linux-kernel - Re: [PATCH 2/2] drivers: core: Remove glue dirs from sysfs earlier

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Date:   Mon, 2 Jul 2018 19:26:59 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Tejun Heo <tj@...nel.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Joel Stanley <joel@....id.au>
Subject: Re: [PATCH 2/2] drivers: core: Remove glue dirs from sysfs earlier

On Mon, Jul 2, 2018 at 7:15 PM Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> It's whitespace-damaged on purpose. It's probably broken shit. DO NOT
> USE UNDER ANY CIRCUMSTANCES.  Think of it more as a "something like
> this might work, but probably doesn't". Maybe it gives you an idea,
> although that idea might be "Linus has finally lost it".

Even if it were to work, it should probably just be done inside kernfs
and exposed as some kind of "kernfs_remove_if_empty()" function.

We happen to know that we hold the lock that creates all the entries
in the glue directory (and we don't allow users to move or create
stuff, afaik, even if we alloc chmod etc), so there should be no
races, but a generic kernfs helper function would probably have to get
proper locks and check it the right way.

                Linus