driver core: bus: constantify the bus_find_* functions

All of the bus find and iterator functions do not modify the struct
bus_type passed to them, so mark them as constant to enforce this rule.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230208111330.439504-4-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/bus.c

@@ -331,7 +331,7 @@ static struct device *next_device(struct klist_iter *i)
  * to retain this data, it should do so, and increment the reference
  * count in the supplied callback.
  */
-int bus_for_each_dev(struct bus_type *bus, struct device *start,
+int bus_for_each_dev(const struct bus_type *bus, struct device *start,
 		     void *data, int (*fn)(struct device *, void *))
 {
 	struct klist_iter i;
@@ -365,7 +365,7 @@ EXPORT_SYMBOL_GPL(bus_for_each_dev);
  * if it does.  If the callback returns non-zero, this function will
  * return to the caller and not iterate over any more devices.
  */
-struct device *bus_find_device(struct bus_type *bus,
+struct device *bus_find_device(const struct bus_type *bus,
 			       struct device *start, const void *data,
 			       int (*match)(struct device *dev, const void *data))
 {
@@ -416,7 +416,7 @@ static struct device_driver *next_driver(struct klist_iter *i)
  * in the callback. It must also be sure to increment the refcount
  * so it doesn't disappear before returning to the caller.
  */
-int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
+int bus_for_each_drv(const struct bus_type *bus, struct device_driver *start,
 		     void *data, int (*fn)(struct device_driver *, void *))
 {
 	struct klist_iter i;

include/linux/device/bus.h

@@ -149,9 +149,9 @@ int device_match_acpi_handle(struct device *dev, const void *handle);
 int device_match_any(struct device *dev, const void *unused);
 
 /* iterator helpers for buses */
-int bus_for_each_dev(struct bus_type *bus, struct device *start, void *data,
+int bus_for_each_dev(const struct bus_type *bus, struct device *start, void *data,
 		     int (*fn)(struct device *dev, void *data));
-struct device *bus_find_device(struct bus_type *bus, struct device *start,
+struct device *bus_find_device(const struct bus_type *bus, struct device *start,
 			       const void *data,
 			       int (*match)(struct device *dev, const void *data));
 /**
@@ -161,7 +161,7 @@ struct device *bus_find_device(struct bus_type *bus, struct device *start,
  * @start: Device to begin with
  * @name: name of the device to match
  */
-static inline struct device *bus_find_device_by_name(struct bus_type *bus,
+static inline struct device *bus_find_device_by_name(const struct bus_type *bus,
 						     struct device *start,
 						     const char *name)
 {
@@ -175,7 +175,7 @@ static inline struct device *bus_find_device_by_name(struct bus_type *bus,
  * @np: of_node of the device to match.
  */
 static inline struct device *
-bus_find_device_by_of_node(struct bus_type *bus, const struct device_node *np)
+bus_find_device_by_of_node(const struct bus_type *bus, const struct device_node *np)
 {
 	return bus_find_device(bus, NULL, np, device_match_of_node);
 }
@@ -187,7 +187,7 @@ bus_find_device_by_of_node(struct bus_type *bus, const struct device_node *np)
  * @fwnode: fwnode of the device to match.
  */
 static inline struct device *
-bus_find_device_by_fwnode(struct bus_type *bus, const struct fwnode_handle *fwnode)
+bus_find_device_by_fwnode(const struct bus_type *bus, const struct fwnode_handle *fwnode)
 {
 	return bus_find_device(bus, NULL, fwnode, device_match_fwnode);
 }
@@ -198,7 +198,7 @@ bus_find_device_by_fwnode(struct bus_type *bus, const struct fwnode_handle *fwno
  * @bus: bus type
  * @devt: device type of the device to match.
  */
-static inline struct device *bus_find_device_by_devt(struct bus_type *bus,
+static inline struct device *bus_find_device_by_devt(const struct bus_type *bus,
 						     dev_t devt)
 {
 	return bus_find_device(bus, NULL, &devt, device_match_devt);
@@ -211,7 +211,7 @@ static inline struct device *bus_find_device_by_devt(struct bus_type *bus,
  * @cur: device to begin the search with.
  */
 static inline struct device *
-bus_find_next_device(struct bus_type *bus,struct device *cur)
+bus_find_next_device(const struct bus_type *bus,struct device *cur)
 {
 	return bus_find_device(bus, cur, NULL, device_match_any);
 }
@@ -226,19 +226,19 @@ struct acpi_device;
  * @adev: ACPI COMPANION device to match.
  */
 static inline struct device *
-bus_find_device_by_acpi_dev(struct bus_type *bus, const struct acpi_device *adev)
+bus_find_device_by_acpi_dev(const struct bus_type *bus, const struct acpi_device *adev)
 {
 	return bus_find_device(bus, NULL, adev, device_match_acpi_dev);
 }
 #else
 static inline struct device *
-bus_find_device_by_acpi_dev(struct bus_type *bus, const void *adev)
+bus_find_device_by_acpi_dev(const struct bus_type *bus, const void *adev)
 {
 	return NULL;
 }
 #endif
 
-int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
+int bus_for_each_drv(const struct bus_type *bus, struct device_driver *start,
 		     void *data, int (*fn)(struct device_driver *, void *));
 void bus_sort_breadthfirst(struct bus_type *bus,
 			   int (*compare)(const struct device *a,