Loading...
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;
}
|