vfio/mbochs: make mbochs_class constant

Since commit 43a7206b0963 ("driver core: class: make class_register() take
a const *"), the driver core allows for struct class to be in read-only
memory, so move the mbochs_class structure to be declared at build time
placing it into read-only memory, instead of having to be dynamically
allocated at boot time.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
Link: https://lore.kernel.org/r/20240301-class_cleanup-vfio-v1-2-9236d69083f5@marliere.net
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
index 93405264ff2337870e8c0693a0759540424a2f81..9062598ea03de322c19b9358fc1bdc44da6d53e7 100644 (file)
--- a/samples/vfio-mdev/mbochs.c
+++ b/samples/vfio-mdev/mbochs.c
@@ -133,7 +133,9 @@ static struct mdev_type *mbochs_mdev_types[] = {
 };
 
 static dev_t           mbochs_devt;
-static struct class    *mbochs_class;
+static const struct class mbochs_class = {
+       .name = MBOCHS_CLASS_NAME,
+};
 static struct cdev     mbochs_cdev;
 static struct device   mbochs_dev;
 static struct mdev_parent mbochs_parent;
@@ -1422,13 +1424,10 @@ static int __init mbochs_dev_init(void)
        if (ret)
                goto err_cdev;
 
-       mbochs_class = class_create(MBOCHS_CLASS_NAME);
-       if (IS_ERR(mbochs_class)) {
-               pr_err("Error: failed to register mbochs_dev class\n");
-               ret = PTR_ERR(mbochs_class);
+       ret = class_register(&mbochs_class);
+       if (ret)
                goto err_driver;
-       }
-       mbochs_dev.class = mbochs_class;
+       mbochs_dev.class = &mbochs_class;
        mbochs_dev.release = mbochs_device_release;
        dev_set_name(&mbochs_dev, "%s", MBOCHS_NAME);
 
@@ -1448,7 +1447,7 @@ err_device:
        device_del(&mbochs_dev);
 err_put:
        put_device(&mbochs_dev);
-       class_destroy(mbochs_class);
+       class_unregister(&mbochs_class);
 err_driver:
        mdev_unregister_driver(&mbochs_driver);
 err_cdev:
@@ -1466,8 +1465,7 @@ static void __exit mbochs_dev_exit(void)
        mdev_unregister_driver(&mbochs_driver);
        cdev_del(&mbochs_cdev);
        unregister_chrdev_region(mbochs_devt, MINORMASK + 1);
-       class_destroy(mbochs_class);
-       mbochs_class = NULL;
+       class_unregister(&mbochs_class);
 }
 
 MODULE_IMPORT_NS(DMA_BUF);