linux-kernel - [PATCH] misc: genwqe: make class_genwqe a static const structure

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Date:   Thu, 10 Aug 2023 22:27:11 +0400
From:   Ivan Orlov <ivan.orlov0322@...il.com>
To:     haver@...ux.ibm.com, arnd@...db.de, gregkh@...uxfoundation.org
Cc:     Ivan Orlov <ivan.orlov0322@...il.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] misc: genwqe: make class_genwqe a static const structure

Now that the driver core allows for struct class to be in read-only
memory, move the class_genwqe structure to be declared at build time
placing it into read-only memory, instead of having to be dynamically
allocated at boot time. Update the 'class_genwqe' field of the
'genwqe_dev' struct correspondingly.

Suggested-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ivan Orlov <ivan.orlov0322@...il.com>
---
 drivers/misc/genwqe/card_base.c | 49 +++++++++++++++++----------------
 drivers/misc/genwqe/card_base.h |  2 +-
 2 files changed, 27 insertions(+), 24 deletions(-)

diff --git a/drivers/misc/genwqe/card_base.c b/drivers/misc/genwqe/card_base.c
index b03010810b89..224a7e97cbea 100644
--- a/drivers/misc/genwqe/card_base.c
+++ b/drivers/misc/genwqe/card_base.c
@@ -42,7 +42,7 @@ MODULE_VERSION(DRV_VERSION);
 MODULE_LICENSE("GPL");
 
 static char genwqe_driver_name[] = GENWQE_DEVNAME;
-static struct class *class_genwqe;
+
 static struct dentry *debugfs_genwqe;
 static struct genwqe_dev *genwqe_devices[GENWQE_CARD_NO_MAX];
 
@@ -104,6 +104,26 @@ static const struct pci_device_id genwqe_device_table[] = {
 
 MODULE_DEVICE_TABLE(pci, genwqe_device_table);
 
+/**
+ * genwqe_devnode() - Set default access mode for genwqe devices.
+ * @dev:	Pointer to device (unused)
+ * @mode:	Carrier to pass-back given mode (permissions)
+ *
+ * Default mode should be rw for everybody. Do not change default
+ * device name.
+ */
+static char *genwqe_devnode(const struct device *dev, umode_t *mode)
+{
+	if (mode)
+		*mode = 0666;
+	return NULL;
+}
+
+static const struct class class_genwqe = {
+	.name = GENWQE_DEVNAME,
+	.devnode = genwqe_devnode,
+};
+
 /**
  * genwqe_dev_alloc() - Create and prepare a new card descriptor
  *
@@ -126,7 +146,7 @@ static struct genwqe_dev *genwqe_dev_alloc(void)
 		return ERR_PTR(-ENOMEM);
 
 	cd->card_idx = i;
-	cd->class_genwqe = class_genwqe;
+	cd->class_genwqe = &class_genwqe;
 	cd->debugfs_genwqe = debugfs_genwqe;
 
 	/*
@@ -1339,21 +1359,6 @@ static struct pci_driver genwqe_driver = {
 	.err_handler = &genwqe_err_handler,
 };
 
-/**
- * genwqe_devnode() - Set default access mode for genwqe devices.
- * @dev:	Pointer to device (unused)
- * @mode:	Carrier to pass-back given mode (permissions)
- *
- * Default mode should be rw for everybody. Do not change default
- * device name.
- */
-static char *genwqe_devnode(const struct device *dev, umode_t *mode)
-{
-	if (mode)
-		*mode = 0666;
-	return NULL;
-}
-
 /**
  * genwqe_init_module() - Driver registration and initialization
  */
@@ -1361,14 +1366,12 @@ static int __init genwqe_init_module(void)
 {
 	int rc;
 
-	class_genwqe = class_create(GENWQE_DEVNAME);
-	if (IS_ERR(class_genwqe)) {
+	rc = class_register(&class_genwqe);
+	if (rc) {
 		pr_err("[%s] create class failed\n", __func__);
 		return -ENOMEM;
 	}
 
-	class_genwqe->devnode = genwqe_devnode;
-
 	debugfs_genwqe = debugfs_create_dir(GENWQE_DEVNAME, NULL);
 
 	rc = pci_register_driver(&genwqe_driver);
@@ -1381,7 +1384,7 @@ static int __init genwqe_init_module(void)
 
  err_out0:
 	debugfs_remove(debugfs_genwqe);
-	class_destroy(class_genwqe);
+	class_unregister(&class_genwqe);
 	return rc;
 }
 
@@ -1392,7 +1395,7 @@ static void __exit genwqe_exit_module(void)
 {
 	pci_unregister_driver(&genwqe_driver);
 	debugfs_remove(debugfs_genwqe);
-	class_destroy(class_genwqe);
+	class_unregister(&class_genwqe);
 }
 
 module_init(genwqe_init_module);
diff --git a/drivers/misc/genwqe/card_base.h b/drivers/misc/genwqe/card_base.h
index 0e902977d35f..d700266f2cd0 100644
--- a/drivers/misc/genwqe/card_base.h
+++ b/drivers/misc/genwqe/card_base.h
@@ -289,7 +289,7 @@ struct genwqe_dev {
 
 	/* char device */
 	dev_t  devnum_genwqe;		/* major/minor num card */
-	struct class *class_genwqe;	/* reference to class object */
+	const struct class *class_genwqe;	/* reference to class object */
 	struct device *dev;		/* for device creation */
 	struct cdev cdev_genwqe;	/* char device for card */
 
-- 
2.34.1