linux-kernel - Re: [GIT PULL] Driver core fixes for 5.7-rc7

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Date:   Sun, 24 May 2020 17:38:54 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>
Subject: Re: [GIT PULL] Driver core fixes for 5.7-rc7 - take 2

On Sun, May 24, 2020 at 05:00:18PM +0200, Greg KH wrote:
> On Sat, May 23, 2020 at 11:14:28AM -0700, Linus Torvalds wrote:
> > On Sat, May 23, 2020 at 8:29 AM Greg KH <gregkh@...uxfoundation.org> wrote:
> > >
> > > The kobject patch that was originally in here has now been reverted, as
> > > Guenter reported boot problems with it on some of his systems.
> > 
> > Hmm. That original patch looks obviously buggy: in kobject_cleanup()
> > it would end up doing "kobject_put(parent)" regardless of whether it
> > had actually done __kobject_del() or not.
> > 
> > That _could_ have been intentional, but considering the commit
> > message, it clearly wasn't in this case.  It might be worth re-trying
> > to the commit, just with that fixed.
> 
> Turns out that wasn't the real problem here, the culprit is the
> lib/test_printf.c code trying to tear down a kobject tree from the
> parent down to the children (i.e. in the backwards order).

The fix for this is now posted here:
	https://lore.kernel.org/lkml/20200524153041.2361-1-gregkh@linuxfoundation.org/

along with a kobject change to emit the remove uevent when the object is
removed from sysfs (and still has a valid parent pointer), and not some
unspecified time in the future.

Let's see if people find this a better solution, and if so, I'll send it
to you later in the week.

thanks,

greg k-h