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@xxxxxx>
> ---
>
> 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
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