![Nikolaus Schulz](/assets/img/avatar_default.png)
Since most dvb ioctls wrap their real work with dvb_usercopy, the static mutex used in dvb_usercopy effectively is a global lock for dvb ioctls. Unfortunately, frontend ioctls can be blocked by the frontend thread for several seconds; this leads to unacceptable lock contention. Mitigate that by pushing the mutex from dvb_usercopy down to the individual, device specific ioctls. There are 10 such ioctl functions using dvb_usercopy, either calling it directly, or via the trivial wrapper dvb_generic_ioctl. The following already employ their own locking and look safe: • dvb_demux_ioctl (as per dvb_demux_do_ioctl) • dvb_dvr_ioctl (as per dvb_dvr_do_ioctl) • dvb_osd_ioctl (as per single non-trivial callee) • fdtv_ca_ioctl (as per callees) • dvb_frontend_ioctl The following functions do not, and are thus changed to use a device specific mutex: • dvb_net_ioctl (as per dvb_net_do_ioctl) • dvb_ca_en50221_io_ioctl (as per dvb_ca_en50221_io_do_ioctl) • dvb_video_ioctl • dvb_audio_ioctl • dvb_ca_ioctl Signed-off-by: Nikolaus Schulz <schulz@macnetix.de> Signed-off-by: Michael Krufky <mkrufky@linuxtv.org> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
506 lines
12 KiB
C
506 lines
12 KiB
C
/*
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* dvbdev.c
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*
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* Copyright (C) 2000 Ralph Metzler <ralph@convergence.de>
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* & Marcus Metzler <marcus@convergence.de>
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* for convergence integrated media GmbH
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public License
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* as published by the Free Software Foundation; either version 2.1
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* of the License, or (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 Lesser General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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*/
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/device.h>
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#include <linux/fs.h>
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#include <linux/cdev.h>
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#include <linux/mutex.h>
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#include "dvbdev.h"
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static DEFINE_MUTEX(dvbdev_mutex);
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static int dvbdev_debug;
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module_param(dvbdev_debug, int, 0644);
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MODULE_PARM_DESC(dvbdev_debug, "Turn on/off device debugging (default:off).");
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#define dprintk if (dvbdev_debug) printk
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static LIST_HEAD(dvb_adapter_list);
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static DEFINE_MUTEX(dvbdev_register_lock);
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static const char * const dnames[] = {
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"video", "audio", "sec", "frontend", "demux", "dvr", "ca",
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"net", "osd"
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};
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#ifdef CONFIG_DVB_DYNAMIC_MINORS
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#define MAX_DVB_MINORS 256
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#define DVB_MAX_IDS MAX_DVB_MINORS
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#else
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#define DVB_MAX_IDS 4
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#define nums2minor(num,type,id) ((num << 6) | (id << 4) | type)
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#define MAX_DVB_MINORS (DVB_MAX_ADAPTERS*64)
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#endif
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static struct class *dvb_class;
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static struct dvb_device *dvb_minors[MAX_DVB_MINORS];
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static DECLARE_RWSEM(minor_rwsem);
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static int dvb_device_open(struct inode *inode, struct file *file)
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{
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struct dvb_device *dvbdev;
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mutex_lock(&dvbdev_mutex);
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down_read(&minor_rwsem);
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dvbdev = dvb_minors[iminor(inode)];
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if (dvbdev && dvbdev->fops) {
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int err = 0;
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const struct file_operations *old_fops;
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file->private_data = dvbdev;
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old_fops = file->f_op;
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file->f_op = fops_get(dvbdev->fops);
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if (file->f_op == NULL) {
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file->f_op = old_fops;
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goto fail;
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}
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if(file->f_op->open)
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err = file->f_op->open(inode,file);
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if (err) {
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fops_put(file->f_op);
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file->f_op = fops_get(old_fops);
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}
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fops_put(old_fops);
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up_read(&minor_rwsem);
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mutex_unlock(&dvbdev_mutex);
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return err;
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}
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fail:
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up_read(&minor_rwsem);
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mutex_unlock(&dvbdev_mutex);
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return -ENODEV;
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}
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static const struct file_operations dvb_device_fops =
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{
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.owner = THIS_MODULE,
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.open = dvb_device_open,
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.llseek = noop_llseek,
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};
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static struct cdev dvb_device_cdev;
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int dvb_generic_open(struct inode *inode, struct file *file)
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{
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struct dvb_device *dvbdev = file->private_data;
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if (!dvbdev)
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return -ENODEV;
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if (!dvbdev->users)
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return -EBUSY;
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if ((file->f_flags & O_ACCMODE) == O_RDONLY) {
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if (!dvbdev->readers)
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return -EBUSY;
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dvbdev->readers--;
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} else {
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if (!dvbdev->writers)
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return -EBUSY;
