linux-kernel - Re: [PATCH 1/2] drivers: core: Don't try to use a dead glue

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Message-ID: <57c12574e0daf5f38dd8e871299b8dd4f41c5d53.camel@kernel.crashing.org>
Date:   Mon, 23 Jul 2018 10:35:43 +1000
From:   Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Joel Stanley <joel@....id.au>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] drivers: core: Don't try to use a dead glue_dir

On Sat, 2018-07-21 at 09:53 +0200, Greg Kroah-Hartman wrote:
> > > So I hate using kobject_get_unless_zero(), and resisted ever adding it
> > > to the tree as it shows a bad locking/tree situation as you point out
> > > here.  But for some reason, the block developers seemed to insist they
> > > needed it, and so it is in the tree for them.  I don't want it to spread
> > > if at all possible, which makes me want to reject this patch as this
> > > should be "a case that can never be hit".
> > 
> > Except it can in that situation... at least unless you get my patch 2/2
> > (or the newer one I'm about to send that avoids adding a child counter
> > and uses the one in kernfs instead).
> 
> To follow up on this.  I've applied the 2/2 patch for this series, so
> this 1/2 "should" not be needed.  Ben, if you still see this trigger
> with that, I guess I can take this, but it still feels wrong to me :)

I've tested my repro-case with only patch 2 and it doesn't trigger
anymore, as expected.

That said, you and Linus might want to sync your clocks on how sysfs
"should" work :-)

Cheers,
Ben.