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/*
* Copyright (c) 2004 Michael Telahun Makonnen <mtm@FreeBSD.Org>
* Copyright (c) 1997 John Birrell <jb@cimlogic.com.au>.
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by John Birrell.
* 4. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL 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 <sys/types.h>
#include <machine/atomic.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sched.h>
#include <pthread.h>
#include <unistd.h>
#include <libc_private.h>
#include "thr_private.h"
#define THR_SPIN_MAGIC 0xdadadada
#define THR_SPIN_UNOWNED (void *)0
#define MAGIC_TEST_RETURN_ON_FAIL(l) \
do { \
if ((l) == NULL || (l)->s_magic != THR_SPIN_MAGIC) \
return (EINVAL); \
} while(0)
__weak_reference(_pthread_spin_destroy, pthread_spin_destroy);
__weak_reference(_pthread_spin_init, pthread_spin_init);
__weak_reference(_pthread_spin_lock, pthread_spin_lock);
__weak_reference(_pthread_spin_trylock, pthread_spin_trylock);
__weak_reference(_pthread_spin_unlock, pthread_spin_unlock);
int
_pthread_spin_destroy(pthread_spinlock_t *lock)
{
MAGIC_TEST_RETURN_ON_FAIL((*lock));
if ((*lock)->s_owner == THR_SPIN_UNOWNED) {
(*lock)->s_magic = 0;
free((*lock));
*lock = NULL;
return (0);
}
return (EBUSY);
}
int
_pthread_spin_init(pthread_spinlock_t *lock, int pshared)
{
struct pthread_spinlock *s;
if (*lock != NULL) {
if ((*lock)->s_magic == THR_SPIN_MAGIC)
return (EBUSY);
}
s = (struct pthread_spinlock *)malloc(sizeof(struct pthread_spinlock));
if (s == NULL)
return (ENOMEM);
s->s_magic = THR_SPIN_MAGIC;
s->s_owner = THR_SPIN_UNOWNED;
*lock = s;
return (0);
}
/*
* If the caller sets nonblocking to 1, this function will return
* immediately without acquiring the lock it is owned by another thread.
* If set to 0, it will keep spinning until it acquires the lock.
*/
int
_pthread_spin_lock(pthread_spinlock_t *lock)
{
MAGIC_TEST_RETURN_ON_FAIL(*lock);
if ((*lock)->s_owner == curthread)
return (EDEADLK);
while (atomic_cmpset_acq_ptr(&(*lock)->s_owner, THR_SPIN_UNOWNED,
(void *)curthread) != 1)
; /* SPIN */
return (0);
}
int
_pthread_spin_trylock(pthread_spinlock_t *lock)
{
MAGIC_TEST_RETURN_ON_FAIL(*lock);
if (atomic_cmpset_acq_ptr(&(*lock)->s_owner, THR_SPIN_UNOWNED,
(void *)curthread) == 1)
return (0);
return (EBUSY);
}
int
_pthread_spin_unlock(pthread_spinlock_t *lock)
{
MAGIC_TEST_RETURN_ON_FAIL(*lock);
if (atomic_cmpset_rel_ptr(&(*lock)->s_owner, (void *)curthread,
THR_SPIN_UNOWNED) == 1)
return (0);
return (EPERM);
}
void
_spinunlock(spinlock_t *lck)
{
if (umtx_unlock((struct umtx *)lck, curthread->thr_id))
abort();
}
/*
* Lock a location for the running thread. Yield to allow other
* threads to run if this thread is blocked because the lock is
* not available. Note that this function does not sleep. It
* assumes that the lock will be available very soon.
*/
void
_spinlock(spinlock_t *lck)
{
if (umtx_lock((struct umtx *)lck, curthread->thr_id))
abort();
}
int
_spintrylock(spinlock_t *lck)
{
int error;
error = umtx_lock((struct umtx *)lck, curthread->thr_id);
if (error != 0 && error != EBUSY)
abort();
return (error);
}
/*
* Lock a location for the running thread. Yield to allow other
* threads to run if this thread is blocked because the lock is
* not available. Note that this function does not sleep. It
* assumes that the lock will be available very soon.
*
* This function checks if the running thread has already locked the
* location, warns if this occurs and creates a thread dump before
* returning.
*/
void
_spinlock_debug(spinlock_t *lck, char *fname, int lineno)
{
if (umtx_lock((struct umtx *)lck, curthread->thr_id))
abort();
}
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