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dvbdev->writers--;
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}
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dvbdev->users--;
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return 0;
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}
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EXPORT_SYMBOL(dvb_generic_open);
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int dvb_generic_release(struct inode *inode, struct file *file)
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{
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struct dvb_device *dvbdev = file->private_data;
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if (!dvbdev)
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return -ENODEV;
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if ((file->f_flags & O_ACCMODE) == O_RDONLY) {
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dvbdev->readers++;
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} else {
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dvbdev->writers++;
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}
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dvbdev->users++;
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return 0;
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}
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EXPORT_SYMBOL(dvb_generic_release);
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long dvb_generic_ioctl(struct file *file,
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unsigned int cmd, unsigned long arg)
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{
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struct dvb_device *dvbdev = file->private_data;
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if (!dvbdev)
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return -ENODEV;
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if (!dvbdev->kernel_ioctl)
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return -EINVAL;
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return dvb_usercopy(file, cmd, arg, dvbdev->kernel_ioctl);
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}
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EXPORT_SYMBOL(dvb_generic_ioctl);
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static int dvbdev_get_free_id (struct dvb_adapter *adap, int type)
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{
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u32 id = 0;
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while (id < DVB_MAX_IDS) {
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struct dvb_device *dev;
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list_for_each_entry(dev, &adap->device_list, list_head)
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if (dev->type == type && dev->id == id)
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goto skip;
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return id;
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skip:
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id++;
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}
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return -ENFILE;
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}
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int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev,
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const struct dvb_device *template, void *priv, int type)
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{
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struct dvb_device *dvbdev;
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struct file_operations *dvbdevfops;
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struct device *clsdev;
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int minor;
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int id;
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mutex_lock(&dvbdev_register_lock);
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if ((id = dvbdev_get_free_id (adap, type)) < 0){
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mutex_unlock(&dvbdev_register_lock);
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*pdvbdev = NULL;
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printk(KERN_ERR "%s: couldn't find free device id\n", __func__);
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return -ENFILE;
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}
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*pdvbdev = dvbdev = kmalloc(sizeof(struct dvb_device), GFP_KERNEL);
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if (!dvbdev){
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mutex_unlock(&dvbdev_register_lock);
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return -ENOMEM;
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}
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dvbdevfops = kzalloc(sizeof(struct file_operations), GFP_KERNEL);
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if (!dvbdevfops){
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kfree (dvbdev);
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mutex_unlock(&dvbdev_register_lock);
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return -ENOMEM;
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}
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memcpy(dvbdev, template, sizeof(struct dvb_device));
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dvbdev->type = type;
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dvbdev->id = id;
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dvbdev->adapter = adap;
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dvbdev->priv = priv;
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dvbdev->fops = dvbdevfops;
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init_waitqueue_head (&dvbdev->wait_queue);
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memcpy(dvbdevfops, template->fops, sizeof(struct file_operations));
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dvbdevfops->owner = adap->module;
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list_add_tail (&dvbdev->list_head, &adap->device_list);
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down_write(&minor_rwsem);
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#ifdef CONFIG_DVB_DYNAMIC_MINORS
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for (minor = 0; minor < MAX_DVB_MINORS; minor++)
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if (dvb_minors[minor] == NULL)
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break;
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if (minor == MAX_DVB_MINORS) {
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kfree(dvbdevfops);
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kfree(dvbdev);
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up_write(&minor_rwsem);
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mutex_unlock(&dvbdev_register_lock);
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return -EINVAL;
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}
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#else
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minor = nums2minor(adap->num, type, id);
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#endif
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dvbdev->minor = minor;
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dvb_minors[minor] = dvbdev;
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up_write(&minor_rwsem);
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mutex_unlock(&dvbdev_register_lock);
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clsdev = device_create(dvb_class, adap->device,
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MKDEV(DVB_MAJOR, minor),
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dvbdev, "dvb%d.%s%d", adap->num, dnames[type], id);
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if (IS_ERR(clsdev)) {
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printk(KERN_ERR "%s: failed to create device dvb%d.%s%d (%ld)\n",
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__func__, adap->num, dnames[type], id, PTR_ERR(clsdev));
