linux-kernel - Re: [PATCH] kobject: Make sure the parent does not get released before its children

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Message-ID: <20200515151036.GA2574646@kroah.com>
Date:   Fri, 15 May 2020 17:10:36 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:     Randy Dunlap <rdunlap@...radead.org>,
        Brendan Higgins <brendanhiggins@...gle.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Naresh Kamboju <naresh.kamboju@...aro.org>,
        kernel test robot <rong.a.chen@...el.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH] kobject: Make sure the parent does not get released
 before its children

On Thu, May 14, 2020 at 09:54:15AM +0300, Heikki Krogerus wrote:
> On Wed, May 13, 2020 at 04:14:51PM -0700, Randy Dunlap wrote:
> > On 5/13/20 2:30 PM, Brendan Higgins wrote:
> > > On Wed, May 13, 2020 at 8:18 AM Heikki Krogerus
> > > <heikki.krogerus@...ux.intel.com> wrote:
> > >>
> > >> In the function kobject_cleanup(), kobject_del(kobj) is
> > >> called before the kobj->release(). That makes it possible to
> > >> release the parent of the kobject before the kobject itself.
> > >>
> > >> To fix that, adding function __kboject_del() that does
> > >> everything that kobject_del() does except release the parent
> > >> reference. kobject_cleanup() then calls __kobject_del()
> > >> instead of kobject_del(), and separately decrements the
> > >> reference count of the parent kobject after kobj->release()
> > >> has been called.
> > >>
> > >> Reported-by: Naresh Kamboju <naresh.kamboju@...aro.org>
> > >> Reported-by: kernel test robot <rong.a.chen@...el.com>
> > >> Fixes: 7589238a8cf3 ("Revert "software node: Simplify software_node_release() function"")
> > >> Cc: Brendan Higgins <brendanhiggins@...gle.com>
> > >> Cc: Randy Dunlap <rdunlap@...radead.org>
> > >> Suggested-by: "Rafael J. Wysocki" <rafael@...nel.org>
> > >> Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> > > 
> > > Reviewed-by: Brendan Higgins <brendanhiggins@...gle.com>
> > > Tested-by: Brendan Higgins <brendanhiggins@...gle.com>
> > > 
> > 
> > Acked-by: Randy Dunlap <rdunlap@...radead.org>
> > Tested-by: Randy Dunlap <rdunlap@...radead.org>
> 
> Thanks guys. Sorry about the mix-up.

I didn't get the chance to review this today, will do so on Monday,
thanks.

greg k-h