ipmi: make ipmi_class a static const structure

Now that the driver core allows for struct class to be in read-only
memory, move the ipmi_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: Corey Minyard <minyard@acm.org>
Cc: openipmi-developer@lists.sourceforge.net
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Message-Id: <20230620143701.577657-2-gregkh@linuxfoundation.org>
Signed-off-by: Corey Minyard <minyard@acm.org>

drivers/char/ipmi/ipmi_devintf.c

@@ -807,7 +807,9 @@ struct ipmi_reg_list {
 static LIST_HEAD(reg_list);
 static DEFINE_MUTEX(reg_list_mutex);
 
-static struct class *ipmi_class;
+static const struct class ipmi_class = {
+	.name = "ipmi",
+};
 
 static void ipmi_new_smi(int if_num, struct device *device)
 {
@@ -822,7 +824,7 @@ static void ipmi_new_smi(int if_num, struct device *device)
 	entry->dev = dev;
 
 	mutex_lock(&reg_list_mutex);
-	device_create(ipmi_class, device, dev, NULL, "ipmi%d", if_num);
+	device_create(&ipmi_class, device, dev, NULL, "ipmi%d", if_num);
 	list_add(&entry->link, &reg_list);
 	mutex_unlock(&reg_list_mutex);
 }
@@ -840,7 +842,7 @@ static void ipmi_smi_gone(int if_num)
 			break;
 		}
 	}
-	device_destroy(ipmi_class, dev);
+	device_destroy(&ipmi_class, dev);
 	mutex_unlock(&reg_list_mutex);
 }
 
@@ -860,15 +862,13 @@ static int __init init_ipmi_devintf(void)
 
 	pr_info("ipmi device interface\n");
 
-	ipmi_class = class_create("ipmi");
-	if (IS_ERR(ipmi_class)) {
-		pr_err("ipmi: can't register device class\n");
-		return PTR_ERR(ipmi_class);
-	}
+	rv = class_register(&ipmi_class);
+	if (rv)
+		return rv;
 
 	rv = register_chrdev(ipmi_major, DEVICE_NAME, &ipmi_fops);
 	if (rv < 0) {
-		class_destroy(ipmi_class);
+		class_unregister(&ipmi_class);
 		pr_err("ipmi: can't get major %d\n", ipmi_major);
 		return rv;
 	}
@@ -880,7 +880,7 @@ static int __init init_ipmi_devintf(void)
 	rv = ipmi_smi_watcher_register(&smi_watcher);
 	if (rv) {
 		unregister_chrdev(ipmi_major, DEVICE_NAME);
-		class_destroy(ipmi_class);
+		class_unregister(&ipmi_class);
 		pr_warn("ipmi: can't register smi watcher\n");
 		return rv;
 	}
@@ -895,11 +895,11 @@ static void __exit cleanup_ipmi(void)
 	mutex_lock(&reg_list_mutex);
 	list_for_each_entry_safe(entry, entry2, &reg_list, link) {
 		list_del(&entry->link);
-		device_destroy(ipmi_class, entry->dev);
+		device_destroy(&ipmi_class, entry->dev);
 		kfree(entry);
 	}
 	mutex_unlock(&reg_list_mutex);
-	class_destroy(ipmi_class);
+	class_unregister(&ipmi_class);
 	ipmi_smi_watcher_unregister(&smi_watcher);
 	unregister_chrdev(ipmi_major, DEVICE_NAME);
 }