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Subject: Re: [PATCH v4] media: em28xx: Fix race condition between open and
 init function
To:     Igor Matheus Andrade Torrente <igormtorrente@gmail.com>,
        mchehab@kernel.org, skhan@linuxfoundation.org
Cc:     linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        kernel test robot <lkp@intel.com>,
        syzbot+b2391895514ed9ef4a8e@syzkaller.appspotmail.com
References: <20210503173716.21652-1-igormtorrente@gmail.com>
 <20210503173716.21652-2-igormtorrente@gmail.com>
From:   Hans Verkuil <hverkuil-cisco@xs4all.nl>
Message-ID: <f7721e24-e153-7fa7-6c2d-505f91bac112@xs4all.nl>
Date:   Wed, 5 May 2021 13:21:39 +0200
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Hi Igor,

On 03/05/2021 19:37, Igor Matheus Andrade Torrente wrote:
> Fixes a race condition - for lack of a more precise term - between
> em28xx_v4l2_open and em28xx_v4l2_init, by detaching the v4l2_dev,
> media_pad and vdev structs from the em28xx_v4l2, and managing the
> lifetime of those objects more dynamicaly.
> 
> The race happens when a thread[1] - containing the em28xx_v4l2_init()
> code - calls the v4l2_mc_create_media_graph(), and it return a error,
> if a thread[2] - running v4l2_open() - pass the verification point
> and reaches the em28xx_v4l2_open() before the thread[1] finishes
> the deregistration of v4l2 subsystem, the thread[1] will free all
> resources before the em28xx_v4l2_open() can process their things,
> because the em28xx_v4l2_init() has the dev->lock. And all this lead
> the thread[2] to cause a user-after-free.

This isn't the right approach. This driver is quite old and tried to do
life-time management itself (and poorly at that), while today there are
better mechanisms, something that your patch tries to use to some extent.

The cleanup for em28xx-video.c has to take place in the release callback
of struct v4l2_device. All allocated memory can be cleaned up there. The
release callback of the video_device structs can just remains as it is today,
i.e. video_device_release_empty.

Also, the video_unregister_device calls should be replaced by
vb2_video_unregister_device, see include/media/videobuf2-v4l2.h why.

The v4l2->ref can be removed, since struct v4l2_device takes over that role.

And when the release callback of v4l2_device is called, then you can call
kref_get(&dev->ref). That reference count really just needs to be incremented
once in em28xx_v4l2_init and decremented once in the v4l2_device release callback,
and not for every open and close.

I hope I haven't forgotten anything.

Regards,

	Hans


> 
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-and-tested-by: syzbot+b2391895514ed9ef4a8e@syzkaller.appspotmail.com
> Signed-off-by: Igor Matheus Andrade Torrente <igormtorrente@gmail.com>
> ---
> 
> V2: Add v4l2_i2c_new_subdev null check
>     Deal with v4l2 subdevs dependencies
> 
> V3: Fix link error when compiled as a module
> 
> V4: Remove duplicated v4l2_device_disconnect
>     in the em28xx_v4l2_fini
> 
> ---
>  drivers/media/usb/em28xx/em28xx-camera.c |   4 +-
>  drivers/media/usb/em28xx/em28xx-video.c  | 299 +++++++++++++++--------
>  drivers/media/usb/em28xx/em28xx.h        |   6 +-
>  3 files changed, 208 insertions(+), 101 deletions(-)
> 
> diff --git a/drivers/media/usb/em28xx/em28xx-camera.c b/drivers/media/usb/em28xx/em28xx-camera.c
> index d1e66b503f4d..436c5a8cbbb6 100644
