Re: [PATCH 30/31] driver/base: implement subsys_virtual_register()

Tejun Heo
2013-03-05T20:43:34Z

On Sun, Mar 03, 2013 at 07:42:31AM +0100, Kay Sievers wrote:
> On Sat, Mar 2, 2013 at 7:17 PM, Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> > On Fri, Mar 01, 2013 at 07:24:21PM -0800, Tejun Heo wrote:
> >> 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.
> >
> > I'm almost afraid to ask what you want to export to userspace for a
> > workqueue that userspace would care about...
> >
> > If you create a subsystem, the devices will show up under the virtual
> > "bus" if you don't give them a parent, so this patch shouldn't be
> > needed, unless you are abusing the driver model. What am I missing
> > here?
>
> Unfortunately, the parent == NULL --> /sys/devices/virtual/<subsys>/
> we have only implemented for classes, and not for buses. We should fix
> that.

Greg, how should I proceed on this? As I wrote before, I don't really
care about where or how. As long as I can make workqueues visible to
userland, I'm happy.

Thanks.

--
tejun