Messages in this thread | | | Subject | Re: [RFC] New kobject/kset/ktype documentation and example code | From | Kay Sievers <> | Date | Wed, 28 Nov 2007 18:00:27 +0100 |
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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
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