> --- a/drivers/media/usb/em28xx/em28xx-camera.c
> +++ b/drivers/media/usb/em28xx/em28xx-camera.c
> @@ -340,7 +340,7 @@ int em28xx_init_camera(struct em28xx *dev)
>  		v4l2->sensor_xtal = 4300000;
>  		pdata.xtal = v4l2->sensor_xtal;
>  		if (NULL ==
> -		    v4l2_i2c_new_subdev_board(&v4l2->v4l2_dev, adap,
> +		    v4l2_i2c_new_subdev_board(v4l2->v4l2_dev, adap,
>  					      &mt9v011_info, NULL))
>  			return -ENODEV;
>  		v4l2->vinmode = EM28XX_VINMODE_RGB8_GRBG;
> @@ -394,7 +394,7 @@ int em28xx_init_camera(struct em28xx *dev)
>  		v4l2->sensor_yres = 480;
>  
>  		subdev =
> -		     v4l2_i2c_new_subdev_board(&v4l2->v4l2_dev, adap,
> +		     v4l2_i2c_new_subdev_board(v4l2->v4l2_dev, adap,
>  					       &ov2640_info, NULL);
>  		if (!subdev)
>  			return -ENODEV;
> diff --git a/drivers/media/usb/em28xx/em28xx-video.c b/drivers/media/usb/em28xx/em28xx-video.c
> index 6b84c3413e83..6bc6baf88644 100644
> --- a/drivers/media/usb/em28xx/em28xx-video.c
> +++ b/drivers/media/usb/em28xx/em28xx-video.c
> @@ -184,7 +184,7 @@ static int em28xx_vbi_supported(struct em28xx *dev)
>   */
>  static void em28xx_wake_i2c(struct em28xx *dev)
>  {
> -	struct v4l2_device *v4l2_dev = &dev->v4l2->v4l2_dev;
> +	struct v4l2_device *v4l2_dev = dev->v4l2->v4l2_dev;
>  
>  	v4l2_device_call_all(v4l2_dev, 0, core,  reset, 0);
>  	v4l2_device_call_all(v4l2_dev, 0, video, s_routing,
> @@ -974,9 +974,17 @@ static void em28xx_v4l2_create_entities(struct em28xx *dev)
>  	struct em28xx_v4l2 *v4l2 = dev->v4l2;
>  	int ret, i;
>  
> +	v4l2->video_pad = kzalloc(sizeof(*v4l2->video_pad), GFP_KERNEL);
> +	if (!v4l2->video_pad) {
> +		dev_err(&dev->intf->dev,
> +			"failed to allocate video pad memory!\n");
> +		v4l2->vdev->entity.num_pads = 0;
> +		return;
> +	}
> +
>  	/* Initialize Video, VBI and Radio pads */
> -	v4l2->video_pad.flags = MEDIA_PAD_FL_SINK;
> -	ret = media_entity_pads_init(&v4l2->vdev.entity, 1, &v4l2->video_pad);
> +	v4l2->video_pad->flags = MEDIA_PAD_FL_SINK;
> +	ret = media_entity_pads_init(&v4l2->vdev->entity, 1, v4l2->video_pad);
>  	if (ret < 0)
>  		dev_err(&dev->intf->dev,
>  			"failed to initialize video media entity!\n");
> @@ -1132,11 +1140,11 @@ int em28xx_start_analog_streaming(struct vb2_queue *vq, unsigned int count)
>  			f.type = V4L2_TUNER_RADIO;
>  		else
>  			f.type = V4L2_TUNER_ANALOG_TV;
> -		v4l2_device_call_all(&v4l2->v4l2_dev,
> +		v4l2_device_call_all(v4l2->v4l2_dev,
>  				     0, tuner, s_frequency, &f);
>  
>  		/* Enable video stream at TV decoder */
> -		v4l2_device_call_all(&v4l2->v4l2_dev, 0, video, s_stream, 1);
> +		v4l2_device_call_all(v4l2->v4l2_dev, 0, video, s_stream, 1);
>  	}
>  
>  	v4l2->streaming_users++;
> @@ -1157,7 +1165,7 @@ static void em28xx_stop_streaming(struct vb2_queue *vq)
>  
>  	if (v4l2->streaming_users-- == 1) {
>  		/* Disable video stream at TV decoder */
> -		v4l2_device_call_all(&v4l2->v4l2_dev, 0, video, s_stream, 0);
> +		v4l2_device_call_all(v4l2->v4l2_dev, 0, video, s_stream, 0);
>  
>  		/* Last active user, so shutdown all the URBS */
>  		em28xx_uninit_usb_xfer(dev, EM28XX_ANALOG_MODE);
> @@ -1192,7 +1200,7 @@ void em28xx_stop_vbi_streaming(struct vb2_queue *vq)
>  
>  	if (v4l2->streaming_users-- == 1) {
>  		/* Disable video stream at TV decoder */
> -		v4l2_device_call_all(&v4l2->v4l2_dev, 0, video, s_stream, 0);
> +		v4l2_device_call_all(v4l2->v4l2_dev, 0, video, s_stream, 0);
>  
