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From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Pingfan Liu <kernelfans@gmail.com>
Cc: linux-kernel@vger.kernel.org,
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
 Grygorii Strashko <grygorii.strashko@ti.com>,
 Christoph Hellwig <hch@infradead.org>, Bjorn Helgaas <helgaas@kernel.org>,
 Dave Young <dyoung@redhat.com>, linux-pci@vger.kernel.org,
 linuxppc-dev@lists.ozlabs.org, Linux PM <linux-pm@vger.kernel.org>
Subject: Re: [PATCHv3 0/4] drivers/base: bugfix for supplier<-consumer
 ordering in device_kset
Date: Wed, 04 Jul 2018 12:21:52 +0200
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On Wednesday, July 4, 2018 4:47:07 AM CEST Pingfan Liu wrote:
> On Tue, Jul 3, 2018 at 10:36 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> >
> > On Tuesday, July 3, 2018 8:50:38 AM CEST Pingfan Liu wrote:
> > > commit 52cdbdd49853 ("driver core: correct device's shutdown order")
> > > places an assumption of supplier<-consumer order on the process of probe.
> > > But it turns out to break down the parent <- child order in some scene.
> > > E.g in pci, a bridge is enabled by pci core, and behind it, the devices
> > > have been probed. Then comes the bridge's module, which enables extra
> > > feature(such as hotplug) on this bridge.
> >
> > So what *exactly* does happen in that case?
> >
> I saw the  shpc_probe() is called on the bridge, although the probing
> failed on that bare-metal. But if it success, then it will enable the
> hotplug feature on the bridge.

I don't understand what you are saying here, sorry.

device_reorder_to_tail() walks the entire device hierarchy below the target
and moves all of the children in there *after* their parents.

How can it break "the parent <- child order" then?

Thanks,
Rafael