[PATCH] nvdimm: make nd_class constant

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

Now that the driver core allows for struct class to be in read-only
memory, we should make all 'class' structures declared at build time
placing them into read-only memory, instead of having to be dynamically
allocated at runtime.

Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: nvdimm@lists.linux.dev
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/nvdimm/bus.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
index 508aed017ddc..101c425f3e8b 100644
--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -25,9 +25,12 @@
 
 int nvdimm_major;
 static int nvdimm_bus_major;
-static struct class *nd_class;
 static DEFINE_IDA(nd_ida);
 
+static const struct class nd_class = {
+	.name = "nd",
+};
+
 static int to_nd_device_type(const struct device *dev)
 {
 	if (is_nvdimm(dev))
@@ -742,7 +745,7 @@ int nvdimm_bus_create_ndctl(struct nvdimm_bus *nvdimm_bus)
 	device_initialize(dev);
 	lockdep_set_class(&dev->mutex, &nvdimm_ndctl_key);
 	device_set_pm_not_required(dev);
-	dev->class = nd_class;
+	dev->class = &nd_class;
 	dev->parent = &nvdimm_bus->dev;
 	dev->devt = devt;
 	dev->release = ndctl_release;
@@ -765,7 +768,7 @@ int nvdimm_bus_create_ndctl(struct nvdimm_bus *nvdimm_bus)
 
 void nvdimm_bus_destroy_ndctl(struct nvdimm_bus *nvdimm_bus)
 {
-	device_destroy(nd_class, MKDEV(nvdimm_bus_major, nvdimm_bus->id));
+	device_destroy(&nd_class, MKDEV(nvdimm_bus_major, nvdimm_bus->id));
 }
 
 static const struct nd_cmd_desc __nd_cmd_dimm_descs[] = {
@@ -1320,11 +1323,9 @@ int __init nvdimm_bus_init(void)
 		goto err_dimm_chrdev;
 	nvdimm_major = rc;
 
-	nd_class = class_create("nd");
-	if (IS_ERR(nd_class)) {
-		rc = PTR_ERR(nd_class);
+	rc = class_register(&nd_class);
+	if (rc)
 		goto err_class;
-	}
 
 	rc = driver_register(&nd_bus_driver.drv);
 	if (rc)
@@ -1333,7 +1334,7 @@ int __init nvdimm_bus_init(void)
 	return 0;
 
  err_nd_bus:
-	class_destroy(nd_class);
+	class_unregister(&nd_class);
  err_class:
 	unregister_chrdev(nvdimm_major, "dimmctl");
  err_dimm_chrdev:
@@ -1347,7 +1348,7 @@ int __init nvdimm_bus_init(void)
 void nvdimm_bus_exit(void)
 {
 	driver_unregister(&nd_bus_driver.drv);
-	class_destroy(nd_class);
+	class_unregister(&nd_class);
 	unregister_chrdev(nvdimm_bus_major, "ndctl");
 	unregister_chrdev(nvdimm_major, "dimmctl");
 	bus_unregister(&nvdimm_bus_type);
-- 
2.45.2