1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
|
/*-
* Copyright (c) 2004 Michael Telahun Makonnen <mtm@FreeBSD.Org>
* All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*
* $FreeBSD$
*/
#include <pthread.h>
#include <stdlib.h>
#include <string.h>
#include "thr_private.h"
__weak_reference(_pthread_barrier_destroy, pthread_barrier_destroy);
__weak_reference(_pthread_barrier_init, pthread_barrier_init);
__weak_reference(_pthread_barrier_wait, pthread_barrier_wait);
int
_pthread_barrier_destroy(pthread_barrier_t *barrier)
{
if (*barrier == NULL)
return (EINVAL);
if ((*barrier)->b_subtotal > 0)
return (EBUSY);
PTHREAD_ASSERT((*barrier)->b_subtotal == 0,
"barrier count must be zero when destroyed");
free(*barrier);
*barrier = NULL;
return (0);
}
int
_pthread_barrier_init(pthread_barrier_t *barrier,
const pthread_barrierattr_t attr, unsigned int count)
{
if (count < 1)
return (EINVAL);
*barrier =
(struct pthread_barrier *)malloc(sizeof(struct pthread_barrier));
if (*barrier == NULL)
return (ENOMEM);
memset((void *)*barrier, 0, sizeof(struct pthread_barrier));
(*barrier)->b_total = count;
TAILQ_INIT(&(*barrier)->b_barrq);
return (0);
}
int
_pthread_barrier_wait(pthread_barrier_t *barrier)
{
struct pthread_barrier *b;
struct pthread *ptd;
int error;
if (*barrier == NULL)
return (EINVAL);
/*
* Check if threads waiting on the barrier can be released. If
* so, release them and make this last thread the special thread.
*/
error = 0;
b = *barrier;
UMTX_LOCK(&b->b_lock);
if (b->b_subtotal == (b->b_total - 1)) {
TAILQ_FOREACH(ptd, &b->b_barrq, sqe) {
PTHREAD_LOCK(ptd);
TAILQ_REMOVE(&b->b_barrq, ptd, sqe);
ptd->flags &= ~PTHREAD_FLAGS_IN_BARRQ;
ptd->flags |= PTHREAD_FLAGS_BARR_REL;
PTHREAD_WAKE(ptd);
PTHREAD_UNLOCK(ptd);
}
b->b_subtotal = 0;
UMTX_UNLOCK(&b->b_lock);
return (PTHREAD_BARRIER_SERIAL_THREAD);
}
/*
* More threads need to reach the barrier. Suspend this thread.
*/
PTHREAD_LOCK(curthread);
TAILQ_INSERT_HEAD(&b->b_barrq, curthread, sqe);
curthread->flags |= PTHREAD_FLAGS_IN_BARRQ;
PTHREAD_UNLOCK(curthread);
b->b_subtotal++;
PTHREAD_ASSERT(b->b_subtotal < b->b_total,
"the number of threads waiting at a barrier is too large");
UMTX_UNLOCK(&b->b_lock);
do {
error = _thread_suspend(curthread, NULL);
if (error == EINTR) {
/*
* Make sure this thread wasn't released from
* the barrier while it was handling the signal.
*/
PTHREAD_LOCK(curthread);
if ((curthread->flags & PTHREAD_FLAGS_BARR_REL) != 0) {
curthread->flags &= ~PTHREAD_FLAGS_BARR_REL;
PTHREAD_UNLOCK(curthread);
error = 0;
break;
}
PTHREAD_UNLOCK(curthread);
}
} while (error == EINTR);
return (error);
}
|
