From patchwork Thu Apr 30 00:42:04 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jay Vosburgh X-Patchwork-Id: 1279797 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=linux-pci-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=canonical.com Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 49CGmg5b2Gz9sSK for ; Thu, 30 Apr 2020 10:42:11 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726505AbgD3AmK (ORCPT ); Wed, 29 Apr 2020 20:42:10 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:52092 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726309AbgD3AmK (ORCPT ); Wed, 29 Apr 2020 20:42:10 -0400 Received: from 1.general.jvosburgh.us.vpn ([10.172.68.206] helo=famine.localdomain) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1jTxHC-0006r5-O9; Thu, 30 Apr 2020 00:42:06 +0000 Received: by famine.localdomain (Postfix, from userid 1000) id E2C17630E4; Wed, 29 Apr 2020 17:42:04 -0700 (PDT) Received: from famine (localhost [127.0.0.1]) by famine.localdomain (Postfix) with ESMTP id D417EAC1DB; Wed, 29 Apr 2020 17:42:04 -0700 (PDT) From: Jay Vosburgh To: linux-pci@vger.kernel.org Cc: Bjorn Helgaas , Kuppuswamy Sathyanarayanan Subject: [PATCH] PCI/ERR: Resolve regression in pcie_do_recovery X-Mailer: MH-E 8.6+git; nmh 1.6; GNU Emacs 27.0.50 MIME-Version: 1.0 Content-ID: <12114.1588207324.1@famine> Date: Wed, 29 Apr 2020 17:42:04 -0700 Message-ID: <12115.1588207324@famine> Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org 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 {