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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DF58ACCA470 for ; Wed, 1 Jun 2022 14:11:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231843AbiFAOLu (ORCPT ); Wed, 1 Jun 2022 10:11:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46490 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354620AbiFAOJu (ORCPT ); Wed, 1 Jun 2022 10:09:50 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95A1D101FF; Wed, 1 Jun 2022 07:01:18 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 31B29B81AF7; Wed, 1 Jun 2022 14:01:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D2B0FC385B8; Wed, 1 Jun 2022 14:01:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1654092075; bh=Mp4/GXgP2filxJIR06FyyxnCFKyje/qMW3/pzxMQAow=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TcZIkoTOqhf/ss0IfePtpdbfpz/ji7bIIBNmQ9zG5bH3QCEiBFqlQEo1oPCfW1OEG sAtxZGA7PbpDf6KX+E1WRWgjZjfMfQB75AyUas9quQMAwQS7ZN/4i13i458CVB9GTH kLHaTb0FD0OjIubUZLQvY4ItmkEo1QsiPAGCOzf5jrzLHzEUkcjZrIP28iVm5CaZZz 6Lzm8BPWNnKdmRWI1ckU+MiIhf9PlIZjEgD/3uCc+T4O8xKQPSgUv2HUYd33GAAt44 FYuRuWDjhsUw3JipBJtB9QOHMDq8stQyS8VKV4wzaQm2Pk86AKOYigP+iZMtREdc/r 5qRi0JOHx8nVQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Yicong Yang , Jay Zhou , Bjorn Helgaas , Sasha Levin , linux-pci@vger.kernel.org Subject: [PATCH AUTOSEL 4.9 08/11] PCI: Avoid pci_dev_lock() AB/BA deadlock with sriov_numvfs_store() Date: Wed, 1 Jun 2022 10:00:57 -0400 Message-Id: <20220601140100.2005469-8-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220601140100.2005469-1-sashal@kernel.org> References: <20220601140100.2005469-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org From: Yicong Yang [ Upstream commit a91ee0e9fca9d7501286cfbced9b30a33e52740a ] The sysfs sriov_numvfs_store() path acquires the device lock before the config space access lock: sriov_numvfs_store device_lock # A (1) acquire device lock sriov_configure vfio_pci_sriov_configure # (for example) vfio_pci_core_sriov_configure pci_disable_sriov sriov_disable pci_cfg_access_lock pci_wait_cfg # B (4) wait for dev->block_cfg_access == 0 Previously, pci_dev_lock() acquired the config space access lock before the device lock: pci_dev_lock pci_cfg_access_lock dev->block_cfg_access = 1 # B (2) set dev->block_cfg_access = 1 device_lock # A (3) wait for device lock Any path that uses pci_dev_lock(), e.g., pci_reset_function(), may deadlock with sriov_numvfs_store() if the operations occur in the sequence (1) (2) (3) (4). Avoid the deadlock by reversing the order in pci_dev_lock() so it acquires the device lock before the config space access lock, the same as the sriov_numvfs_store() path. [bhelgaas: combined and adapted commit log from Jay Zhou's independent subsequent posting: https://lore.kernel.org/r/20220404062539.1710-1-jianjay.zhou@huawei.com] Link: https://lore.kernel.org/linux-pci/1583489997-17156-1-git-send-email-yangyicong@hisilicon.com/ Also-posted-by: Jay Zhou Signed-off-by: Yicong Yang Signed-off-by: Bjorn Helgaas Signed-off-by: Sasha Levin --- drivers/pci/pci.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 2cf13578fe75..e6e0012269cd 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4079,18 +4079,18 @@ static int __pci_dev_reset(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; @@ -4098,8 +4098,8 @@ 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); } /** -- 2.35.1