e62165c8b0
used LIBTHREAD_1_0 as its version definition, but now needs to define its symbols in the same namespace used by libc. The compatibility hooks allows you to use libraries and binaries built and linked to libpthread before libc was built with symbol versioning. The shims can be removed if libpthread is given a version bump. Reviewed by: davidxu
439 lines
11 KiB
C
439 lines
11 KiB
C
/*-
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* Copyright (c) 1998 Alex Nash
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <errno.h>
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#include <limits.h>
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#include <stdlib.h>
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#include "namespace.h"
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#include <pthread.h>
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#include "un-namespace.h"
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#include "thr_private.h"
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/* maximum number of times a read lock may be obtained */
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#define MAX_READ_LOCKS (INT_MAX - 1)
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LT10_COMPAT_PRIVATE(_pthread_rwlock_destroy);
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LT10_COMPAT_DEFAULT(pthread_rwlock_destroy);
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LT10_COMPAT_PRIVATE(_pthread_rwlock_init);
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LT10_COMPAT_DEFAULT(pthread_rwlock_init);
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LT10_COMPAT_PRIVATE(_pthread_rwlock_rdlock);
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LT10_COMPAT_DEFAULT(pthread_rwlock_rdlock);
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LT10_COMPAT_PRIVATE(_pthread_rwlock_timedrdlock);
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LT10_COMPAT_DEFAULT(pthread_rwlock_timedrdlock);
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LT10_COMPAT_PRIVATE(_pthread_rwlock_tryrdlock);
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LT10_COMPAT_DEFAULT(pthread_rwlock_tryrdlock);
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LT10_COMPAT_PRIVATE(_pthread_rwlock_trywrlock);
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LT10_COMPAT_DEFAULT(pthread_rwlock_trywrlock);
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LT10_COMPAT_PRIVATE(_pthread_rwlock_unlock);
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LT10_COMPAT_DEFAULT(pthread_rwlock_unlock);
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LT10_COMPAT_PRIVATE(_pthread_rwlock_wrlock);
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LT10_COMPAT_DEFAULT(pthread_rwlock_wrlock);
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LT10_COMPAT_PRIVATE(_pthread_rwlock_timedwrlock);
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LT10_COMPAT_DEFAULT(pthread_rwlock_timedwrlock);
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__weak_reference(_pthread_rwlock_destroy, pthread_rwlock_destroy);
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__weak_reference(_pthread_rwlock_init, pthread_rwlock_init);
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__weak_reference(_pthread_rwlock_rdlock, pthread_rwlock_rdlock);
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__weak_reference(_pthread_rwlock_timedrdlock, pthread_rwlock_timedrdlock);
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__weak_reference(_pthread_rwlock_tryrdlock, pthread_rwlock_tryrdlock);
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__weak_reference(_pthread_rwlock_trywrlock, pthread_rwlock_trywrlock);
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__weak_reference(_pthread_rwlock_unlock, pthread_rwlock_unlock);
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__weak_reference(_pthread_rwlock_wrlock, pthread_rwlock_wrlock);
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__weak_reference(_pthread_rwlock_timedwrlock, pthread_rwlock_timedwrlock);
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/*
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* Prototypes
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*/
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static int init_static(pthread_rwlock_t *rwlock);
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static int
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init_static(pthread_rwlock_t *rwlock)
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{
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struct pthread *thread = _get_curthread();
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int ret;
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THR_LOCK_ACQUIRE(thread, &_rwlock_static_lock);
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if (*rwlock == NULL)
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ret = _pthread_rwlock_init(rwlock, NULL);
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else
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ret = 0;
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THR_LOCK_RELEASE(thread, &_rwlock_static_lock);
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return (ret);
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}
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int
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_pthread_rwlock_destroy (pthread_rwlock_t *rwlock)
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{
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int ret;
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if (rwlock == NULL)
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ret = EINVAL;
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else {
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pthread_rwlock_t prwlock;
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prwlock = *rwlock;
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_pthread_mutex_destroy(&prwlock->lock);
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_pthread_cond_destroy(&prwlock->read_signal);
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_pthread_cond_destroy(&prwlock->write_signal);
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free(prwlock);
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*rwlock = NULL;
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ret = 0;
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}
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return (ret);
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}
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int
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_pthread_rwlock_init (pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr)
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{
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pthread_rwlock_t prwlock;
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int ret;
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/* allocate rwlock object */
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prwlock = (pthread_rwlock_t)malloc(sizeof(struct pthread_rwlock));
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if (prwlock == NULL)
