[PATCH] V4L: dynamically allocate video_device nodes in subdevices

[PATCH] V4L: dynamically allocate video_device nodes in subdevices

[Guennadi Liakhovetski]

Currently only very few drivers actually use video_device nodes, embedded
in struct v4l2_subdev. Allocate these nodes dynamically for those drivers
to save memory for the rest.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
---

Only compile tested. Please, give it a spin on affected hardware.

 drivers/media/video/v4l2-device.c |   28 +++++++++++++++++++++++++---
 include/media/v4l2-subdev.h       |   10 ++++++++--
 2 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c
index c72856c..0c0f6ba 100644
--- a/drivers/media/video/v4l2-device.c
+++ b/drivers/media/video/v4l2-device.c
@@ -21,6 +21,7 @@
 #include <linux/types.h>
 #include <linux/ioctl.h>
 #include <linux/i2c.h>
+#include <linux/slab.h>
 #if defined(CONFIG_SPI)
 #include <linux/spi/spi.h>
 #endif
@@ -194,6 +195,7 @@ EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
 int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
 {
 	struct video_device *vdev;
+	struct v4l2_devnode *node;
 	struct v4l2_subdev *sd;
 	int err;
 
@@ -204,7 +206,13 @@ int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
 		if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
 			continue;
 
-		vdev = &sd->devnode;
+		node = kzalloc(sizeof(*node), GFP_KERNEL);
+		if (!node) {
+			err = -ENOMEM;
+			goto clean_up;
+		}
+		vdev = &node->vdev;
+
 		strlcpy(vdev->name, sd->name, sizeof(vdev->name));
 		vdev->v4l2_dev = v4l2_dev;
 		vdev->fops = &v4l2_subdev_fops;
@@ -213,13 +221,25 @@ int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
 		err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
 					      sd->owner);
 		if (err < 0)
-			return err;
+			goto clean_up;
 #if defined(CONFIG_MEDIA_CONTROLLER)
 		sd->entity.v4l.major = VIDEO_MAJOR;
 		sd->entity.v4l.minor = vdev->minor;
 #endif
+		sd->devnode = node;
 	}
 	return 0;
+
+clean_up:
+	list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
+		if (!sd->devnode)
+			break;
+		video_unregister_device(&sd->devnode->vdev);
+		kfree(sd->devnode);
+		sd->devnode = NULL;
+	}
+
+	return err;
 }
 EXPORT_SYMBOL_GPL(v4l2_device_register_subdev_nodes);
 
@@ -245,7 +265,9 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
 	if (v4l2_dev->mdev)
 		media_device_unregister_entity(&sd->entity);
 #endif
-	video_unregister_device(&sd->devnode);
+	video_unregister_device(&sd->devnode->vdev);
+	kfree(sd->devnode);
+	sd->devnode = NULL;
 	module_put(sd->owner);
 }
 EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index 257da1a..6e958df 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -510,6 +510,12 @@ struct v4l2_subdev_internal_ops {
 /* Set this flag if this subdev generates events. */
 #define V4L2_SUBDEV_FL_HAS_EVENTS		(1U << 3)
 
+/* video_device with a reverse lookup */
+struct v4l2_devnode {
+	struct v4l2_subdev *sd;
+	struct video_device vdev;
+};
+
 /* Each instance of a subdev driver should create this struct, either
    stand-alone or embedded in a larger struct.
  */
@@ -534,13 +540,13 @@ struct v4l2_subdev {
 	void *dev_priv;
 	void *host_priv;
 	/* subdev device node */
-	struct video_device devnode;
+	struct v4l2_devnode *devnode;
 };
 
 #define media_entity_to_v4l2_subdev(ent) \
 	container_of(ent, struct v4l2_subdev, entity)
 #define vdev_to_v4l2_subdev(vdev) \
-	container_of(vdev, struct v4l2_subdev, devnode)
+	(container_of(vdev, struct v4l2_devnode, vdev)->sd)
 
 /*
  * Used for storing subdev information per file handle
-- 
1.7.2.5

[PATCH v2] V4L: dynamically allocate video_device nodes in subdevices

[Guennadi Liakhovetski]

Currently only very few drivers actually use video_device nodes, embedded
in struct v4l2_subdev. Allocate these nodes dynamically for those drivers
to save memory for the rest.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
---

v2: Checking for NULL is not always enough, you also have to check the 
right thing for it. In this case it was sd->devnode in 
v4l2_device_unregister_subdev().

 drivers/media/video/v4l2-device.c |   29 ++++++++++++++++++++++++++---
 include/media/v4l2-subdev.h       |   10 ++++++++--
 2 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c
index c72856c..d4c093f 100644
--- a/drivers/media/video/v4l2-device.c
+++ b/drivers/media/video/v4l2-device.c
@@ -21,6 +21,7 @@
 #include <linux/types.h>
 #include <linux/ioctl.h>
 #include <linux/i2c.h>
+#include <linux/slab.h>
 #if defined(CONFIG_SPI)
 #include <linux/spi/spi.h>
 #endif
@@ -194,6 +195,7 @@ EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
 int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
 {
 	struct video_device *vdev;
+	struct v4l2_devnode *node;
 	struct v4l2_subdev *sd;
 	int err;
 
@@ -204,7 +206,13 @@ int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
 		if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
 			continue;
 
-		vdev = &sd->devnode;
+		node = kzalloc(sizeof(*node), GFP_KERNEL);
+		if (!node) {
+			err = -ENOMEM;
+			goto clean_up;
+		}
+		vdev = &node->vdev;
+
 		strlcpy(vdev->name, sd->name, sizeof(vdev->name));
 		vdev->v4l2_dev = v4l2_dev;
 		vdev->fops = &v4l2_subdev_fops;
@@ -213,13 +221,25 @@ int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
 		err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
 					      sd->owner);
 		if (err < 0)
-			return err;
+			goto clean_up;
 #if defined(CONFIG_MEDIA_CONTROLLER)
 		sd->entity.v4l.major = VIDEO_MAJOR;
 		sd->entity.v4l.minor = vdev->minor;
 #endif
+		sd->devnode = node;
 	}
 	return 0;
+
+clean_up:
+	list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
+		if (!sd->devnode)
+			break;
+		video_unregister_device(&sd->devnode->vdev);
+		kfree(sd->devnode);
+		sd->devnode = NULL;
+	}
+
+	return err;
 }
 EXPORT_SYMBOL_GPL(v4l2_device_register_subdev_nodes);
 
@@ -245,7 +265,10 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
 	if (v4l2_dev->mdev)
 		media_device_unregister_entity(&sd->entity);
 #endif
-	video_unregister_device(&sd->devnode);
+	if (sd->devnode)
+		video_unregister_device(&sd->devnode->vdev);
+	kfree(sd->devnode);
+	sd->devnode = NULL;
 	module_put(sd->owner);
 }
 EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index 257da1a..6e958df 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -510,6 +510,12 @@ struct v4l2_subdev_internal_ops {
 /* Set this flag if this subdev generates events. */
 #define V4L2_SUBDEV_FL_HAS_EVENTS		(1U << 3)
 
+/* video_device with a reverse lookup */
+struct v4l2_devnode {
+	struct v4l2_subdev *sd;
+	struct video_device vdev;
+};
+
 /* Each instance of a subdev driver should create this struct, either
    stand-alone or embedded in a larger struct.
  */
@@ -534,13 +540,13 @@ struct v4l2_subdev {
 	void *dev_priv;
 	void *host_priv;
 	/* subdev device node */
-	struct video_device devnode;
+	struct v4l2_devnode *devnode;
 };
 
 #define media_entity_to_v4l2_subdev(ent) \
 	container_of(ent, struct v4l2_subdev, entity)
 #define vdev_to_v4l2_subdev(vdev) \
-	container_of(vdev, struct v4l2_subdev, devnode)
+	(container_of(vdev, struct v4l2_devnode, vdev)->sd)
 
 /*
  * Used for storing subdev information per file handle
-- 
1.7.2.5

Re: [PATCH v2] V4L: dynamically allocate video_device nodes in subdevices

[Laurent Pinchart]

Hi Guennadi,

On Friday 09 September 2011 19:45:57 Guennadi Liakhovetski wrote:
> Currently only very few drivers actually use video_device nodes, embedded
> in struct v4l2_subdev. Allocate these nodes dynamically for those drivers
> to save memory for the rest.

