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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 86467C33CA2 for ; Thu, 9 Jan 2020 00:16:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 56B202067D for ; Thu, 9 Jan 2020 00:16:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727664AbgAIAQO (ORCPT ); Wed, 8 Jan 2020 19:16:14 -0500 Received: from mga07.intel.com ([134.134.136.100]:43048 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726438AbgAIAQO (ORCPT ); Wed, 8 Jan 2020 19:16:14 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 08 Jan 2020 16:16:13 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,411,1571727600"; d="scan'208";a="217653155" Received: from linux.intel.com ([10.54.29.200]) by fmsmga007.fm.intel.com with ESMTP; 08 Jan 2020 16:16:12 -0800 Received: from [10.54.74.33] (skuppusw-desk.jf.intel.com [10.54.74.33]) by linux.intel.com (Postfix) with ESMTP id BC1C25803E3; Wed, 8 Jan 2020 16:16:12 -0800 (PST) Reply-To: sathyanarayanan.kuppuswamy@linux.intel.com Subject: Re: [PATCH v11 1/8] PCI/ERR: Update error status after reset_link() To: Bjorn Helgaas Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, ashok.raj@intel.com, keith.busch@intel.com References: <20200104025414.GA85401@google.com> From: Kuppuswamy Sathyanarayanan Organization: Intel Message-ID: <7f7fdfec-5060-bcaa-38c4-6b973149e5cc@linux.intel.com> Date: Wed, 8 Jan 2020 16:14:09 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20200104025414.GA85401@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Bjorn, Thanks for the comments. On 1/3/20 6:54 PM, Bjorn Helgaas wrote: > On Fri, Jan 03, 2020 at 05:03:03PM -0800, Kuppuswamy Sathyanarayanan wrote: >> On 1/3/20 4:34 PM, Bjorn Helgaas wrote: >>> On Thu, Dec 26, 2019 at 04:39:07PM -0800, sathyanarayanan.kuppuswamy@linux.intel.com wrote: >>>> From: Kuppuswamy Sathyanarayanan >>>> >>>> Commit bdb5ac85777d ("PCI/ERR: Handle fatal error recovery") uses >>>> reset_link() to recover from fatal errors. But, if the reset is >>>> successful there is no need to continue the rest of the error recovery >>>> checks. Also, during fatal error recovery, if the initial value of error >>>> status is PCI_ERS_RESULT_DISCONNECT or PCI_ERS_RESULT_NO_AER_DRIVER then >>>> even after successful recovery (using reset_link()) pcie_do_recovery() >>>> will report the recovery result as failure. So update the status of >>>> error after reset_link(). >>> I like the part about updating "status" with the result of >>> reset_link(), and I split that into its own patch because it >>> seems like a fix that *can* be separated. >>> >>> But I'm not convinced that we should skip the ->slot_reset() >>> callbacks if the reset_link() was successful. >> If reset_link() call is successful then the result value will be >> "PCI_ERS_RESULT_RECOVERED". So even if you proceed with >> rest of the code, slot_reset() will never get called right ? > The current code: > > if (state == pci_channel_io_frozen && > reset_link(dev, service) != PCI_ERS_RESULT_RECOVERED) > goto failed; > ... > if (status == PCI_ERS_RESULT_NEED_RESET) { > status = PCI_ERS_RESULT_RECOVERED; > pci_walk_bus(bus, report_slot_reset, &status); > > doesn't save the result of reset_link(), so if status was > PCI_ERS_RESULT_NEED_RESET and the reset succeeds, we will call > ->slot_reset(). > > After your patch, if "state == pci_channel_io_frozen", we *never* call > ->slot_reset(). > > Do you think that matches pci-error-recovery.rst? It doesn't seem > like it to me, but perhaps I haven't read it closely enough. Documentation does not have clear details on what to do with return value of reset_link() ( step 3). But IMO, if step 3 recovers the device and returns PCI_ERS_RESULT_RECOVERED then there is no need to proceed to slot reset (step 4). May be we should update the Documentation ? Keith, You have any comments ? > >>> According to >>> Documentation/PCI/pci-error-recovery.rst, we should call >>> ->slot_reset() after completion of the reset. >>> >>> For example, rsxx_err_handler implements ->slot_reset(), but >>> not ->resume(). If we reset the device, we'll claim success and >>> return, but we won't call rsxx_slot_reset(), which does a bunch >>> of important-looking recovery stuff. >>> >>> If pci-error-recovery.rst is wrong, we should fix that (after >>> auditing all the drivers to make sure they match). >>> >>>> Fixes: bdb5ac85777d ("PCI/ERR: Handle fatal error recovery") >>>> Cc: Ashok Raj >>>> Cc: Keith Busch >>>> Signed-off-by: Kuppuswamy Sathyanarayanan >>>> Acked-by: Keith Busch >>>> --- >>>> drivers/pci/pcie/err.c | 10 +++++++--- >>>> 1 file changed, 7 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c >>>> index b0e6048a9208..53cd9200ec2c 100644 >>>> --- a/drivers/pci/pcie/err.c >>>> +++ b/drivers/pci/pcie/err.c >>>> @@ -204,9 +204,12 @@ void pcie_do_recovery(struct pci_dev *dev, enum pci_channel_state state, >>>> else >>>> pci_walk_bus(bus, report_normal_detected, &status); >>>> - if (state == pci_channel_io_frozen && >>>> - reset_link(dev, service) != PCI_ERS_RESULT_RECOVERED) >>>> - goto failed; >>>> + if (state == pci_channel_io_frozen) { >>>> + status = reset_link(dev, service); >>>> + if (status != PCI_ERS_RESULT_RECOVERED) >>>> + goto failed; >>>> + goto done; >>>> + } >>>> if (status == PCI_ERS_RESULT_CAN_RECOVER) { >>>> status = PCI_ERS_RESULT_RECOVERED; >>>> @@ -228,6 +231,7 @@ void pcie_do_recovery(struct pci_dev *dev, enum pci_channel_state state, >>>> if (status != PCI_ERS_RESULT_RECOVERED) >>>> goto failed; >>>> +done: >>>> pci_dbg(dev, "broadcast resume message\n"); >>>> pci_walk_bus(bus, report_resume, &status); >>>> -- >>>> 2.21.0 >>>> >> -- >> Sathyanarayanan Kuppuswamy >> Linux kernel developer >> -- Sathyanarayanan Kuppuswamy Linux kernel developer