From patchwork Wed Feb 5 09:18:03 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yicong Yang X-Patchwork-Id: 1233728 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-pci-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=hisilicon.com Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 48CGKp6qDGz9s3x for ; Wed, 5 Feb 2020 20:22:06 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728079AbgBEJWF (ORCPT ); Wed, 5 Feb 2020 04:22:05 -0500 Received: from szxga06-in.huawei.com ([45.249.212.32]:45228 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728035AbgBEJWF (ORCPT ); Wed, 5 Feb 2020 04:22:05 -0500 Received: from DGGEMS412-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 0F697B646FFE7539EDF6; Wed, 5 Feb 2020 17:22:04 +0800 (CST) Received: from localhost.localdomain (10.67.165.24) by DGGEMS412-HUB.china.huawei.com (10.3.19.212) with Microsoft SMTP Server id 14.3.439.0; Wed, 5 Feb 2020 17:21:56 +0800 From: Yicong Yang To: , CC: , Subject: [PATCH 1/2] PCI: Change lock order in pci_dev_lock() Date: Wed, 5 Feb 2020 17:18:03 +0800 Message-ID: <1580894283-20790-1-git-send-email-yangyicong@hisilicon.com> X-Mailer: git-send-email 2.8.1 MIME-Version: 1.0 X-Originating-IP: [10.67.165.24] X-CFilter-Loop: Reflected Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org In pci_dev_lock(), we hold pci_lock for configuration access first, then is device_lock. But in sriov enable routine, we hold device_lock first and pci_lock subsequently. The inconsistent lock order will have potential deadlock problem. In pci_dev_lock(): pci_dev_lock() pci_cfg_access_lock() device_lock() When adding VF by sysfs: sriov_numvfs_store() device_lock() ... sriov_enable() pci_cfg_access_lock() Adjust the lock order in pci_dev_lock(), pci_dev_trylock() and pci_dev_unlock() to avoid potential deadlock condition. Signed-off-by: Yicong Yang --- drivers/pci/pci.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index e87196c..78c99ef 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4876,18 +4876,19 @@ static int pci_dev_reset_slot_function(struct pci_dev *dev, int probe) static void pci_dev_lock(struct pci_dev *dev) { - pci_cfg_access_lock(dev); /* block PM suspend, driver probe, etc. */ device_lock(&dev->dev); + + pci_cfg_access_lock(dev); } /* Return 1 on successful lock, 0 on contention */ static int pci_dev_trylock(struct pci_dev *dev) { - if (pci_cfg_access_trylock(dev)) { - if (device_trylock(&dev->dev)) + if (device_trylock(&dev->dev)) { + if (pci_cfg_access_trylock(dev)) return 1; - pci_cfg_access_unlock(dev); + device_unlock(&dev->dev); } return 0; @@ -4895,8 +4896,8 @@ static int pci_dev_trylock(struct pci_dev *dev) static void pci_dev_unlock(struct pci_dev *dev) { - device_unlock(&dev->dev); pci_cfg_access_unlock(dev); + device_unlock(&dev->dev); } static void pci_dev_save_and_disable(struct pci_dev *dev)