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3fedd148 DK |
1 | /** |
2 | * @file medlock.c | |
3 | * | |
4 | * @brief Implements the device lock class. | |
5 | * @note Copyright (C) 2006 Meilhaus Electronic GmbH (support@meilhaus.de) | |
6 | * @author Guenter Gebhardt | |
7 | */ | |
8 | ||
9 | /* | |
10 | * Copyright (C) 2007 Meilhaus Electronic GmbH (support@meilhaus.de) | |
11 | * | |
12 | * This file is free software; you can redistribute it and/or modify | |
13 | * it under the terms of the GNU General Public License as published by | |
14 | * the Free Software Foundation; either version 2 of the License, or | |
15 | * (at your option) any later version. | |
16 | * | |
17 | * This program is distributed in the hope that it will be useful, | |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | * GNU General Public License for more details. | |
21 | * | |
22 | * You should have received a copy of the GNU General Public License | |
23 | * along with this program; if not, write to the Free Software | |
24 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
25 | */ | |
26 | ||
27 | #include <linux/spinlock.h> | |
28 | ||
29 | #include "medefines.h" | |
30 | #include "meerror.h" | |
31 | ||
32 | #include "medebug.h" | |
33 | #include "meslist.h" | |
34 | #include "mesubdevice.h" | |
35 | #include "medlock.h" | |
36 | ||
37 | int me_dlock_enter(struct me_dlock *dlock, struct file *filep) | |
38 | { | |
39 | PDEBUG_LOCKS("executed.\n"); | |
40 | ||
41 | spin_lock(&dlock->spin_lock); | |
42 | ||
43 | if ((dlock->filep) != NULL && (dlock->filep != filep)) { | |
44 | PERROR("Device is locked by another process.\n"); | |
45 | spin_unlock(&dlock->spin_lock); | |
46 | return ME_ERRNO_LOCKED; | |
47 | } | |
48 | ||
49 | dlock->count++; | |
50 | ||
51 | spin_unlock(&dlock->spin_lock); | |
52 | ||
53 | return ME_ERRNO_SUCCESS; | |
54 | } | |
55 | ||
56 | int me_dlock_exit(struct me_dlock *dlock, struct file *filep) | |
57 | { | |
58 | PDEBUG_LOCKS("executed.\n"); | |
59 | ||
60 | spin_lock(&dlock->spin_lock); | |
61 | dlock->count--; | |
62 | spin_unlock(&dlock->spin_lock); | |
63 | ||
64 | return ME_ERRNO_SUCCESS; | |
65 | } | |
66 | ||
67 | int me_dlock_lock(struct me_dlock *dlock, | |
451084d2 | 68 | struct file *filep, int lock, int flags, me_slist_t *slist) |
3fedd148 DK |
69 | { |
70 | int err = ME_ERRNO_SUCCESS; | |
71 | int i; | |
72 | me_subdevice_t *subdevice; | |
73 | ||
74 | PDEBUG_LOCKS("executed.\n"); | |
75 | ||
76 | spin_lock(&dlock->spin_lock); | |
77 | ||
78 | switch (lock) { | |
79 | ||
80 | case ME_LOCK_RELEASE: | |
81 | if ((dlock->filep == filep) || (dlock->filep == NULL)) { | |
82 | dlock->filep = NULL; | |
83 | ||
84 | /* Unlock all possibly locked subdevices. */ | |
85 | ||
86 | for (i = 0; i < me_slist_get_number_subdevices(slist); | |
87 | i++) { | |
88 | subdevice = me_slist_get_subdevice(slist, i); | |
89 | ||
90 | if (subdevice) | |
91 | err = | |
92 | subdevice-> | |
93 | me_subdevice_lock_subdevice | |
94 | (subdevice, filep, ME_LOCK_RELEASE, | |
95 | flags); | |
96 | else | |
97 | err = ME_ERRNO_INTERNAL; | |
98 | } | |
99 | } | |
100 | ||
101 | break; | |
102 | ||
103 | case ME_LOCK_SET: | |
104 | if (dlock->count) { | |
105 | PERROR("Device is used by another process.\n"); | |
106 | err = ME_ERRNO_USED; | |
107 | } else if ((dlock->filep != NULL) && (dlock->filep != filep)) { | |
108 | PERROR("Device is locked by another process.\n"); | |
109 | err = ME_ERRNO_LOCKED; | |
110 | } else if (dlock->filep == NULL) { | |
111 | /* Check any subdevice is locked by another process. */ | |
112 | ||
113 | for (i = 0; i < me_slist_get_number_subdevices(slist); | |
114 | i++) { | |
115 | subdevice = me_slist_get_subdevice(slist, i); | |
116 | ||
117 | if (subdevice) { | |
118 | if ((err = | |
119 | subdevice-> | |
120 | me_subdevice_lock_subdevice | |
121 | (subdevice, filep, ME_LOCK_CHECK, | |
122 | flags))) { | |
123 | PERROR | |
124 | ("A subdevice is locked by another process.\n"); | |
125 | break; | |
126 | } | |
127 | } else { | |
128 | err = ME_ERRNO_INTERNAL; | |
129 | } | |
130 | } | |
131 | ||
132 | /* If no subdevices are locked by other processes, | |
133 | we can take ownership of the device. Otherwise we jump ahead. */ | |
134 | if (!err) | |
135 | dlock->filep = filep; | |
136 | } | |
137 | ||
138 | break; | |
139 | ||
140 | case ME_LOCK_CHECK: | |
141 | if (dlock->count) { | |
142 | err = ME_ERRNO_USED; | |
143 | } else if ((dlock->filep != NULL) && (dlock->filep != filep)) { | |
144 | err = ME_ERRNO_LOCKED; | |
145 | } else if (dlock->filep == NULL) { | |
146 | for (i = 0; i < me_slist_get_number_subdevices(slist); | |
147 | i++) { | |
148 | subdevice = me_slist_get_subdevice(slist, i); | |
149 | ||
150 | if (subdevice) { | |
151 | if ((err = | |
152 | subdevice-> | |
153 | me_subdevice_lock_subdevice | |
154 | (subdevice, filep, ME_LOCK_CHECK, | |
155 | flags))) { | |
156 | PERROR | |
157 | ("A subdevice is locked by another process.\n"); | |
158 | break; | |
159 | } | |
160 | } else { | |
161 | err = ME_ERRNO_INTERNAL; | |
162 | } | |
163 | } | |
164 | } | |
165 | ||
166 | break; | |
167 | ||
168 | default: | |
169 | PERROR("Invalid lock.\n"); | |
170 | ||
171 | err = ME_ERRNO_INVALID_LOCK; | |
172 | ||
173 | break; | |
174 | } | |
175 | ||
176 | spin_unlock(&dlock->spin_lock); | |
177 | ||
178 | return err; | |
179 | } | |
180 | ||
181 | void me_dlock_deinit(struct me_dlock *dlock) | |
182 | { | |
183 | PDEBUG_LOCKS("executed.\n"); | |
184 | } | |
185 | ||
451084d2 | 186 | int me_dlock_init(me_dlock_t *dlock) |
3fedd148 DK |
187 | { |
188 | PDEBUG_LOCKS("executed.\n"); | |
189 | ||
190 | dlock->filep = NULL; | |
191 | dlock->count = 0; | |
192 | spin_lock_init(&dlock->spin_lock); | |
193 | ||
194 | return 0; | |
195 | } |