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>
diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
index 99f7ee4..02b9cc7 100644
--- a/drivers/media/video/v4l2-dev.c
+++ b/drivers/media/video/v4l2-dev.c
@@ -60,6 +60,12 @@
__ATTR_NULL
};
+/*
+ * Active devices
+ */
+static struct video_device *video_device[VIDEO_NUM_DEVICES];
+static DEFINE_MUTEX(videodev_lock);
+
struct video_device *video_device_alloc(void)
{
return kzalloc(sizeof(struct video_device), GFP_KERNEL);
@@ -79,11 +85,41 @@
}
EXPORT_SYMBOL(video_device_release_empty);
+/* Called when the last user of the character device is gone. */
+static void v4l2_chardev_release(struct kobject *kobj)
+{
+ struct video_device *vfd = container_of(kobj, struct video_device, cdev.kobj);
+
+ mutex_lock(&videodev_lock);
+ if (video_device[vfd->minor] != vfd)
+ panic("videodev: bad release");
+
+ /* Free up this device for reuse */
+ video_device[vfd->minor] = NULL;
+ mutex_unlock(&videodev_lock);
+
+ /* Release the character device */
+ vfd->cdev_release(kobj);
+ /* Release video_device and perform other
+ cleanups as needed. */
+ if (vfd->release)
+ vfd->release(vfd);
+}
+
+/* The new kobj_type for the character device */
+static struct kobj_type v4l2_ktype_cdev_default = {
+ .release = v4l2_chardev_release,
+};
+
static void video_release(struct device *cd)
{
struct video_device *vfd = container_of(cd, struct video_device, dev);
- vfd->release(vfd);
+ /* It's now safe to delete the char device.
+ This will either trigger the v4l2_chardev_release immediately (if
+ the refcount goes to 0) or later when the last user of the
+ character device closes it. */
+ cdev_del(&vfd->cdev);
}
static struct class video_class = {
@@ -92,56 +128,12 @@
.dev_release = video_release,
};
-/*
- * Active devices
- */
-
-static struct video_device *video_device[VIDEO_NUM_DEVICES];
-static DEFINE_MUTEX(videodev_lock);
-
struct video_device *video_devdata(struct file *file)
{
return video_device[iminor(file->f_path.dentry->d_inode)];
}
EXPORT_SYMBOL(video_devdata);
-/*
- * Open a video device - FIXME: Obsoleted
- */
-static int video_open(struct inode *inode, struct file *file)
-{
- unsigned int minor = iminor(inode);
- int err = 0;
- struct video_device *vfl;
- const struct file_operations *old_fops;
-
- if (minor >= VIDEO_NUM_DEVICES)
- return -ENODEV;
- mutex_lock(&videodev_lock);
- vfl = video_device[minor];
- if (vfl == NULL) {
- mutex_unlock(&videodev_lock);
- request_module("char-major-%d-%d", VIDEO_MAJOR, minor);
- mutex_lock(&videodev_lock);
- vfl = video_device[minor];
- if (vfl == NULL) {
- mutex_unlock(&videodev_lock);
- return -ENODEV;
- }
- }
- old_fops = file->f_op;
- file->f_op = fops_get(vfl->fops);
- if (file->f_op->open)
- err = file->f_op->open(inode, file);
- if (err) {
- fops_put(file->f_op);
- file->f_op = fops_get(old_fops);
- }
- fops_put(old_fops);
- mutex_unlock(&videodev_lock);
- return err;
-}
-
/**
* get_index - assign stream number based on parent device
* @vdev: video_device to assign index number to, vdev->dev should be assigned
@@ -261,6 +253,9 @@
return -EINVAL;
}
+ /* Initialize the character device */
+ cdev_init(&vfd->cdev, vfd->fops);
+ vfd->cdev.owner = vfd->fops->owner;
/* pick a minor number */
mutex_lock(&videodev_lock);
if (nr >= 0 && nr < end-base) {
@@ -294,6 +289,11 @@
goto fail_minor;
}
+ ret = cdev_add(&vfd->cdev, MKDEV(VIDEO_MAJOR, vfd->minor), 1);
+ if (ret < 0) {
+ printk(KERN_ERR "%s: cdev_add failed\n", __func__);
+ goto fail_minor;
+ }
/* sysfs class */
memset(&vfd->dev, 0, sizeof(vfd->dev));
/* The memset above cleared the device's drvdata, so
@@ -307,11 +307,17 @@
ret = device_register(&vfd->dev);
if (ret < 0) {
printk(KERN_ERR "%s: device_register failed\n", __func__);
- goto fail_minor;
+ goto del_cdev;
}
-
+ /* Remember the cdev's release function */
+ vfd->cdev_release = vfd->cdev.kobj.ktype->release;
+ /* Install our own */
+ vfd->cdev.kobj.ktype = &v4l2_ktype_cdev_default;
return 0;
+del_cdev:
+ cdev_del(&vfd->cdev);
+
fail_minor:
mutex_lock(&videodev_lock);
video_device[vfd->minor] = NULL;
@@ -331,42 +337,29 @@
void video_unregister_device(struct video_device *vfd)
{
- mutex_lock(&videodev_lock);
- if (video_device[vfd->minor] != vfd)
- panic("videodev: bad unregister");
-
- video_device[vfd->minor] = NULL;
device_unregister(&vfd->dev);
- mutex_unlock(&videodev_lock);
}
EXPORT_SYMBOL(video_unregister_device);
/*
- * Video fs operations
- */
-static const struct file_operations video_fops = {
- .owner = THIS_MODULE,
- .llseek = no_llseek,
- .open = video_open,
-};
-
-/*
* Initialise video for linux
*/
-
static int __init videodev_init(void)
{
+ dev_t dev = MKDEV(VIDEO_MAJOR, 0);
int ret;
printk(KERN_INFO "Linux video capture interface: v2.00\n");
- if (register_chrdev(VIDEO_MAJOR, VIDEO_NAME, &video_fops)) {
- printk(KERN_WARNING "video_dev: unable to get major %d\n", VIDEO_MAJOR);
- return -EIO;
+ ret = register_chrdev_region(dev, VIDEO_NUM_DEVICES, VIDEO_NAME);
+ if (ret < 0) {
+ printk(KERN_WARNING "videodev: unable to get major %d\n",
+ VIDEO_MAJOR);
+ return ret;
}
ret = class_register(&video_class);
if (ret < 0) {
- unregister_chrdev(VIDEO_MAJOR, VIDEO_NAME);
+ unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
printk(KERN_WARNING "video_dev: class_register failed\n");
return -EIO;
}
@@ -376,8 +369,10 @@
static void __exit videodev_exit(void)
{
+ dev_t dev = MKDEV(VIDEO_MAJOR, 0);
+
class_unregister(&video_class);
- unregister_chrdev(VIDEO_MAJOR, VIDEO_NAME);
+ unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
}
module_init(videodev_init)