>  		/* Last active user, so shutdown all the URBS */
>  		em28xx_uninit_usb_xfer(dev, EM28XX_ANALOG_MODE);
> @@ -1286,7 +1294,7 @@ static int em28xx_vb2_setup(struct em28xx *dev)
>  
>  static void video_mux(struct em28xx *dev, int index)
>  {
> -	struct v4l2_device *v4l2_dev = &dev->v4l2->v4l2_dev;
> +	struct v4l2_device *v4l2_dev = dev->v4l2->v4l2_dev;
>  
>  	dev->ctl_input = index;
>  	dev->ctl_ainput = INPUT(index)->amux;
> @@ -1565,7 +1573,7 @@ static int vidioc_querystd(struct file *file, void *priv, v4l2_std_id *norm)
>  {
>  	struct em28xx *dev = video_drvdata(file);
>  
> -	v4l2_device_call_all(&dev->v4l2->v4l2_dev, 0, video, querystd, norm);
> +	v4l2_device_call_all(dev->v4l2->v4l2_dev, 0, video, querystd, norm);
>  
>  	return 0;
>  }
> @@ -1596,7 +1604,7 @@ static int vidioc_s_std(struct file *file, void *priv, v4l2_std_id norm)
>  		      &v4l2->hscale, &v4l2->vscale);
>  
>  	em28xx_resolution_set(dev);
> -	v4l2_device_call_all(&v4l2->v4l2_dev, 0, video, s_std, v4l2->norm);
> +	v4l2_device_call_all(v4l2->v4l2_dev, 0, video, s_std, v4l2->norm);
>  
>  	return 0;
>  }
> @@ -1616,7 +1624,7 @@ static int vidioc_g_parm(struct file *file, void *priv,
>  	p->parm.capture.readbuffers = EM28XX_MIN_BUF;
>  	p->parm.capture.capability = V4L2_CAP_TIMEPERFRAME;
>  	if (dev->is_webcam) {
> -		rc = v4l2_device_call_until_err(&v4l2->v4l2_dev, 0,
> +		rc = v4l2_device_call_until_err(v4l2->v4l2_dev, 0,
>  						video, g_frame_interval, &ival);
>  		if (!rc)
>  			p->parm.capture.timeperframe = ival.interval;
> @@ -1648,7 +1656,7 @@ static int vidioc_s_parm(struct file *file, void *priv,
>  	memset(&p->parm, 0, sizeof(p->parm));
>  	p->parm.capture.readbuffers = EM28XX_MIN_BUF;
>  	p->parm.capture.capability = V4L2_CAP_TIMEPERFRAME;
> -	rc = v4l2_device_call_until_err(&dev->v4l2->v4l2_dev, 0,
> +	rc = v4l2_device_call_until_err(dev->v4l2->v4l2_dev, 0,
>  					video, s_frame_interval, &ival);
>  	if (!rc)
>  		p->parm.capture.timeperframe = ival.interval;
> @@ -1675,7 +1683,7 @@ static int vidioc_enum_input(struct file *file, void *priv,
>  	if (INPUT(n)->type == EM28XX_VMUX_TELEVISION)
>  		i->type = V4L2_INPUT_TYPE_TUNER;
>  
> -	i->std = dev->v4l2->vdev.tvnorms;
> +	i->std = dev->v4l2->vdev->tvnorms;
>  	/* webcams do not have the STD API */
>  	if (dev->is_webcam)
>  		i->capabilities = 0;
> @@ -1839,7 +1847,7 @@ static int vidioc_g_tuner(struct file *file, void *priv,
>  
>  	strscpy(t->name, "Tuner", sizeof(t->name));
>  
> -	v4l2_device_call_all(&dev->v4l2->v4l2_dev, 0, tuner, g_tuner, t);
> +	v4l2_device_call_all(dev->v4l2->v4l2_dev, 0, tuner, g_tuner, t);
>  	return 0;
>  }
>  
> @@ -1851,7 +1859,7 @@ static int vidioc_s_tuner(struct file *file, void *priv,
>  	if (t->index != 0)
>  		return -EINVAL;
>  
> -	v4l2_device_call_all(&dev->v4l2->v4l2_dev, 0, tuner, s_tuner, t);
> +	v4l2_device_call_all(dev->v4l2->v4l2_dev, 0, tuner, s_tuner, t);
>  	return 0;
>  }
>  
> @@ -1878,8 +1886,8 @@ static int vidioc_s_frequency(struct file *file, void *priv,
>  	if (f->tuner != 0)
>  		return -EINVAL;
>  
> -	v4l2_device_call_all(&v4l2->v4l2_dev, 0, tuner, s_frequency, f);
> -	v4l2_device_call_all(&v4l2->v4l2_dev, 0, tuner, g_frequency, &new_freq);
> +	v4l2_device_call_all(v4l2->v4l2_dev, 0, tuner, s_frequency, f);
> +	v4l2_device_call_all(v4l2->v4l2_dev, 0, tuner, g_frequency, &new_freq);
>  	v4l2->frequency = new_freq.frequency;
>  
>  	return 0;
