dmaengine: idxd: constify the struct device_type usage

Since commit aed65af ("drivers: make device_type const"), the driver
core can properly handle constant struct device_type. Move the
dsa_device_type, iax_device_type, idxd_wq_device_type, idxd_cdev_file_type,
idxd_cdev_device_type and idxd_group_device_type variables to be constant
structures as well, placing it into read-only memory which can not be
modified at runtime.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: "Ricardo B. Marliere" <ricardo@marliere.net>
Reviewed-by: Fenghua Yu <fenghua.yu@intel.com>
Link: https://lore.kernel.org/r/20240219-device_cleanup-dmaengine-v1-1-9f72f3cf3587@marliere.net
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: rbmarliere

drivers/dma/idxd/cdev.c

@@ -152,7 +152,7 @@ static void idxd_file_dev_release(struct device *dev)
 	mutex_unlock(&wq->wq_lock);
 }
 
-static struct device_type idxd_cdev_file_type = {
+static const struct device_type idxd_cdev_file_type = {
 	.name = "idxd_file",
 	.release = idxd_file_dev_release,
 	.groups = cdev_file_attribute_groups,
@@ -169,7 +169,7 @@ static void idxd_cdev_dev_release(struct device *dev)
 	kfree(idxd_cdev);
 }
 
-static struct device_type idxd_cdev_device_type = {
+static const struct device_type idxd_cdev_device_type = {
 	.name = "idxd_cdev",
 	.release = idxd_cdev_dev_release,
 };

drivers/dma/idxd/idxd.h

@@ -282,7 +282,7 @@ typedef int (*load_device_defaults_fn_t) (struct idxd_device *idxd);
 struct idxd_driver_data {
 	const char *name_prefix;
 	enum idxd_type type;
-	struct device_type *dev_type;
+	const struct device_type *dev_type;
 	int compl_size;
 	int align;
 	int evl_cr_off;
@@ -520,11 +520,11 @@ extern const struct bus_type dsa_bus_type;
 
 extern bool support_enqcmd;
 extern struct ida idxd_ida;
-extern struct device_type dsa_device_type;
-extern struct device_type iax_device_type;
-extern struct device_type idxd_wq_device_type;
-extern struct device_type idxd_engine_device_type;
-extern struct device_type idxd_group_device_type;
+extern const struct device_type dsa_device_type;
+extern const struct device_type iax_device_type;
+extern const struct device_type idxd_wq_device_type;
+extern const struct device_type idxd_engine_device_type;
+extern const struct device_type idxd_group_device_type;
 
 static inline bool is_dsa_dev(struct idxd_dev *idxd_dev)
 {

drivers/dma/idxd/sysfs.c

@@ -91,7 +91,7 @@ static void idxd_conf_engine_release(struct device *dev)
 	kfree(engine);
 }
 
-struct device_type idxd_engine_device_type = {
+const struct device_type idxd_engine_device_type = {
 	.name = "engine",
 	.release = idxd_conf_engine_release,
 	.groups = idxd_engine_attribute_groups,
@@ -577,7 +577,7 @@ static void idxd_conf_group_release(struct device *dev)
 	kfree(group);
 }
 
-struct device_type idxd_group_device_type = {
+const struct device_type idxd_group_device_type = {
 	.name = "group",
 	.release = idxd_conf_group_release,
 	.groups = idxd_group_attribute_groups,
@@ -1369,7 +1369,7 @@ static void idxd_conf_wq_release(struct device *dev)
 	kfree(wq);
 }
 
-struct device_type idxd_wq_device_type = {
+const struct device_type idxd_wq_device_type = {
 	.name = "wq",
 	.release = idxd_conf_wq_release,
 	.groups = idxd_wq_attribute_groups,
@@ -1798,13 +1798,13 @@ static void idxd_conf_device_release(struct device *dev)
 	kfree(idxd);
 }
 
-struct device_type dsa_device_type = {
+const struct device_type dsa_device_type = {
 	.name = "dsa",
 	.release = idxd_conf_device_release,
 	.groups = idxd_attribute_groups,
 };
 
-struct device_type iax_device_type = {
+const struct device_type iax_device_type = {
 	.name = "iax",
 	.release = idxd_conf_device_release,
 	.groups = idxd_attribute_groups,