From patchwork Mon Jun 25 10:10:46 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hari Vyas X-Patchwork-Id: 934143 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-pci-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=broadcom.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=broadcom.com header.i=@broadcom.com header.b="OxX8SAAT"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 41DlLK0X1qz9rvt for ; Mon, 25 Jun 2018 20:10:49 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755176AbeFYKKr (ORCPT ); Mon, 25 Jun 2018 06:10:47 -0400 Received: from mail-ed1-f65.google.com ([209.85.208.65]:40715 "EHLO mail-ed1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755174AbeFYKKq (ORCPT ); Mon, 25 Jun 2018 06:10:46 -0400 Received: by mail-ed1-f65.google.com with SMTP id m15-v6so2814977edr.7 for ; Mon, 25 Jun 2018 03:10:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; h=from:to:cc:subject:date:message-id; bh=k4mqFYtaXVXkvJ0m4nZqsW5ftfSPibnWKtsDlI0mxhA=; b=OxX8SAATiqq+Mqljxm3vQcMEKelN3YlO8ox8sSA1Hoj3AJqf0hO/qAlj4nvHEKsvFw OUy1LQ/ozEon4RqdVaTYohvFetnHa2r3rrRr9pMBZhza9poO72S2bGVegQbLpqOdGcIr 6/7AQut8gpAGSStBghjKVlbGzdLXz2alsNpMw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=k4mqFYtaXVXkvJ0m4nZqsW5ftfSPibnWKtsDlI0mxhA=; b=e52EFMgVg/MLVb4vL+oC+A6wvBWvwhYTSGCbMfeKMkJg3LEde2S69UoX0uMTla5R7T 7of6sGnMbE4CZLr7PIfnrnyIDMzcIRID1qXrJkxYUfat+3KuasBGzAhQPSpJlVfgGuW7 jKNeAPtpswuUyQ4HKjKymt5aeAjxs0lV8ZdWQKRW7aLfbdAK6mXbBPKhViPP3LbL+v5w fffgcWq59caEQgunG1zGgw5CaxFZc7oXK3TawURrxrM16xASBTjeEps5HULCBzXZHWaG 3HbQKGjdqfBKCuRVS3guBS4+xVt9L6L3Gq0Oej+rBi9tx9V+H4G89j1XkndyQOzir+uN pF5w== X-Gm-Message-State: APt69E2Q6K/dWBLk2UXLxP1RqveuTdP8GYdUvo4TfoL19CwgQlSFPMmt P05j5/70ubUgPz6+pSdAy4t7Hw== X-Google-Smtp-Source: ADUXVKKTHs7pHYO4uZGIUKPGdfoXY887dRkm6iFICXP5fJ3KLU0uEnVTyAU5RUYh6WM30tqDtC4mHg== X-Received: by 2002:a50:86f6:: with SMTP id 51-v6mr1900690edu.312.1529921445385; Mon, 25 Jun 2018 03:10:45 -0700 (PDT) Received: from hariv-server.dhcp.broadcom.net ([192.19.234.250]) by smtp.gmail.com with ESMTPSA id x41-v6sm1823042edm.59.2018.06.25.03.10.43 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 25 Jun 2018 03:10:44 -0700 (PDT) From: Hari Vyas To: bhelgaas@google.com Cc: linux-pci@vger.kernel.org, ray.jui@broadcom.com, Hari Vyas Subject: [PATCH] PCI: Data corruption happening due to race condition Date: Mon, 25 Jun 2018 15:40:46 +0530 Message-Id: <1529921446-20452-1-git-send-email-hari.vyas@broadcom.com> X-Mailer: git-send-email 1.9.1 Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org When a pci device is detected, a variable is_added is set to 1 in pci device structure and proc, sys entries are created. When a pci device is removed, first is_added is checked for one and then device is detached with clearing of proc and sys entries and at end, is_added is set to 0. is_added and is_busmaster are bit fields in pci_dev structure sharing same memory location. A strange issue was observed with multiple times removal and rescan of a pcie nvme device using sysfs commands where is_added flag was observed as zero instead of one while removing device and proc,sys entries are not cleared. This causes issue in later device addition with warning message "proc_dir_entry" already registered. Debugging revealed a race condition between pcie core driver enabling is_added bit(pci_bus_add_device()) and nvme driver reset work-queue enabling is_busmaster