451084d2e0
Cc: David Kiliani <mail@davidkiliani.de> Signed-off-by: Alexander Beregalov <a.beregalov@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
137 lines
2.9 KiB
C
137 lines
2.9 KiB
C
/**
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* @file meslock.c
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*
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* @brief Implements the subdevice lock class.
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* @note Copyright (C) 2006 Meilhaus Electronic GmbH (support@meilhaus.de)
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* @author Guenter Gebhardt
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*/
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/*
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* Copyright (C) 2006 Meilhaus Electronic GmbH (support@meilhaus.de)
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*
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* This file is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/spinlock.h>
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#include "medefines.h"
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#include "meerror.h"
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#include "medebug.h"
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#include "meslock.h"
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int me_slock_enter(struct me_slock *slock, struct file *filep)
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{
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PDEBUG_LOCKS("executed.\n");
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spin_lock(&slock->spin_lock);
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if ((slock->filep) != NULL && (slock->filep != filep)) {
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PERROR("Subdevice is locked by another process.\n");
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spin_unlock(&slock->spin_lock);
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return ME_ERRNO_LOCKED;
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}
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slock->count++;
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spin_unlock(&slock->spin_lock);
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return ME_ERRNO_SUCCESS;
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}
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int me_slock_exit(struct me_slock *slock, struct file *filep)
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{
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PDEBUG_LOCKS("executed.\n");
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spin_lock(&slock->spin_lock);
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slock->count--;
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spin_unlock(&slock->spin_lock);
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return ME_ERRNO_SUCCESS;
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}
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int me_slock_lock(struct me_slock *slock, struct file *filep, int lock)
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{
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PDEBUG_LOCKS("executed.\n");
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switch (lock) {
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case ME_LOCK_RELEASE:
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spin_lock(&slock->spin_lock);
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if (slock->filep == filep)
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slock->filep = NULL;
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spin_unlock(&slock->spin_lock);
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break;
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case ME_LOCK_SET:
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spin_lock(&slock->spin_lock);
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if (slock->count) {
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spin_unlock(&slock->spin_lock);
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PERROR("Subdevice is used by another process.\n");
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return ME_ERRNO_USED;
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} else if (slock->filep == NULL)
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slock->filep = filep;
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else if (slock->filep != filep) {
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spin_unlock(&slock->spin_lock);
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PERROR("Subdevice is locked by another process.\n");
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return ME_ERRNO_LOCKED;
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}
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spin_unlock(&slock->spin_lock);
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break;
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case ME_LOCK_CHECK:
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spin_lock(&slock->spin_lock);
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if (slock->count) {
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spin_unlock(&slock->spin_lock);
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return ME_ERRNO_USED;
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} else if ((slock->filep != NULL) && (slock->filep != filep)) {
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spin_unlock(&slock->spin_lock);
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return ME_ERRNO_LOCKED;
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}
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spin_unlock(&slock->spin_lock);
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break;
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default:
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break;
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}
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return ME_ERRNO_SUCCESS;
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}
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void me_slock_deinit(struct me_slock *slock)
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{
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PDEBUG_LOCKS("executed.\n");
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}
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int me_slock_init(me_slock_t *slock)
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{
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PDEBUG_LOCKS("executed.\n");
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slock->filep = NULL;
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slock->count = 0;
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spin_lock_init(&slock->spin_lock);
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return 0;
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}
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