[PATCH 3/4] vfio-mdev: Make mdev_parent private

[Alex Williamson]

From: Alex Williamson <alwillia@xxxxxxxx>

Rather than hoping for good behavior by marking some elements
internal, enforce it by making the entire structure private and
creating an accessor function for the one useful external field.

Cc: Kirti Wankhede <kwankhede@xxxxxxxxxx>
Cc: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx>
Cc: Zhi Wang <zhi.a.wang@xxxxxxxxx>
Cc: Jike Song <jike.song@xxxxxxxxx>
Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
---
 drivers/gpu/drm/i915/gvt/kvmgt.c |    2 +-
 drivers/vfio/mdev/mdev_core.c    |    6 ++++++
 drivers/vfio/mdev/mdev_private.h |   10 ++++++++++
 include/linux/mdev.h             |   15 ++-------------
 samples/vfio-mdev/mtty.c         |    2 +-
 5 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 081ada2..3850032 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -396,7 +396,7 @@ static int intel_vgpu_create(struct kobject *kobj, struct mdev_device *mdev)
 	struct device *pdev;
 	void *gvt;
 
-	pdev = mdev->parent->dev;
+	pdev = mdev_parent_dev(mdev);
 	gvt = kdev_to_i915(pdev)->gvt;
 
 	type = intel_gvt_find_vgpu_type(gvt, kobject_name(kobj));
diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index 4a140e0..6078d99 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -27,6 +27,12 @@
 static DEFINE_MUTEX(parent_list_lock);
 static struct class_compat *mdev_bus_compat_class;
 
+struct device *mdev_parent_dev(struct mdev_device *mdev)
+{
+	return mdev->parent->dev;
+}
+EXPORT_SYMBOL(mdev_parent_dev);
+
 static int _find_mdev_device(struct device *dev, void *data)
 {
 	struct mdev_device *mdev;
diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
index 0b72c2d9..b05dd22 100644
--- a/drivers/vfio/mdev/mdev_private.h
+++ b/drivers/vfio/mdev/mdev_private.h
@@ -16,6 +16,16 @@
 int  mdev_bus_register(void);
 void mdev_bus_unregister(void);
 
+struct mdev_parent {
+	struct device *dev;
+	const struct mdev_parent_ops *ops;
+	struct kref ref;
+	struct mutex lock;
+	struct list_head next;
+	struct kset *mdev_types_kset;
+	struct list_head type_list;
+};
+
 struct mdev_type {
 	struct kobject kobj;
 	struct kobject *devices_kobj;
diff --git a/include/linux/mdev.h b/include/linux/mdev.h
index f7c04bb..ccdf3c5 100644
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -13,19 +13,6 @@
 #ifndef MDEV_H
 #define MDEV_H
 
-/* Parent device */
-struct mdev_parent {
-	struct device			*dev;
-	const struct mdev_parent_ops	*ops;
-
-	/* internal */
-	struct kref		ref;
-	struct mutex		lock;
-	struct list_head	next;
-	struct kset		*mdev_types_kset;
-	struct list_head	type_list;
-};
-
 /* Mediated device */
 struct mdev_device {
 	struct device		dev;
@@ -164,4 +151,6 @@ extern int  mdev_register_device(struct device *dev,
 extern int  mdev_register_driver(struct mdev_driver *drv, struct module *owner);
 extern void mdev_unregister_driver(struct mdev_driver *drv);
 
+extern struct device *mdev_parent_dev(struct mdev_device *mdev);
+
 #endif /* MDEV_H */
diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
index 1a74f0e..5e13efc 100644
--- a/samples/vfio-mdev/mtty.c
+++ b/samples/vfio-mdev/mtty.c
@@ -734,7 +734,7 @@ int mtty_create(struct kobject *kobj, struct mdev_device *mdev)
 
 	for (i = 0; i < 2; i++) {
 		snprintf(name, MTTY_STRING_LEN, "%s-%d",
-			dev_driver_string(mdev->parent->dev), i + 1);
+			dev_driver_string(mdev_parent_dev(mdev)), i + 1);
 		if (!strcmp(kobj->name, name)) {
 			nr_ports = i + 1;
 			break;