From patchwork Fri Jan 11 15:37:01 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sergei Miroshnichenko X-Patchwork-Id: 10758283 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id BD2A317D2 for ; Fri, 11 Jan 2019 15:43:56 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AB6702848B for ; Fri, 11 Jan 2019 15:43:56 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9FA3B284E4; Fri, 11 Jan 2019 15:43:56 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 37018284C0 for ; Fri, 11 Jan 2019 15:43:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731978AbfAKPnz (ORCPT ); Fri, 11 Jan 2019 10:43:55 -0500 Received: from mta-01.yadro.com ([89.207.88.251]:40076 "EHLO mta-01.yadro.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731890AbfAKPny (ORCPT ); Fri, 11 Jan 2019 10:43:54 -0500 Received: from localhost (unknown [127.0.0.1]) by mta-01.yadro.com (Postfix) with ESMTP id F27D7419CC for ; Fri, 11 Jan 2019 15:37:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=yadro.com; h= content-type:content-type:content-transfer-encoding:mime-version :references:in-reply-to:x-mailer:message-id:date:date:subject :subject:from:from:received:received:received; s=mta-01; t= 1547221048; x=1549035449; bh=b+JeZ61WD50Ta00T2UkPhromaBKmR9w433T eAZj3MaI=; b=f6x5FAlbVVDGnBFHmS85kQzs/N/hqvaItXeeSAQSGXrBKcYva54 WMcDlp14cpxbyTlfEb+iXTu2X/Br0SGXKmYspc+9wLXKMuqVBfZED+E0Tr207ifZ pqk+aO4tE3VWm3SyG8Xb4pBT1krcMOsKQbE32/WjFudzZ0FsJmP40/mY= X-Virus-Scanned: amavisd-new at yadro.com Received: from mta-01.yadro.com ([127.0.0.1]) by localhost (mta-01.yadro.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id PIEC7nbw6B6J for ; Fri, 11 Jan 2019 18:37:28 +0300 (MSK) Received: from T-EXCH-02.corp.yadro.com (t-exch-02.corp.yadro.com [172.17.10.102]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mta-01.yadro.com (Postfix) with ESMTPS id 8A017419BD for ; Fri, 11 Jan 2019 18:37:24 +0300 (MSK) Received: from NB-148.yadro.com (172.17.15.60) by T-EXCH-02.corp.yadro.com (172.17.10.102) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P384) id 15.1.669.32; Fri, 11 Jan 2019 18:37:24 +0300 From: Sergey Miroshnichenko To: CC: , Sergey Miroshnichenko Subject: [PATCH RFC v2 15/21] PCI: Fix race condition in pci_enable/disable_device() Date: Fri, 11 Jan 2019 18:37:01 +0300 Message-ID: <20190111153707.10140-16-s.miroshnichenko@yadro.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190111153707.10140-1-s.miroshnichenko@yadro.com> References: <20190111153707.10140-1-s.miroshnichenko@yadro.com> MIME-Version: 1.0 X-Originating-IP: [172.17.15.60] X-ClientProxiedBy: T-EXCH-01.corp.yadro.com (172.17.10.101) To T-EXCH-02.corp.yadro.com (172.17.10.102) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP CPU0 CPU1 pci_enable_device_mem() pci_enable_device_mem() pci_enable_bridge() pci_enable_bridge() pci_is_enabled() return false; atomic_inc_return(enable_cnt) Start actual enabling the bridge ... pci_is_enabled() ... return true; ... Start memory requests <-- FAIL ... Set the PCI_COMMAND_MEMORY bit <-- Must wait for this This patch protects the pci_enable/disable_device() and pci_enable_bridge() with mutexes. Signed-off-by: Sergey Miroshnichenko --- drivers/pci/pci.c | 26 ++++++++++++++++++++++---- drivers/pci/probe.c | 1 + include/linux/pci.h | 1 + 3 files changed, 24 insertions(+), 4 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 71e056771e67..a5266f31b612 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1595,6 +1595,8 @@ static void pci_enable_bridge(struct pci_dev *dev) struct pci_dev *bridge; int retval; + mutex_lock(&dev->enable_mutex); + bridge = pci_upstream_bridge(dev); if (bridge) pci_enable_bridge(bridge); @@ -1602,6 +1604,7 @@ static void pci_enable_bridge(struct pci_dev *dev) if (pci_is_enabled(dev)) { if (!dev->is_busmaster) pci_set_master(dev); + mutex_unlock(&dev->enable_mutex); return; } @@ -1610,11 +1613,14 @@ static void pci_enable_bridge(struct pci_dev *dev) pci_err(dev, "Error enabling bridge (%d), continuing\n", retval); pci_set_master(dev); + mutex_unlock(&dev->enable_mutex); } static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags) { struct pci_dev *bridge; + /* Enable-locking of bridges is performed within the pci_enable_bridge() */ + bool need_lock = !dev->subordinate; int err; int i, bars = 0; @@ -1630,8 +1636,13 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags) dev->current_state = (pmcsr & PCI_PM_CTRL_STATE_MASK); } - if (atomic_inc_return(&dev->enable_cnt) > 1) + if (need_lock) + mutex_lock(&dev->enable_mutex); + if (pci_is_enabled(dev)) { + if (need_lock) + mutex_unlock(&dev->enable_mutex); return 0; /* already enabled */ + } bridge = pci_upstream_bridge(dev); if (bridge) @@ -1646,8 +1657,10 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags) bars |= (1 << i); err = do_pci_enable_device(dev, bars); - if (err < 0) - atomic_dec(&dev->enable_cnt); + if (err >= 0) + atomic_inc(&dev->enable_cnt); + if (need_lock) + mutex_unlock(&dev->enable_mutex); return err; } @@ -1890,15 +1903,20 @@ void pci_disable_device(struct pci_dev *dev) if (dr) dr->enabled = 0; + mutex_lock(&dev->enable_mutex); dev_WARN_ONCE(&dev->dev, atomic_read(&dev->enable_cnt) <= 0, "disabling already-disabled device"); - if (atomic_dec_return(&dev->enable_cnt) != 0) + if (atomic_dec_return(&dev->enable_cnt) != 0) { + mutex_unlock(&dev->enable_mutex); return; + } do_pci_disable_device(dev); dev->is_busmaster = 0; + + mutex_unlock(&dev->enable_mutex); } EXPORT_SYMBOL(pci_disable_device); diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 34c769b25055..4726049a19ad 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2197,6 +2197,7 @@ struct pci_dev *pci_alloc_dev(struct pci_bus *bus) INIT_LIST_HEAD(&dev->bus_list); dev->dev.type = &pci_dev_type; dev->bus = pci_bus_get(bus); + mutex_init(&dev->enable_mutex); return dev; } diff --git a/include/linux/pci.h b/include/linux/pci.h index 161a9b8a854e..311d51d0a59a 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -417,6 +417,7 @@ struct pci_dev { unsigned int no_vf_scan:1; /* Don't scan for VFs after IOV enablement */ pci_dev_flags_t dev_flags; atomic_t enable_cnt; /* pci_enable_device has been called */ + struct mutex enable_mutex; u32 saved_config_space[16]; /* Config space saved at suspend time */ struct hlist_head saved_cap_space;