From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0992EC4361B for ; Thu, 3 Dec 2020 22:26:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A8B962228A for ; Thu, 3 Dec 2020 22:26:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729618AbgLCW0a (ORCPT ); Thu, 3 Dec 2020 17:26:30 -0500 Received: from mail.kernel.org ([198.145.29.99]:53180 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728375AbgLCW03 (ORCPT ); Thu, 3 Dec 2020 17:26:29 -0500 Date: Thu, 3 Dec 2020 16:25:46 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1607034348; bh=yVGI5M3I+UaUj1E+WUU3WDgydAUggfjpWAyIFD8U8a0=; h=From:To:Cc:Subject:In-Reply-To:From; b=gnJTeSyyvIGQsuiX/SRqFPYlTpyAxvF61lG4Fzo2zV21oYkSGG88LokJnP0Oqmsei 4DH0S3EA46iatrqA4Fq8J1MJZ1O43gmkPW5I94429Vi1hWRpyg/5EMeW05Qi7qTCWA ENlVjSewzZzGnVvUA6Vcnp0AGqiVvQsvY8XDMh9+WFrjlSScThiNx0iDGPf3DMzR5b 5GSWPT6kNlbkLt8x4/TkcsUxC6m8GrpHM4DZVE2LCAMUnH1zUgaox5QXtANsxUD5I3 X/1/0JVVDYAhpIkdE6NI3Yp1hhr8VtH4ZFyZKOKOdNibnAcr6kmZrNFDlq70zGXP0K Rsfk+DDONtQXg== From: Bjorn Helgaas To: "Kelley, Sean V" Cc: "bhelgaas@google.com" , Jonathan Cameron , "xerces.zhao@gmail.com" , "Wysocki, Rafael J" , "Raj, Ashok" , "Luck, Tony" , "Kuppuswamy, Sathyanarayanan" , "Zhuo, Qiuxu" , Linux PCI , Linux Kernel Mailing List , Kuppuswamy Sathyanarayanan Subject: Re: [PATCH v12 05/15] PCI/ERR: Simplify by using pci_upstream_bridge() Message-ID: <20201203222546.GA1600426@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 03, 2020 at 06:45:00PM +0000, Kelley, Sean V wrote: > Just confirming that when switched from dev->bus->self to > pci_upstream_bridge() we’re okay with the NULL case: > > > On Nov 20, 2020, at 4:10 PM, Sean V Kelley wrote: > > > > Use pci_upstream_bridge() in place of dev->bus->self. No functional change > > intended. > > > > [bhelgaas: split to separate patch] > > Link: https://lore.kernel.org/r/20201002184735.1229220-6-seanvk.dev@oregontracks.org > > Signed-off-by: Sean V Kelley > > Signed-off-by: Bjorn Helgaas > > Acked-by: Jonathan Cameron > > Reviewed-by: Kuppuswamy Sathyanarayanan > > --- > > drivers/pci/pcie/err.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c > > index db149c6ce4fb..05f61da5ed9d 100644 > > --- a/drivers/pci/pcie/err.c > > +++ b/drivers/pci/pcie/err.c > > @@ -159,7 +159,7 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev, > > */ > > if (!(pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT || > > pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM)) > > - dev = dev->bus->self; > > + dev = pci_upstream_bridge(dev); > > The only case where pci_upstream_bridge(dev) could be NULL is if > dev->bus is the root bus and we are being selective based on the > type. Yes, pci_upstream_bridge(dev) returns NULL if dev is on a root bus. I think bus->self is NULL for root buses anyway, so I think this patch is OK at least at this point in the series. > Even later in this series when we actually add in RC_EC/RC_END we > maintain the conditional checks: > > https://lore.kernel.org/linux-pci/20201121001036.8560-11-sean.v.kelley@intel.com/ > > pci_ers_result_t pcie_do_recovery(struct pci_dev *dev, > > @@ -174,10 +180,13 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev, > > > /* > * Error recovery runs on all subordinates of the bridge. If the > - * bridge detected the error, it is cleared at the end. > + * bridge detected the error, it is cleared at the end. For RCiEPs > + * we should reset just the RCiEP itself. > > */ > if (type == PCI_EXP_TYPE_ROOT_PORT || > - type == PCI_EXP_TYPE_DOWNSTREAM) > + type == PCI_EXP_TYPE_DOWNSTREAM || > + type == PCI_EXP_TYPE_RC_EC || > + type == PCI_EXP_TYPE_RC_END) > bridge = dev; > else > bridge = pci_upstream_bridge(dev); > > I believe we are okay here. Well, I think we're at least no worse than today. Today we keep "bridge == dev" for Root Ports and Downstream Ports, and use "bridge = dev->bus->self" for everything else. After this series we keep "bridge == dev" for RCEC and RCiEPs in addition. I'm not sure about PCI_EXP_TYPE_PCI_BRIDGE, which is a PCIe-to-PCI bridge. According to the ancient "PCI Express to PCI/PCI-X Bridge Specification" r1.0 of July 14, 2003, sec 5.23, these bridges can have an AER Capability (with different format that I don't see mentioned elsewhere). But this AER Capability doesn't have the Root registers, so I assume it would have to be below a Root Port in order to actually signal the errors, which would mean it could not be on a root bus. So I don't really *love* the fact that we use pci_upstream_bridge() and rely on these assumptions that the result will not be NULL, but I guess it's OK for now. > > bus = dev->subordinate; > > > > pci_dbg(dev, "broadcast error_detected message\n"); > > -- > > 2.29.2 > > > > >