Hi Hans,
Thank you for the patch.
On Thu, Feb 21, 2019 at 03:21:46PM +0100, Hans Verkuil wrote:
> It is not possible to use devm_kzalloc since that memory is
> freed immediately when the device instance is unbound.
>
> Various objects like the video device may still be in use
> since someone has the device node open, and when that is closed
> it expects the memory to be around.
>
> So use kzalloc and release it at the appropriate time.
You're opening a can of worms, we have tons of drivers that use
devm_kzalloc() :-) I however believe this is the right course of action.
> Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
> ---
> drivers/media/platform/vim2m.c | 20 +++++++++++++++-----
> 1 file changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/media/platform/vim2m.c b/drivers/media/platform/vim2m.c
> index a27d3052bb62..bfb3e3eb48d1 100644
> --- a/drivers/media/platform/vim2m.c
> +++ b/drivers/media/platform/vim2m.c
> @@ -1087,6 +1087,16 @@ static int vim2m_release(struct file *file)
> return 0;
> }
>
> +static void vim2m_device_release(struct video_device *vdev)
> +{
> + struct vim2m_dev *dev = container_of(vdev, struct vim2m_dev, vfd);
> +
> + dprintk(dev, "Releasing last dev\n");
Do we really need a debug printk here ?
> + v4l2_device_unregister(&dev->v4l2_dev);
> + v4l2_m2m_release(dev->m2m_dev);
> + kfree(dev);
> +}
> +
> static const struct v4l2_file_operations vim2m_fops = {
> .owner = THIS_MODULE,
> .open = vim2m_open,
> @@ -1102,7 +1112,7 @@ static const struct video_device vim2m_videodev = {
> .fops = &vim2m_fops,
> .ioctl_ops = &vim2m_ioctl_ops,
> .minor = -1,
> - .release = video_device_release_empty,
> + .release = vim2m_device_release,
> .device_caps = V4L2_CAP_VIDEO_M2M | V4L2_CAP_STREAMING,
> };
>
> @@ -1123,13 +1133,13 @@ static int vim2m_probe(struct platform_device *pdev)
> struct video_device *vfd;
> int ret;
>
> - dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
> + dev = kzalloc(sizeof(*dev), GFP_KERNEL);
> if (!dev)
> return -ENOMEM;
>
> ret = v4l2_device_register(&pdev->dev, &dev->v4l2_dev);
> if (ret)
> - return ret;
> + goto unreg_free;
>
> atomic_set(&dev->num_inst, 0);
> mutex_init(&dev->dev_mutex);
> @@ -1192,6 +1202,8 @@ static int vim2m_probe(struct platform_device *pdev)
> video_unregister_device(&dev->vfd);
> unreg_v4l2:
> v4l2_device_unregister(&dev->v4l2_dev);
> +unreg_free:
I'd call the label error_free, and rename the other ones with an error_
prefix, as you don't register anything here.
With these two small issues fixes,
Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> + kfree(dev);
>
> return ret;
> }
> @@ -1207,9 +1219,7 @@ static int vim2m_remove(struct platform_device *pdev)
> v4l2_m2m_unregister_media_controller(dev->m2m_dev);
> media_device_cleanup(&dev->mdev);
> #endif
> - v4l2_m2m_release(dev->m2m_dev);
> video_unregister_device(&dev->vfd);
> - v4l2_device_unregister(&dev->v4l2_dev);
>
> return 0;
> }
--
Regards,
Laurent Pinchart
