1/*	$NetBSD: pthread_spin.c,v 1.11 2023/05/25 14:30:03 riastradh 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 1.11 2023/05/25 14:30:03 riastradh Exp $");
38
39/* Need to use libc-private names for atomic operations. */
40#include "../../common/lib/libc/atomic/atomic_op_namespace.h"
41
42#include <sys/types.h>
43#include <sys/ras.h>
44
45#include <machine/lock.h>
46
47#include <errno.h>
48#include <unistd.h>
49#include <stdio.h>
50#include <stdlib.h>
51
52#include "pthread.h"
53#include "pthread_int.h"
54
55int
56pthread_spin_init(pthread_spinlock_t *lock, int pshared)
57{
58
59	pthread__error(EINVAL, "Invalid pshared",
60	    pshared == PTHREAD_PROCESS_PRIVATE ||
61	    pshared == PTHREAD_PROCESS_SHARED);
62
63	lock->pts_magic = _PT_SPINLOCK_MAGIC;
64
65	/*
66	 * We don't actually use the pshared flag for anything;
67	 * CPU simple locks have all the process-shared properties
68	 * that we want anyway.
69	 */
70	lock->pts_flags = pshared;
71	pthread_lockinit(&lock->pts_spin);
72
73	return 0;
74}
75
76int
77pthread_spin_destroy(pthread_spinlock_t *lock)
78{
79
80	pthread__error(EINVAL, "Invalid spinlock",
81	    lock->pts_magic == _PT_SPINLOCK_MAGIC);
82
83	if (!__SIMPLELOCK_UNLOCKED_P(&lock->pts_spin))
84		return EBUSY;
85
86	lock->pts_magic = _PT_SPINLOCK_DEAD;
87
88	return 0;
89}
90
91int
92pthread_spin_lock(pthread_spinlock_t *lock)
93{
94	pthread_t self;
95
96	pthread__error(EINVAL, "Invalid spinlock",
97	    lock->pts_magic == _PT_SPINLOCK_MAGIC);
98
99	self = pthread__self();
100	while (pthread__spintrylock(self, &lock->pts_spin) == 0) {
101		pthread__smt_wait();
102	}
103
104	return 0;
105}
106
107int
108pthread_spin_trylock(pthread_spinlock_t *lock)
109{
110	pthread_t self;
111
112	pthread__error(EINVAL, "Invalid spinlock",
113	    lock->pts_magic == _PT_SPINLOCK_MAGIC);
114
115	self = pthread__self();
116	if (pthread__spintrylock(self, &lock->pts_spin) == 0)
117		return EBUSY;
118	return 0;
119}
120
121int
122pthread_spin_unlock(pthread_spinlock_t *lock)
123{
124	pthread_t self;
125
126	pthread__error(EINVAL, "Invalid spinlock",
127	    lock->pts_magic == _PT_SPINLOCK_MAGIC);
128
129	self = pthread__self();
130	pthread__spinunlock(self, &lock->pts_spin);
131	pthread__smt_wake();
132
133	return 0;
134}
135