Thanks for the patch.

> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> ---
> 
> v2: Checking for NULL is not always enough, you also have to check the
> right thing for it. In this case it was sd->devnode in
> v4l2_device_unregister_subdev().
> 
>  drivers/media/video/v4l2-device.c |   29 ++++++++++++++++++++++++++---
>  include/media/v4l2-subdev.h       |   10 ++++++++--
>  2 files changed, 34 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/media/video/v4l2-device.c
> b/drivers/media/video/v4l2-device.c index c72856c..d4c093f 100644
> --- a/drivers/media/video/v4l2-device.c
> +++ b/drivers/media/video/v4l2-device.c
> @@ -21,6 +21,7 @@
>  #include <linux/types.h>
>  #include <linux/ioctl.h>
>  #include <linux/i2c.h>
> +#include <linux/slab.h>
>  #if defined(CONFIG_SPI)
>  #include <linux/spi/spi.h>
>  #endif
> @@ -194,6 +195,7 @@ EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
>  int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
>  {
>  	struct video_device *vdev;
> +	struct v4l2_devnode *node;
>  	struct v4l2_subdev *sd;
>  	int err;
> 
> @@ -204,7 +206,13 @@ int v4l2_device_register_subdev_nodes(struct
> v4l2_device *v4l2_dev) if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
>  			continue;
> 
> -		vdev = &sd->devnode;
> +		node = kzalloc(sizeof(*node), GFP_KERNEL);
> +		if (!node) {
> +			err = -ENOMEM;
> +			goto clean_up;
> +		}
> +		vdev = &node->vdev;
> +
>  		strlcpy(vdev->name, sd->name, sizeof(vdev->name));
>  		vdev->v4l2_dev = v4l2_dev;
>  		vdev->fops = &v4l2_subdev_fops;
> @@ -213,13 +221,25 @@ int v4l2_device_register_subdev_nodes(struct
> v4l2_device *v4l2_dev) err = __video_register_device(vdev,
> VFL_TYPE_SUBDEV, -1, 1,
>  					      sd->owner);
>  		if (err < 0)
> -			return err;
> +			goto clean_up;
>  #if defined(CONFIG_MEDIA_CONTROLLER)
>  		sd->entity.v4l.major = VIDEO_MAJOR;
>  		sd->entity.v4l.minor = vdev->minor;
>  #endif
> +		sd->devnode = node;
>  	}
>  	return 0;
> +
> +clean_up:
> +	list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
> +		if (!sd->devnode)
> +			break;
> +		video_unregister_device(&sd->devnode->vdev);
> +		kfree(sd->devnode);
> +		sd->devnode = NULL;
> +	}
> +
> +	return err;
>  }
>  EXPORT_SYMBOL_GPL(v4l2_device_register_subdev_nodes);
> 
> @@ -245,7 +265,10 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev
> *sd) if (v4l2_dev->mdev)
>  		media_device_unregister_entity(&sd->entity);
>  #endif
> -	video_unregister_device(&sd->devnode);
> +	if (sd->devnode)
> +		video_unregister_device(&sd->devnode->vdev);
> +	kfree(sd->devnode);

Won't this crash if the node is open ? I think you need to refcount it.

> +	sd->devnode = NULL;
>  	module_put(sd->owner);
>  }
>  EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);
> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> index 257da1a..6e958df 100644
> --- a/include/media/v4l2-subdev.h
> +++ b/include/media/v4l2-subdev.h
> @@ -510,6 +510,12 @@ struct v4l2_subdev_internal_ops {
>  /* Set this flag if this subdev generates events. */
>  #define V4L2_SUBDEV_FL_HAS_EVENTS		(1U << 3)
> 
> +/* video_device with a reverse lookup */
> +struct v4l2_devnode {
> +	struct v4l2_subdev *sd;
> +	struct video_device vdev;
> +};
> +

Instead of that, why don't you store the subdev pointer in the video_device 
driver data ?

>  /* Each instance of a subdev driver should create this struct, either
>     stand-alone or embedded in a larger struct.
>   */
> @@ -534,13 +540,13 @@ struct v4l2_subdev {
>  	void *dev_priv;
>  	void *host_priv;
>  	/* subdev device node */
> -	struct video_device devnode;
> +	struct v4l2_devnode *devnode;
>  };
> 
>  #define media_entity_to_v4l2_subdev(ent) \
>  	container_of(ent, struct v4l2_subdev, entity)
>  #define vdev_to_v4l2_subdev(vdev) \
> -	container_of(vdev, struct v4l2_subdev, devnode)
> +	(container_of(vdev, struct v4l2_devnode, vdev)->sd)
> 
>  /*
>   * Used for storing subdev information per file handle

-- 
Regards,

Laurent Pinchart

Re: [PATCH v2] V4L: dynamically allocate video_device nodes in subdevices

[Guennadi Liakhovetski]

Hi Laurent

On Fri, 9 Sep 2011, Laurent Pinchart wrote:

> Hi Guennadi,
> 
> On Friday 09 September 2011 19:45:57 Guennadi Liakhovetski wrote:
> > Currently only very few drivers actually use video_device nodes, embedded
> > in struct v4l2_subdev. Allocate these nodes dynamically for those drivers
> > to save memory for the rest.
> 
> Thanks for the patch.
> 
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> > ---
> > 
> > v2: Checking for NULL is not always enough, you also have to check the
> > right thing for it. In this case it was sd->devnode in
> > v4l2_device_unregister_subdev().
> > 
> >  drivers/media/video/v4l2-device.c |   29 ++++++++++++++++++++++++++---
> >  include/media/v4l2-subdev.h       |   10 ++++++++--
> >  2 files changed, 34 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/media/video/v4l2-device.c
> > b/drivers/media/video/v4l2-device.c index c72856c..d4c093f 100644
> > --- a/drivers/media/video/v4l2-device.c
> > +++ b/drivers/media/video/v4l2-device.c
> > @@ -21,6 +21,7 @@
> >  #include <linux/types.h>
> >  #include <linux/ioctl.h>
> >  #include <linux/i2c.h>
> > +#include <linux/slab.h>
> >  #if defined(CONFIG_SPI)
> >  #include <linux/spi/spi.h>
> >  #endif
> > @@ -194,6 +195,7 @@ EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
> >  int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
> >  {
> >  	struct video_device *vdev;
> > +	struct v4l2_devnode *node;
> >  	struct v4l2_subdev *sd;
> >  	int err;
> > 
> > @@ -204,7 +206,13 @@ int v4l2_device_register_subdev_nodes(struct
> > v4l2_device *v4l2_dev) if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
> >  			continue;
> > 
> > -		vdev = &sd->devnode;
> > +		node = kzalloc(sizeof(*node), GFP_KERNEL);
> > +		if (!node) {
> > +			err = -ENOMEM;
> > +			goto clean_up;
> > +		}
> > +		vdev = &node->vdev;
> > +
> >  		strlcpy(vdev->name, sd->name, sizeof(vdev->name));
> >  		vdev->v4l2_dev = v4l2_dev;
> >  		vdev->fops = &v4l2_subdev_fops;
> > @@ -213,13 +221,25 @@ int v4l2_device_register_subdev_nodes(struct
> > v4l2_device *v4l2_dev) err = __video_register_device(vdev,
> > VFL_TYPE_SUBDEV, -1, 1,
> >  					      sd->owner);
> >  		if (err < 0)
> > -			return err;
> > +			goto clean_up;
> >  #if defined(CONFIG_MEDIA_CONTROLLER)
> >  		sd->entity.v4l.major = VIDEO_MAJOR;
> >  		sd->entity.v4l.minor = vdev->minor;
> >  #endif
> > +		sd->devnode = node;
> >  	}
> >  	return 0;
> > +
> > +clean_up:
> > +	list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
> > +		if (!sd->devnode)
> > +			break;
> > +		video_unregister_device(&sd->devnode->vdev);
> > +		kfree(sd->devnode);
> > +		sd->devnode = NULL;
> > +	}
> > +
> > +	return err;
> >  }
> >  EXPORT_SYMBOL_GPL(v4l2_device_register_subdev_nodes);
> > 
> > @@ -245,7 +265,10 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev
> > *sd) if (v4l2_dev->mdev)
> >  		media_device_unregister_entity(&sd->entity);
> >  #endif
> > -	video_unregister_device(&sd->devnode);
> > +	if (sd->devnode)
> > +		video_unregister_device(&sd->devnode->vdev);
> > +	kfree(sd->devnode);
> 
> Won't this crash if the node is open ? I think you need to refcount it.

