freebsd-skq/lib/libthr/thread/thr_rwlockattr.c
David Xu de1e74c6a5 Revert revision 214007, I realized that MySQL wants to resolve
a silly rwlock deadlock problem, the deadlock is caused by writer
waiters, if a thread has already locked a reader lock, and wants to
acquire another reader lock, it will be blocked by writer waiters,
but we had already fixed it years ago.
2010-10-20 02:34:02 +00:00

100 lines
2.8 KiB
C

/*-
* Copyright (c) 1998 Alex Nash
* All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*
* $FreeBSD$
*/
#include "namespace.h"
#include <errno.h>
#include <stdlib.h>
#include <pthread.h>
#include "un-namespace.h"
#include "thr_private.h"
__weak_reference(_pthread_rwlockattr_destroy, pthread_rwlockattr_destroy);
__weak_reference(_pthread_rwlockattr_getpshared, pthread_rwlockattr_getpshared);
__weak_reference(_pthread_rwlockattr_init, pthread_rwlockattr_init);
__weak_reference(_pthread_rwlockattr_setpshared, pthread_rwlockattr_setpshared);
int
_pthread_rwlockattr_destroy(pthread_rwlockattr_t *rwlockattr)
{
pthread_rwlockattr_t prwlockattr;
if (rwlockattr == NULL)
return(EINVAL);
prwlockattr = *rwlockattr;
if (prwlockattr == NULL)
return(EINVAL);
free(prwlockattr);
return(0);
}
int
_pthread_rwlockattr_getpshared(const pthread_rwlockattr_t *rwlockattr,
int *pshared)
{
*pshared = (*rwlockattr)->pshared;
return(0);
}
int
_pthread_rwlockattr_init(pthread_rwlockattr_t *rwlockattr)
{
pthread_rwlockattr_t prwlockattr;
if (rwlockattr == NULL)
return(EINVAL);
prwlockattr = (pthread_rwlockattr_t)
malloc(sizeof(struct pthread_rwlockattr));
if (prwlockattr == NULL)
return(ENOMEM);
prwlockattr->pshared = PTHREAD_PROCESS_PRIVATE;
*rwlockattr = prwlockattr;
return(0);
}
int
_pthread_rwlockattr_setpshared(pthread_rwlockattr_t *rwlockattr, int pshared)
{
/* Only PTHREAD_PROCESS_PRIVATE is supported. */
if (pshared != PTHREAD_PROCESS_PRIVATE)
return(EINVAL);
(*rwlockattr)->pshared = pshared;
return(0);
}