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From: Kay Sievers <kay@vrfy.org>
Date: Sun, 3 Mar 2013 07:42:31 +0100
Message-ID: <CAPXgP11Zuz166v_M2EhGDY1U5vKtUwE+fTPAWYEu7UxXsr=g=A@mail.gmail.com>
Subject: Re: [PATCH 30/31] driver/base: implement subsys_virtual_register()
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Tejun Heo <tj@kernel.org>, linux-kernel@vger.kernel.org,
        laijs@cn.fujitsu.com, axboe@kernel.dk, jmoyer@redhat.com,
        zab@redhat.com
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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.

Kay
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