5e53a4f90f
Mainly focus on files that use BSD 2-Clause license, however the tool I was using mis-identified many licenses so this was mostly a manual - error prone - task. The Software Package Data Exchange (SPDX) group provides a specification to make it easier for automated tools to detect and summarize well known opensource licenses. We are gradually adopting the specification, noting that the tags are considered only advisory and do not, in any way, superceed or replace the license texts.
378 lines
9.7 KiB
C
378 lines
9.7 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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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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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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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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_Static_assert(sizeof(struct pthread_rwlock) <= PAGE_SIZE,
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"pthread_rwlock is too large for off-page");
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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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static int init_static(struct pthread *thread, pthread_rwlock_t *rwlock);
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static int init_rwlock(pthread_rwlock_t *rwlock, pthread_rwlock_t *rwlock_out);
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static int __always_inline
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check_and_init_rwlock(pthread_rwlock_t *rwlock, pthread_rwlock_t *rwlock_out)
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{
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if (__predict_false(*rwlock == THR_PSHARED_PTR ||
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*rwlock <= THR_RWLOCK_DESTROYED))
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return (init_rwlock(rwlock, rwlock_out));
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*rwlock_out = *rwlock;
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return (0);
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}
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static int __noinline
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init_rwlock(pthread_rwlock_t *rwlock, pthread_rwlock_t *rwlock_out)
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{
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pthread_rwlock_t prwlock;
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int ret;
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if (*rwlock == THR_PSHARED_PTR) {
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prwlock = __thr_pshared_offpage(rwlock, 0);
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if (prwlock == NULL)
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return (EINVAL);
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} else if ((prwlock = *rwlock) <= THR_RWLOCK_DESTROYED) {
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if (prwlock == THR_RWLOCK_INITIALIZER) {
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ret = init_static(_get_curthread(), rwlock);
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if (ret != 0)
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return (ret);
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} else if (prwlock == THR_RWLOCK_DESTROYED) {
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return (EINVAL);
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}
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prwlock = *rwlock;
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}
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*rwlock_out = prwlock;
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return (0);
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}
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static int
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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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if (attr == NULL || *attr == NULL ||
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(*attr)->pshared == PTHREAD_PROCESS_PRIVATE) {
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prwlock = calloc(1, sizeof(struct pthread_rwlock));
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if (prwlock == NULL)
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return (ENOMEM);
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*rwlock = prwlock;
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} else {
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prwlock = __thr_pshared_offpage(rwlock, 1);
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if (prwlock == NULL)
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return (EFAULT);
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prwlock->lock.rw_flags |= USYNC_PROCESS_SHARED;
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*rwlock = THR_PSHARED_PTR;
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}
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return (0);
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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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pthread_rwlock_t prwlock;
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int ret;
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prwlock = *rwlock;
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if (prwlock == THR_RWLOCK_INITIALIZER)
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ret = 0;
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else if (prwlock == THR_RWLOCK_DESTROYED)
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ret = EINVAL;
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else if (prwlock == THR_PSHARED_PTR) {
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*rwlock = THR_RWLOCK_DESTROYED;
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__thr_pshared_destroy(rwlock);
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ret = 0;
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} else {
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*rwlock = THR_RWLOCK_DESTROYED;
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free(prwlock);
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ret = 0;
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}
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return (ret);
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}
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static int
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init_static(struct pthread *thread, pthread_rwlock_t *rwlock)
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{
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int ret;
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THR_LOCK_ACQUIRE(thread, &_rwlock_static_lock);
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if (*rwlock == THR_RWLOCK_INITIALIZER)
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ret = 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_init(pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr)
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{
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*rwlock = NULL;
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return (rwlock_init(rwlock, attr));
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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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struct pthread *curthread = _get_curthread();
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pthread_rwlock_t prwlock;
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int flags;
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int ret;
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ret = check_and_init_rwlock(rwlock, &prwlock);
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if (ret != 0)
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return (ret);
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if (curthread->rdlock_count) {
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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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flags = URWLOCK_PREFER_READER;
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} else {
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flags = 0;
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}
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/*
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* POSIX said the validity of the abstimeout parameter need
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* not be checked if the lock can be immediately acquired.
