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=-8.3 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=ham 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 C7D1CC28CBC for ; Sat, 9 May 2020 08:34:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9AE862192A for ; Sat, 9 May 2020 08:34:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726948AbgEIIeh (ORCPT ); Sat, 9 May 2020 04:34:37 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:59872 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726214AbgEIIeh (ORCPT ); Sat, 9 May 2020 04:34:37 -0400 Received: from DGGEMS414-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 9DB68CB884DC8E8DFBE3; Sat, 9 May 2020 16:34:33 +0800 (CST) Received: from [10.65.58.147] (10.65.58.147) by DGGEMS414-HUB.china.huawei.com (10.3.19.214) with Microsoft SMTP Server id 14.3.487.0; Sat, 9 May 2020 16:34:23 +0800 Subject: Re: [PATCH] PCI/ERR: Resolve regression in pcie_do_recovery To: Jay Vosburgh , , Bjorn Helgaas , Kuppuswamy Sathyanarayanan References: <12115.1588207324@famine> From: Yicong Yang CC: liudongdong 00290354 , Linuxarm Message-ID: Date: Sat, 9 May 2020 16:34:53 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <12115.1588207324@famine> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.65.58.147] X-CFilter-Loop: Reflected Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org [ +cc dongdong as we met the issue ] Hi, The regression happened with our intel 82599 network adaptor. A DPC event happened on the device, recovery returns successful but the device is not enabled. As we only reset link, but don't call driver specific handler(mmio enable/slot reset). If we met an error with IO blocked, the logic should be: 1. try to reset link 2. broadcast report_frozen_detected on the bus 3. do what drivers suggest(mmio enable/slot reset) Currently only step 1 is performed, and returns directly. I tried the patch below and it solves the issues. The differences from Jay's one is that it merge the return value to the status and it match the logic I mentioned above. Regards, Yicong diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c index 14bb8f5..6f8870c 100644 --- a/drivers/pci/pcie/err.c +++ b/drivers/pci/pcie/err.c @@ -164,12 +164,12 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev, pci_dbg(dev, "broadcast error_detected message\n"); if (state == pci_channel_io_frozen) { - pci_walk_bus(bus, report_frozen_detected, &status); status = reset_link(dev); if (status != PCI_ERS_RESULT_RECOVERED) { pci_warn(dev, "link reset failed\n"); goto failed; } + pci_walk_bus(bus, report_frozen_detected, &status); } else { pci_walk_bus(bus, report_normal_detected, &status); } On 2020/4/30 8:42, Jay Vosburgh wrote: > Commit 6d2c89441571 ("PCI/ERR: Update error status after > reset_link()"), introduced a regression, as pcie_do_recovery will > discard the status result from report_frozen_detected. This can cause a > failure to recover if _NEED_RESET is returned by report_frozen_detected > and report_slot_reset is not invoked. > > Such an event can be induced for testing purposes by reducing > the Max_Payload_Size of a PCIe bridge to less than that of a device > downstream from the bridge, and then initating I/O through the device, > resulting in oversize transactions. In the presence of DPC, this > results in a containment event and attempted reset and recovery via > pcie_do_recovery. After 6d2c89441571 report_slot_reset is not invoked, > and the device does not recover. > > Inspection shows a similar path is plausible for a return of > _CAN_RECOVER and the invocation of report_mmio_enabled. > > Resolve this by preserving the result of report_frozen_detected if > reset_link does not return _DISCONNECT. > > Fixes: 6d2c89441571 ("PCI/ERR: Update error status after reset_link()") > Signed-off-by: Jay Vosburgh > > --- > drivers/pci/pcie/err.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c > index 14bb8f54723e..e4274562f3a0 100644 > --- a/drivers/pci/pcie/err.c > +++ b/drivers/pci/pcie/err.c > @@ -164,10 +164,17 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev, > > pci_dbg(dev, "broadcast error_detected message\n"); > if (state == pci_channel_io_frozen) { > + pci_ers_result_t status2; > + > pci_walk_bus(bus, report_frozen_detected, &status); > - status = reset_link(dev); > - if (status != PCI_ERS_RESULT_RECOVERED) { > + /* preserve status from report_frozen_detected to > + * insure report_mmio_enabled or report_slot_reset are > + * invoked even if reset_link returns _RECOVERED. > + */ > + status2 = reset_link(dev); > + if (status2 != PCI_ERS_RESULT_RECOVERED) { > pci_warn(dev, "link reset failed\n"); > + status = status2; > goto failed; > } > } else {