Re: [RFC] New kobject/kset/ktype documentation and example code

Cornelia Huck
2007-11-28T16:12:48Z

On Wed, 28 Nov 2007 16:57:48 +0100,
Kay Sievers <kay.sievers@vrfy.org> wrote:

> On Wed, 2007-11-28 at 16:48 +0100, Cornelia Huck wrote:
> > On Wed, 28 Nov 2007 13:23:02 +0100,
> > Kay Sievers <kay.sievers@vrfy.org> wrote:
> > > On Wed, 2007-11-28 at 12:45 +0100, Cornelia Huck wrote:
> > > > On Tue, 27 Nov 2007 15:02:52 -0800, Greg KH <greg@kroah.com> wrote:
>
> > > > > The uevent function will be called when the uevent is about to be sent to
> > > > > userspace to allow more environment variables to be added to the uevent.
> > > >
> > > > It may be helpful to mention which uevents are by default created by
> > > > the kobject core (KOBJ_ADD, KOBJ_DEL, KOBJ_MOVE).
> > >
> > > I think, we should remove all these default events from the kobject
> > > core. We will not be able to manage the timing issues and "raw" kobject
> > > users should request the events on their own, when they are finished
> > > adding stuff to the kobject. I see currently no way to solve the
> > > "attributes created after the event" problem. The new
> > > *_create_and_register functions do not allow default attributes to be
> > > created, which will just lead to serious trouble when someone wants to
> > > use udev to set defaults and such things. We may just want to require an
> > > explicit call to send the event?
> >
> > There will always be attributes that will show up later (for example,
> > after a device is activated). Probably the best approach is to keep the
> > default uevents, but have the attribute-adder send another uevent when
> > they are done?
>
> Uh, that's more an exception where we can't give guarantees because of
> very specific hardware setups, and it would be an additional "change"
> event. There are valid cases for this, but only a _very_ few.
>
> There is absolutely no reason not to do it right with the "add" event,
> just because we are too lazy to solve it proper the current code. It's
> just so broken by design, what we are doing today. :)

I'm worrying a bit about changes that impact the whole code tree in
lots of places. I'd be fine with the device layer doing its uevent
manually in device_add() at the very end, though. (This would allow
drivers to add attributes in their probe function before the uevent,
for example.)