> @@ -1897,7 +1905,7 @@ static int vidioc_g_chip_info(struct file *file, void *priv,
>  		strscpy(chip->name, "ac97", sizeof(chip->name));
>  	else
>  		strscpy(chip->name,
> -			dev->v4l2->v4l2_dev.name, sizeof(chip->name));
> +			dev->v4l2->v4l2_dev->name, sizeof(chip->name));
>  	return 0;
>  }
>  
> @@ -2095,7 +2103,7 @@ static int radio_g_tuner(struct file *file, void *priv,
>  
>  	strscpy(t->name, "Radio", sizeof(t->name));
>  
> -	v4l2_device_call_all(&dev->v4l2->v4l2_dev, 0, tuner, g_tuner, t);
> +	v4l2_device_call_all(dev->v4l2->v4l2_dev, 0, tuner, g_tuner, t);
>  
>  	return 0;
>  }
> @@ -2108,7 +2116,7 @@ static int radio_s_tuner(struct file *file, void *priv,
>  	if (t->index != 0)
>  		return -EINVAL;
>  
> -	v4l2_device_call_all(&dev->v4l2->v4l2_dev, 0, tuner, s_tuner, t);
> +	v4l2_device_call_all(dev->v4l2->v4l2_dev, 0, tuner, s_tuner, t);
>  
>  	return 0;
>  }
> @@ -2160,6 +2168,11 @@ static int em28xx_v4l2_open(struct file *filp)
>  	if (mutex_lock_interruptible(&dev->lock))
>  		return -ERESTARTSYS;
>  
> +	if (!dev->v4l2) {
> +		mutex_unlock(&dev->lock);
> +		return -ENODEV;
> +	}
> +
>  	ret = v4l2_fh_open(filp);
>  	if (ret) {
>  		dev_err(&dev->intf->dev,
> @@ -2184,9 +2197,10 @@ static int em28xx_v4l2_open(struct file *filp)
>  
>  	if (vdev->vfl_type == VFL_TYPE_RADIO) {
>  		em28xx_videodbg("video_open: setting radio device\n");
> -		v4l2_device_call_all(&v4l2->v4l2_dev, 0, tuner, s_radio);
> +		v4l2_device_call_all(v4l2->v4l2_dev, 0, tuner, s_radio);
>  	}
>  
> +	v4l2_device_get(v4l2->v4l2_dev);
>  	kref_get(&dev->ref);
>  	kref_get(&v4l2->ref);
>  	v4l2->users++;
> @@ -2222,7 +2236,7 @@ static int em28xx_v4l2_fini(struct em28xx *dev)
>  
>  	mutex_lock(&dev->lock);
>  
> -	v4l2_device_disconnect(&v4l2->v4l2_dev);
> +	v4l2_device_disconnect(v4l2->v4l2_dev);
>  
>  	em28xx_uninit_usb_xfer(dev, EM28XX_ANALOG_MODE);
>  
> @@ -2238,14 +2252,14 @@ static int em28xx_v4l2_fini(struct em28xx *dev)
>  			 video_device_node_name(&v4l2->vbi_dev));
>  		video_unregister_device(&v4l2->vbi_dev);
>  	}
> -	if (video_is_registered(&v4l2->vdev)) {
> +	if (video_is_registered(v4l2->vdev)) {
>  		dev_info(&dev->intf->dev, "V4L2 device %s deregistered\n",
> -			 video_device_node_name(&v4l2->vdev));
> -		video_unregister_device(&v4l2->vdev);
> +			 video_device_node_name(v4l2->vdev));
> +		video_unregister_device(v4l2->vdev);
>  	}
>  
>  	v4l2_ctrl_handler_free(&v4l2->ctrl_handler);
> -	v4l2_device_unregister(&v4l2->v4l2_dev);
> +	v4l2_device_put(v4l2->v4l2_dev);
>  
>  	kref_put(&v4l2->ref, em28xx_free_v4l2);
>  
> @@ -2305,7 +2319,7 @@ static int em28xx_v4l2_close(struct file *filp)
>  			goto exit;
>  
>  		/* Save some power by putting tuner to sleep */
> -		v4l2_device_call_all(&v4l2->v4l2_dev, 0, tuner, standby);
> +		v4l2_device_call_all(v4l2->v4l2_dev, 0, tuner, standby);
>  
>  		/* do this before setting alternate! */
>  		em28xx_set_mode(dev, EM28XX_SUSPEND);
> @@ -2322,6 +2336,7 @@ static int em28xx_v4l2_close(struct file *filp)
>  	}
>  
>  exit:
> +	v4l2_device_put(v4l2->v4l2_dev);
>  	v4l2->users--;
>  	kref_put(&v4l2->ref, em28xx_free_v4l2);
>  	mutex_unlock(&dev->lock);
> @@ -2330,6 +2345,17 @@ static int em28xx_v4l2_close(struct file *filp)
>  	return 0;
>  }
>  
> +static void em28xx_vdev_release(struct video_device *vdev)
> +{
> +#ifdef CONFIG_MEDIA_CONTROLLER
> +	int i;
> +
> +	for (i = 0; i < vdev->entity.num_pads; i++)
