Re: [PATCH v3 1/2] firmware: google: Expose CBMEM over sysfs

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Thu, Nov 28, 2019 at 01:50:50PM +0100, patrick.rudolph@9elements.com wrote:
> +static int cbmem_probe(struct coreboot_device *cdev)
> +{
> +	struct device *dev = &cdev->dev;
> +	struct cb_priv *priv;
> +	int err;
> +
> +	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	memcpy(&priv->entry, &cdev->cbmem_entry, sizeof(priv->entry));
> +
> +	priv->remap = memremap(priv->entry.address,
> +			       priv->entry.entry_size, MEMREMAP_WB);
> +	if (!priv->remap) {
> +		err = -ENOMEM;
> +		goto failure;
> +	}
> +
> +	err = sysfs_create_group(&dev->kobj, &cb_mem_attr_group);

You just raced with userspace and lost :(

Set the driver's default attribute group up to point at
cb_mem_attr_group and the driver core will handle creating and removing
the group automatically for you correctly.

thanks,

greg k-h