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
130
131
132
133
134
135
136
|
/**
* @file meslock.c
*
* @brief Implements the subdevice lock class.
* @note Copyright (C) 2006 Meilhaus Electronic GmbH (support@meilhaus.de)
* @author Guenter Gebhardt
*/
/*
* Copyright (C) 2006 Meilhaus Electronic GmbH (support@meilhaus.de)
*
* This file is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/spinlock.h>
#include "medefines.h"
#include "meerror.h"
#include "medebug.h"
#include "meslock.h"
int me_slock_enter(struct me_slock *slock, struct file *filep)
{
PDEBUG_LOCKS("executed.\n");
spin_lock(&slock->spin_lock);
if ((slock->filep) != NULL && (slock->filep != filep)) {
PERROR("Subdevice is locked by another process.\n");
spin_unlock(&slock->spin_lock);
return ME_ERRNO_LOCKED;
}
slock->count++;
spin_unlock(&slock->spin_lock);
return ME_ERRNO_SUCCESS;
}
int me_slock_exit(struct me_slock *slock, struct file *filep)
{
PDEBUG_LOCKS("executed.\n");
spin_lock(&slock->spin_lock);
slock->count--;
spin_unlock(&slock->spin_lock);
return ME_ERRNO_SUCCESS;
}
int me_slock_lock(struct me_slock *slock, struct file *filep, int lock)
{
PDEBUG_LOCKS("executed.\n");
switch (lock) {
case ME_LOCK_RELEASE:
spin_lock(&slock->spin_lock);
if (slock->filep == filep)
slock->filep = NULL;
spin_unlock(&slock->spin_lock);
break;
case ME_LOCK_SET:
spin_lock(&slock->spin_lock);
if (slock->count) {
spin_unlock(&slock->spin_lock);
PERROR("Subdevice is used by another process.\n");
return ME_ERRNO_USED;
} else if (slock->filep == NULL)
slock->filep = filep;
else if (slock->filep != filep) {
spin_unlock(&slock->spin_lock);
PERROR("Subdevice is locked by another process.\n");
return ME_ERRNO_LOCKED;
}
spin_unlock(&slock->spin_lock);
break;
case ME_LOCK_CHECK:
spin_lock(&slock->spin_lock);
if (slock->count) {
spin_unlock(&slock->spin_lock);
return ME_ERRNO_USED;
} else if ((slock->filep != NULL) && (slock->filep != filep)) {
spin_unlock(&slock->spin_lock);
return ME_ERRNO_LOCKED;
}
spin_unlock(&slock->spin_lock);
break;
default:
break;
}
return ME_ERRNO_SUCCESS;
}
void me_slock_deinit(struct me_slock *slock)
{
PDEBUG_LOCKS("executed.\n");
}
int me_slock_init(me_slock_t *slock)
{
PDEBUG_LOCKS("executed.\n");
slock->filep = NULL;
slock->count = 0;
spin_lock_init(&slock->spin_lock);
return 0;
}
|