Hm, I've been thinking about it, but maybe not far enough.

> 
> > +	sd->devnode = NULL;
> >  	module_put(sd->owner);
> >  }
> >  EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);
> > diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> > index 257da1a..6e958df 100644
> > --- a/include/media/v4l2-subdev.h
> > +++ b/include/media/v4l2-subdev.h
> > @@ -510,6 +510,12 @@ struct v4l2_subdev_internal_ops {
> >  /* Set this flag if this subdev generates events. */
> >  #define V4L2_SUBDEV_FL_HAS_EVENTS		(1U << 3)
> > 
> > +/* video_device with a reverse lookup */
> > +struct v4l2_devnode {
> > +	struct v4l2_subdev *sd;
> > +	struct video_device vdev;
> > +};
> > +
> 
> Instead of that, why don't you store the subdev pointer in the video_device 
> driver data ?

Is it free yet? Could do, sure.

> >  /* Each instance of a subdev driver should create this struct, either
> >     stand-alone or embedded in a larger struct.
> >   */
> > @@ -534,13 +540,13 @@ struct v4l2_subdev {
> >  	void *dev_priv;
> >  	void *host_priv;
> >  	/* subdev device node */
> > -	struct video_device devnode;
> > +	struct v4l2_devnode *devnode;
> >  };
> > 
> >  #define media_entity_to_v4l2_subdev(ent) \
> >  	container_of(ent, struct v4l2_subdev, entity)
> >  #define vdev_to_v4l2_subdev(vdev) \
> > -	container_of(vdev, struct v4l2_subdev, devnode)
> > +	(container_of(vdev, struct v4l2_devnode, vdev)->sd)
> > 
> >  /*
> >   * Used for storing subdev information per file handle

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/

[PATCH v3] V4L: dynamically allocate video_device nodes in subdevices

[Guennadi Liakhovetski]

Currently only very few drivers actually use video_device nodes, embedded
in struct v4l2_subdev. Allocate these nodes dynamically for those drivers
to save memory for the rest.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
---

v3: addressed comments from Laurent Pinchart - thanks

1. switch to using a device-release method, instead of freeing directly in 
v4l2_device_unregister_subdev()

2. switch to using drvdata instead of a wrapper struct

 drivers/media/video/v4l2-device.c |   41 ++++++++++++++++++++++++++++++++----
 include/media/v4l2-subdev.h       |    4 +-
 2 files changed, 38 insertions(+), 7 deletions(-)

diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c
index c72856c..9bf3d70 100644
--- a/drivers/media/video/v4l2-device.c
+++ b/drivers/media/video/v4l2-device.c
@@ -21,6 +21,7 @@
 #include <linux/types.h>
 #include <linux/ioctl.h>
 #include <linux/i2c.h>
+#include <linux/slab.h>
 #if defined(CONFIG_SPI)
 #include <linux/spi/spi.h>
 #endif
@@ -191,6 +192,13 @@ int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
 }
 EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
 
+void v4l2_device_release_subdev_node(struct video_device *vdev)
+{
+	struct v4l2_subdev *sd = video_get_drvdata(vdev);
+	sd->devnode = NULL;
+	kfree(vdev);
+}
+
 int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
 {
 	struct video_device *vdev;
@@ -204,22 +212,42 @@ int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
 		if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
 			continue;
 
-		vdev = &sd->devnode;
+		vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
+		if (!vdev) {
+			err = -ENOMEM;
+			goto clean_up;
+		}
+
+		video_set_drvdata(vdev, sd);
 		strlcpy(vdev->name, sd->name, sizeof(vdev->name));
 		vdev->v4l2_dev = v4l2_dev;
 		vdev->fops = &v4l2_subdev_fops;
-		vdev->release = video_device_release_empty;
+		vdev->release = v4l2_device_release_subdev_node;
 		vdev->ctrl_handler = sd->ctrl_handler;
 		err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
 					      sd->owner);
-		if (err < 0)
-			return err;
+		if (err < 0) {
+			kfree(vdev);
+			goto clean_up;
+		}
+		get_device(&vdev->dev);
 #if defined(CONFIG_MEDIA_CONTROLLER)
 		sd->entity.v4l.major = VIDEO_MAJOR;
 		sd->entity.v4l.minor = vdev->minor;
 #endif
+		sd->devnode = vdev;
 	}
 	return 0;
+
+clean_up:
+	list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
+		if (!sd->devnode)
+			break;
+		video_unregister_device(sd->devnode);
+		put_device(&sd->devnode->dev);
+	}
+
+	return err;
 }
 EXPORT_SYMBOL_GPL(v4l2_device_register_subdev_nodes);
 
@@ -245,7 +273,10 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
 	if (v4l2_dev->mdev)
 		media_device_unregister_entity(&sd->entity);
 #endif
-	video_unregister_device(&sd->devnode);
+	if (sd->devnode) {
+		video_unregister_device(sd->devnode);
+		put_device(&sd->devnode->dev);
+	}
 	module_put(sd->owner);
 }
 EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index 257da1a..5dd049a 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -534,13 +534,13 @@ struct v4l2_subdev {
 	void *dev_priv;
 	void *host_priv;
 	/* subdev device node */
-	struct video_device devnode;
+	struct video_device *devnode;
 };
 
 #define media_entity_to_v4l2_subdev(ent) \
 	container_of(ent, struct v4l2_subdev, entity)
 #define vdev_to_v4l2_subdev(vdev) \
-	container_of(vdev, struct v4l2_subdev, devnode)
+	video_get_drvdata(vdev)
 
 /*
  * Used for storing subdev information per file handle
-- 
1.7.2.5

Re: [PATCH v3] V4L: dynamically allocate video_device nodes in subdevices

[Laurent Pinchart]

Hi Guennadi,

On Monday 12 September 2011 12:55:46 Guennadi Liakhovetski wrote:
> Currently only very few drivers actually use video_device nodes, embedded
> in struct v4l2_subdev. Allocate these nodes dynamically for those drivers
> to save memory for the rest.
> 
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> ---
> 
> v3: addressed comments from Laurent Pinchart - thanks

Thanks for the patch. Just one small comment below.

