vfio/mdev: Add mdev/mtype_get_type_group_id()

This returns the index in the supported_type_groups array that is
associated with the mdev_type attached to the struct mdev_device or its
containing struct kobject.

Each mdev_device can be spawned from exactly one mdev_type, which in turn
originates from exactly one supported_type_group.

Drivers are using weird string calculations to try and get back to this
index, providing a direct access to the index removes a bunch of wonky
driver code.

mdev_type->group can be deleted as the group is obtained using the
type_group_id.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Message-Id: <11-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

1 files changed, 9 insertions, 6 deletions

diff --git a/drivers/vfio/mdev/mdev_sysfs.c b/drivers/vfio/mdev/mdev_sysfs.c
index 8c169d12ba7d..712fbc78b12e 100644
--- a/drivers/vfio/mdev/mdev_sysfs.c
+++ b/drivers/vfio/mdev/mdev_sysfs.c
@@ -92,9 +92,11 @@ static struct kobj_type mdev_type_ktype = {
 };
 
 static struct mdev_type *add_mdev_supported_type(struct mdev_parent *parent,
-						 struct attribute_group *group)
+						 unsigned int type_group_id)
 {
 	struct mdev_type *type;
+	struct attribute_group *group =
+		parent->ops->supported_type_groups[type_group_id];
 	int ret;
 
 	if (!group->name) {
@@ -110,6 +112,7 @@ static struct mdev_type *add_mdev_supported_type(struct mdev_parent *parent,
 	type->parent = parent;
 	/* Pairs with the put in mdev_type_release() */
 	mdev_get_parent(parent);
+	type->type_group_id = type_group_id;
 
 	ret = kobject_init_and_add(&type->kobj, &mdev_type_ktype, NULL,
 				   "%s-%s", dev_driver_string(parent->dev),
@@ -135,8 +138,6 @@ static struct mdev_type *add_mdev_supported_type(struct mdev_parent *parent,
 		ret = -ENOMEM;
 		goto attrs_failed;
 	}
-
-	type->group = group;
 	return type;
 
 attrs_failed:
@@ -151,8 +152,11 @@ attr_create_failed:
 
 static void remove_mdev_supported_type(struct mdev_type *type)
 {
+	struct attribute_group *group =
+		type->parent->ops->supported_type_groups[type->type_group_id];
+
 	sysfs_remove_files(&type->kobj,
-			   (const struct attribute **)type->group->attrs);
+			   (const struct attribute **)group->attrs);
 	kobject_put(type->devices_kobj);
 	sysfs_remove_file(&type->kobj, &mdev_type_attr_create.attr);
 	kobject_del(&type->kobj);
@@ -166,8 +170,7 @@ static int add_mdev_supported_type_groups(struct mdev_parent *parent)
 	for (i = 0; parent->ops->supported_type_groups[i]; i++) {
 		struct mdev_type *type;
 
-		type = add_mdev_supported_type(parent,
-					parent->ops->supported_type_groups[i]);
+		type = add_mdev_supported_type(parent, i);
 		if (IS_ERR(type)) {
 			struct mdev_type *ltype, *tmp;