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return PTR_ERR(clsdev);
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}
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dprintk(KERN_DEBUG "DVB: register adapter%d/%s%d @ minor: %i (0x%02x)\n",
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adap->num, dnames[type], id, minor, minor);
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return 0;
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}
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EXPORT_SYMBOL(dvb_register_device);
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void dvb_unregister_device(struct dvb_device *dvbdev)
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{
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if (!dvbdev)
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return;
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down_write(&minor_rwsem);
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dvb_minors[dvbdev->minor] = NULL;
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up_write(&minor_rwsem);
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device_destroy(dvb_class, MKDEV(DVB_MAJOR, dvbdev->minor));
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list_del (&dvbdev->list_head);
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kfree (dvbdev->fops);
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kfree (dvbdev);
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}
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EXPORT_SYMBOL(dvb_unregister_device);
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static int dvbdev_check_free_adapter_num(int num)
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{
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struct list_head *entry;
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list_for_each(entry, &dvb_adapter_list) {
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struct dvb_adapter *adap;
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adap = list_entry(entry, struct dvb_adapter, list_head);
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if (adap->num == num)
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return 0;
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}
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return 1;
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}
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static int dvbdev_get_free_adapter_num (void)
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{
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int num = 0;
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while (num < DVB_MAX_ADAPTERS) {
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if (dvbdev_check_free_adapter_num(num))
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return num;
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num++;
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}
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return -ENFILE;
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}
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int dvb_register_adapter(struct dvb_adapter *adap, const char *name,
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struct module *module, struct device *device,
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short *adapter_nums)
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{
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int i, num;
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mutex_lock(&dvbdev_register_lock);
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for (i = 0; i < DVB_MAX_ADAPTERS; ++i) {
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num = adapter_nums[i];
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if (num >= 0 && num < DVB_MAX_ADAPTERS) {
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/* use the one the driver asked for */
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if (dvbdev_check_free_adapter_num(num))
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break;
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} else {
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num = dvbdev_get_free_adapter_num();
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break;
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}
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num = -1;
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}
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if (num < 0) {
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mutex_unlock(&dvbdev_register_lock);
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return -ENFILE;
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}
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memset (adap, 0, sizeof(struct dvb_adapter));
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INIT_LIST_HEAD (&adap->device_list);
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printk(KERN_INFO "DVB: registering new adapter (%s)\n", name);
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adap->num = num;
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adap->name = name;
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adap->module = module;
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adap->device = device;
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adap->mfe_shared = 0;
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adap->mfe_dvbdev = NULL;
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mutex_init (&adap->mfe_lock);
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list_add_tail (&adap->list_head, &dvb_adapter_list);
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mutex_unlock(&dvbdev_register_lock);
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return num;
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}
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EXPORT_SYMBOL(dvb_register_adapter);
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int dvb_unregister_adapter(struct dvb_adapter *adap)
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{
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mutex_lock(&dvbdev_register_lock);
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list_del (&adap->list_head);
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mutex_unlock(&dvbdev_register_lock);
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return 0;
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}
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EXPORT_SYMBOL(dvb_unregister_adapter);
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/* if the miracle happens and "generic_usercopy()" is included into
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the kernel, then this can vanish. please don't make the mistake and
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define this as video_usercopy(). this will introduce a dependecy
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to the v4l "videodev.o" module, which is unnecessary for some
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cards (ie. the budget dvb-cards don't need the v4l module...) */
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int dvb_usercopy(struct file *file,
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unsigned int cmd, unsigned long arg,
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int (*func)(struct file *file,
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unsigned int cmd, void *arg))
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{
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char sbuf[128];
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void *mbuf = NULL;
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void *parg = NULL;
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int err = -EINVAL;
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/* Copy arguments into temp kernel buffer */
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switch (_IOC_DIR(cmd)) {
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case _IOC_NONE:
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/*
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* For this command, the pointer is actually an integer
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* argument.