> 1. switch to using a device-release method, instead of freeing directly in
> v4l2_device_unregister_subdev()
> 
> 2. switch to using drvdata instead of a wrapper struct
> 
>  drivers/media/video/v4l2-device.c |   41
> ++++++++++++++++++++++++++++++++---- include/media/v4l2-subdev.h       |  
>  4 +-
>  2 files changed, 38 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/media/video/v4l2-device.c
> b/drivers/media/video/v4l2-device.c index c72856c..9bf3d70 100644
> --- a/drivers/media/video/v4l2-device.c
> +++ b/drivers/media/video/v4l2-device.c
> @@ -21,6 +21,7 @@
>  #include <linux/types.h>
>  #include <linux/ioctl.h>
>  #include <linux/i2c.h>
> +#include <linux/slab.h>
>  #if defined(CONFIG_SPI)
>  #include <linux/spi/spi.h>
>  #endif
> @@ -191,6 +192,13 @@ int v4l2_device_register_subdev(struct v4l2_device
> *v4l2_dev, }
>  EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
> 
> +void v4l2_device_release_subdev_node(struct video_device *vdev)
> +{
> +	struct v4l2_subdev *sd = video_get_drvdata(vdev);
> +	sd->devnode = NULL;
> +	kfree(vdev);
> +}
> +
>  int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
>  {
>  	struct video_device *vdev;
> @@ -204,22 +212,42 @@ int v4l2_device_register_subdev_nodes(struct
> v4l2_device *v4l2_dev) if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
>  			continue;
> 
> -		vdev = &sd->devnode;
> +		vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
> +		if (!vdev) {
> +			err = -ENOMEM;
> +			goto clean_up;
> +		}
> +
> +		video_set_drvdata(vdev, sd);
>  		strlcpy(vdev->name, sd->name, sizeof(vdev->name));
>  		vdev->v4l2_dev = v4l2_dev;
>  		vdev->fops = &v4l2_subdev_fops;
> -		vdev->release = video_device_release_empty;
> +		vdev->release = v4l2_device_release_subdev_node;
>  		vdev->ctrl_handler = sd->ctrl_handler;
>  		err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
>  					      sd->owner);
> -		if (err < 0)
> -			return err;
> +		if (err < 0) {
> +			kfree(vdev);
> +			goto clean_up;
> +		}
> +		get_device(&vdev->dev);

Is get_device() (and the corresponding put_device() calls below) required ? I 
thought device_register() initialized the reference count to 1 (don't take my 
word for it though).

>  #if defined(CONFIG_MEDIA_CONTROLLER)
>  		sd->entity.v4l.major = VIDEO_MAJOR;
>  		sd->entity.v4l.minor = vdev->minor;
>  #endif
> +		sd->devnode = vdev;
>  	}
>  	return 0;
> +
> +clean_up:
> +	list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
> +		if (!sd->devnode)
> +			break;
> +		video_unregister_device(sd->devnode);
> +		put_device(&sd->devnode->dev);
> +	}
> +
> +	return err;
>  }
>  EXPORT_SYMBOL_GPL(v4l2_device_register_subdev_nodes);
> 
> @@ -245,7 +273,10 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev
> *sd) if (v4l2_dev->mdev)
>  		media_device_unregister_entity(&sd->entity);
>  #endif
> -	video_unregister_device(&sd->devnode);
> +	if (sd->devnode) {
> +		video_unregister_device(sd->devnode);
> +		put_device(&sd->devnode->dev);
> +	}
>  	module_put(sd->owner);
>  }
>  EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);
> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> index 257da1a..5dd049a 100644
> --- a/include/media/v4l2-subdev.h
> +++ b/include/media/v4l2-subdev.h
> @@ -534,13 +534,13 @@ struct v4l2_subdev {
>  	void *dev_priv;
>  	void *host_priv;
>  	/* subdev device node */
> -	struct video_device devnode;
> +	struct video_device *devnode;
>  };
> 
>  #define media_entity_to_v4l2_subdev(ent) \
>  	container_of(ent, struct v4l2_subdev, entity)
>  #define vdev_to_v4l2_subdev(vdev) \
> -	container_of(vdev, struct v4l2_subdev, devnode)
> +	video_get_drvdata(vdev)
> 
>  /*
>   * Used for storing subdev information per file handle

-- 
Regards,

Laurent Pinchart

Re: [PATCH v3] V4L: dynamically allocate video_device nodes in subdevices

[Guennadi Liakhovetski]

On Tue, 13 Sep 2011, Laurent Pinchart wrote:

> Hi Guennadi,
> 
> On Monday 12 September 2011 12:55:46 Guennadi Liakhovetski wrote:
> > Currently only very few drivers actually use video_device nodes, embedded
> > in struct v4l2_subdev. Allocate these nodes dynamically for those drivers
> > to save memory for the rest.
> > 
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> > ---
> > 
> > v3: addressed comments from Laurent Pinchart - thanks
> 
> Thanks for the patch. Just one small comment below.
> 
> > 1. switch to using a device-release method, instead of freeing directly in
> > v4l2_device_unregister_subdev()
> > 
> > 2. switch to using drvdata instead of a wrapper struct
> > 
> >  drivers/media/video/v4l2-device.c |   41
> > ++++++++++++++++++++++++++++++++---- include/media/v4l2-subdev.h       |  
> >  4 +-
> >  2 files changed, 38 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/media/video/v4l2-device.c
> > b/drivers/media/video/v4l2-device.c index c72856c..9bf3d70 100644
> > --- a/drivers/media/video/v4l2-device.c
> > +++ b/drivers/media/video/v4l2-device.c
> > @@ -21,6 +21,7 @@
> >  #include <linux/types.h>
> >  #include <linux/ioctl.h>
> >  #include <linux/i2c.h>
> > +#include <linux/slab.h>
> >  #if defined(CONFIG_SPI)
> >  #include <linux/spi/spi.h>
> >  #endif
> > @@ -191,6 +192,13 @@ int v4l2_device_register_subdev(struct v4l2_device
> > *v4l2_dev, }
> >  EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
> > 
> > +void v4l2_device_release_subdev_node(struct video_device *vdev)
> > +{
> > +	struct v4l2_subdev *sd = video_get_drvdata(vdev);
> > +	sd->devnode = NULL;
> > +	kfree(vdev);
> > +}
> > +
> >  int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
> >  {
> >  	struct video_device *vdev;
> > @@ -204,22 +212,42 @@ int v4l2_device_register_subdev_nodes(struct
> > v4l2_device *v4l2_dev) if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
> >  			continue;
> > 
> > -		vdev = &sd->devnode;
> > +		vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
> > +		if (!vdev) {
> > +			err = -ENOMEM;
> > +			goto clean_up;
> > +		}
> > +
> > +		video_set_drvdata(vdev, sd);
> >  		strlcpy(vdev->name, sd->name, sizeof(vdev->name));
> >  		vdev->v4l2_dev = v4l2_dev;
> >  		vdev->fops = &v4l2_subdev_fops;
> > -		vdev->release = video_device_release_empty;
> > +		vdev->release = v4l2_device_release_subdev_node;
> >  		vdev->ctrl_handler = sd->ctrl_handler;
> >  		err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
> >  					      sd->owner);
> > -		if (err < 0)
> > -			return err;
> > +		if (err < 0) {
> > +			kfree(vdev);
> > +			goto clean_up;
> > +		}
> > +		get_device(&vdev->dev);
> 
> Is get_device() (and the corresponding put_device() calls below) required ? I 
> thought device_register() initialized the reference count to 1 (don't take my 
> word for it though).

Indeed, I think, you're right. Will update.

