On Tue, Jun 14, 2022 at 3:52 AM Parav Pandit <parav at nvidia.com>
wrote:>
> vduse devices are not backed by any real devices such as PCI. Hence it
> doesn't have any parent device linked to it.
>
> Kernel driver model in [1] suggests to avoid an empty device
> release callback.
>
> Hence tie the mgmtdevice object's life cycle to an allocate dummy
struct
> device instead of static one.
>
> [1]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/core-api/kobject.rst?h=v5.18-rc7#n284
>
> Signed-off-by: Parav Pandit <parav at nvidia.com>
Acked-by: Jason Wang <jasowang at redhat.com>
> ---
> changelog:
> v0->v1:
> - removed typo in device name of "-la"
> ---
> drivers/vdpa/vdpa_user/vduse_dev.c | 60 ++++++++++++++++++------------
> 1 file changed, 37 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c
b/drivers/vdpa/vdpa_user/vduse_dev.c
> index 776ad7496f53..3bc27de58f46 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -1476,16 +1476,12 @@ static char *vduse_devnode(struct device *dev,
umode_t *mode)
> return kasprintf(GFP_KERNEL, "vduse/%s", dev_name(dev));
> }
>
> -static void vduse_mgmtdev_release(struct device *dev)
> -{
> -}
> -
> -static struct device vduse_mgmtdev = {
> - .init_name = "vduse",
> - .release = vduse_mgmtdev_release,
> +struct vduse_mgmt_dev {
> + struct vdpa_mgmt_dev mgmt_dev;
> + struct device dev;
> };
>
> -static struct vdpa_mgmt_dev mgmt_dev;
> +static struct vduse_mgmt_dev *vduse_mgmt;
>
> static int vduse_dev_init_vdpa(struct vduse_dev *dev, const char *name)
> {
> @@ -1510,7 +1506,7 @@ static int vduse_dev_init_vdpa(struct vduse_dev *dev,
const char *name)
> }
> set_dma_ops(&vdev->vdpa.dev, &vduse_dev_dma_ops);
> vdev->vdpa.dma_dev = &vdev->vdpa.dev;
> - vdev->vdpa.mdev = &mgmt_dev;
> + vdev->vdpa.mdev = &vduse_mgmt->mgmt_dev;
>
> return 0;
> }
> @@ -1556,34 +1552,52 @@ static struct virtio_device_id id_table[] = {
> { 0 },
> };
>
> -static struct vdpa_mgmt_dev mgmt_dev = {
> - .device = &vduse_mgmtdev,
> - .id_table = id_table,
> - .ops = &vdpa_dev_mgmtdev_ops,
> -};
> +static void vduse_mgmtdev_release(struct device *dev)
> +{
> + struct vduse_mgmt_dev *mgmt_dev;
> +
> + mgmt_dev = container_of(dev, struct vduse_mgmt_dev, dev);
> + kfree(mgmt_dev);
> +}
>
> static int vduse_mgmtdev_init(void)
> {
> int ret;
>
> - ret = device_register(&vduse_mgmtdev);
> - if (ret)
> + vduse_mgmt = kzalloc(sizeof(*vduse_mgmt), GFP_KERNEL);
> + if (!vduse_mgmt)
> + return -ENOMEM;
> +
> + ret = dev_set_name(&vduse_mgmt->dev, "vduse");
> + if (ret) {
> + kfree(vduse_mgmt);
> return ret;
> + }
>
> - ret = vdpa_mgmtdev_register(&mgmt_dev);
> + vduse_mgmt->dev.release = vduse_mgmtdev_release;
> +
> + ret = device_register(&vduse_mgmt->dev);
> if (ret)
> - goto err;
> + goto dev_reg_err;
>
> - return 0;
> -err:
> - device_unregister(&vduse_mgmtdev);
> + vduse_mgmt->mgmt_dev.id_table = id_table;
> + vduse_mgmt->mgmt_dev.ops = &vdpa_dev_mgmtdev_ops;
> + vduse_mgmt->mgmt_dev.device = &vduse_mgmt->dev;
> + ret = vdpa_mgmtdev_register(&vduse_mgmt->mgmt_dev);
> + if (ret)
> + device_unregister(&vduse_mgmt->dev);
> +
> + return ret;
> +
> +dev_reg_err:
> + put_device(&vduse_mgmt->dev);
> return ret;
> }
>
> static void vduse_mgmtdev_exit(void)
> {
> - vdpa_mgmtdev_unregister(&mgmt_dev);
> - device_unregister(&vduse_mgmtdev);
> + vdpa_mgmtdev_unregister(&vduse_mgmt->mgmt_dev);
> + device_unregister(&vduse_mgmt->dev);
> }
>
> static int vduse_init(void)
> --
> 2.26.2
>