Re: [PATCH v4] media: em28xx: Fix race condition between open and init function

[Igor Torrente <igormtorrente@gmail.com>]

On 5/6/21 4:47 AM, Hans Verkuil wrote:
> On 05/05/2021 21:54, Igor Torrente wrote:
>>
>>
>> On 5/5/21 8:21 AM, Hans Verkuil wrote:
>>> 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.
>>>
>>
>> Do you mean only the free of v4l2 and v4l2_device structs? Or the
>> release callback should include vb2_video_unregister_device,
>> v4l2_ctrl_handler_free, etc in the release callback?
> 
> I meant any freeing of resources, so v4l2_ctrl_handler_free, any kfree()s,
> etc. The vb2_video_unregister_device() must be called when the device is
> disconnected, or the probe fails. vb2_video_unregister_device() cancels any
> streaming video nodes and marks the video device as being unregistered, thus
> preventing applications from attempting to open it again.
> 

Ok, got it, I was doing wrong here.

> When the last filehandle for these video nodes is closed, then the release
> callback of v4l2_device is called, and that's where you can free all v4l2 memory
> and do the final kref_put(&dev->ref).
> 
> Regards,
> 
> 	Hans
> 

Thanks,
Igor M. A. Torrente

>>
>>> 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
>>
>> Thanks for the review,
>> ---
>> Igor M. A. Torrente
>>
>>
>>>
>>> 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
>>>>    };
>>>>
>>>
>