What's tha KOBJ_MAX action used for?

[Greg KH]

A: http://en.wikipedia.org/wiki/Top_post
Q: Were do I find info about this thing called top-posting?
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

A: No.
Q: Should I include quotations after my reply?

http://daringfireball.net/2007/07/on_top

On Tue, Jul 14, 2020 at 04:36:15PM +0200, Garrit Franke wrote:
> Thanks for your replies. Also, thanks greg for your thorough review on my
> corresponding patch (https://lkml.org/lkml/2020/7/14/84), I learned a lot!
> 
> I have been digging around about Kobjects a bit. They are nicely documented.
> Still, no documentation exists about this KOBJ_MAX action.

Please look at commit 60a96a59569b ("Driver core: accept all valid
action-strings in uevent-trigger") in the tree.  That's when it was
added, and it was used.

Then a short bit later, 5c5daf657cb5 ("Driver core: exclude
kobject_uevent.c for !CONFIG_HOTPLUG") stopped using it in the .c files,
and no one noticed that it should have been removed.


> This post on stackoverflow mentions that it's a "special" field that marks the
> end of the enum (if I understand correctly):
> https://stackoverflow.com/a/23149574/9046809
> This lead me to think that this is a convention I'm not aware of, but
> I could not find any
> resources that described such a thing, so I discarded that idea.
> 
> If I understand correctly, this action can in fact be passed to userspace by the
> kobject_uevent function, so it would be a bad idea to remove it. Is my
> reasoning correct?

Yes, if it did get passed to userspace.  But it doesn't, as you can see
by the last commit I referenced above.  We pass strings to userspace for
the kobject events and we take that same string sent to us from
userspace to send "fake" kobject uevents as well.

Also, the loop that we checked for KOBJ_MAX is no longer present, we do
a much more sane ARRAY_SIZE() check, right?  So I don't think it's
needed.

Can you rewrite your changelog text with all of this new information and
resend it?  I'll be glad to take the patch then.

thanks,

greg k-h