Thanks
Guennadi

> 
> >  #if defined(CONFIG_MEDIA_CONTROLLER)
> >  		sd->entity.v4l.major = VIDEO_MAJOR;
> >  		sd->entity.v4l.minor = vdev->minor;
> >  #endif
> > +		sd->devnode = vdev;
> >  	}
> >  	return 0;
> > +
> > +clean_up:
> > +	list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
> > +		if (!sd->devnode)
> > +			break;
> > +		video_unregister_device(sd->devnode);
> > +		put_device(&sd->devnode->dev);
> > +	}
> > +
> > +	return err;
> >  }
> >  EXPORT_SYMBOL_GPL(v4l2_device_register_subdev_nodes);
> > 
> > @@ -245,7 +273,10 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev
> > *sd) if (v4l2_dev->mdev)
> >  		media_device_unregister_entity(&sd->entity);
> >  #endif
> > -	video_unregister_device(&sd->devnode);
> > +	if (sd->devnode) {
> > +		video_unregister_device(sd->devnode);
> > +		put_device(&sd->devnode->dev);
> > +	}
> >  	module_put(sd->owner);
> >  }
> >  EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);
> > diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> > index 257da1a..5dd049a 100644
> > --- a/include/media/v4l2-subdev.h
> > +++ b/include/media/v4l2-subdev.h
> > @@ -534,13 +534,13 @@ struct v4l2_subdev {
> >  	void *dev_priv;
> >  	void *host_priv;
> >  	/* subdev device node */
> > -	struct video_device devnode;
> > +	struct video_device *devnode;
> >  };
> > 
> >  #define media_entity_to_v4l2_subdev(ent) \
> >  	container_of(ent, struct v4l2_subdev, entity)
> >  #define vdev_to_v4l2_subdev(vdev) \
> > -	container_of(vdev, struct v4l2_subdev, devnode)
> > +	video_get_drvdata(vdev)
> > 
> >  /*
> >   * Used for storing subdev information per file handle
> 
> -- 
> Regards,
> 
> Laurent Pinchart
> 

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/

Re: [PATCH v3] V4L: dynamically allocate video_device nodes in subdevices

[Laurent Pinchart]

Hi Guennadi,

On Tuesday 13 September 2011 11:26:23 Guennadi Liakhovetski wrote:
> On Tue, 13 Sep 2011, Laurent Pinchart wrote:
> > On Monday 12 September 2011 12:55:46 Guennadi Liakhovetski wrote:
> > > Currently only very few drivers actually use video_device nodes,
> > > embedded in struct v4l2_subdev. Allocate these nodes dynamically for
> > > those drivers to save memory for the rest.
> > > 
> > > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> > > ---
> > > 
> > > v3: addressed comments from Laurent Pinchart - thanks
> > 
> > Thanks for the patch. Just one small comment below.
> > 
> > > 1. switch to using a device-release method, instead of freeing directly
> > > in v4l2_device_unregister_subdev()
> > > 
> > > 2. switch to using drvdata instead of a wrapper struct
> > > 
> > >  drivers/media/video/v4l2-device.c |   41
> > > 
> > > ++++++++++++++++++++++++++++++++---- include/media/v4l2-subdev.h      
> > > |
> > > 
> > >  4 +-
> > >  2 files changed, 38 insertions(+), 7 deletions(-)
> > > 
> > > diff --git a/drivers/media/video/v4l2-device.c
> > > b/drivers/media/video/v4l2-device.c index c72856c..9bf3d70 100644
> > > --- a/drivers/media/video/v4l2-device.c
> > > +++ b/drivers/media/video/v4l2-device.c
> > > @@ -21,6 +21,7 @@
> > > 
> > >  #include <linux/types.h>
> > >  #include <linux/ioctl.h>
> > >  #include <linux/i2c.h>
> > > 
> > > +#include <linux/slab.h>
> > > 
> > >  #if defined(CONFIG_SPI)
> > >  #include <linux/spi/spi.h>
> > >  #endif
> > > 
> > > @@ -191,6 +192,13 @@ int v4l2_device_register_subdev(struct v4l2_device
> > > *v4l2_dev, }
> > > 
> > >  EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
> > > 
> > > +void v4l2_device_release_subdev_node(struct video_device *vdev)
> > > +{
> > > +	struct v4l2_subdev *sd = video_get_drvdata(vdev);
> > > +	sd->devnode = NULL;
> > > +	kfree(vdev);
> > > +}
> > > +
> > > 
> > >  int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
> > >  {
> > >  
> > >  	struct video_device *vdev;
> > > 
> > > @@ -204,22 +212,42 @@ int v4l2_device_register_subdev_nodes(struct
> > > v4l2_device *v4l2_dev) if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
> > > 
> > >  			continue;
> > > 
> > > -		vdev = &sd->devnode;
> > > +		vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
> > > +		if (!vdev) {
> > > +			err = -ENOMEM;
> > > +			goto clean_up;
> > > +		}
> > > +
> > > +		video_set_drvdata(vdev, sd);
> > > 
> > >  		strlcpy(vdev->name, sd->name, sizeof(vdev->name));
> > >  		vdev->v4l2_dev = v4l2_dev;
> > >  		vdev->fops = &v4l2_subdev_fops;
> > > 
> > > -		vdev->release = video_device_release_empty;
> > > +		vdev->release = v4l2_device_release_subdev_node;
> > > 
> > >  		vdev->ctrl_handler = sd->ctrl_handler;
> > >  		err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
> > >  		
> > >  					      sd->owner);
> > > 
> > > -		if (err < 0)
> > > -			return err;
> > > +		if (err < 0) {
> > > +			kfree(vdev);
> > > +			goto clean_up;
> > > +		}
> > > +		get_device(&vdev->dev);
> > 
> > Is get_device() (and the corresponding put_device() calls below) required
> > ? I thought device_register() initialized the reference count to 1
> > (don't take my word for it though).
> 
> Indeed, I think, you're right. Will update.

Please test it as well :-)

-- 
Regards,

Laurent Pinchart

Re: [PATCH v3] V4L: dynamically allocate video_device nodes in subdevices

[Guennadi Liakhovetski]

On Tue, 13 Sep 2011, Laurent Pinchart wrote:

