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  */
27 
28 #include "namespace.h"
29 #include <machine/tls.h>
30 #include <errno.h>
31 #include <stdlib.h>
32 #include <pthread.h>
33 #include <pthread_np.h>
34 #include "un-namespace.h"
35 
36 #include "thr_private.h"
37 
38 #define SPIN_COUNT 100000
39 
40 int
41 _pthread_spin_init(pthread_spinlock_t *lock, int pshared)
42 {
43 	pthread_spinlock_t lck;
44 
45 	if (lock == NULL || pshared != PTHREAD_PROCESS_PRIVATE)
46 		return (EINVAL);
47 	lck = __malloc(sizeof(struct __pthread_spinlock_s));
48 	if (lck == NULL)
49 		return (ENOMEM);
50 	_thr_umtx_init(&lck->s_lock);
51 	*lock = lck;
52 
53 	return (0);
54 }
55 
56 int
57 _pthread_spin_destroy(pthread_spinlock_t *lock)
58 {
59 	int ret;
60 
61 	if (lock == NULL || *lock == NULL) {
62 		ret = EINVAL;
63 	} else {
64 		__free(*lock);
65 		*lock = NULL;
66 		ret = 0;
67 	}
68 
69 	return (ret);
70 }
71 
72 int
73 _pthread_spin_trylock(pthread_spinlock_t *lock)
74 {
75 	pthread_t curthread = tls_get_curthread();
76 	pthread_spinlock_t lck;
77 
78 	if (lock == NULL || (lck = *lock) == NULL)
79 		return (EINVAL);
80 	return (THR_UMTX_TRYLOCK_PERSIST(curthread, &lck->s_lock));
81 }
82 
83 int
84 _pthread_spin_lock(pthread_spinlock_t *lock)
85 {
86 	pthread_t curthread;
87 	pthread_spinlock_t lck;
88 	int count;
89 
90 	if (lock == NULL || (lck = *lock) == NULL)
91 		return (EINVAL);
92 
93 	curthread = tls_get_curthread();
94 	count = SPIN_COUNT;
95 	while (THR_UMTX_TRYLOCK_PERSIST(curthread, &lck->s_lock) != 0) {
96 		while (lck->s_lock) {
97 			CPU_SPINWAIT;	/* tell cpu we are spinning */
98 			if (--count <= 0) {
99 				count = SPIN_COUNT;
100 				_pthread_yield();
101 			}
102 		}
103 	}
104 	return (0);
105 }
106 
107 int
108 _pthread_spin_unlock(pthread_spinlock_t *lock)
109 {
110 	pthread_t curthread = tls_get_curthread();
111 	pthread_spinlock_t lck;
112 
113 	if (lock == NULL || (lck = *lock) == NULL)
114 		return (EINVAL);
115 	/* XXX: shouldn't return status? */
116 	THR_UMTX_UNLOCK_PERSIST(curthread, &lck->s_lock);
117 	return (0);
118 }
119 
120 __strong_reference(_pthread_spin_init, pthread_spin_init);
121 __strong_reference(_pthread_spin_destroy, pthread_spin_destroy);
122 __strong_reference(_pthread_spin_trylock, pthread_spin_trylock);
123 __strong_reference(_pthread_spin_lock, pthread_spin_lock);
124 __strong_reference(_pthread_spin_unlock, pthread_spin_unlock);
125