Commit 9cc61e5f authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman
Browse files

driver core: bus: move dev_root out of struct bus_type 

Now that all accesses of dev_root is through the bus_get_dev_root()
call, move the pointer out of struct bus_type and into the private
dynamic structure, subsys_private.

With this change, there is no modifiable portions of struct bus_type so
it can be marked as a constant structure and moved to read-only memory.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230313182918.1312597-22-gregkh@linuxfoundation.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent bf6479db

drivers/base/base.h

+2 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
 *                 on this bus.

 * @bus - pointer back to the struct bus_type that this structure is associated

 *        with.

 * @dev_root: Default device to use as the parent.

 *

 * @glue_dirs - "glue" directory to put in-between the parent device to

 *              avoid namespace conflicts
@@ -49,6 +50,7 @@ struct subsys_private { 
	struct blocking_notifier_head bus_notifier;

	unsigned int drivers_autoprobe:1;

	struct bus_type *bus;

	struct device *dev_root;



	struct kset glue_dirs;

	struct class *class;

drivers/base/bus.c

+22 −6
Original line number Diff line number Diff line
@@ -935,8 +935,8 @@ void bus_unregister(const struct bus_type *bus) 
		return;



	pr_debug("bus: '%s': unregistering\n", bus->name);

	if (bus->dev_root)

		device_unregister(bus->dev_root);

	if (sp->dev_root)

		device_unregister(sp->dev_root);



	bus_kobj = &sp->subsys.kobj;

	sysfs_remove_groups(bus_kobj, bus->bus_groups);
@@ -1198,6 +1198,7 @@ static int subsys_register(struct bus_type *subsys, 
			   const struct attribute_group **groups,

			   struct kobject *parent_of_root)

{

	struct subsys_private *sp;

	struct device *dev;

	int err;
@@ -1205,6 +1206,12 @@ static int subsys_register(struct bus_type *subsys, 
	if (err < 0)

		return err;



	sp = bus_to_subsys(subsys);

	if (!sp) {

		err = -EINVAL;

		goto err_sp;

	}



	dev = kzalloc(sizeof(struct device), GFP_KERNEL);

	if (!dev) {

		err = -ENOMEM;
@@ -1223,7 +1230,8 @@ static int subsys_register(struct bus_type *subsys, 
	if (err < 0)

		goto err_dev_reg;



	subsys->dev_root = dev;

	sp->dev_root = dev;

	subsys_put(sp);

	return 0;



err_dev_reg:
@@ -1232,6 +1240,8 @@ static int subsys_register(struct bus_type *subsys, 
err_name:

	kfree(dev);

err_dev:

	subsys_put(sp);

err_sp:

	bus_unregister(subsys);

	return err;

}
@@ -1349,9 +1359,15 @@ bool bus_is_registered(const struct bus_type *bus) 
 */

struct device *bus_get_dev_root(const struct bus_type *bus)

{

	if (bus)

		return get_device(bus->dev_root);

	struct subsys_private *sp = bus_to_subsys(bus);

	struct device *dev_root;



	if (!sp)

		return NULL;



	dev_root = get_device(sp->dev_root);

	subsys_put(sp);

	return dev_root;

}

EXPORT_SYMBOL_GPL(bus_get_dev_root);

include/linux/device/bus.h

+0 −2
Original line number Diff line number Diff line
@@ -26,7 +26,6 @@ struct fwnode_handle; 
 *

 * @name:	The name of the bus.

 * @dev_name:	Used for subsystems to enumerate devices like ("foo%u", dev->id).

 * @dev_root:	Default device to use as the parent.

 * @bus_groups:	Default attributes of the bus.

 * @dev_groups:	Default attributes of the devices on the bus.

 * @drv_groups: Default attributes of the device drivers on the bus.
@@ -82,7 +81,6 @@ struct fwnode_handle; 
struct bus_type {

	const char		*name;

	const char		*dev_name;

	struct device		*dev_root;

	const struct attribute_group **bus_groups;

	const struct attribute_group **dev_groups;

	const struct attribute_group **drv_groups;