK
|
|
if ((rwlock == NULL) || (rwlock->ptr_magic != _PT_RWLOCK_MAGIC))
|
|
return EINVAL;
|
|
if (abs_timeout == NULL)
|
|
return EINVAL;
|
|
#endif
|
|
if ((abs_timeout->tv_nsec >= 1000000000) ||
|
|
(abs_timeout->tv_nsec < 0) ||
|
|
(abs_timeout->tv_sec < 0))
|
|
return EINVAL;
|
|
|
|
self = pthread__self();
|
|
pthread_spinlock(self, &rwlock->ptr_interlock);
|
|
#ifdef ERRORCHECK
|
|
if (rwlock->ptr_writer == self) {
|
|
pthread_spinunlock(self, &rwlock->ptr_interlock);
|
|
return EDEADLK;
|
|
}
|
|
#endif
|
|
/*
|
|
* Prefer writers to readers here; permit writers even if there are
|
|
* waiting readers.
|
|
*/
|
|
retval = 0;
|
|
while (retval == 0 &&
|
|
((rwlock->ptr_nreaders > 0) || (rwlock->ptr_writer != NULL))) {
|
|
#ifdef ERRORCHECK
|
|
if (pthread__started == 0) {
|
|
pthread_spinunlock(self, &rwlock->ptr_interlock);
|
|
return EDEADLK;
|
|
}
|
|
#endif
|
|
PTQ_INSERT_TAIL(&rwlock->ptr_wblocked, self, pt_sleep);
|
|
self->pt_sleeponq = 1;
|
|
self->pt_sleepobj = &rwlock->ptr_wblocked;
|
|
retval = pthread__park(self, &rwlock->ptr_interlock,
|
|
&rwlock->ptr_wblocked, abs_timeout, 0,
|
|
&rwlock->ptr_wblocked);
|
|
}
|
|
|
|
if ((rwlock->ptr_nreaders == 0) && (rwlock->ptr_writer == NULL)) {
|
|
rwlock->ptr_writer = self;
|
|
retval = 0;
|
|
}
|
|
pthread_spinunlock(self, &rwlock->ptr_interlock);
|
|
|
|
return retval;
|
|
}
|
|
|
|
|
|
int
|
|
pthread_rwlock_unlock(pthread_rwlock_t *rwlock)
|
|
{
|
|
pthread_t self, writer;
|
|
#ifdef ERRORCHECK
|
|
if ((rwlock == NULL) || (rwlock->ptr_magic != _PT_RWLOCK_MAGIC))
|
|
return EINVAL;
|
|
#endif
|
|
writer = NULL;
|
|
self = pthread__self();
|
|
|
|
pthread_spinlock(self, &rwlock->ptr_interlock);
|
|
if (rwlock->ptr_writer != NULL) {
|
|
/* Releasing a write lock. */
|
|
#ifdef ERRORCHECK
|
|
if (rwlock->ptr_writer != self) {
|
|
pthread_spinunlock(self, &rwlock->ptr_interlock);
|
|
return EPERM;
|
|
}
|
|
#endif
|
|
rwlock->ptr_writer = NULL;
|
|
writer = PTQ_FIRST(&rwlock->ptr_wblocked);
|
|
if (writer != NULL) {
|
|
PTQ_REMOVE(&rwlock->ptr_wblocked, writer, pt_sleep);
|
|
}
|
|
} else
|
|
#ifdef ERRORCHECK
|
|
if (rwlock->ptr_nreaders > 0)
|
|
#endif
|
|
{
|
|
/* Releasing a read lock. */
|
|
rwlock->ptr_nreaders--;
|
|
if (rwlock->ptr_nreaders == 0) {
|
|
writer = PTQ_FIRST(&rwlock->ptr_wblocked);
|
|
if (writer != NULL)
|
|
PTQ_REMOVE(&rwlock->ptr_wblocked, writer,
|
|
pt_sleep);
|
|
}
|
|
#ifdef ERRORCHECK
|
|
} else {
|
|
pthread_spinunlock(self, &rwlock->ptr_interlock);
|
|
return EPERM;
|
|
#endif
|
|
}
|
|
|
|
if (writer != NULL)
|
|
pthread__unpark(self, &rwlock->ptr_interlock,
|
|
&rwlock->ptr_wblocked, writer);
|
|
else
|
|
pthread__unpark_all(self, &rwlock->ptr_interlock,
|
|
&rwlock->ptr_rblocked);
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
int
|
|
pthread_rwlockattr_init(pthread_rwlockattr_t *attr)
|
|
{
|
|
#ifdef ERRORCHECK
|
|
if (attr == NULL)
|
|
return EINVAL;
|
|
#endif
|
|
attr->ptra_magic = _PT_RWLOCKATTR_MAGIC;
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
int
|
|
pthread_rwlockattr_destroy(pthread_rwlockattr_t *attr)
|
|
{
|
|
#ifdef ERRORCHECK
|
|
if ((attr == NULL) ||
|
|
(attr->ptra_magic != _PT_RWLOCKATTR_MAGIC))
|
|
return EINVAL;
|
|
#endif
|
|
attr->ptra_magic = _PT_RWLOCKATTR_DEAD;
|
|
|
|
return 0;
|
|
}
|