From: Jason Gunthorpe <jgg@nvidia.com>
Date: Mon, 11 Apr 2022 16:14:00 +0200
Subject: vfio/mdev: Remove mdev_parent_ops dev_attr_groups
Git-commit: e6486939d8ea22569af942a1888aa3824f59cc5e
Patch-mainline: v5.19-rc1
References: bsc#1205701

This is only used by one sample to print a fixed string that is pointless.

In general, having a device driver attach sysfs attributes to the parent
is horrific. This should never happen, and always leads to some kind of
liftime bug as it become very difficult for the sysfs attribute to go back
to any data owned by the device driver.

Remove the general mechanism to create this abuse.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20220411141403.86980-32-hch@lst.de
Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/vfio/mdev/mdev_sysfs.c |   12 ++----------
 include/linux/mdev.h           |    2 --
 samples/vfio-mdev/mtty.c       |   30 +-----------------------------
 3 files changed, 3 insertions(+), 41 deletions(-)

--- a/drivers/vfio/mdev/mdev_sysfs.c
+++ b/drivers/vfio/mdev/mdev_sysfs.c
@@ -197,7 +197,6 @@ void parent_remove_sysfs_files(struct md
 		remove_mdev_supported_type(type);
 	}
 
-	sysfs_remove_groups(&parent->dev->kobj, parent->ops->dev_attr_groups);
 	kset_unregister(parent->mdev_types_kset);
 }
 
@@ -213,17 +212,10 @@ int parent_create_sysfs_files(struct mde
 
 	INIT_LIST_HEAD(&parent->type_list);
 
-	ret = sysfs_create_groups(&parent->dev->kobj,
-				  parent->ops->dev_attr_groups);
-	if (ret)
-		goto create_err;
-
 	ret = add_mdev_supported_type_groups(parent);
 	if (ret)
-		sysfs_remove_groups(&parent->dev->kobj,
-				    parent->ops->dev_attr_groups);
-	else
-		return ret;
+		goto create_err;
+	return 0;
 
 create_err:
 	kset_unregister(parent->mdev_types_kset);
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -36,7 +36,6 @@ struct device *mtype_get_parent_dev(stru
  *
  * @owner:		The module owner.
  * @device_driver:	Which device driver to probe() on newly created devices
- * @dev_attr_groups:	Attributes of the parent device.
  * @mdev_attr_groups:	Attributes of the mediated device.
  * @supported_type_groups: Attributes to define supported types. It is mandatory
  *			to provide supported types.
@@ -47,7 +46,6 @@ struct device *mtype_get_parent_dev(stru
 struct mdev_parent_ops {
 	struct module   *owner;
 	struct mdev_driver *device_driver;
-	const struct attribute_group **dev_attr_groups;
 	const struct attribute_group **mdev_attr_groups;
 	struct attribute_group **supported_type_groups;
 };
--- a/samples/vfio-mdev/mtty.c
+++ b/samples/vfio-mdev/mtty.c
@@ -1219,37 +1219,10 @@ static void mtty_close(struct vfio_devic
 }
 
 static ssize_t
-sample_mtty_dev_show(struct device *dev, struct device_attribute *attr,
-		     char *buf)
-{
-	return sprintf(buf, "This is phy device\n");
-}
-
-static DEVICE_ATTR_RO(sample_mtty_dev);
-
-static struct attribute *mtty_dev_attrs[] = {
-	&dev_attr_sample_mtty_dev.attr,
-	NULL,
-};
-
-static const struct attribute_group mtty_dev_group = {
-	.name  = "mtty_dev",
-	.attrs = mtty_dev_attrs,
-};
-
-static const struct attribute_group *mtty_dev_groups[] = {
-	&mtty_dev_group,
-	NULL,
-};
-
-static ssize_t
 sample_mdev_dev_show(struct device *dev, struct device_attribute *attr,
 		     char *buf)
 {
-	if (mdev_from_dev(dev))
-		return sprintf(buf, "This is MDEV %s\n", dev_name(dev));
-
-	return sprintf(buf, "\n");
+	return sprintf(buf, "This is MDEV %s\n", dev_name(dev));
 }
 
 static DEVICE_ATTR_RO(sample_mdev_dev);
@@ -1346,7 +1319,6 @@ static struct mdev_driver mtty_driver =
 static const struct mdev_parent_ops mdev_fops = {
 	.owner                  = THIS_MODULE,
 	.device_driver		= &mtty_driver,
-	.dev_attr_groups        = mtty_dev_groups,
 	.supported_type_groups  = mdev_type_groups,
 };