Commit d73ce004 authored by Tejun Heo's avatar Tejun Heo
Browse files

driver/base: implement subsys_virtual_register() 



Kay tells me the most appropriate place to expose workqueues to
userland would be /sys/devices/virtual/workqueues/WQ_NAME which is
symlinked to /sys/bus/workqueue/devices/WQ_NAME and that we're lacking
a way to do that outside of driver core as virtual_device_parent()
isn't exported and there's no inteface to conveniently create a
virtual subsystem.

This patch implements subsys_virtual_register() by factoring out
subsys_register() from subsys_system_register() and using it with
virtual_device_parent() as the origin directory.  It's identical to
subsys_system_register() other than the origin directory but we aren't
gonna restrict the device names which should be used under it.

This will be used to expose workqueue attributes to userland.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
parent 6dbe51c2

drivers/base/base.h

+2 −0
Original line number Diff line number Diff line
@@ -101,6 +101,8 @@ static inline int hypervisor_init(void) { return 0; } 
extern int platform_bus_init(void);

extern void cpu_dev_init(void);



struct kobject *virtual_device_parent(struct device *dev);



extern int bus_add_device(struct device *dev);

extern void bus_probe_device(struct device *dev);

extern void bus_remove_device(struct device *dev);

drivers/base/bus.c

+52 −21
Original line number Diff line number Diff line
@@ -1205,26 +1205,10 @@ static void system_root_device_release(struct device *dev) 
{

	kfree(dev);

}

/**

 * subsys_system_register - register a subsystem at /sys/devices/system/

 * @subsys: system subsystem

 * @groups: default attributes for the root device

 *

 * All 'system' subsystems have a /sys/devices/system/<name> root device

 * with the name of the subsystem. The root device can carry subsystem-

 * wide attributes. All registered devices are below this single root

 * device and are named after the subsystem with a simple enumeration

 * number appended. The registered devices are not explicitely named;

 * only 'id' in the device needs to be set.

 *

 * Do not use this interface for anything new, it exists for compatibility

 * with bad ideas only. New subsystems should use plain subsystems; and

 * add the subsystem-wide attributes should be added to the subsystem

 * directory itself and not some create fake root-device placed in

 * /sys/devices/system/<name>.

 */

int subsys_system_register(struct bus_type *subsys,

			   const struct attribute_group **groups)



static int subsys_register(struct bus_type *subsys,

			   const struct attribute_group **groups,

			   struct kobject *parent_of_root)

{

	struct device *dev;

	int err;
@@ -1243,7 +1227,7 @@ int subsys_system_register(struct bus_type *subsys, 
	if (err < 0)

		goto err_name;



	dev->kobj.parent = &system_kset->kobj;

	dev->kobj.parent = parent_of_root;

	dev->groups = groups;

	dev->release = system_root_device_release;
@@ -1263,8 +1247,55 @@ err_dev: 
	bus_unregister(subsys);

	return err;

}



/**

 * subsys_system_register - register a subsystem at /sys/devices/system/

 * @subsys: system subsystem

 * @groups: default attributes for the root device

 *

 * All 'system' subsystems have a /sys/devices/system/<name> root device

 * with the name of the subsystem. The root device can carry subsystem-

 * wide attributes. All registered devices are below this single root

 * device and are named after the subsystem with a simple enumeration

 * number appended. The registered devices are not explicitely named;

 * only 'id' in the device needs to be set.

 *

 * Do not use this interface for anything new, it exists for compatibility

 * with bad ideas only. New subsystems should use plain subsystems; and

 * add the subsystem-wide attributes should be added to the subsystem

 * directory itself and not some create fake root-device placed in

 * /sys/devices/system/<name>.

 */

int subsys_system_register(struct bus_type *subsys,

			   const struct attribute_group **groups)

{

	return subsys_register(subsys, groups, &system_kset->kobj);

}

EXPORT_SYMBOL_GPL(subsys_system_register);



/**

 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/

 * @subsys: virtual subsystem

 * @groups: default attributes for the root device

 *

 * All 'virtual' subsystems have a /sys/devices/system/<name> root device

 * with the name of the subystem.  The root device can carry subsystem-wide

 * attributes.  All registered devices are below this single root device.

 * There's no restriction on device naming.  This is for kernel software

 * constructs which need sysfs interface.

 */

int subsys_virtual_register(struct bus_type *subsys,

			    const struct attribute_group **groups)

{

	struct kobject *virtual_dir;



	virtual_dir = virtual_device_parent(NULL);

	if (!virtual_dir)

		return -ENOMEM;



	return subsys_register(subsys, groups, virtual_dir);

}



int __init buses_init(void)

{

	bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);

drivers/base/core.c

+1 −1
Original line number Diff line number Diff line
@@ -690,7 +690,7 @@ void device_initialize(struct device *dev) 
	set_dev_node(dev, -1);

}



static struct kobject *virtual_device_parent(struct device *dev)

struct kobject *virtual_device_parent(struct device *dev)

{

	static struct kobject *virtual_dir = NULL;

include/linux/device.h

+2 −0
Original line number Diff line number Diff line
@@ -302,6 +302,8 @@ void subsys_interface_unregister(struct subsys_interface *sif); 


int subsys_system_register(struct bus_type *subsys,

			   const struct attribute_group **groups);

int subsys_virtual_register(struct bus_type *subsys,

			    const struct attribute_group **groups);



/**

 * struct class - device classes

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