From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org ([198.145.29.96]:49638 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751595AbdI1Qrs (ORCPT ); Thu, 28 Sep 2017 12:47:48 -0400 Subject: Re: [PATCH 3/4] pci aer: fix deadlock in do_recovery To: Govindarajulu Varadarajan , benve@cisco.com, bhelgaas@google.com, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, jlbec@evilplan.org, hch@lst.de, mingo@redhat.com, peterz@infradead.org References: <20170927214220.41216-1-gvaradar@cisco.com> <20170927214220.41216-4-gvaradar@cisco.com> From: Sinan Kaya Message-ID: <2dc437fe-2ab4-23e3-44f3-f06feaf88d86@codeaurora.org> Date: Thu, 28 Sep 2017 12:47:45 -0400 MIME-Version: 1.0 In-Reply-To: <20170927214220.41216-4-gvaradar@cisco.com> Content-Type: text/plain; charset=utf-8 Sender: linux-pci-owner@vger.kernel.org List-ID: On 9/27/2017 5:42 PM, Govindarajulu Varadarajan wrote: > CPU0 CPU1 > --------------------------------------------------------------------- > __driver_attach() > device_lock(&dev->mutex) <--- device mutex lock here > driver_probe_device() > pci_enable_sriov() > pci_iov_add_virtfn() > pci_device_add() > aer_isr() <--- pci aer error > do_recovery() > broadcast_error_message() > pci_walk_bus() > down_read(&pci_bus_sem) <--- rd sem How about releasing the device_lock here on CPU0? or in other words keep device_lock as short as possible? > down_write(&pci_bus_sem) <-- stuck on wr sem > report_error_detected() > device_lock(&dev->mutex)<--- DEAD LOCK -- Sinan Kaya Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.