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/**
* @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;
}
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