V4L/DVB (8852): v4l2: use register_chrdev_region instead of register_chrdev
Replace the old register_chrdev with the more flexible register_chrdev_region. Ensure that the release() is called when the very last chardev usage was released, and not when the sysfs devices were removed. This should simplify hotpluggable drivers considerably. Tested-by: Mike Isely <isely@isely.net> Tested-by: Laurent Pinchart <laurent.pinchart@skynet.be> Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl> Acked-by: David Ellingsworth <david@identd.dyndns.org> Reviewed-by: Hans de Goede <j.w.r.degoede@hhs.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>hifive-unleashed-5.1
Hans Verkuil
Mauro Carvalho Chehab
parent
187565c43a
commit
7f8ecfab7a
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@ -60,6 +60,12 @@ static struct device_attribute video_device_attrs[] = {
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__ATTR_NULL
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};
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/*
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* Active devices
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*/
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static struct video_device *video_device[VIDEO_NUM_DEVICES];
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static DEFINE_MUTEX(videodev_lock);
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struct video_device *video_device_alloc(void)
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{
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return kzalloc(sizeof(struct video_device), GFP_KERNEL);
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@ -79,11 +85,41 @@ void video_device_release_empty(struct video_device *vfd)
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}
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EXPORT_SYMBOL(video_device_release_empty);
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/* Called when the last user of the character device is gone. */
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static void v4l2_chardev_release(struct kobject *kobj)
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{
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struct video_device *vfd = container_of(kobj, struct video_device, cdev.kobj);
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mutex_lock(&videodev_lock);
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if (video_device[vfd->minor] != vfd)
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panic("videodev: bad release");
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/* Free up this device for reuse */
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video_device[vfd->minor] = NULL;
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mutex_unlock(&videodev_lock);
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/* Release the character device */
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vfd->cdev_release(kobj);
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/* Release video_device and perform other
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cleanups as needed. */
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if (vfd->release)
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vfd->release(vfd);
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}
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/* The new kobj_type for the character device */
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static struct kobj_type v4l2_ktype_cdev_default = {
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.release = v4l2_chardev_release,
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};
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static void video_release(struct device *cd)
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{
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struct video_device *vfd = container_of(cd, struct video_device, dev);
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vfd->release(vfd);
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/* It's now safe to delete the char device.
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This will either trigger the v4l2_chardev_release immediately (if
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the refcount goes to 0) or later when the last user of the
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character device closes it. */
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cdev_del(&vfd->cdev);
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}
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static struct class video_class = {
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@ -92,56 +128,12 @@ static struct class video_class = {
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.dev_release = video_release,
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};
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/*
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* Active devices
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*/
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static struct video_device *video_device[VIDEO_NUM_DEVICES];
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static DEFINE_MUTEX(videodev_lock);
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struct video_device *video_devdata(struct file *file)
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{
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return video_device[iminor(file->f_path.dentry->d_inode)];
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}
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EXPORT_SYMBOL(video_devdata);
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/*
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* Open a video device - FIXME: Obsoleted
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*/
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static int video_open(struct inode *inode, struct file *file)
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{
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unsigned int minor = iminor(inode);
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int err = 0;
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struct video_device *vfl;
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const struct file_operations *old_fops;
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if (minor >= VIDEO_NUM_DEVICES)
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return -ENODEV;
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mutex_lock(&videodev_lock);
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vfl = video_device[minor];
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if (vfl == NULL) {
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mutex_unlock(&videodev_lock);
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request_module("char-major-%d-%d", VIDEO_MAJOR, minor);
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mutex_lock(&videodev_lock);
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vfl = video_device[minor];
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if (vfl == NULL) {
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mutex_unlock(&videodev_lock);
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return -ENODEV;
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}
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}
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old_fops = file->f_op;
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file->f_op = fops_get(vfl->fops);
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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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mutex_unlock(&videodev_lock);
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return err;
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}
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/**
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* get_index - assign stream number based on parent device
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* @vdev: video_device to assign index number to, vdev->dev should be assigned
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@ -261,6 +253,9 @@ int video_register_device_index(struct video_device *vfd, int type, int nr,