> Hi Guennadi,
> 
> On Tuesday 13 September 2011 11:26:23 Guennadi Liakhovetski wrote:
> > On Tue, 13 Sep 2011, Laurent Pinchart wrote:
> > > On Monday 12 September 2011 12:55:46 Guennadi Liakhovetski wrote:
> > > > Currently only very few drivers actually use video_device nodes,
> > > > embedded in struct v4l2_subdev. Allocate these nodes dynamically for
> > > > those drivers to save memory for the rest.
> > > > 
> > > > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> > > > ---
> > > > 
> > > > v3: addressed comments from Laurent Pinchart - thanks
> > > 
> > > Thanks for the patch. Just one small comment below.
> > > 
> > > > 1. switch to using a device-release method, instead of freeing directly
> > > > in v4l2_device_unregister_subdev()
> > > > 
> > > > 2. switch to using drvdata instead of a wrapper struct
> > > > 
> > > >  drivers/media/video/v4l2-device.c |   41
> > > > 
> > > > ++++++++++++++++++++++++++++++++---- include/media/v4l2-subdev.h      
> > > > |
> > > > 
> > > >  4 +-
> > > >  2 files changed, 38 insertions(+), 7 deletions(-)
> > > > 
> > > > diff --git a/drivers/media/video/v4l2-device.c
> > > > b/drivers/media/video/v4l2-device.c index c72856c..9bf3d70 100644
> > > > --- a/drivers/media/video/v4l2-device.c
> > > > +++ b/drivers/media/video/v4l2-device.c
> > > > @@ -21,6 +21,7 @@
> > > > 
> > > >  #include <linux/types.h>
> > > >  #include <linux/ioctl.h>
> > > >  #include <linux/i2c.h>
> > > > 
> > > > +#include <linux/slab.h>
> > > > 
> > > >  #if defined(CONFIG_SPI)
> > > >  #include <linux/spi/spi.h>
> > > >  #endif
> > > > 
> > > > @@ -191,6 +192,13 @@ int v4l2_device_register_subdev(struct v4l2_device
> > > > *v4l2_dev, }
> > > > 
> > > >  EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
> > > > 
> > > > +void v4l2_device_release_subdev_node(struct video_device *vdev)
> > > > +{
> > > > +	struct v4l2_subdev *sd = video_get_drvdata(vdev);
> > > > +	sd->devnode = NULL;
> > > > +	kfree(vdev);
> > > > +}
> > > > +
> > > > 
> > > >  int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
> > > >  {
> > > >  
> > > >  	struct video_device *vdev;
> > > > 
> > > > @@ -204,22 +212,42 @@ int v4l2_device_register_subdev_nodes(struct
> > > > v4l2_device *v4l2_dev) if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
> > > > 
> > > >  			continue;
> > > > 
> > > > -		vdev = &sd->devnode;
> > > > +		vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
> > > > +		if (!vdev) {
> > > > +			err = -ENOMEM;
> > > > +			goto clean_up;
> > > > +		}
> > > > +
> > > > +		video_set_drvdata(vdev, sd);
> > > > 
> > > >  		strlcpy(vdev->name, sd->name, sizeof(vdev->name));
> > > >  		vdev->v4l2_dev = v4l2_dev;
> > > >  		vdev->fops = &v4l2_subdev_fops;
> > > > 
> > > > -		vdev->release = video_device_release_empty;
> > > > +		vdev->release = v4l2_device_release_subdev_node;
> > > > 
> > > >  		vdev->ctrl_handler = sd->ctrl_handler;
> > > >  		err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
> > > >  		
> > > >  					      sd->owner);
> > > > 
> > > > -		if (err < 0)
> > > > -			return err;
> > > > +		if (err < 0) {
> > > > +			kfree(vdev);
> > > > +			goto clean_up;
> > > > +		}
> > > > +		get_device(&vdev->dev);
> > > 
> > > Is get_device() (and the corresponding put_device() calls below) required
> > > ? I thought device_register() initialized the reference count to 1
> > > (don't take my word for it though).
> > 
> > Indeed, I think, you're right. Will update.
> 
> Please test it as well :-)

I'm afraid, testing it wouldn't be very easy for me: I only have one 
system here, on which MC is used - the beagle-board. And it is not an easy 
nor a quick exersize to bring it up and run a test on it;-) But if noone 
else finds time to test it and if we're not confident enough in its 
correctness, well, we'll have to wait until I find time to do that...

BTW, there's one more improvement to be made for this patch:

-void v4l2_device_release_subdev_node(struct video_device *vdev)
+static void v4l2_device_release_subdev_node(struct video_device *vdev)

My copy-paste from video_device_release_empty() was too precise:-(

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/

[PATCH v4] V4L: dynamically allocate video_device nodes in subdevices

[Guennadi Liakhovetski]

Currently only very few drivers actually use video_device nodes, embedded
in struct v4l2_subdev. Allocate these nodes dynamically for those drivers
to save memory for the rest.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
---

v4:

1. added "static" in v4l2_device_release_subdev_node() definition
2. removed superfluous get_device() and put_device() (thanks to Laurent 
for pointing out)

 drivers/media/video/v4l2-device.c |   36 +++++++++++++++++++++++++++++++-----
 include/media/v4l2-subdev.h       |    4 ++--
 2 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c
index c72856c..8abf830 100644
--- a/drivers/media/video/v4l2-device.c
+++ b/drivers/media/video/v4l2-device.c
@@ -21,6 +21,7 @@
 #include <linux/types.h>
 #include <linux/ioctl.h>
 #include <linux/i2c.h>
+#include <linux/slab.h>
 #if defined(CONFIG_SPI)
 #include <linux/spi/spi.h>
 #endif
@@ -191,6 +192,13 @@ int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
 }
 EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
 
+static void v4l2_device_release_subdev_node(struct video_device *vdev)
+{
+	struct v4l2_subdev *sd = video_get_drvdata(vdev);
+	sd->devnode = NULL;
+	kfree(vdev);
+}
+
 int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
 {
 	struct video_device *vdev;
@@ -204,22 +212,40 @@ int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
 		if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
 			continue;
 
-		vdev = &sd->devnode;
+		vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
+		if (!vdev) {
+			err = -ENOMEM;
+			goto clean_up;
+		}
+
+		video_set_drvdata(vdev, sd);
 		strlcpy(vdev->name, sd->name, sizeof(vdev->name));
 		vdev->v4l2_dev = v4l2_dev;
 		vdev->fops = &v4l2_subdev_fops;
-		vdev->release = video_device_release_empty;
+		vdev->release = v4l2_device_release_subdev_node;
 		vdev->ctrl_handler = sd->ctrl_handler;
 		err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
 					      sd->owner);
-		if (err < 0)
-			return err;
+		if (err < 0) {
+			kfree(vdev);
+			goto clean_up;
+		}
 #if defined(CONFIG_MEDIA_CONTROLLER)
 		sd->entity.v4l.major = VIDEO_MAJOR;
 		sd->entity.v4l.minor = vdev->minor;
 #endif
+		sd->devnode = vdev;
 	}
 	return 0;
+
+clean_up:
+	list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
+		if (!sd->devnode)
+			break;
+		video_unregister_device(sd->devnode);
+	}
+
+	return err;
 }
 EXPORT_SYMBOL_GPL(v4l2_device_register_subdev_nodes);
 
@@ -245,7 +271,7 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
 	if (v4l2_dev->mdev)
 		media_device_unregister_entity(&sd->entity);
 #endif
-	video_unregister_device(&sd->devnode);
+	video_unregister_device(sd->devnode);
 	module_put(sd->owner);
 }
 EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index 257da1a..5dd049a 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -534,13 +534,13 @@ struct v4l2_subdev {
 	void *dev_priv;
 	void *host_priv;
 	/* subdev device node */
-	struct video_device devnode;
+	struct video_device *devnode;
 };
 
 #define media_entity_to_v4l2_subdev(ent) \
 	container_of(ent, struct v4l2_subdev, entity)
 #define vdev_to_v4l2_subdev(vdev) \
-	container_of(vdev, struct v4l2_subdev, devnode)
+	video_get_drvdata(vdev)
 
 /*
  * Used for storing subdev information per file handle
-- 
1.7.2.5

Re: [PATCH v4] V4L: dynamically allocate video_device nodes in subdevices

[Sylwester Nawrocki]

Hi Guennadi,

On 09/13/2011 04:48 PM, Guennadi Liakhovetski wrote:
> Currently only very few drivers actually use video_device nodes, embedded
> in struct v4l2_subdev. Allocate these nodes dynamically for those drivers
> to save memory for the rest.
> 
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>

I have tested this patch with Samsung FIMC driver and with MC enabled
sensor driver.
After some hundreds of module load/unload I didn't observe anything unusual.
The patch seem to be safe for device node enabled subdevs. You can stick my:

Tested-by: Sylwester Nawrocki <s.nawrocki@samsung.com>

if you feel so.


