1 /*-
2  * Copyright (c) 2003 David Xu <davidxu@freebsd.org>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  *
26  * $DragonFly: src/lib/libthread_xu/thread/thr_pspinlock.c,v 1.4 2006/04/06 13:03:09 davidxu Exp $
27  */
28 
29 #include "namespace.h"
30 #include <machine/tls.h>
31 
32 #include <errno.h>
33 #include <stdlib.h>
34 #include <pthread.h>
35 #include <pthread_np.h>
36 #include "un-namespace.h"
37 
38 #include "thr_private.h"
39 
40 #define SPIN_COUNT 100000
41 
42 int
43 _pthread_spin_init(pthread_spinlock_t *lock, int pshared)
44 {
45 	struct pthread_spinlock	*lck;
46 	int ret;
47 
48 	if (lock == NULL || pshared != PTHREAD_PROCESS_PRIVATE)
49 		ret = EINVAL;
50 	else if ((lck = malloc(sizeof(struct pthread_spinlock))) == NULL)
51 		ret = ENOMEM;
52 	else {
53 		_thr_umtx_init(&lck->s_lock);
54 		*lock = lck;
55 		ret = 0;
56 	}
57 
58 	return (ret);
59 }
60 
61 int
62 _pthread_spin_destroy(pthread_spinlock_t *lock)
63 {
64 	int ret;
65 
66 	if (lock == NULL || *lock == NULL)
67 		ret = EINVAL;
68 	else {
69 		free(*lock);
70 		*lock = NULL;
71 		ret = 0;
72 	}
73 
74 	return (ret);
75 }
76 
77 int
78 _pthread_spin_trylock(pthread_spinlock_t *lock)
79 {
80 	struct pthread *curthread = tls_get_curthread();
81 	struct pthread_spinlock	*lck;
82 	int ret;
83 
84 	if (lock == NULL || (lck = *lock) == NULL)
85 		ret = EINVAL;
86 	else
87 		ret = THR_UMTX_TRYLOCK(curthread, &lck->s_lock);
88 	return (ret);
89 }
90 
91 int
92 _pthread_spin_lock(pthread_spinlock_t *lock)
93 {
94 	struct pthread *curthread = tls_get_curthread();
95 	struct pthread_spinlock	*lck;
96 	int ret, count;
97 
98 	if (lock == NULL || (lck = *lock) == NULL)
99 		ret = EINVAL;
100 	else {
101 		count = SPIN_COUNT;
102 		while ((ret = THR_UMTX_TRYLOCK(curthread, &lck->s_lock)) != 0) {
103 			while (lck->s_lock) {
104 #ifdef __i386__
105 				/* tell cpu we are spinning */
106 				__asm __volatile("pause");
107 #endif
108 				if (--count <= 0) {
109 					count = SPIN_COUNT;
110 					_pthread_yield();
111 				}
112 			}
113 		}
114 		ret = 0;
115 	}
116 
117 	return (ret);
118 }
119 
120 int
121 _pthread_spin_unlock(pthread_spinlock_t *lock)
122 {
123 	struct pthread *curthread = tls_get_curthread();
124 	struct pthread_spinlock	*lck;
125 	int ret;
126 
127 	if (lock == NULL || (lck = *lock) == NULL)
128 		ret = EINVAL;
129 	else {
130 		THR_UMTX_UNLOCK(curthread, &lck->s_lock);
131 		ret = 0;
132 	}
133 	return (ret);
134 }
135 
136 __strong_reference(_pthread_spin_init, pthread_spin_init);
137 __strong_reference(_pthread_spin_destroy, pthread_spin_destroy);
138 __strong_reference(_pthread_spin_trylock, pthread_spin_trylock);
139 __strong_reference(_pthread_spin_lock, pthread_spin_lock);
140 __strong_reference(_pthread_spin_unlock, pthread_spin_unlock);
141 
142