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/**
* @file medlock.c
*
* @brief Implements the device lock class.
* @note Copyright (C) 2006 Meilhaus Electronic GmbH (support@meilhaus.de)
* @author Guenter Gebhardt
*/
/*
* Copyright (C) 2007 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 "meslist.h"
#include "mesubdevice.h"
#include "medlock.h"
int me_dlock_enter(struct me_dlock *dlock, struct file *filep)
{
PDEBUG_LOCKS("executed.\n");
spin_lock(&dlock->spin_lock);
if ((dlock->filep) != NULL && (dlock->filep != filep)) {
PERROR("Device is locked by another process.\n");
spin_unlock(&dlock->spin_lock);
return ME_ERRNO_LOCKED;
}
dlock->count++;
spin_unlock(&dlock->spin_lock);
return ME_ERRNO_SUCCESS;
}
int me_dlock_exit(struct me_dlock *dlock, struct file *filep)
{
PDEBUG_LOCKS("executed.\n");
spin_lock(&dlock->spin_lock);
dlock->count--;
spin_unlock(&dlock->spin_lock);
return ME_ERRNO_SUCCESS;
}
int me_dlock_lock(struct me_dlock *dlock,
struct file *filep, int lock, int flags, me_slist_t * slist)
{
int err = ME_ERRNO_SUCCESS;
int i;
me_subdevice_t *subdevice;
PDEBUG_LOCKS("executed.\n");
spin_lock(&dlock->spin_lock);
switch (lock) {
case ME_LOCK_RELEASE:
if ((dlock->filep == filep) || (dlock->filep == NULL)) {
dlock->filep = NULL;
/* Unlock all possibly locked subdevices. */
for (i = 0; i < me_slist_get_number_subdevices(slist);
i++) {
subdevice = me_slist_get_subdevice(slist, i);
if (subdevice)
err =
subdevice->
me_subdevice_lock_subdevice
(subdevice, filep, ME_LOCK_RELEASE,
flags);
else
err = ME_ERRNO_INTERNAL;
}
}
break;
case ME_LOCK_SET:
if (dlock->count) {
PERROR("Device is used by another process.\n");
err = ME_ERRNO_USED;
} else if ((dlock->filep != NULL) && (dlock->filep != filep)) {
PERROR("Device is locked by another process.\n");
err = ME_ERRNO_LOCKED;
} else if (dlock->filep == NULL) {
/* Check any subdevice is locked by another process. */
for (i = 0; i < me_slist_get_number_subdevices(slist);
i++) {
subdevice = me_slist_get_subdevice(slist, i);
if (subdevice) {
if ((err =
subdevice->
me_subdevice_lock_subdevice
(subdevice, filep, ME_LOCK_CHECK,
flags))) {
PERROR
("A subdevice is locked by another process.\n");
break;
}
} else {
err = ME_ERRNO_INTERNAL;
}
}
/* If no subdevices are locked by other processes,
we can take ownership of the device. Otherwise we jump ahead. */
if (!err)
dlock->filep = filep;
}
break;
case ME_LOCK_CHECK:
if (dlock->count) {
err = ME_ERRNO_USED;
} else if ((dlock->filep != NULL) && (dlock->filep != filep)) {
err = ME_ERRNO_LOCKED;
} else if (dlock->filep == NULL) {
for (i = 0; i < me_slist_get_number_subdevices(slist);
i++) {
subdevice = me_slist_get_subdevice(slist, i);
if (subdevice) {
if ((err =
subdevice->
me_subdevice_lock_subdevice
(subdevice, filep, ME_LOCK_CHECK,
flags))) {
PERROR
("A subdevice is locked by another process.\n");
break;
}
} else {
err = ME_ERRNO_INTERNAL;
}
}
}
break;
default:
PERROR("Invalid lock.\n");
err = ME_ERRNO_INVALID_LOCK;
break;
}
spin_unlock(&dlock->spin_lock);
return err;
}
void me_dlock_deinit(struct me_dlock *dlock)
{
PDEBUG_LOCKS("executed.\n");
}
int me_dlock_init(me_dlock_t * dlock)
{
PDEBUG_LOCKS("executed.\n");
dlock->filep = NULL;
dlock->count = 0;
spin_lock_init(&dlock->spin_lock);
return 0;
}
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