Re: [PATCH] block: rbd: switch to dynamic root device

Viacheslav Dubeyko
2026-04-24T18:48:54Z

On Fri, 2026-04-24 at 12:39 +0200, Johan Hovold wrote:
> Driver core expects devices to be dynamically allocated and will, for
> example, complain loudly when no release function has been provided.
>
> Use root_device_register() to allocate and register the root device
> instead of open coding using a static device.

I think the approach makes sense. Ilya, what do you think? Do we have any
objection?

>
> Signed-off-by: Johan Hovold <johan@kernel.org>
> ---
> drivers/block/rbd.c | 23 +++++++----------------
> 1 file changed, 7 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index e7da06200c1e..ffab1b4e7c25 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -580,14 +580,7 @@ static const struct bus_type rbd_bus_type = {
> .bus_groups = rbd_bus_groups,
> };
>
> -static void rbd_root_dev_release(struct device *dev)
> -{
> -}
> -
> -static struct device rbd_root_dev = {
> - .init_name = "rbd",
> - .release = rbd_root_dev_release,
> -};
> +static struct device *rbd_root_dev;
>
> static __printf(2, 3)
> void rbd_warn(struct rbd_device *rbd_dev, const char *fmt, ...)
> @@ -5390,7 +5383,7 @@ static struct rbd_device *__rbd_dev_create(struct rbd_spec *spec)
>
> rbd_dev->dev.bus = &rbd_bus_type;
> rbd_dev->dev.type = &rbd_device_type;
> - rbd_dev->dev.parent = &rbd_root_dev;
> + rbd_dev->dev.parent = rbd_root_dev;
> device_initialize(&rbd_dev->dev);
>
> return rbd_dev;
> @@ -7331,15 +7324,13 @@ static int __init rbd_sysfs_init(void)
> {
> int ret;
>
> - ret = device_register(&rbd_root_dev);
> - if (ret < 0) {
> - put_device(&rbd_root_dev);
> - return ret;
> - }
> + rbd_root_dev = root_device_register("rbd");
> + if (IS_ERR(rbd_root_dev))
> + return PTR_ERR(rbd_root_dev);
>
> ret = bus_register(&rbd_bus_type);
> if (ret < 0)
> - device_unregister(&rbd_root_dev);
> + root_device_unregister(rbd_root_dev);

I think we need to assign NULL here:

rbd_root_dev = NULL;

>
> return ret;
> }
> @@ -7347,7 +7338,7 @@ static int __init rbd_sysfs_init(void)
> static void __exit rbd_sysfs_cleanup(void)
> {
> bus_unregister(&rbd_bus_type);
> - device_unregister(&rbd_root_dev);
> + root_device_unregister(rbd_root_dev);

The same issue here:

rbd_root_dev = NULL;

Thanks,
Slava.

> }
>
> static int __init rbd_slab_init(void)