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/* $NetBSD: pthread_lock.c,v 1.20 2007/03/24 18:52:00 ad Exp $ */
/*-
* Copyright (c) 2001, 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_lock.c,v 1.20 2007/03/24 18:52:00 ad Exp $");
#include <sys/types.h>
#include <sys/lock.h>
#include <sys/ras.h>
#include <errno.h>
#include <unistd.h>
#include <stdio.h>
#include "pthread.h"
#include "pthread_int.h"
#ifdef PTHREAD_SPIN_DEBUG_PRINT
#define SDPRINTF(x) DPRINTF(x)
#else
#define SDPRINTF(x)
#endif
/* This does not belong here. */
#if defined(i386) || defined(__x86_64__)
#define smt_pause() __asm __volatile("rep; nop" ::: "memory")
#else
#define smt_pause() /* nothing */
#endif
extern int pthread__nspins;
static int pthread__atomic;
RAS_DECL(pthread__lock);
void
pthread__simple_lock_init(__cpu_simple_lock_t *alp)
{
if (pthread__atomic) {
__cpu_simple_lock_init(alp);
return;
}
*alp = __SIMPLELOCK_UNLOCKED;
}
int
pthread__simple_lock_try(__cpu_simple_lock_t *alp)
{
__cpu_simple_lock_t old;
if (pthread__atomic)
return __cpu_simple_lock_try(alp);
RAS_START(pthread__lock);
old = *alp;
*alp = __SIMPLELOCK_LOCKED;
RAS_END(pthread__lock);
return old == __SIMPLELOCK_UNLOCKED;
}
inline void
pthread__simple_unlock(__cpu_simple_lock_t *alp)
{
if (pthread__atomic) {
__cpu_simple_unlock(alp);
return;
}
*alp = __SIMPLELOCK_UNLOCKED;
}
/*
* Initialize the locking primitives. On uniprocessors, we always
* use Restartable Atomic Sequences if they are available. Otherwise,
* we fall back onto machine-dependent atomic lock primitives.
*/
void
pthread__lockprim_init(int ncpu)
{
if (ncpu != 1) {
pthread__atomic = 1;
return;
}
if (rasctl(RAS_ADDR(pthread__lock), RAS_SIZE(pthread__lock),
RAS_INSTALL) != 0) {
pthread__atomic = 1;
return;
}
}
void
pthread_lockinit(pthread_spin_t *lock)
{
pthread__simple_lock_init(lock);
}
void
pthread_spinlock(pthread_t thread, pthread_spin_t *lock)
{
int count, ret;
count = pthread__nspins;
SDPRINTF(("(pthread_spinlock %p) spinlock %p (count %d)\n",
thread, lock, thread->pt_spinlocks));
#ifdef PTHREAD_SPIN_DEBUG
pthread__assert(thread->pt_spinlocks >= 0);
#endif
thread->pt_spinlocks++;
if (__predict_true(pthread__simple_lock_try(lock))) {
PTHREADD_ADD(PTHREADD_SPINLOCKS);
return;
}
do {
while ((ret = pthread__simple_lock_try(lock)) == 0 &&
--count) {
smt_pause();
}
if (ret == 1)
break;
SDPRINTF(("(pthread_spinlock %p) retrying spinlock %p "
"(count %d)\n", thread, lock,
thread->pt_spinlocks));
thread->pt_spinlocks--;
/* XXXLWP far from ideal */
sched_yield();
count = pthread__nspins;
thread->pt_spinlocks++;
} while (/*CONSTCOND*/ 1);
PTHREADD_ADD(PTHREADD_SPINLOCKS);
}
int
pthread_spintrylock(pthread_t thread, pthread_spin_t *lock)
{
int ret;
SDPRINTF(("(pthread_spintrylock %p) spinlock %p (count %d)\n",
thread, lock, thread->pt_spinlocks));
thread->pt_spinlocks++;
ret = pthread__simple_lock_try(lock);
if (!ret)
thread->pt_spinlocks--;
return ret;
}
void
pthread_spinunlock(pthread_t thread, pthread_spin_t *lock)
{
SDPRINTF(("(pthread_spinunlock %p) spinlock %p (count %d)\n",
thread, lock, thread->pt_spinlocks));
pthread__simple_unlock(lock);
thread->pt_spinlocks--;
#ifdef PTHREAD_SPIN_DEBUG
pthread__assert(thread->pt_spinlocks >= 0);
#endif
PTHREADD_ADD(PTHREADD_SPINUNLOCKS);
}
/*
* Public (POSIX-specified) spinlocks.
*/
int
pthread_spin_init(pthread_spinlock_t *lock, int pshared)
{
#ifdef ERRORCHECK
if (lock == NULL || (pshared != PTHREAD_PROCESS_PRIVATE &&
pshared != PTHREAD_PROCESS_SHARED))
return EINVAL;
#endif
lock->pts_magic = _PT_SPINLOCK_MAGIC;
/*
* We don't actually use the pshared flag for anything;
* CPU simple locks have all the process-shared properties
* that we want anyway.
*/
lock->pts_flags = pshared;
pthread_lockinit(&lock->pts_spin);
return 0;
}
int
pthread_spin_destroy(pthread_spinlock_t *lock)
{
#ifdef ERRORCHECK
if (lock == NULL || lock->pts_magic != _PT_SPINLOCK_MAGIC)
return EINVAL;
if (lock->pts_spin != __SIMPLELOCK_UNLOCKED)
return EBUSY;
#endif
lock->pts_magic = _PT_SPINLOCK_DEAD;
return 0;
}
int
pthread_spin_lock(pthread_spinlock_t *lock)
{
#ifdef ERRORCHECK
if (lock == NULL || lock->pts_magic != _PT_SPINLOCK_MAGIC)
return EINVAL;
#endif
while (pthread__simple_lock_try(&lock->pts_spin) == 0) {
smt_pause();
}
return 0;
}
int
pthread_spin_trylock(pthread_spinlock_t *lock)
{
#ifdef ERRORCHECK
if (lock == NULL || lock->pts_magic != _PT_SPINLOCK_MAGIC)
return EINVAL;
#endif
if (pthread__simple_lock_try(&lock->pts_spin) == 0)
return EBUSY;
return 0;
}
int
pthread_spin_unlock(pthread_spinlock_t *lock)
{
#ifdef ERRORCHECK
if (lock == NULL || lock->pts_magic != _PT_SPINLOCK_MAGIC)
return EINVAL;
#endif
pthread__simple_unlock(&lock->pts_spin);
return 0;
}
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