vfio/mdev: Correct the function signatures for the mdev_type_attributes

The driver core standard is to pass in the properly typed object, the
properly typed attribute and the buffer data. It stems from the root
kobject method:

  ssize_t (*show)(struct kobject *kobj, struct kobj_attribute *attr,..)

Each subclass of kobject should provide their own function with the same
signature but more specific types, eg struct device uses:

  ssize_t (*show)(struct device *dev, struct device_attribute *attr,..)

In this case the existing signature is:

  ssize_t (*show)(struct kobject *kobj, struct device *dev,..)

Where kobj is a 'struct mdev_type *' and dev is 'mdev_type->parent->dev'.

Change the mdev_type related sysfs attribute functions to:

  ssize_t (*show)(struct mdev_type *mtype, struct mdev_type_attribute *attr,..)

In order to restore type safety and match the driver core standard

There are no current users of 'attr', but if it is ever needed it would be
hard to add in retroactively, so do it now.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Message-Id: <18-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

1 files changed, 14 insertions, 10 deletions

diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c
index da88fd7dd423..885b88ea20e2 100644
--- a/samples/vfio-mdev/mdpy.c
+++ b/samples/vfio-mdev/mdpy.c
@@ -652,18 +652,21 @@ static const struct attribute_group *mdev_dev_groups[] = {
 	NULL,
 };
 
-static ssize_t
-name_show(struct kobject *kobj, struct device *dev, char *buf)
+static ssize_t name_show(struct mdev_type *mtype,
+			 struct mdev_type_attribute *attr, char *buf)
 {
-	return sprintf(buf, "%s\n", kobj->name);
+	const struct mdpy_type *type =
+		&mdpy_types[mtype_get_type_group_id(mtype)];
+
+	return sprintf(buf, "%s\n", type->name);
 }
 static MDEV_TYPE_ATTR_RO(name);
 
-static ssize_t
-description_show(struct kobject *kobj, struct device *dev, char *buf)
+static ssize_t description_show(struct mdev_type *mtype,
+				struct mdev_type_attribute *attr, char *buf)
 {
 	const struct mdpy_type *type =
-		&mdpy_types[mtype_get_type_group_id(kobj)];
+		&mdpy_types[mtype_get_type_group_id(mtype)];
 
 	return sprintf(buf, "virtual display, %dx%d framebuffer\n",
 		       type ? type->width  : 0,
@@ -671,15 +674,16 @@ description_show(struct kobject *kobj, struct device *dev, char *buf)
 }
 static MDEV_TYPE_ATTR_RO(description);
 
-static ssize_t
-available_instances_show(struct kobject *kobj, struct device *dev, char *buf)
+static ssize_t available_instances_show(struct mdev_type *mtype,
+					struct mdev_type_attribute *attr,
+					char *buf)
 {
 	return sprintf(buf, "%d\n", max_devices - mdpy_count);
 }
 static MDEV_TYPE_ATTR_RO(available_instances);
 
-static ssize_t device_api_show(struct kobject *kobj, struct device *dev,
-			       char *buf)
+static ssize_t device_api_show(struct mdev_type *mtype,
+			       struct mdev_type_attribute *attr, char *buf)
 {
 	return sprintf(buf, "%s\n", VFIO_DEVICE_API_PCI_STRING);
 }