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

Greg Kroah-Hartman
2013-03-07T23:31:14Z

On Tue, Mar 05, 2013 at 12:43:27PM -0800, Tejun Heo wrote:
> 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.

Sorry for the delay, I'm at a conference all this week, and haven't had
much time to think about this.

If Kay says this is ok for now, that's good enough for me.

thanks,

greg k-h