bit (by pci_set_master()). As both fields are not handled in atomic manner and that clears is_added bit. Fix protects is_added and is_busmaster bits updation by a spin locking mechanism. Signed-off-by: Hari Vyas Reviewed-by: Ray Jui --- drivers/pci/bus.c | 3 +++ drivers/pci/pci-driver.c | 2 ++ drivers/pci/pci.c | 7 +++++++ drivers/pci/remove.c | 5 +++++ include/linux/pci.h | 1 + 5 files changed, 18 insertions(+) diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c index 35b7fc8..61d389d 100644 --- a/drivers/pci/bus.c +++ b/drivers/pci/bus.c @@ -310,6 +310,7 @@ void __weak pcibios_bus_add_device(struct pci_dev *pdev) { } void pci_bus_add_device(struct pci_dev *dev) { int retval; + unsigned long flags; /* * Can not put in pci_device_add yet because resources @@ -330,7 +331,9 @@ void pci_bus_add_device(struct pci_dev *dev) return; } + spin_lock_irqsave(&dev->lock, flags); dev->is_added = 1; + spin_unlock_irqrestore(&dev->lock, flags); } EXPORT_SYMBOL_GPL(pci_bus_add_device); diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index c125d53..547bcd7 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -123,6 +123,8 @@ static ssize_t new_id_store(struct device_driver *driver, const char *buf, pdev->subsystem_device = subdevice; pdev->class = class; + spin_lock_init(&pdev->lock); + if (pci_match_id(pdrv->id_table, pdev)) retval = -EEXIST; diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 97acba7..bcb1f96 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1649,6 +1649,7 @@ void pci_disable_enabled_device(struct pci_dev *dev) void pci_disable_device(struct pci_dev *dev) { struct pci_devres *dr; + unsigned long flags; dr = find_pci_dr(dev); if (dr) @@ -1662,7 +1663,9 @@ void pci_disable_device(struct pci_dev *dev) do_pci_disable_device(dev); + spin_lock_irqsave(&dev->lock, flags); dev->is_busmaster = 0; + spin_unlock_irqrestore(&dev->lock, flags); } EXPORT_SYMBOL(pci_disable_device); @@ -3664,6 +3667,7 @@ void __iomem *devm_pci_remap_cfg_resource(struct device *dev, static void __pci_set_master(struct pci_dev *dev, bool enable) { u16 old_cmd, cmd; + unsigned long flags; pci_read_config_word(dev, PCI_COMMAND, &old_cmd); if (enable) @@ -3675,7 +3679,10 @@ static void __pci_set_master(struct pci_dev *dev, bool enable) enable ? "enabling" : "disabling"); pci_write_config_word(dev, PCI_COMMAND, cmd); } + + spin_lock_irqsave(&dev->lock, flags); dev->is_busmaster = enable; + spin_unlock_irqrestore(&dev->lock, flags); } /** diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c index 6f072ea..ff57bd6 100644 --- a/drivers/pci/remove.c +++ b/drivers/pci/remove.c @@ -17,13 +17,18 @@ static void pci_free_resources(struct pci_dev *dev) static void pci_stop_dev(struct pci_dev *dev) { + unsigned long flags; + pci_pme_active(dev, false); if (dev->is_added) { device_release_driver(&dev->dev); pci_proc_detach_device(dev); pci_remove_sysfs_dev_files(dev); + + spin_lock_irqsave(&dev->lock, flags); dev->is_added = 0; + spin_unlock_irqrestore(&dev->lock, flags); } if (dev->bus->self) diff --git a/include/linux/pci.h b/include/linux/pci.h index 340029b..6940825 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -365,6 +365,7 @@ struct pci_dev { bool match_driver; /* Skip attaching driver */ + spinlock_t lock; /* Protect is_added and is_busmaster */ unsigned int transparent:1; /* Subtractive decode bridge */ unsigned int multifunction:1; /* Multi-function device */