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return (ENOMEM);
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/* initialize the lock */
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if ((ret = _pthread_mutex_init(&prwlock->lock, NULL)) != 0)
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free(prwlock);
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else {
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/* initialize the read condition signal */
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ret = _pthread_cond_init(&prwlock->read_signal, NULL);
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if (ret != 0) {
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_pthread_mutex_destroy(&prwlock->lock);
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free(prwlock);
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} else {
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/* initialize the write condition signal */
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ret = _pthread_cond_init(&prwlock->write_signal, NULL);
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if (ret != 0) {
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_pthread_cond_destroy(&prwlock->read_signal);
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_pthread_mutex_destroy(&prwlock->lock);
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free(prwlock);
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} else {
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/* success */
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prwlock->state = 0;
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prwlock->blocked_writers = 0;
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*rwlock = prwlock;
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}
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}
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}
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return (ret);
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}
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static int
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rwlock_rdlock_common (pthread_rwlock_t *rwlock, const struct timespec *abstime)
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{
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pthread_rwlock_t prwlock;
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struct pthread *curthread;
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int ret;
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if (rwlock == NULL)
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return (EINVAL);
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prwlock = *rwlock;
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/* check for static initialization */
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if (prwlock == NULL) {
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if ((ret = init_static(rwlock)) != 0)
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return (ret);
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prwlock = *rwlock;
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}
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/* grab the monitor lock */
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if ((ret = _thr_mutex_lock(&prwlock->lock)) != 0)
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return (ret);
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/* check lock count */
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if (prwlock->state == MAX_READ_LOCKS) {
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_thr_mutex_unlock(&prwlock->lock);
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return (EAGAIN);
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}
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curthread = _get_curthread();
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if ((curthread->rdlock_count > 0) && (prwlock->state > 0)) {
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/*
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* To avoid having to track all the rdlocks held by
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* a thread or all of the threads that hold a rdlock,
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* we keep a simple count of all the rdlocks held by
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* a thread. If a thread holds any rdlocks it is
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* possible that it is attempting to take a recursive
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* rdlock. If there are blocked writers and precedence
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* is given to them, then that would result in the thread
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* deadlocking. So allowing a thread to take the rdlock
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* when it already has one or more rdlocks avoids the
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* deadlock. I hope the reader can follow that logic ;-)
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*/
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; /* nothing needed */
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} else {
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/* give writers priority over readers */
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while (prwlock->blocked_writers || prwlock->state < 0) {
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if (abstime)
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ret = _pthread_cond_timedwait
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(&prwlock->read_signal,
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&prwlock->lock, abstime);
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else
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ret = _thr_cond_wait(&prwlock->read_signal,
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&prwlock->lock);
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if (ret != 0) {
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/* can't do a whole lot if this fails */
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_thr_mutex_unlock(&prwlock->lock);
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return (ret);
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}
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}
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}
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curthread->rdlock_count++;
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prwlock->state++; /* indicate we are locked for reading */
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/*
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* Something is really wrong if this call fails. Returning
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* error won't do because we've already obtained the read
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* lock. Decrementing 'state' is no good because we probably
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* don't have the monitor lock.