> +		kfree(&vdev->entity.pads[i]);
> +#endif
> +	kfree(vdev);
> +}
> +
>  static const struct v4l2_file_operations em28xx_v4l_fops = {
>  	.owner         = THIS_MODULE,
>  	.open          = em28xx_v4l2_open,
> @@ -2387,7 +2413,7 @@ static const struct v4l2_ioctl_ops video_ioctl_ops = {
>  static const struct video_device em28xx_video_template = {
>  	.fops		= &em28xx_v4l_fops,
>  	.ioctl_ops	= &video_ioctl_ops,
> -	.release	= video_device_release_empty,
> +	.release	= em28xx_vdev_release,
>  	.tvnorms	= V4L2_STD_ALL,
>  };
>  
> @@ -2445,7 +2471,7 @@ static void em28xx_vdev_init(struct em28xx *dev,
>  			     const char *type_name)
>  {
>  	*vfd		= *template;
> -	vfd->v4l2_dev	= &dev->v4l2->v4l2_dev;
> +	vfd->v4l2_dev	= dev->v4l2->v4l2_dev;
>  	vfd->lock	= &dev->lock;
>  	if (dev->is_webcam)
>  		vfd->tvnorms = 0;
> @@ -2459,7 +2485,7 @@ static void em28xx_vdev_init(struct em28xx *dev,
>  static void em28xx_tuner_setup(struct em28xx *dev, unsigned short tuner_addr)
>  {
>  	struct em28xx_v4l2      *v4l2 = dev->v4l2;
> -	struct v4l2_device      *v4l2_dev = &v4l2->v4l2_dev;
> +	struct v4l2_device      *v4l2_dev = v4l2->v4l2_dev;
>  	struct tuner_setup      tun_setup;
>  	struct v4l2_frequency   f;
>  
> @@ -2517,6 +2543,22 @@ static void em28xx_tuner_setup(struct em28xx *dev, unsigned short tuner_addr)
>  	v4l2_device_call_all(v4l2_dev, 0, tuner, s_frequency, &f);
>  }
>  
> +static void em28xx_v4l2_dev_release(struct v4l2_device *v4l2_dev)
> +{
> +	struct v4l2_subdev *sd, *next;
> +	struct i2c_client *client;
> +
> +	list_for_each_entry_safe(sd, next, &v4l2_dev->subdevs, list) {
> +		v4l2_device_unregister_subdev(sd);
> +		client = sd->dev_priv;
> +		if (client && !client->dev.of_node && !client->dev.fwnode &&
> +		    sd->flags & V4L2_SUBDEV_FL_IS_I2C)
> +			i2c_unregister_device(client);
> +	}
> +
> +	kfree(v4l2_dev);
> +}
> +
>  static int em28xx_v4l2_init(struct em28xx *dev)
>  {
>  	u8 val;
> @@ -2524,6 +2566,7 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>  	unsigned int maxw;
>  	struct v4l2_ctrl_handler *hdl;
>  	struct em28xx_v4l2 *v4l2;
> +	struct v4l2_subdev *sd;
>  
>  	if (dev->is_audio_only) {
>  		/* Shouldn't initialize IR for this interface */
> @@ -2541,26 +2584,35 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>  
>  	v4l2 = kzalloc(sizeof(*v4l2), GFP_KERNEL);
>  	if (!v4l2) {
> -		mutex_unlock(&dev->lock);
> -		return -ENOMEM;
> +		ret = -ENOMEM;
> +		goto v4l2_error;
>  	}
> +
>  	kref_init(&v4l2->ref);
>  	v4l2->dev = dev;
>  	dev->v4l2 = v4l2;
>  
> +	v4l2->v4l2_dev = kzalloc(sizeof(*v4l2->v4l2_dev), GFP_KERNEL);
> +	if (!v4l2->v4l2_dev) {
> +		ret = -ENOMEM;
> +		goto v4l2_dev_error;
> +	}
> +
> +	v4l2->v4l2_dev->release = em28xx_v4l2_dev_release;
> +
>  #ifdef CONFIG_MEDIA_CONTROLLER
> -	v4l2->v4l2_dev.mdev = dev->media_dev;
> +	v4l2->v4l2_dev->mdev = dev->media_dev;
>  #endif
> -	ret = v4l2_device_register(&dev->intf->dev, &v4l2->v4l2_dev);
> +	ret = v4l2_device_register(&dev->intf->dev, v4l2->v4l2_dev);
>  	if (ret < 0) {
>  		dev_err(&dev->intf->dev,
>  			"Call to v4l2_device_register() failed!\n");
> -		goto err;
> +		goto v4l2_device_register_error;
>  	}
>  
>  	hdl = &v4l2->ctrl_handler;
>  	v4l2_ctrl_handler_init(hdl, 8);
> -	v4l2->v4l2_dev.ctrl_handler = hdl;
> +	v4l2->v4l2_dev->ctrl_handler = hdl;
>  
>  	if (dev->is_webcam)
>  		v4l2->progressive = true;
> @@ -2574,25 +2626,49 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>  
