On Wednesday, June 15, 2011 10:36:26 Laurent Pinchart wrote:
> Entities associated with video device nodes are unregistered in
> video_unregister_device(). This destroys the entity even though it can
> still be accessed through open video device nodes.
>
> Move the media_device_unregister_entity() call from
> video_unregister_device() to v4l2_device_release() to ensure that the
> entity isn't unregistered until the last reference to the video device
> is released.
>
> Also remove the media_entity_get()/put() calls from v4l2-dev.c. Those
> functions were designed for subdevs, to avoid a parent module from being
> removed while still accessible through board code. They're not currently
> needed for video device nodes, and will oops when a hotpluggable device
> is disconnected during streaming, as media_entity_put() called in
> v4l2_device_release() tries to access entity->parent->dev->driver which
> is set to NULL when the device is disconnected.
Looks good.
Acked-by: Hans Verkuil <hans.verk...@cisco.com>
Regards,
Hans
>
> Signed-off-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
> ---
> drivers/media/video/v4l2-dev.c | 36 +++++++-----------------------------
> 1 files changed, 7 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
> index 19d5ae2..5dc1fa1 100644
> --- a/drivers/media/video/v4l2-dev.c
> +++ b/drivers/media/video/v4l2-dev.c
> @@ -167,6 +167,12 @@ static void v4l2_device_release(struct device *cd)
>
> mutex_unlock(&videodev_lock);
>
> +#if defined(CONFIG_MEDIA_CONTROLLER)
> + if (vdev->v4l2_dev && vdev->v4l2_dev->mdev &&
> + vdev->vfl_type != VFL_TYPE_SUBDEV)
> + media_device_unregister_entity(&vdev->entity);
> +#endif
> +
> /* Release video_device and perform other
> cleanups as needed. */
> vdev->release(vdev);
> @@ -405,17 +411,6 @@ static int v4l2_open(struct inode *inode, struct file
*filp)
> /* and increase the device refcount */
> video_get(vdev);
> mutex_unlock(&videodev_lock);
> -#if defined(CONFIG_MEDIA_CONTROLLER)
> - if (vdev->v4l2_dev && vdev->v4l2_dev->mdev &&
> - vdev->vfl_type != VFL_TYPE_SUBDEV) {
> - entity = media_entity_get(&vdev->entity);
> - if (!entity) {
> - ret = -EBUSY;
> - video_put(vdev);
> - return ret;
> - }
> - }
> -#endif
> if (vdev->fops->open) {
> if (vdev->lock && mutex_lock_interruptible(vdev->lock)) {
> ret = -ERESTARTSYS;
> @@ -431,14 +426,8 @@ static int v4l2_open(struct inode *inode, struct file
*filp)
>
> err:
> /* decrease the refcount in case of an error */
> - if (ret) {
> -#if defined(CONFIG_MEDIA_CONTROLLER)
> - if (vdev->v4l2_dev && vdev->v4l2_dev->mdev &&
> - vdev->vfl_type != VFL_TYPE_SUBDEV)
> - media_entity_put(entity);
> -#endif
> + if (ret)
> video_put(vdev);
> - }
> return ret;
> }
>
> @@ -455,11 +444,6 @@ static int v4l2_release(struct inode *inode, struct
file *filp)
> if (vdev->lock)
> mutex_unlock(vdev->lock);
> }
> -#if defined(CONFIG_MEDIA_CONTROLLER)
> - if (vdev->v4l2_dev && vdev->v4l2_dev->mdev &&
> - vdev->vfl_type != VFL_TYPE_SUBDEV)
> - media_entity_put(&vdev->entity);
> -#endif
> /* decrease the refcount unconditionally since the release()
> return value is ignored. */
> video_put(vdev);
> @@ -754,12 +738,6 @@ void video_unregister_device(struct video_device *vdev)
> if (!vdev || !video_is_registered(vdev))
> return;
>
> -#if defined(CONFIG_MEDIA_CONTROLLER)
> - if (vdev->v4l2_dev && vdev->v4l2_dev->mdev &&
> - vdev->vfl_type != VFL_TYPE_SUBDEV)
> - media_device_unregister_entity(&vdev->entity);
> -#endif
> -
> mutex_lock(&videodev_lock);
> /* This must be in a critical section to prevent a race with v4l2_open.
> * Once this bit has been cleared video_get may never be called again.
> --
> 1.7.3.4
>
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