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return -EINVAL;
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}
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/* Initialize the character device */
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cdev_init(&vfd->cdev, vfd->fops);
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vfd->cdev.owner = vfd->fops->owner;
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/* pick a minor number */
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mutex_lock(&videodev_lock);
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if (nr >= 0 && nr < end-base) {
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@ -294,6 +289,11 @@ int video_register_device_index(struct video_device *vfd, int type, int nr,
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goto fail_minor;
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}
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ret = cdev_add(&vfd->cdev, MKDEV(VIDEO_MAJOR, vfd->minor), 1);
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if (ret < 0) {
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printk(KERN_ERR "%s: cdev_add failed\n", __func__);
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goto fail_minor;
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}
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/* sysfs class */
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memset(&vfd->dev, 0, sizeof(vfd->dev));
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/* The memset above cleared the device's drvdata, so
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@ -307,11 +307,17 @@ int video_register_device_index(struct video_device *vfd, int type, int nr,
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ret = device_register(&vfd->dev);
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if (ret < 0) {
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printk(KERN_ERR "%s: device_register failed\n", __func__);
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goto fail_minor;
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goto del_cdev;
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}
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/* Remember the cdev's release function */
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vfd->cdev_release = vfd->cdev.kobj.ktype->release;
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/* Install our own */
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vfd->cdev.kobj.ktype = &v4l2_ktype_cdev_default;
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return 0;
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del_cdev:
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cdev_del(&vfd->cdev);
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fail_minor:
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mutex_lock(&videodev_lock);
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video_device[vfd->minor] = NULL;
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@ -331,42 +337,29 @@ EXPORT_SYMBOL(video_register_device_index);
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void video_unregister_device(struct video_device *vfd)
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{
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mutex_lock(&videodev_lock);
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if (video_device[vfd->minor] != vfd)
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panic("videodev: bad unregister");
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video_device[vfd->minor] = NULL;
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device_unregister(&vfd->dev);
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mutex_unlock(&videodev_lock);
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}
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EXPORT_SYMBOL(video_unregister_device);
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/*
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* Video fs operations
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*/
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static const struct file_operations video_fops = {
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.owner = THIS_MODULE,
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.llseek = no_llseek,
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.open = video_open,
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};
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/*
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* Initialise video for linux
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*/
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static int __init videodev_init(void)
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{
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dev_t dev = MKDEV(VIDEO_MAJOR, 0);
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int ret;
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printk(KERN_INFO "Linux video capture interface: v2.00\n");
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if (register_chrdev(VIDEO_MAJOR, VIDEO_NAME, &video_fops)) {
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printk(KERN_WARNING "video_dev: unable to get major %d\n", VIDEO_MAJOR);
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return -EIO;
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ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
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if (ret < 0) {
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printk(KERN_WARNING "videodev: unable to get major %d\n",
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VIDEO_MAJOR);
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return ret;
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}
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ret = class_register(&video_class);
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if (ret < 0) {
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unregister_chrdev(VIDEO_MAJOR, VIDEO_NAME);
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unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
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printk(KERN_WARNING "video_dev: class_register failed\n");
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return -EIO;
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}
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@ -376,8 +369,10 @@ static int __init videodev_init(void)
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static void __exit videodev_exit(void)
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{
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dev_t dev = MKDEV(VIDEO_MAJOR, 0);
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class_unregister(&video_class);
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unregister_chrdev(VIDEO_MAJOR, VIDEO_NAME);
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unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
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}
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module_init(videodev_init)
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@ -12,6 +12,7 @@
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#include <linux/poll.h>
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#include <linux/fs.h>
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#include <linux/device.h>
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#include <linux/cdev.h>
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#include <linux/mutex.h>
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#include <linux/videodev2.h>
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@ -47,6 +48,8 @@ struct video_device
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/* sysfs */
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struct device dev; /* v4l device */
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struct cdev cdev; /* character device */
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void (*cdev_release)(struct kobject *kobj);
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struct device *parent; /* device parent */
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/* device info */
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