Thanks,
Sylwester Nawrocki
Samsung Poland R&D Center

> ---
> 
> v4:
> 
> 1. added "static" in v4l2_device_release_subdev_node() definition
> 2. removed superfluous get_device() and put_device() (thanks to Laurent 
> for pointing out)
> 
>  drivers/media/video/v4l2-device.c |   36 +++++++++++++++++++++++++++++++-----
>  include/media/v4l2-subdev.h       |    4 ++--
>  2 files changed, 33 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c
> index c72856c..8abf830 100644
> --- a/drivers/media/video/v4l2-device.c
> +++ b/drivers/media/video/v4l2-device.c
> @@ -21,6 +21,7 @@
>  #include <linux/types.h>
>  #include <linux/ioctl.h>
>  #include <linux/i2c.h>
> +#include <linux/slab.h>
>  #if defined(CONFIG_SPI)
>  #include <linux/spi/spi.h>
>  #endif
> @@ -191,6 +192,13 @@ int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
>  }
>  EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
>  
> +static void v4l2_device_release_subdev_node(struct video_device *vdev)
> +{
> +	struct v4l2_subdev *sd = video_get_drvdata(vdev);
> +	sd->devnode = NULL;
> +	kfree(vdev);
> +}
> +
>  int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
>  {
>  	struct video_device *vdev;
> @@ -204,22 +212,40 @@ int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
>  		if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
>  			continue;
>  
> -		vdev = &sd->devnode;
> +		vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
> +		if (!vdev) {
> +			err = -ENOMEM;
> +			goto clean_up;
> +		}
> +
> +		video_set_drvdata(vdev, sd);
>  		strlcpy(vdev->name, sd->name, sizeof(vdev->name));
>  		vdev->v4l2_dev = v4l2_dev;
>  		vdev->fops = &v4l2_subdev_fops;
> -		vdev->release = video_device_release_empty;
> +		vdev->release = v4l2_device_release_subdev_node;
>  		vdev->ctrl_handler = sd->ctrl_handler;
>  		err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
>  					      sd->owner);
> -		if (err < 0)
> -			return err;
> +		if (err < 0) {
> +			kfree(vdev);
> +			goto clean_up;
> +		}
>  #if defined(CONFIG_MEDIA_CONTROLLER)
>  		sd->entity.v4l.major = VIDEO_MAJOR;
>  		sd->entity.v4l.minor = vdev->minor;
>  #endif
> +		sd->devnode = vdev;
>  	}
>  	return 0;
> +
> +clean_up:
> +	list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
> +		if (!sd->devnode)
> +			break;
> +		video_unregister_device(sd->devnode);
> +	}
> +
> +	return err;
>  }
>  EXPORT_SYMBOL_GPL(v4l2_device_register_subdev_nodes);
>  
> @@ -245,7 +271,7 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
>  	if (v4l2_dev->mdev)
>  		media_device_unregister_entity(&sd->entity);
>  #endif
> -	video_unregister_device(&sd->devnode);
> +	video_unregister_device(sd->devnode);
>  	module_put(sd->owner);
>  }
>  EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);
> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> index 257da1a..5dd049a 100644
> --- a/include/media/v4l2-subdev.h
> +++ b/include/media/v4l2-subdev.h
> @@ -534,13 +534,13 @@ struct v4l2_subdev {
>  	void *dev_priv;
>  	void *host_priv;
>  	/* subdev device node */
> -	struct video_device devnode;
> +	struct video_device *devnode;
>  };
>  
>  #define media_entity_to_v4l2_subdev(ent) \
>  	container_of(ent, struct v4l2_subdev, entity)
>  #define vdev_to_v4l2_subdev(vdev) \
> -	container_of(vdev, struct v4l2_subdev, devnode)
> +	video_get_drvdata(vdev)
>  
>  /*
>   * Used for storing subdev information per file handle


-- 
Sylwester Nawrocki
Samsung Poland R&D Center

Re: [PATCH v4] V4L: dynamically allocate video_device nodes in subdevices

[Laurent Pinchart]

Hi Guennadi,

On Tuesday 13 September 2011 16:48:10 Guennadi Liakhovetski wrote:
> Currently only very few drivers actually use video_device nodes, embedded
> in struct v4l2_subdev. Allocate these nodes dynamically for those drivers
> to save memory for the rest.
> 
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

I will try to test the patch tomorrow on an OMAP3 system.

-- 
Regards,

Laurent Pinchart

Re: [PATCH v4] V4L: dynamically allocate video_device nodes in subdevices

[Guennadi Liakhovetski]

Hi Sylwester

On Tue, 13 Sep 2011, Sylwester Nawrocki wrote:

> Hi Guennadi,
> 
> On 09/13/2011 04:48 PM, Guennadi Liakhovetski wrote:
> > Currently only very few drivers actually use video_device nodes, embedded
> > in struct v4l2_subdev. Allocate these nodes dynamically for those drivers
> > to save memory for the rest.
> > 
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> 
> I have tested this patch with Samsung FIMC driver and with MC enabled
> sensor driver.
> After some hundreds of module load/unload I didn't observe anything unusual.
> The patch seem to be safe for device node enabled subdevs. You can stick my:
> 
> Tested-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
> 
> if you feel so.

Thanks very much for testing! However, depending on your test scenario, 
you might still not notice a problem by just loading and unloading of 
modules. It would, however, be useful to execute just one test:

1. add one line v4l2-device.c:

diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c
index a3b89f4..33226857 100644
--- a/drivers/media/video/v4l2-device.c
+++ b/drivers/media/video/v4l2-device.c
@@ -195,6 +195,7 @@ EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
 static void v4l2_device_release_subdev_node(struct video_device *vdev)
 {
 	struct v4l2_subdev *sd = video_get_drvdata(vdev);
+	dev_info(&vdev->dev, "%s()\n", __func__);
 	sd->devnode = NULL;
 	kfree(vdev);
 }

2. with this patch start and stop capture

3. check dmesg - v4l2_device_release_subdev_node() output should not be 
there yet

4. rmmod modules, then the output should be there

If you could test that - that would be great!

Thanks
Guennadi

> Thanks,
> Sylwester Nawrocki
> Samsung Poland R&D Center
> 
> > ---
> > 
> > v4:
> > 
> > 1. added "static" in v4l2_device_release_subdev_node() definition
> > 2. removed superfluous get_device() and put_device() (thanks to Laurent 
> > for pointing out)
> > 
> >  drivers/media/video/v4l2-device.c |   36 +++++++++++++++++++++++++++++++-----
> >  include/media/v4l2-subdev.h       |    4 ++--
> >  2 files changed, 33 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c
> > index c72856c..8abf830 100644
> > --- a/drivers/media/video/v4l2-device.c
> > +++ b/drivers/media/video/v4l2-device.c
> > @@ -21,6 +21,7 @@
> >  #include <linux/types.h>
> >  #include <linux/ioctl.h>
> >  #include <linux/i2c.h>
> > +#include <linux/slab.h>
> >  #if defined(CONFIG_SPI)
> >  #include <linux/spi/spi.h>
> >  #endif
> > @@ -191,6 +192,13 @@ int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
> >  }
> >  EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
> >  
> > +static void v4l2_device_release_subdev_node(struct video_device *vdev)
> > +{
> > +	struct v4l2_subdev *sd = video_get_drvdata(vdev);
> > +	sd->devnode = NULL;
> > +	kfree(vdev);
> > +}
> > +
> >  int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
> >  {
> >  	struct video_device *vdev;
> > @@ -204,22 +212,40 @@ int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
> >  		if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
> >  			continue;
> >  
> > -		vdev = &sd->devnode;
> > +		vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
> > +		if (!vdev) {
> > +			err = -ENOMEM;
> > +			goto clean_up;
> > +		}
> > +
> > +		video_set_drvdata(vdev, sd);
> >  		strlcpy(vdev->name, sd->name, sizeof(vdev->name));
> >  		vdev->v4l2_dev = v4l2_dev;
> >  		vdev->fops = &v4l2_subdev_fops;
> > -		vdev->release = video_device_release_empty;
> > +		vdev->release = v4l2_device_release_subdev_node;
> >  		vdev->ctrl_handler = sd->ctrl_handler;
> >  		err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
> >  					      sd->owner);
> > -		if (err < 0)
> > -			return err;
> > +		if (err < 0) {
> > +			kfree(vdev);
> > +			goto clean_up;
> > +		}
> >  #if defined(CONFIG_MEDIA_CONTROLLER)
> >  		sd->entity.v4l.major = VIDEO_MAJOR;
> >  		sd->entity.v4l.minor = vdev->minor;
> >  #endif
> > +		sd->devnode = vdev;
> >  	}
> >  	return 0;
> > +
> > +clean_up:
> > +	list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
> > +		if (!sd->devnode)
> > +			break;
> > +		video_unregister_device(sd->devnode);
> > +	}
> > +
> > +	return err;
> >  }
> >  EXPORT_SYMBOL_GPL(v4l2_device_register_subdev_nodes);
> >  
> > @@ -245,7 +271,7 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
> >  	if (v4l2_dev->mdev)
> >  		media_device_unregister_entity(&sd->entity);
> >  #endif
> > -	video_unregister_device(&sd->devnode);
> > +	video_unregister_device(sd->devnode);
> >  	module_put(sd->owner);
> >  }
> >  EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);
> > diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> > index 257da1a..5dd049a 100644
> > --- a/include/media/v4l2-subdev.h
> > +++ b/include/media/v4l2-subdev.h
> > @@ -534,13 +534,13 @@ struct v4l2_subdev {
> >  	void *dev_priv;
> >  	void *host_priv;
> >  	/* subdev device node */
> > -	struct video_device devnode;
> > +	struct video_device *devnode;
> >  };
> >  
> >  #define media_entity_to_v4l2_subdev(ent) \
> >  	container_of(ent, struct v4l2_subdev, entity)
> >  #define vdev_to_v4l2_subdev(vdev) \
> > -	container_of(vdev, struct v4l2_subdev, devnode)
> > +	video_get_drvdata(vdev)
> >  
> >  /*
> >   * Used for storing subdev information per file handle
> 
> 
> -- 
> Sylwester Nawrocki
> Samsung Poland R&D Center
> 

