From: Jori Koolstra <jkoolstra@xs4all.nl>
Date: Sun, 8 Mar 2026 21:49:39 +0000 (+0100)
Subject: vfio: mdev: replace mtty_dev->vd_class with a const struct class
X-Git-Tag: v7.1-rc1~132^2~19
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=06ed87b3197e9b80dccac0b764fdffe44192e010;p=thirdparty%2Fkernel%2Fstable.git

vfio: mdev: replace mtty_dev->vd_class with a const struct class

The class_create() call has been deprecated in favor of class_register()
as the driver core now allows for a struct class to be in read-only
memory. Replace mtty_dev->vd_class with a const struct class and drop the
class_create() call.

Compile tested and found no errors/warns in dmesg after enabling
CONFIG_VFIO and CONFIG_SAMPLE_VFIO_MDEV_MTTY.

Link: https://lore.kernel.org/all/2023040244-duffel-pushpin-f738@gregkh/

Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jori Koolstra <jkoolstra@xs4all.nl>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20260308214939.1215682-1-jkoolstra@xs4all.nl
Signed-off-by: Alex Williamson <alex@shazbot.org>
---

diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
index bd92c38379b87..01a9db84c4ab4 100644
--- a/samples/vfio-mdev/mtty.c
+++ b/samples/vfio-mdev/mtty.c
@@ -68,9 +68,12 @@
  * Global Structures
  */
 
+static const struct class mtty_class = {
+	.name	= MTTY_CLASS_NAME
+};
+
 static struct mtty_dev {
 	dev_t		vd_devt;
-	struct class	*vd_class;
 	struct cdev	vd_cdev;
 	struct idr	vd_idr;
 	struct device	dev;
@@ -1980,15 +1983,14 @@ static int __init mtty_dev_init(void)
 	if (ret)
 		goto err_cdev;
 
-	mtty_dev.vd_class = class_create(MTTY_CLASS_NAME);
+	ret = class_register(&mtty_class);
 
-	if (IS_ERR(mtty_dev.vd_class)) {
+	if (ret) {
 		pr_err("Error: failed to register mtty_dev class\n");
-		ret = PTR_ERR(mtty_dev.vd_class);
 		goto err_driver;
 	}
 
-	mtty_dev.dev.class = mtty_dev.vd_class;
+	mtty_dev.dev.class = &mtty_class;
 	mtty_dev.dev.release = mtty_device_release;
 	dev_set_name(&mtty_dev.dev, "%s", MTTY_NAME);
 
@@ -2007,7 +2009,7 @@ err_device:
 	device_del(&mtty_dev.dev);
 err_put:
 	put_device(&mtty_dev.dev);
-	class_destroy(mtty_dev.vd_class);
+	class_unregister(&mtty_class);
 err_driver:
 	mdev_unregister_driver(&mtty_driver);
 err_cdev:
@@ -2026,8 +2028,7 @@ static void __exit mtty_dev_exit(void)
 	mdev_unregister_driver(&mtty_driver);
 	cdev_del(&mtty_dev.vd_cdev);
 	unregister_chrdev_region(mtty_dev.vd_devt, MINORMASK + 1);
-	class_destroy(mtty_dev.vd_class);
-	mtty_dev.vd_class = NULL;
+	class_unregister(&mtty_class);
 	pr_info("mtty_dev: Unloaded!\n");
 }