From:   "Tian, Kevin" <kevin.tian@intel.com>
To:     "Liu, Yi L" <yi.l.liu@intel.com>,
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Subject: RE: [PATCH v2 12/14] vfio: Add cdev for vfio_device
Thread-Topic: [PATCH v2 12/14] vfio: Add cdev for vfio_device
Thread-Index: AQHZOgpE7PZdngC1BkqJuLKfKdQ4lK7DHWfg
Date:   Tue, 7 Feb 2023 07:54:06 +0000
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References: <20230206090532.95598-1-yi.l.liu@intel.com>
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> From: Liu, Yi L <yi.l.liu@intel.com>
> Sent: Monday, February 6, 2023 5:06 PM
> +
> +static struct vfio {
> +	dev_t device_devt;
> +} vfio;

the structure is meaningless.

> +int vfio_device_fops_open(struct inode *inode, struct file *filep)
> +{
> +	struct vfio_device *device =3D container_of(inode->i_cdev,
> +						  struct vfio_device, cdev);
> +	struct vfio_device_file *df;
> +	int ret;
> +
> +	if (!vfio_device_try_get_registration(device))
> +		return -ENODEV;
> +
> +	/*
> +	 * device access is blocked until .open_device() is called
> +	 * in BIND_IOMMUFD.
> +	 */

this comment is more related to the whole function instead of the
following allocation code. Move it to be the function comment.

> @@ -51,6 +52,7 @@ struct vfio_device {
>  	/* Members below here are private, not for driver use */
>  	unsigned int index;
>  	struct device device;	/* device.kref covers object life circle */
> +	struct cdev cdev;

only if CDEV is configured.