Home | History | Annotate | Line # | Download | only in libpthread
pthread_spin.c revision 1.6.32.1 
      1 /*	$NetBSD: pthread_spin.c,v 1.6.32.1 2020/04/08 14:07:15 martin Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2001, 2006, 2007 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Nathan J. Williams and Andrew Doran.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 /*
     33  * Public (POSIX-specified) spinlocks.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 __RCSID("$NetBSD: pthread_spin.c,v 1.6.32.1 2020/04/08 14:07:15 martin Exp $");
     38 
     39 #include <sys/types.h>
     40 #include <sys/ras.h>
     41 
     42 #include <machine/lock.h>
     43 
     44 #include <errno.h>
     45 #include <unistd.h>
     46 #include <stdio.h>
     47 #include <stdlib.h>
     48 
     49 #include "pthread.h"
     50 #include "pthread_int.h"
     51 
     52 int
     53 pthread_spin_init(pthread_spinlock_t *lock, int pshared)
     54 {
     55 
     56 	pthread__error(EINVAL, "Invalid pshared",
     57 	    pshared == PTHREAD_PROCESS_PRIVATE ||
     58 	    pshared == PTHREAD_PROCESS_SHARED);
     59 
     60 	lock->pts_magic = _PT_SPINLOCK_MAGIC;
     61 
     62 	/*
     63 	 * We don't actually use the pshared flag for anything;
     64 	 * CPU simple locks have all the process-shared properties
     65 	 * that we want anyway.
     66 	 */
     67 	lock->pts_flags = pshared;
     68 	pthread_lockinit(&lock->pts_spin);
     69 
     70 	return 0;
     71 }
     72 
     73 int
     74 pthread_spin_destroy(pthread_spinlock_t *lock)
     75 {
     76 
     77 	pthread__error(EINVAL, "Invalid spinlock",
     78 	    lock->pts_magic == _PT_SPINLOCK_MAGIC);
     79 
     80 	if (!__SIMPLELOCK_UNLOCKED_P(&lock->pts_spin))
     81 		return EBUSY;
     82 
     83 	lock->pts_magic = _PT_SPINLOCK_DEAD;
     84 
     85 	return 0;
     86 }
     87 
     88 int
     89 pthread_spin_lock(pthread_spinlock_t *lock)
     90 {
     91 	pthread_t self;
     92 
     93 	pthread__error(EINVAL, "Invalid spinlock",
     94 	    lock->pts_magic == _PT_SPINLOCK_MAGIC);
     95 
     96 	self = pthread__self();
     97 	while (pthread__spintrylock(self, &lock->pts_spin) == 0) {
     98 		pthread__smt_pause();
     99 	}
    100 
    101 	return 0;
    102 }
    103 
    104 int
    105 pthread_spin_trylock(pthread_spinlock_t *lock)
    106 {
    107 	pthread_t self;
    108 
    109 	pthread__error(EINVAL, "Invalid spinlock",
    110 	    lock->pts_magic == _PT_SPINLOCK_MAGIC);
    111 
    112 	self = pthread__self();
    113 	if (pthread__spintrylock(self, &lock->pts_spin) == 0)
    114 		return EBUSY;
    115 	return 0;
    116 }
    117 
    118 int
    119 pthread_spin_unlock(pthread_spinlock_t *lock)
    120 {
    121 	pthread_t self;
    122 
    123 	pthread__error(EINVAL, "Invalid spinlock",
    124 	    lock->pts_magic == _PT_SPINLOCK_MAGIC);
    125 
    126 	self = pthread__self();
    127 	pthread__spinunlock(self, &lock->pts_spin);
    128 	pthread__smt_wake();
    129 
    130 	return 0;
    131 }
    132