From 7f8ecfab7a1d256707502207c56dd4bf3e3a026e Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Fri, 29 Aug 2008 17:31:35 -0300 Subject: [PATCH] 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 Tested-by: Laurent Pinchart Signed-off-by: Hans Verkuil Acked-by: David Ellingsworth Reviewed-by: Hans de Goede Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/v4l2-dev.c | 131 ++++++++++++++++----------------- include/media/v4l2-dev.h | 3 + 2 files changed, 66 insertions(+), 68 deletions(-) diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c index 99f7ee4bc50..02b9cc76d36 100644 --- a/drivers/media/video/v4l2-dev.c +++ b/drivers/media/video/v4l2-dev.c @@ -60,6 +60,12 @@ static struct device_attribute video_device_attrs[] = { __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 @@ void video_device_release_empty(struct video_device *vfd) } 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 @@ static struct class video_class = { .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 @@ int video_register_device_index(struct video_device *vfd, int type, int nr, 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 @@ int video_register_device_index(struct video_device *vfd, int type, int nr, 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 @@ int video_register_device_index(struct video_device *vfd, int type, int nr, 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 @@ EXPORT_SYMBOL(video_register_device_index); 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 int __init videodev_init(void) 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) diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h index fb92e3d22d7..d129b56e1a9 100644 --- a/include/media/v4l2-dev.h +++ b/include/media/v4l2-dev.h @@ -12,6 +12,7 @@ #include #include #include +#include #include #include @@ -47,6 +48,8 @@ struct video_device /* sysfs */ struct device dev; /* v4l device */ + struct cdev cdev; /* character device */ + void (*cdev_release)(struct kobject *kobj); struct device *parent; /* device parent */ /* device info */ -- 2.41.1