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: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 56536f4b0f6b..f58084a86e8c 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -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;