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*/
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parg = (void *) arg;
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break;
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case _IOC_READ: /* some v4l ioctls are marked wrong ... */
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case _IOC_WRITE:
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case (_IOC_WRITE | _IOC_READ):
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if (_IOC_SIZE(cmd) <= sizeof(sbuf)) {
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parg = sbuf;
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} else {
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/* too big to allocate from stack */
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mbuf = kmalloc(_IOC_SIZE(cmd),GFP_KERNEL);
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if (NULL == mbuf)
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return -ENOMEM;
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parg = mbuf;
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}
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err = -EFAULT;
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if (copy_from_user(parg, (void __user *)arg, _IOC_SIZE(cmd)))
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goto out;
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break;
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}
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/* call driver */
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if ((err = func(file, cmd, parg)) == -ENOIOCTLCMD)
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err = -ENOTTY;
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if (err < 0)
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goto out;
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/* Copy results into user buffer */
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switch (_IOC_DIR(cmd))
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{
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case _IOC_READ:
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case (_IOC_WRITE | _IOC_READ):
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if (copy_to_user((void __user *)arg, parg, _IOC_SIZE(cmd)))
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err = -EFAULT;
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break;
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}
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out:
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kfree(mbuf);
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return err;
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}
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static int dvb_uevent(struct device *dev, struct kobj_uevent_env *env)
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{
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struct dvb_device *dvbdev = dev_get_drvdata(dev);
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add_uevent_var(env, "DVB_ADAPTER_NUM=%d", dvbdev->adapter->num);
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add_uevent_var(env, "DVB_DEVICE_TYPE=%s", dnames[dvbdev->type]);
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add_uevent_var(env, "DVB_DEVICE_NUM=%d", dvbdev->id);
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return 0;
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}
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static char *dvb_devnode(struct device *dev, umode_t *mode)
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{
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struct dvb_device *dvbdev = dev_get_drvdata(dev);
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return kasprintf(GFP_KERNEL, "dvb/adapter%d/%s%d",
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dvbdev->adapter->num, dnames[dvbdev->type], dvbdev->id);
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}
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static int __init init_dvbdev(void)
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{
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int retval;
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dev_t dev = MKDEV(DVB_MAJOR, 0);
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if ((retval = register_chrdev_region(dev, MAX_DVB_MINORS, "DVB")) != 0) {
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printk(KERN_ERR "dvb-core: unable to get major %d\n", DVB_MAJOR);
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return retval;
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}
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cdev_init(&dvb_device_cdev, &dvb_device_fops);
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if ((retval = cdev_add(&dvb_device_cdev, dev, MAX_DVB_MINORS)) != 0) {
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printk(KERN_ERR "dvb-core: unable register character device\n");
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goto error;
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}
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dvb_class = class_create(THIS_MODULE, "dvb");
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if (IS_ERR(dvb_class)) {
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retval = PTR_ERR(dvb_class);
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goto error;
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}
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dvb_class->dev_uevent = dvb_uevent;
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dvb_class->devnode = dvb_devnode;
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return 0;
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error:
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cdev_del(&dvb_device_cdev);
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unregister_chrdev_region(dev, MAX_DVB_MINORS);
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return retval;
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}
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static void __exit exit_dvbdev(void)
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{
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class_destroy(dvb_class);
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cdev_del(&dvb_device_cdev);
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unregister_chrdev_region(MKDEV(DVB_MAJOR, 0), MAX_DVB_MINORS);
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}
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subsys_initcall(init_dvbdev);
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module_exit(exit_dvbdev);
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MODULE_DESCRIPTION("DVB Core Driver");
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MODULE_AUTHOR("Marcus Metzler, Ralph Metzler, Holger Waechtler");
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MODULE_LICENSE("GPL");
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