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 990CDCCA48F for ; Tue, 7 Jun 2022 18:31:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352901AbiFGSbV (ORCPT ); Tue, 7 Jun 2022 14:31:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35356 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352040AbiFGSCf (ORCPT ); Tue, 7 Jun 2022 14:02:35 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C2EEE33368; Tue, 7 Jun 2022 10:46:51 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 990D261534; Tue, 7 Jun 2022 17:46:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A177EC385A5; Tue, 7 Jun 2022 17:46:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1654624010; bh=nXNs2TKaYBe3HGWE0Y7zWPQB9J0WpS5ZjTFwM5df4Yo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rUHKzGozoHz1doLQLdqlGK06nSYgF85Vd/+t83STQHGL9gsVM7w0TX2vKXhmqHxSh FJM/aQYAm78DRvUa+7FzeamhObYSCfn+oYIvEZhnncU8poY5xph4tE2WOSJ0SMuH8L 2zWe8b30agD1yie2EGOHLCBrbzUkAo1ibLRPV7QE= 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 5.15 170/667] PCI: Avoid pci_dev_lock() AB/BA deadlock with sriov_numvfs_store() Date: Tue, 7 Jun 2022 18:57:15 +0200 Message-Id: <20220607164939.911914526@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220607164934.766888869@linuxfoundation.org> References: <20220607164934.766888869@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: linux-kernel@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 0380543d10fd..09815cbc18f9 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -5079,18 +5079,18 @@ static int pci_reset_bus_function(struct pci_dev *dev, bool 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 */ 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; @@ -5099,8 +5099,8 @@ EXPORT_SYMBOL_GPL(pci_dev_trylock); void pci_dev_unlock(struct pci_dev *dev) { - device_unlock(&dev->dev); pci_cfg_access_unlock(dev); + device_unlock(&dev->dev); } EXPORT_SYMBOL_GPL(pci_dev_unlock); -- 2.35.1