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 05FA5CCA470 for ; Wed, 1 Jun 2022 14:11:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355093AbiFAOLf (ORCPT ); Wed, 1 Jun 2022 10:11:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51178 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354746AbiFAOJd (ORCPT ); Wed, 1 Jun 2022 10:09:33 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CFA07DD9; Wed, 1 Jun 2022 07:00:45 -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 6A2B3B81B00; Wed, 1 Jun 2022 14:00:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3D5E8C34119; Wed, 1 Jun 2022 14:00:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1654092043; bh=l+ydTVCoI/F/gcw+1njuIFQl4UOoJOs9shlOSimZeMU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Pi02pB3gD6xQDdR73nxrwWNUptqsfVazGhCwVL3zrBdFivg7FY8UbGmzCvEZfkyUW M1tBZxIuNlrRlhkPavO861H0F2Wrc/ZXkt5P2JIkckICKZU8hzAX1yCBVrfr9k/AWy tygd1JoliXJwx+8mU/abSsT6WBBAeZU2/KX2GqnmXaheg/ZjsovDqN1+cZqAuzP/66 bsXCCbRn1okTdKn3BFGG2cOb0bLrfCikSn1EOVUHKyVPGe+/1UoQEBRqxZ/PCaq9hd HMfa/i0aBPm9YVvtI+/ipSgoG0oiVKpWk4KUU6jzjeFF69xHTQcSS7sMYlKjbQvToV w7gc6B50z0ZQA== 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 4.14 09/14] PCI: Avoid pci_dev_lock() AB/BA deadlock with sriov_numvfs_store() Date: Wed, 1 Jun 2022 10:00:22 -0400 Message-Id: <20220601140027.2005280-9-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220601140027.2005280-1-sashal@kernel.org> References: <20220601140027.2005280-1-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 4ff7f2575d28..efcd06064953 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4153,18 +4153,18 @@ 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; @@ -4172,8 +4172,8 @@ 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) -- 2.35.1