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*/
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ret = _thr_rwlock_tryrdlock(&prwlock->lock, flags);
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if (ret == 0) {
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curthread->rdlock_count++;
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return (ret);
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}
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if (__predict_false(abstime &&
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(abstime->tv_nsec >= 1000000000 || abstime->tv_nsec < 0)))
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return (EINVAL);
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for (;;) {
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/* goto kernel and lock it */
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ret = __thr_rwlock_rdlock(&prwlock->lock, flags, abstime);
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if (ret != EINTR)
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break;
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/* if interrupted, try to lock it in userland again. */
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if (_thr_rwlock_tryrdlock(&prwlock->lock, flags) == 0) {
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ret = 0;
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break;
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}
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}
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if (ret == 0)
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curthread->rdlock_count++;
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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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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 = _get_curthread();
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pthread_rwlock_t prwlock;
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int flags;
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int ret;
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ret = check_and_init_rwlock(rwlock, &prwlock);
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if (ret != 0)
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return (ret);
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if (curthread->rdlock_count) {
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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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flags = URWLOCK_PREFER_READER;
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} else {
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flags = 0;
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}
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ret = _thr_rwlock_tryrdlock(&prwlock->lock, flags);
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if (ret == 0)
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curthread->rdlock_count++;
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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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struct pthread *curthread = _get_curthread();
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pthread_rwlock_t prwlock;
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int ret;
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ret = check_and_init_rwlock(rwlock, &prwlock);
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if (ret != 0)
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return (ret);
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ret = _thr_rwlock_trywrlock(&prwlock->lock);
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if (ret == 0)
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prwlock->owner = TID(curthread);
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return (ret);
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}
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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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struct pthread *curthread = _get_curthread();
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pthread_rwlock_t prwlock;
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int ret;
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ret = check_and_init_rwlock(rwlock, &prwlock);
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if (ret != 0)
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return (ret);
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/*
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* POSIX said the validity of the abstimeout parameter need
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* not be checked if the lock can be immediately acquired.
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*/
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ret = _thr_rwlock_trywrlock(&prwlock->lock);
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if (ret == 0) {
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prwlock->owner = TID(curthread);
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return (ret);
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}
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if (__predict_false(abstime &&
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(abstime->tv_nsec >= 1000000000 || abstime->tv_nsec < 0)))
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return (EINVAL);
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for (;;) {
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/* goto kernel and lock it */
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ret = __thr_rwlock_wrlock(&prwlock->lock, abstime);
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if (ret == 0) {
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prwlock->owner = TID(curthread);
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break;
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}
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if (ret != EINTR)
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break;
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/* if interrupted, try to lock it in userland again. */
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if (_thr_rwlock_trywrlock(&prwlock->lock) == 0) {
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ret = 0;
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prwlock->owner = TID(curthread);
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break;
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}
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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_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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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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int
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_pthread_rwlock_unlock(pthread_rwlock_t *rwlock)
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{
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struct pthread *curthread = _get_curthread();
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pthread_rwlock_t prwlock;
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int ret;
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int32_t state;
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if (*rwlock == THR_PSHARED_PTR) {
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prwlock = __thr_pshared_offpage(rwlock, 0);
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if (prwlock == NULL)
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return (EINVAL);
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} else {
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prwlock = *rwlock;
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}
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if (__predict_false(prwlock <= THR_RWLOCK_DESTROYED))
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return (EINVAL);
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state = prwlock->lock.rw_state;
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if (state & URWLOCK_WRITE_OWNER) {
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if (__predict_false(prwlock->owner != TID(curthread)))
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return (EPERM);
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prwlock->owner = 0;
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}
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ret = _thr_rwlock_unlock(&prwlock->lock);
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if (ret == 0 && (state & URWLOCK_WRITE_OWNER) == 0)
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curthread->rdlock_count--;
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return (ret);
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}
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