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*/
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_thr_mutex_unlock(&prwlock->lock);
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return (ret);
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}
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int
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_pthread_rwlock_rdlock (pthread_rwlock_t *rwlock)
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{
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return (rwlock_rdlock_common(rwlock, NULL));
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}
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__strong_reference(_pthread_rwlock_rdlock, _thr_rwlock_rdlock);
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int
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_pthread_rwlock_timedrdlock (pthread_rwlock_t *rwlock,
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const struct timespec *abstime)
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{
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return (rwlock_rdlock_common(rwlock, abstime));
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}
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int
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_pthread_rwlock_tryrdlock (pthread_rwlock_t *rwlock)
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{
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struct pthread *curthread;
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pthread_rwlock_t prwlock;
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int ret;
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if (rwlock == NULL)
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return (EINVAL);
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prwlock = *rwlock;
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/* check for static initialization */
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if (prwlock == NULL) {
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if ((ret = init_static(rwlock)) != 0)
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return (ret);
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prwlock = *rwlock;
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}
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/* grab the monitor lock */
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if ((ret = _pthread_mutex_lock(&prwlock->lock)) != 0)
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return (ret);
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curthread = _get_curthread();
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if (prwlock->state == MAX_READ_LOCKS)
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ret = EAGAIN;
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else if ((curthread->rdlock_count > 0) && (prwlock->state > 0)) {
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/* see comment for pthread_rwlock_rdlock() */
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curthread->rdlock_count++;
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prwlock->state++;
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}
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/* give writers priority over readers */
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else if (prwlock->blocked_writers || prwlock->state < 0)
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ret = EBUSY;
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else {
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curthread->rdlock_count++;
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prwlock->state++; /* indicate we are locked for reading */
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}
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/* see the comment on this in pthread_rwlock_rdlock */
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_pthread_mutex_unlock(&prwlock->lock);
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return (ret);
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}
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int
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_pthread_rwlock_trywrlock (pthread_rwlock_t *rwlock)
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{
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pthread_rwlock_t prwlock;
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int ret;
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if (rwlock == NULL)
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return (EINVAL);
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prwlock = *rwlock;
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/* check for static initialization */
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if (prwlock == NULL) {
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if ((ret = init_static(rwlock)) != 0)
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return (ret);
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prwlock = *rwlock;
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}
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/* grab the monitor lock */
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if ((ret = _pthread_mutex_lock(&prwlock->lock)) != 0)
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return (ret);
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if (prwlock->state != 0)
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ret = EBUSY;
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else
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/* indicate we are locked for writing */
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prwlock->state = -1;
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/* see the comment on this in pthread_rwlock_rdlock */
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_pthread_mutex_unlock(&prwlock->lock);
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return (ret);
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}
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int
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_pthread_rwlock_unlock (pthread_rwlock_t *rwlock)
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{
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struct pthread *curthread;
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pthread_rwlock_t prwlock;
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int ret;
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if (rwlock == NULL)
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return (EINVAL);
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prwlock = *rwlock;
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if (prwlock == NULL)
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return (EINVAL);
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/* grab the monitor lock */
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if ((ret = _thr_mutex_lock(&prwlock->lock)) != 0)
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return (ret);
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curthread = _get_curthread();
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if (prwlock->state > 0) {
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curthread->rdlock_count--;
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prwlock->state--;
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if (prwlock->state == 0 && prwlock->blocked_writers)
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ret = _thr_cond_signal(&prwlock->write_signal);
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} else if (prwlock->state < 0) {
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prwlock->state = 0;
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if (prwlock->blocked_writers)
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ret = _thr_cond_signal(&prwlock->write_signal);
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else
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ret = _thr_cond_broadcast(&prwlock->read_signal);
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} else
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ret = EINVAL;
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/* see the comment on this in pthread_rwlock_rdlock */
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_thr_mutex_unlock(&prwlock->lock);
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return (ret);
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}
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__strong_reference(_pthread_rwlock_unlock, _thr_rwlock_unlock);
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static int
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rwlock_wrlock_common (pthread_rwlock_t *rwlock, const struct timespec *abstime)
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{
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pthread_rwlock_t prwlock;
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int ret;
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if (rwlock == NULL)
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return (EINVAL);
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prwlock = *rwlock;
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/* check for static initialization */
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if (prwlock == NULL) {
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if ((ret = init_static(rwlock)) != 0)
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return (ret);
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prwlock = *rwlock;
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}
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/* grab the monitor lock */
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if ((ret = _thr_mutex_lock(&prwlock->lock)) != 0)
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return (ret);
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while (prwlock->state != 0) {
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prwlock->blocked_writers++;
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if (abstime != NULL)
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ret = _pthread_cond_timedwait(&prwlock->write_signal,
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&prwlock->lock, abstime);
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else
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ret = _thr_cond_wait(&prwlock->write_signal,
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&prwlock->lock);
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if (ret != 0) {
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prwlock->blocked_writers--;
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_thr_mutex_unlock(&prwlock->lock);
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return (ret);
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}
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prwlock->blocked_writers--;
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}
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/* indicate we are locked for writing */
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prwlock->state = -1;
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/* see the comment on this in pthread_rwlock_rdlock */
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_thr_mutex_unlock(&prwlock->lock);
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return (ret);
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}
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int
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_pthread_rwlock_wrlock (pthread_rwlock_t *rwlock)
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{
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return (rwlock_wrlock_common (rwlock, NULL));
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}
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__strong_reference(_pthread_rwlock_wrlock, _thr_rwlock_wrlock);
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int
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_pthread_rwlock_timedwrlock (pthread_rwlock_t *rwlock,
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const struct timespec *abstime)
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{
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return (rwlock_wrlock_common (rwlock, abstime));
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}
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