>  	/* request some modules */
>  
> -	if (dev->has_msp34xx)
> -		v4l2_i2c_new_subdev(&v4l2->v4l2_dev,
> -				    &dev->i2c_adap[dev->def_i2c_bus],
> -				    "msp3400", 0, msp3400_addrs);
> +	if (dev->has_msp34xx) {
> +		sd = v4l2_i2c_new_subdev(v4l2->v4l2_dev,
> +					 &dev->i2c_adap[dev->def_i2c_bus],
> +					 "msp3400", 0, msp3400_addrs);
> +		if (!sd) {
> +			dev_err(&dev->intf->dev,
> +				"Error while registering msp34xx v4l2 subdevice!\n");
> +			goto v4l2_subdev_register_error;
> +		}
> +	}
>  
> -	if (dev->board.decoder == EM28XX_SAA711X)
> -		v4l2_i2c_new_subdev(&v4l2->v4l2_dev,
> -				    &dev->i2c_adap[dev->def_i2c_bus],
> -				    "saa7115_auto", 0, saa711x_addrs);
> +	if (dev->board.decoder == EM28XX_SAA711X) {
> +		sd = v4l2_i2c_new_subdev(v4l2->v4l2_dev,
> +					 &dev->i2c_adap[dev->def_i2c_bus],
> +					 "saa7115_auto", 0, saa711x_addrs);
> +		if (!sd) {
> +			dev_err(&dev->intf->dev,
> +				"Error while registering EM28XX_SAA711X v4l2 subdevice!\n");
> +			goto v4l2_subdev_register_error;
> +		}
> +	}
>  
> -	if (dev->board.decoder == EM28XX_TVP5150)
> -		v4l2_i2c_new_subdev(&v4l2->v4l2_dev,
> -				    &dev->i2c_adap[dev->def_i2c_bus],
> -				    "tvp5150", 0, tvp5150_addrs);
> +	if (dev->board.decoder == EM28XX_TVP5150) {
> +		sd = v4l2_i2c_new_subdev(v4l2->v4l2_dev,
> +					 &dev->i2c_adap[dev->def_i2c_bus],
> +					 "tvp5150", 0, tvp5150_addrs);
> +		if (!sd) {
> +			dev_err(&dev->intf->dev,
> +				"Error while registering EM28XX_TVP5150 v4l2 subdevice!\n");
> +			goto v4l2_subdev_register_error;
> +		}
> +	}
>  
> -	if (dev->board.adecoder == EM28XX_TVAUDIO)
> -		v4l2_i2c_new_subdev(&v4l2->v4l2_dev,
> -				    &dev->i2c_adap[dev->def_i2c_bus],
> -				    "tvaudio", dev->board.tvaudio_addr, NULL);
> +	if (dev->board.adecoder == EM28XX_TVAUDIO) {
> +		sd = v4l2_i2c_new_subdev(v4l2->v4l2_dev,
> +					 &dev->i2c_adap[dev->def_i2c_bus],
> +					 "tvaudio", dev->board.tvaudio_addr, NULL);
> +		if (!sd) {
> +			dev_err(&dev->intf->dev,
> +				"Error while registering EM28XX_TVAUDIO v4l2 subdevice!\n");
> +			goto v4l2_subdev_register_error;
> +		}
> +	}
>  
>  	/* Initialize tuner and camera */
>  
> @@ -2600,33 +2676,55 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>  		unsigned short tuner_addr = dev->board.tuner_addr;
>  		int has_demod = (dev->board.tda9887_conf & TDA9887_PRESENT);
>  
> -		if (dev->board.radio.type)
> -			v4l2_i2c_new_subdev(&v4l2->v4l2_dev,
> -					    &dev->i2c_adap[dev->def_i2c_bus],
> -					    "tuner", dev->board.radio_addr,
> -					    NULL);
> -
> -		if (has_demod)
> -			v4l2_i2c_new_subdev(&v4l2->v4l2_dev,
> -					    &dev->i2c_adap[dev->def_i2c_bus],
> -					    "tuner", 0,
> -					    v4l2_i2c_tuner_addrs(ADDRS_DEMOD));
> +		if (dev->board.radio.type) {
> +			sd = v4l2_i2c_new_subdev(v4l2->v4l2_dev,
> +						 &dev->i2c_adap[dev->def_i2c_bus],
> +						 "tuner", dev->board.radio_addr,
> +						 NULL);
> +			if (!sd) {
> +				dev_err(&dev->intf->dev,
> +					"Error while registering <name1> v4l2 subdevice!\n");
> +				goto v4l2_subdev_register_error;
> +			}
> +		}
> +
> +		if (has_demod) {
> +			sd = v4l2_i2c_new_subdev(v4l2->v4l2_dev,
> +						 &dev->i2c_adap[dev->def_i2c_bus],
> +						 "tuner", 0,
> +						 v4l2_i2c_tuner_addrs(ADDRS_DEMOD));
> +			if (!sd) {
> +				dev_err(&dev->intf->dev,
> +					"Error while registering <name2> v4l2 subdevice!\n");
