From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Date: Tue, 3 Jul 2018 09:51:06 +0200 From: Lukas Wunner To: Pingfan Liu Cc: linux-kernel@vger.kernel.org, Greg Kroah-Hartman , "Rafael J . Wysocki" , Grygorii Strashko , Christoph Hellwig , Bjorn Helgaas , Dave Young , linux-pci@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCHv3 2/4] drivers/base: utilize device tree info to shutdown devices Message-ID: <20180703075106.GA21136@wunner.de> References: <1530600642-25090-1-git-send-email-kernelfans@gmail.com> <1530600642-25090-3-git-send-email-kernelfans@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1530600642-25090-3-git-send-email-kernelfans@gmail.com> List-ID: On Tue, Jul 03, 2018 at 02:50:40PM +0800, 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. This will break the > parent<-children order and cause failure when "kexec -e" in some scenario. > > The detailed description of the scenario: > An IBM Power9 machine on which, two drivers portdrv_pci and shpchp(a mod) > match the PCI_CLASS_BRIDGE_PCI, but neither of them success to probe due > to some issue. For this case, the bridge is moved after its children in > devices_kset. Then, when "kexec -e", a ata-disk behind the bridge can not > write back buffer in flight due to the former shutdown of the bridge which > clears the BusMaster bit. If you revert commit cc27b735ad3a ("PCI/portdrv: Turn off PCIe services during shutdown"), does the issue go away?