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 8EE6AC433EF for ; Mon, 13 Jun 2022 11:05:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351334AbiFMLFy (ORCPT ); Mon, 13 Jun 2022 07:05:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45272 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351681AbiFMLEv (ORCPT ); Mon, 13 Jun 2022 07:04:51 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D4130326F6; Mon, 13 Jun 2022 03:33:49 -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 5D837B80EA7; Mon, 13 Jun 2022 10:33:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB65BC34114; Mon, 13 Jun 2022 10:33:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1655116426; bh=xry6IlibLXy31UeppTQTdRP7qqE+LKAPoRAOS75hzqo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NgCg6qTPs9FH9IiJI/ZcYSgO6iT/x/YkuyDs7OVnaR7uS/eYK5kUEeQeJLsw0f1sX z5Ap/N42lxMSB9vLzGWmi/lvvHXx90kOFBBvWMCBt0bWv6G+Bw4Oa+FfcD1GrYoaTU i7UdS9N0c4b9CjY+z01MHyjf4Z1ykGnDRKV//JLY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yicong Yang , Bjorn Helgaas , Sasha Levin , Jay Zhou Subject: [PATCH 5.4 073/411] PCI: Avoid pci_dev_lock() AB/BA deadlock with sriov_numvfs_store() Date: Mon, 13 Jun 2022 12:05:46 +0200 Message-Id: <20220613094930.867850069@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220613094928.482772422@linuxfoundation.org> References: <20220613094928.482772422@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@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 d539eb379743..c988aa425ac9 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4915,18 +4915,18 @@ 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; @@ -4934,8 +4934,8 @@ 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