> +				goto v4l2_subdev_register_error;
> +			}
> +		}
> +
>  		if (tuner_addr == 0) {
>  			enum v4l2_i2c_tuner_type type =
>  				has_demod ? ADDRS_TV_WITH_DEMOD : ADDRS_TV;
> -			struct v4l2_subdev *sd;
>  
> -			sd = v4l2_i2c_new_subdev(&v4l2->v4l2_dev,
> +			sd = v4l2_i2c_new_subdev(v4l2->v4l2_dev,
>  						 &dev->i2c_adap[dev->def_i2c_bus],
>  						 "tuner", 0,
>  						 v4l2_i2c_tuner_addrs(type));
> -
> -			if (sd)
> +			if (sd) {
>  				tuner_addr = v4l2_i2c_subdev_addr(sd);
> +			} else {
> +				dev_err(&dev->intf->dev,
> +					"Error while registering <name3> v4l2 subdevice!\n");
> +				goto v4l2_subdev_register_error;
> +			}
> +
>  		} else {
> -			v4l2_i2c_new_subdev(&v4l2->v4l2_dev,
> -					    &dev->i2c_adap[dev->def_i2c_bus],
> -					    "tuner", tuner_addr, NULL);
> +			sd = v4l2_i2c_new_subdev(v4l2->v4l2_dev,
> +						 &dev->i2c_adap[dev->def_i2c_bus],
> +						 "tuner", tuner_addr, NULL);
> +			if (!sd) {
> +				dev_err(&dev->intf->dev,
> +					"Error while registering <name4> v4l2 subdevice!\n");
> +				goto v4l2_subdev_register_error;
> +			}
>  		}
>  
>  		em28xx_tuner_setup(dev, tuner_addr);
> @@ -2686,7 +2784,7 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>  
>  	/* set default norm */
>  	v4l2->norm = V4L2_STD_PAL;
> -	v4l2_device_call_all(&v4l2->v4l2_dev, 0, video, s_std, v4l2->norm);
> +	v4l2_device_call_all(v4l2->v4l2_dev, 0, video, s_std, v4l2->norm);
>  	v4l2->interlaced_fieldmode = EM28XX_INTERLACED_DEFAULT;
>  
>  	/* Analog specific initialization */
> @@ -2756,40 +2854,45 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>  		goto unregister_dev;
>  
>  	/* allocate and fill video video_device struct */
> -	em28xx_vdev_init(dev, &v4l2->vdev, &em28xx_video_template, "video");
> +	v4l2->vdev = kzalloc(sizeof(*v4l2->vdev), GFP_KERNEL);
> +	if (!v4l2->vdev) {
> +		ret = -ENOMEM;
> +		goto unregister_dev;
> +	}
> +
> +	em28xx_vdev_init(dev, v4l2->vdev, &em28xx_video_template, "video");
>  	mutex_init(&v4l2->vb_queue_lock);
>  	mutex_init(&v4l2->vb_vbi_queue_lock);
> -	v4l2->vdev.queue = &v4l2->vb_vidq;
> -	v4l2->vdev.queue->lock = &v4l2->vb_queue_lock;
> -	v4l2->vdev.device_caps = V4L2_CAP_READWRITE | V4L2_CAP_VIDEO_CAPTURE |
> +	v4l2->vdev->queue = &v4l2->vb_vidq;
> +	v4l2->vdev->queue->lock = &v4l2->vb_queue_lock;
> +	v4l2->vdev->device_caps = V4L2_CAP_READWRITE | V4L2_CAP_VIDEO_CAPTURE |
>  				 V4L2_CAP_STREAMING;
>  	if (dev->int_audio_type != EM28XX_INT_AUDIO_NONE)
> -		v4l2->vdev.device_caps |= V4L2_CAP_AUDIO;
> +		v4l2->vdev->device_caps |= V4L2_CAP_AUDIO;
>  	if (dev->tuner_type != TUNER_ABSENT)
> -		v4l2->vdev.device_caps |= V4L2_CAP_TUNER;
> -
> +		v4l2->vdev->device_caps |= V4L2_CAP_TUNER;
>  
>  	/* disable inapplicable ioctls */
>  	if (dev->is_webcam) {
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_QUERYSTD);
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_G_STD);
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_S_STD);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_QUERYSTD);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_G_STD);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_S_STD);
>  	} else {
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_S_PARM);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_S_PARM);
>  	}
>  	if (dev->tuner_type == TUNER_ABSENT) {
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_G_TUNER);
