linux-kernel - Re: [PATCH 4/5] libnvdimm: Drop unused device power management support

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Date:   Fri, 11 Jun 2021 12:47:03 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Dan Williams <dan.j.williams@...el.com>
CC:     <linux-cxl@...r.kernel.org>, <nvdimm@...ts.linux.dev>,
        <ben.widawsky@...el.com>, <alison.schofield@...el.com>,
        <vishal.l.verma@...el.com>, <ira.weiny@...el.com>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/5] libnvdimm: Drop unused device power management
 support

On Thu, 10 Jun 2021 15:26:19 -0700
Dan Williams <dan.j.williams@...el.com> wrote:

> LIBNVDIMM device objects register sysfs power attributes despite nothing
> requiring that support. Clean up sysfs remove the power/ attribute
> group. This requires a device_create() and a device_register() usage to
> be converted to the device_initialize() + device_add() pattern.
> 
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
Trivial comment below. Looks good.

> ---
>  drivers/nvdimm/bus.c |   45 +++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 37 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
> index a11821df83b5..e6aa87043a95 100644
> --- a/drivers/nvdimm/bus.c
> +++ b/drivers/nvdimm/bus.c
> @@ -363,8 +363,13 @@ struct nvdimm_bus *nvdimm_bus_register(struct device *parent,
>  	nvdimm_bus->dev.groups = nd_desc->attr_groups;
>  	nvdimm_bus->dev.bus = &nvdimm_bus_type;
>  	nvdimm_bus->dev.of_node = nd_desc->of_node;
> -	dev_set_name(&nvdimm_bus->dev, "ndbus%d", nvdimm_bus->id);
> -	rc = device_register(&nvdimm_bus->dev);
> +	device_initialize(&nvdimm_bus->dev);
> +	device_set_pm_not_required(&nvdimm_bus->dev);
> +	rc = dev_set_name(&nvdimm_bus->dev, "ndbus%d", nvdimm_bus->id);
> +	if (rc)
> +		goto err;

Maybe mention in patch description that you also now handle errors in
dev_set_name()?

> +
> +	rc = device_add(&nvdimm_bus->dev);
>  	if (rc) {
>  		dev_dbg(&nvdimm_bus->dev, "registration failed: %d\n", rc);
>  		goto err;
> @@ -525,6 +530,7 @@ void __nd_device_register(struct device *dev)
>  		set_dev_node(dev, to_nd_region(dev)->numa_node);
>  
>  	dev->bus = &nvdimm_bus_type;
> +	device_set_pm_not_required(dev);
>  	if (dev->parent) {
>  		get_device(dev->parent);
>  		if (dev_to_node(dev) == NUMA_NO_NODE)
> @@ -717,18 +723,41 @@ const struct attribute_group nd_numa_attribute_group = {
>  	.is_visible = nd_numa_attr_visible,
>  };
>  
> +static void ndctl_release(struct device *dev)
> +{
> +	kfree(dev);
> +}
> +
>  int nvdimm_bus_create_ndctl(struct nvdimm_bus *nvdimm_bus)
>  {
>  	dev_t devt = MKDEV(nvdimm_bus_major, nvdimm_bus->id);
>  	struct device *dev;
> +	int rc;
>  
> -	dev = device_create(nd_class, &nvdimm_bus->dev, devt, nvdimm_bus,
> -			"ndctl%d", nvdimm_bus->id);
> +	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
> +	if (!dev)
> +		return -ENOMEM;
> +	device_initialize(dev);
> +	device_set_pm_not_required(dev);
> +	dev->class = nd_class;
> +	dev->parent = &nvdimm_bus->dev;
> +	dev->devt = devt;
> +	dev->release = ndctl_release;
> +	rc = dev_set_name(dev, "ndctl%d", nvdimm_bus->id);
> +	if (rc)
> +		goto err;
>  
> -	if (IS_ERR(dev))
> -		dev_dbg(&nvdimm_bus->dev, "failed to register ndctl%d: %ld\n",
> -				nvdimm_bus->id, PTR_ERR(dev));
> -	return PTR_ERR_OR_ZERO(dev);
> +	rc = device_add(dev);
> +	if (rc) {
> +		dev_dbg(&nvdimm_bus->dev, "failed to register ndctl%d: %d\n",
> +				nvdimm_bus->id, rc);
> +		goto err;
> +	}
> +	return 0;
> +
> +err:
> +	put_device(dev);
> +	return rc;
>  }
>  
>  void nvdimm_bus_destroy_ndctl(struct nvdimm_bus *nvdimm_bus)
>