dca: make dca_class a static const structure

The driver core allows for struct class to be in read-only memory. Move
the dca_class structure to be declared at build time placing it into
read-only memory, instead of having to be dynamically allocated at boot
time.

Suggested-by: Greg Kroah-Hartman <[e-mail]>
Signed-off-by: Ivan Orlov <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/dca/dca-sysfs.c

···
 #include <linux/gfp.h>
 #include <linux/export.h>
 
-static struct class *dca_class;
+static const struct class dca_class = {
+	.name = "dca",
+};
 static struct idr dca_idr;
 static spinlock_t dca_idr_lock;
 
···
 	struct device *cd;
 	static int req_count;
 
-	cd = device_create(dca_class, dca->cd, MKDEV(0, slot + 1), NULL,
+	cd = device_create(&dca_class, dca->cd, MKDEV(0, slot + 1), NULL,
 			   "requester%d", req_count++);
 	return PTR_ERR_OR_ZERO(cd);
 }
 
 void dca_sysfs_remove_req(struct dca_provider *dca, int slot)
 {
-	device_destroy(dca_class, MKDEV(0, slot + 1));
+	device_destroy(&dca_class, MKDEV(0, slot + 1));
 }
 
 int dca_sysfs_add_provider(struct dca_provider *dca, struct device *dev)
···
 	if (ret < 0)
 		return ret;
 
-	cd = device_create(dca_class, dev, MKDEV(0, 0), NULL, "dca%d", dca->id);
+	cd = device_create(&dca_class, dev, MKDEV(0, 0), NULL, "dca%d", dca->id);
 	if (IS_ERR(cd)) {
 		spin_lock(&dca_idr_lock);
 		idr_remove(&dca_idr, dca->id);
···
 
 int __init dca_sysfs_init(void)
 {
+	int err;
+
 	idr_init(&dca_idr);
 	spin_lock_init(&dca_idr_lock);
 
-	dca_class = class_create("dca");
-	if (IS_ERR(dca_class)) {
+	err = class_register(&dca_class);
+	if (err) {
 		idr_destroy(&dca_idr);
-		return PTR_ERR(dca_class);
+		return err;
 	}
 	return 0;
 }
 
 void __exit dca_sysfs_exit(void)
 {
-	class_destroy(dca_class);
+	class_unregister(&dca_class);
 	idr_destroy(&dca_idr);
 }