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_S_TUNER);
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_G_FREQUENCY);
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_S_FREQUENCY);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_G_TUNER);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_S_TUNER);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_G_FREQUENCY);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_S_FREQUENCY);
>  	}
>  	if (dev->int_audio_type == EM28XX_INT_AUDIO_NONE) {
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_G_AUDIO);
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_S_AUDIO);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_G_AUDIO);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_S_AUDIO);
>  	}
>  
>  	/* register v4l2 video video_device */
> -	ret = video_register_device(&v4l2->vdev, VFL_TYPE_VIDEO,
> +	ret = video_register_device(v4l2->vdev, VFL_TYPE_VIDEO,
>  				    video_nr[dev->devno]);
>  	if (ret) {
>  		dev_err(&dev->intf->dev,
> @@ -2863,7 +2966,7 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>  
>  	dev_info(&dev->intf->dev,
>  		 "V4L2 video device registered as %s\n",
> -		 video_device_node_name(&v4l2->vdev));
> +		 video_device_node_name(v4l2->vdev));
>  
>  	if (video_is_registered(&v4l2->vbi_dev))
>  		dev_info(&dev->intf->dev,
> @@ -2871,7 +2974,7 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>  			 video_device_node_name(&v4l2->vbi_dev));
>  
>  	/* Save some power by putting tuner to sleep */
> -	v4l2_device_call_all(&v4l2->v4l2_dev, 0, tuner, standby);
> +	v4l2_device_call_all(v4l2->v4l2_dev, 0, tuner, standby);
>  
>  	/* initialize videobuf2 stuff */
>  	em28xx_vb2_setup(dev);
> @@ -2897,18 +3000,22 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>  			 video_device_node_name(&v4l2->vbi_dev));
>  		video_unregister_device(&v4l2->vbi_dev);
>  	}
> -	if (video_is_registered(&v4l2->vdev)) {
> +	if (video_is_registered(v4l2->vdev)) {
>  		dev_info(&dev->intf->dev,
>  			 "V4L2 device %s deregistered\n",
> -			 video_device_node_name(&v4l2->vdev));
> -		video_unregister_device(&v4l2->vdev);
> +			 video_device_node_name(v4l2->vdev));
> +		video_unregister_device(v4l2->vdev);
>  	}
>  
>  	v4l2_ctrl_handler_free(&v4l2->ctrl_handler);
> -	v4l2_device_unregister(&v4l2->v4l2_dev);
> -err:
> +v4l2_subdev_register_error:
> +	v4l2_device_disconnect(v4l2->v4l2_dev);
> +v4l2_device_register_error:
> +	v4l2_device_put(v4l2->v4l2_dev);
> +v4l2_dev_error:
>  	dev->v4l2 = NULL;
>  	kref_put(&v4l2->ref, em28xx_free_v4l2);
> +v4l2_error:
>  	mutex_unlock(&dev->lock);
>  	return ret;
>  }
> diff --git a/drivers/media/usb/em28xx/em28xx.h b/drivers/media/usb/em28xx/em28xx.h
> index 6648e11f1271..dbcc297b5a0d 100644
> --- a/drivers/media/usb/em28xx/em28xx.h
> +++ b/drivers/media/usb/em28xx/em28xx.h
> @@ -552,10 +552,10 @@ struct em28xx_v4l2 {
>  	struct kref ref;
>  	struct em28xx *dev;
>  
> -	struct v4l2_device v4l2_dev;
> +	struct v4l2_device *v4l2_dev;
>  	struct v4l2_ctrl_handler ctrl_handler;
>  
> -	struct video_device vdev;
> +	struct video_device *vdev;
>  	struct video_device vbi_dev;
>  	struct video_device radio_dev;
>  
> @@ -601,7 +601,7 @@ struct em28xx_v4l2 {
>  	unsigned int field_count;
>  
>  #ifdef CONFIG_MEDIA_CONTROLLER
> -	struct media_pad video_pad, vbi_pad;
> +	struct media_pad *video_pad, vbi_pad;
>  	struct media_entity *decoder;
>  #endif
>  };
>