David Kiliani | 3fedd14 | 2008-11-01 00:39:12 +0100 | [diff] [blame] | 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, |
| 68 | struct file *filep, int lock, int flags, me_slist_t * slist) |
| 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 | |
| 186 | int me_dlock_init(me_dlock_t * dlock) |
| 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 | } |