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/

Re: [PATCH v4] V4L: dynamically allocate video_device nodes in subdevices

[Sylwester Nawrocki]

Hi Guennadi,

On 09/13/2011 11:18 PM, Guennadi Liakhovetski wrote:
> On Tue, 13 Sep 2011, Sylwester Nawrocki wrote:
>> On 09/13/2011 04:48 PM, Guennadi Liakhovetski wrote:
>>> Currently only very few drivers actually use video_device nodes, embedded
>>> in struct v4l2_subdev. Allocate these nodes dynamically for those drivers
>>> to save memory for the rest.
>>>
>>> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
>>
>> I have tested this patch with Samsung FIMC driver and with MC enabled
>> sensor driver.
>> After some hundreds of module load/unload I didn't observe anything unusual.
>> The patch seem to be safe for device node enabled subdevs. You can stick my:
>>
>> Tested-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
>>
>> if you feel so.
> 
> Thanks very much for testing! However, depending on your test scenario, 
> you might still not notice a problem by just loading and unloading of 
> modules. It would, however, be useful to execute just one test:
> 
> 1. add one line v4l2-device.c:
> 
> diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c
> index a3b89f4..33226857 100644
> --- a/drivers/media/video/v4l2-device.c
> +++ b/drivers/media/video/v4l2-device.c
> @@ -195,6 +195,7 @@ EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
>  static void v4l2_device_release_subdev_node(struct video_device *vdev)
>  {
>  	struct v4l2_subdev *sd = video_get_drvdata(vdev);
> +	dev_info(&vdev->dev, "%s()\n", __func__);
>  	sd->devnode = NULL;
>  	kfree(vdev);
>  }
> 
> 2. with this patch start and stop capture
> 
> 3. check dmesg - v4l2_device_release_subdev_node() output should not be 
> there yet
> 
> 4. rmmod modules, then the output should be there
> 
> If you could test that - that would be great!

OK, I double checked if v4l2_device_release_subdev_node() is called at the right
time, i.e. I've also checked if the streaming works in between the module unload/load.

I'd added the printk and everything behaved as expected, other than I've tracked
down a few minor bugs in the drivers in the meantime;)

I'll keep your patch applied in my development tree.

Thanks,
-- 
Sylwester Nawrocki
Samsung Poland R&D Center

[PATCH v5] V4L: dynamically allocate video_device nodes in subdevices

[Guennadi Liakhovetski]

Currently only very few drivers actually use video_device nodes, embedded
in struct v4l2_subdev. Allocate these nodes dynamically for those drivers
to save memory for the rest.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
---

v5: replace kzalloc() with video_device_alloc() and kfree() with 
video_device_release(), no changes otherwise. I hope, I'm entitled to keep 
the tested- and acked-by's;-)

 drivers/media/video/v4l2-device.c |   36 +++++++++++++++++++++++++++++++-----
 include/media/v4l2-subdev.h       |    4 ++--
 2 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c
index c72856c..93c0350 100644
--- a/drivers/media/video/v4l2-device.c
+++ b/drivers/media/video/v4l2-device.c
@@ -21,6 +21,7 @@
 #include <linux/types.h>
 #include <linux/ioctl.h>
 #include <linux/i2c.h>
+#include <linux/slab.h>
 #if defined(CONFIG_SPI)
 #include <linux/spi/spi.h>
 #endif
@@ -191,6 +192,13 @@ int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
 }
 EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
 
+static void v4l2_device_release_subdev_node(struct video_device *vdev)
+{
+	struct v4l2_subdev *sd = video_get_drvdata(vdev);
+	sd->devnode = NULL;
+	video_device_release(vdev);
+}
+
 int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
 {
 	struct video_device *vdev;
@@ -204,22 +212,40 @@ int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
 		if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
 			continue;
 
-		vdev = &sd->devnode;
+		vdev = video_device_alloc();
+		if (!vdev) {
+			err = -ENOMEM;
+			goto clean_up;
+		}
+
+		video_set_drvdata(vdev, sd);
 		strlcpy(vdev->name, sd->name, sizeof(vdev->name));
 		vdev->v4l2_dev = v4l2_dev;
 		vdev->fops = &v4l2_subdev_fops;
-		vdev->release = video_device_release_empty;
+		vdev->release = v4l2_device_release_subdev_node;
 		vdev->ctrl_handler = sd->ctrl_handler;
 		err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
 					      sd->owner);
-		if (err < 0)
-			return err;
+		if (err < 0) {
+			video_device_release(vdev);
+			goto clean_up;
+		}
 #if defined(CONFIG_MEDIA_CONTROLLER)
 		sd->entity.v4l.major = VIDEO_MAJOR;
 		sd->entity.v4l.minor = vdev->minor;
 #endif
+		sd->devnode = vdev;
 	}
 	return 0;
+
+clean_up:
+	list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
+		if (!sd->devnode)
+			break;
+		video_unregister_device(sd->devnode);
+	}
+
+	return err;
 }
 EXPORT_SYMBOL_GPL(v4l2_device_register_subdev_nodes);
 
@@ -245,7 +271,7 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
 	if (v4l2_dev->mdev)
 		media_device_unregister_entity(&sd->entity);
 #endif
-	video_unregister_device(&sd->devnode);
+	video_unregister_device(sd->devnode);
 	module_put(sd->owner);
 }
 EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index 257da1a..5dd049a 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -534,13 +534,13 @@ struct v4l2_subdev {
 	void *dev_priv;
 	void *host_priv;
 	/* subdev device node */
-	struct video_device devnode;
+	struct video_device *devnode;
 };
 
 #define media_entity_to_v4l2_subdev(ent) \
 	container_of(ent, struct v4l2_subdev, entity)
 #define vdev_to_v4l2_subdev(vdev) \
-	container_of(vdev, struct v4l2_subdev, devnode)
+	video_get_drvdata(vdev)
 
 /*
  * Used for storing subdev information per file handle
-- 
1.7.2.5