From: Kay Sievers <kay.sievers@vrfy.org>
To: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Greg KH <greg@kroah.com>,
linux-kernel@vger.kernel.org,
Alan Stern <stern@rowland.harvard.edu>,
Jonathan Corbet <corbet@lwn.net>,
Randy Dunlap <randy.dunlap@oracle.com>
Subject: Re: [RFC] New kobject/kset/ktype documentation and example code
Date: Wed, 28 Nov 2007 18:00:27 +0100 [thread overview]
Message-ID: <1196269227.3242.93.camel@lov.site> (raw)
In-Reply-To: <20071128175108.5a370684@gondolin.boeblingen.de.ibm.com>
On Wed, 2007-11-28 at 17:51 +0100, Cornelia Huck wrote:
> On Wed, 28 Nov 2007 17:36:29 +0100,
> Kay Sievers <kay.sievers@vrfy.org> wrote:
>
> >
> > On Wed, 2007-11-28 at 17:12 +0100, Cornelia Huck wrote:
> > > 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.)
>
> <Looks at device_add() again: It already throws the uevent manually...>
I think I still remember what I did 2.5 years ago :)
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e57cd73e2e844a3da25cc6b420674c81bbe1b387
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=18c3d5271b472c096adfc856e107c79f6fd30d7d
> > The driver core does use the split already in most places, I did that
> > long ago. There are not too many (~20) users of kobject_register(), and
> > it's a pretty straight-forward change to change that to _init, _add,
> > _uevent, and get rid of that totally useless "convenience api".
> >
> > I think there is no longer any excuse to keep that broken code around,
> > and even require to document that it's broken. The whole purpose of the
> > uevent is userspace consumption, which just doesn't work correctly with
> > the code we offer. The fix is trivial, and should be done now, and we no
> > longer need to fiddle around timing issues, just because we are too
> > lazy.
> >
> > I propose the removal of _all_ funtions that have *register* in their
> > name, and always require the following sequence:
> > _init()
> > _add()
> > _uevent(_ADD)
> >
> > _uevent(_REMOVE)
> > _del()
> > _put()
> >
> > The _create_and_register() functions would become _create_ and_add()
> > and will need an additional _uevent() call after they populated the
> > object.
>
> I'm absolutely fine with doing that at the kobject level (after all,
> it's a quite contained change, and the uevent function explicitely
> works on a kobject).
>
> For the other _register()/_unregister() functions, it's a different
> piece of cake. They are:
> - distributed through lot of different code
> - at a higher level than kobjects, and kobject_uevent() acts on the
> kobject
> - usually encapsulating a sequence that wants to be used by almost all
> callers, and that includes a uevent
>
> I don't think we want people registering a higher level object and then
> wondering why udev doesn't seem to take notice of it.
Oh, I'm just talking about lib/kobject.c. And the new kobj/kset stuff we
added which is currently in the -mm tree.
It suffers from the same old problem, and even gets documentend as
"broken" now. I really think that should be fixed proper instead, and
it's the right time to do it now.
Thanks,
Kay
next prev parent reply other threads:[~2007-11-28 17:01 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-27 23:02 [RFC] New kobject/kset/ktype documentation and example code Greg KH
2007-11-27 23:03 ` [RFC] sample kobject implementation Greg KH
2007-11-27 23:04 ` [RFC] Sample kset/ktype/kobject implementation Greg KH
2007-11-28 16:35 ` Cornelia Huck
2007-11-29 6:11 ` Greg KH
2007-11-29 9:39 ` Cornelia Huck
2007-11-29 20:39 ` Greg KH
2007-11-29 22:11 ` Alan Stern
2007-11-30 5:07 ` Dave Young
2007-11-30 5:57 ` Dave Young
2007-11-30 14:51 ` Alan Stern
2007-11-30 6:41 ` Greg KH
2007-11-27 23:10 ` [RFC] New kobject/kset/ktype documentation and example code Kyle McMartin
2007-11-27 23:29 ` Greg KH
2007-11-27 23:21 ` Frans Pop
2007-11-28 3:50 ` Jonathan Corbet
2007-11-29 5:46 ` Greg KH
2007-11-28 9:01 ` Cornelia Huck
2007-11-28 12:35 ` Kay Sievers
2007-11-28 15:52 ` Cornelia Huck
2007-11-28 16:03 ` Kay Sievers
2007-11-28 16:09 ` Cornelia Huck
2007-11-28 17:06 ` Greg KH
2007-11-28 19:18 ` Alan Stern
2007-11-29 10:12 ` Cornelia Huck
2007-11-29 15:47 ` Alan Stern
2007-11-29 16:28 ` Cornelia Huck
2007-11-29 16:55 ` Alan Stern
2007-11-29 17:52 ` Cornelia Huck
2007-11-29 5:59 ` Greg KH
2007-11-28 11:45 ` Cornelia Huck
2007-11-28 12:23 ` Kay Sievers
2007-11-28 15:48 ` Cornelia Huck
2007-11-28 15:57 ` Kay Sievers
2007-11-28 16:12 ` Cornelia Huck
2007-11-28 16:36 ` Kay Sievers
2007-11-28 16:51 ` Cornelia Huck
2007-11-28 17:00 ` Kay Sievers [this message]
2007-11-29 6:08 ` Greg KH
2007-11-29 7:50 ` Kay Sievers
2007-11-29 9:35 ` Cornelia Huck
2007-11-29 10:53 ` Kay Sievers
2007-11-29 6:02 ` Greg KH
2007-11-29 6:04 ` Greg KH
2007-11-29 9:41 ` Cornelia Huck
2007-11-28 19:03 ` Alan Stern
2007-11-28 19:28 ` Kay Sievers
2007-11-28 19:36 ` Alan Stern
2007-11-28 19:46 ` Kay Sievers
2007-11-28 20:42 ` [PATCH] kobject: make sure kobj->ktype is set before kobject_init Alan Stern
2007-11-28 20:52 ` Kay Sievers
2007-11-28 21:45 ` Greg KH
2007-11-28 22:00 ` Alan Stern
2007-11-28 22:38 ` Greg KH
2007-11-29 10:05 ` Cornelia Huck
2007-11-29 10:59 ` Kay Sievers
2007-11-29 11:48 ` Cornelia Huck
2007-11-29 15:54 ` Alan Stern
2007-11-29 16:04 ` Kay Sievers
2007-11-29 16:21 ` Cornelia Huck
2007-11-29 21:53 ` kobject_init rewrite Greg KH
2007-11-29 21:54 ` Greg KH
2007-11-30 9:31 ` Cornelia Huck
2007-11-29 22:16 ` Alan Stern
2007-11-29 22:24 ` Greg KH
2007-11-29 17:06 ` [PATCH] kobject: make sure kobj->ktype is set before kobject_init Alan Stern
2007-11-29 17:17 ` Kay Sievers
2007-11-29 18:04 ` Alan Stern
2007-11-29 18:33 ` Kay Sievers
2007-11-29 19:05 ` Alan Stern
2007-11-29 19:51 ` Kay Sievers
2007-11-29 20:09 ` Alan Stern
2007-11-29 20:19 ` Kay Sievers
2007-11-29 20:26 ` Kay Sievers
2007-11-30 9:30 ` Cornelia Huck
2007-11-29 6:18 ` [RFC] New kobject/kset/ktype documentation and example code Greg KH
2007-11-29 15:42 ` Alan Stern
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