driver core: make struct device_type.devnode() take a const *

The devnode() callback in struct device_type should not be modifying the
device that is passed into it, so mark it as a const * and propagate the
function signature changes out into all relevant subsystems that use
this callback.

Cc: Jens Axboe <axboe@kernel.dk>
Cc: Alison Schofield <alison.schofield@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Ben Widawsky <bwidawsk@kernel.org>
Cc: Jeremy Kerr <jk@ozlabs.org>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Alistar Popple <alistair@popple.id.au>
Cc: Eddie James <eajames@linux.ibm.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jilin Yuan <yuanjilin@cdjrlc.com>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Won Chung <wonchung@google.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20230111113018.459199-7-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

block/genhd.c

@@ -1201,7 +1201,7 @@ struct class block_class = {
 	.dev_uevent	= block_uevent,
 };
 
-static char *block_devnode(struct device *dev, umode_t *mode,
+static char *block_devnode(const struct device *dev, umode_t *mode,
 			   kuid_t *uid, kgid_t *gid)
 {
 	struct gendisk *disk = dev_to_disk(dev);

drivers/cxl/core/memdev.c

@@ -27,7 +27,7 @@ static void cxl_memdev_release(struct device *dev)
 	kfree(cxlmd);
 }
 
-static char *cxl_memdev_devnode(struct device *dev, umode_t *mode, kuid_t *uid,
+static char *cxl_memdev_devnode(const struct device *dev, umode_t *mode, kuid_t *uid,
 				kgid_t *gid)
 {
 	return kasprintf(GFP_KERNEL, "cxl/%s", dev_name(dev));

drivers/fsi/fsi-core.c

@@ -897,10 +897,10 @@ static const struct attribute_group *cfam_attr_groups[] = {
 	NULL,
 };
 
-static char *cfam_devnode(struct device *dev, umode_t *mode,
+static char *cfam_devnode(const struct device *dev, umode_t *mode,
 			  kuid_t *uid, kgid_t *gid)
 {
-	struct fsi_slave *slave = to_fsi_slave(dev);
+	const struct fsi_slave *slave = to_fsi_slave(dev);
 
 #ifdef CONFIG_FSI_NEW_DEV_NODE
 	return kasprintf(GFP_KERNEL, "fsi/cfam%d", slave->cdev_idx);
@@ -915,7 +915,7 @@ static const struct device_type cfam_type = {
 	.groups = cfam_attr_groups
 };
 
-static char *fsi_cdev_devnode(struct device *dev, umode_t *mode,
+static char *fsi_cdev_devnode(const struct device *dev, umode_t *mode,
 			      kuid_t *uid, kgid_t *gid)
 {
 #ifdef CONFIG_FSI_NEW_DEV_NODE

drivers/hwtracing/intel_th/core.c

@@ -185,11 +185,11 @@ static struct device_type intel_th_source_device_type = {
 	.release	= intel_th_device_release,
 };
 
-static char *intel_th_output_devnode(struct device *dev, umode_t *mode,
+static char *intel_th_output_devnode(const struct device *dev, umode_t *mode,
 				     kuid_t *uid, kgid_t *gid)
 {
-	struct intel_th_device *thdev = to_intel_th_device(dev);
-	struct intel_th *th = to_intel_th(thdev);
+	const struct intel_th_device *thdev = to_intel_th_device(dev);
+	const struct intel_th *th = to_intel_th(thdev);
 	char *node;
 
 	if (thdev->id >= 0)

drivers/hwtracing/intel_th/intel_th.h

@@ -205,7 +205,7 @@ struct intel_th_driver {
  * INTEL_TH_SWITCH and INTEL_TH_SOURCE are children of the intel_th device.
  */
 static inline struct intel_th_device *
-to_intel_th_parent(struct intel_th_device *thdev)
+to_intel_th_parent(const struct intel_th_device *thdev)
 {
 	struct device *parent = thdev->dev.parent;
 
@@ -215,7 +215,7 @@ to_intel_th_parent(struct intel_th_device *thdev)
 	return to_intel_th_device(parent);
 }
 
-static inline struct intel_th *to_intel_th(struct intel_th_device *thdev)
+static inline struct intel_th *to_intel_th(const struct intel_th_device *thdev)
 {
 	if (thdev->type == INTEL_TH_OUTPUT)
 		thdev = to_intel_th_parent(thdev);

drivers/usb/core/usb.c

@@ -505,10 +505,10 @@ static const struct dev_pm_ops usb_device_pm_ops = {
 #endif	/* CONFIG_PM */
 
 
-static char *usb_devnode(struct device *dev,
+static char *usb_devnode(const struct device *dev,
 			 umode_t *mode, kuid_t *uid, kgid_t *gid)
 {
-	struct usb_device *usb_dev;
+	const struct usb_device *usb_dev;
 
 	usb_dev = to_usb_device(dev);
 	return kasprintf(GFP_KERNEL, "bus/usb/%03d/%03d",

include/linux/device.h

@@ -89,7 +89,7 @@ struct device_type {
 	const char *name;
 	const struct attribute_group **groups;
 	int (*uevent)(const struct device *dev, struct kobj_uevent_env *env);
-	char *(*devnode)(struct device *dev, umode_t *mode,
+	char *(*devnode)(const struct device *dev, umode_t *mode,
 			 kuid_t *uid, kgid_t *gid);
 	void (*release)(struct device *dev);