From patchwork Thu Dec 13 00:44:58 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Duyck X-Patchwork-Id: 10727405 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 1D68D91E for ; Thu, 13 Dec 2018 00:45:02 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0C3AF2A519 for ; Thu, 13 Dec 2018 00:45:02 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id F321E2A5B2; Thu, 13 Dec 2018 00:45:01 +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=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_NONE autolearn=unavailable version=3.3.1 Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 99E1C2A582 for ; Thu, 13 Dec 2018 00:45:01 +0000 (UTC) Received: from [127.0.0.1] (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 6AD182119EF44; Wed, 12 Dec 2018 16:45:01 -0800 (PST) X-Original-To: linux-nvdimm@lists.01.org Delivered-To: linux-nvdimm@lists.01.org Received-SPF: None (no SPF record) identity=mailfrom; client-ip=134.134.136.31; helo=mga06.intel.com; envelope-from=alexander.h.duyck@linux.intel.com; receiver=linux-nvdimm@lists.01.org Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 6474B2119EF3A for ; Wed, 12 Dec 2018 16:44:59 -0800 (PST) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Dec 2018 16:44:59 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,346,1539673200"; d="scan'208";a="118349132" Received: from ahduyck-desk1.jf.intel.com ([10.7.198.76]) by orsmga001.jf.intel.com with ESMTP; 12 Dec 2018 16:44:58 -0800 Subject: [driver-core PATCH v9 1/9] driver core: Establish order of operations for device_add and device_del via bitflag From: Alexander Duyck To: linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org Date: Wed, 12 Dec 2018 16:44:58 -0800 Message-ID: <154466189880.9126.10737761541647369077.stgit@ahduyck-desk1.jf.intel.com> In-Reply-To: <154466182249.9126.3905559325944768059.stgit@ahduyck-desk1.jf.intel.com> References: <154466182249.9126.3905559325944768059.stgit@ahduyck-desk1.jf.intel.com> User-Agent: StGit/unknown-version MIME-Version: 1.0 X-BeenThere: linux-nvdimm@lists.01.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Linux-nvdimm developer list." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: len.brown@intel.com, bvanassche@acm.org, linux-pm@vger.kernel.org, alexander.h.duyck@linux.intel.com, linux-nvdimm@lists.01.org, jiangshanlai@gmail.com, mcgrof@kernel.org, pavel@ucw.cz, zwisler@kernel.org, tj@kernel.org, akpm@linux-foundation.org, rafael@kernel.org Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" X-Virus-Scanned: ClamAV using ClamSMTP Add an additional bit flag to the device struct named "dead". This additional flag provides a guarantee that when a device_del is executed on a given interface an async worker will not attempt to attach the driver following the earlier device_del call. Previously this guarantee was not present and could result in the device_del call attempting to remove a driver from an interface only to have the async worker attempt to probe the driver later when it finally completes the asynchronous probe call. One additional change added was that I pulled the check for dev->driver out of the __device_attach_driver call and instead placed it in the __device_attach_async_helper call. This was motivated by the fact that the only other caller of this, __device_attach, had already taken the device_lock() and checked for dev->driver. Instead of testing for this twice in this path it makes more sense to just consolidate the dev->dead and dev->driver checks together into one set of checks. Reviewed-by: Dan Williams Signed-off-by: Alexander Duyck Reviewed-by: Rafael J. Wysocki --- drivers/base/core.c | 11 +++++++++++ drivers/base/dd.c | 22 +++++++++++----------- include/linux/device.h | 5 +++++ 3 files changed, 27 insertions(+), 11 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 0073b09bb99f..950e25495726 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -2080,6 +2080,17 @@ void device_del(struct device *dev) struct kobject *glue_dir = NULL; struct class_interface *class_intf; + /* + * Hold the device lock and set the "dead" flag to guarantee that + * the update behavior is consistent with the other bitfields near + * it and that we cannot have an asynchronous probe routine trying + * to run while we are tearing out the bus/class/sysfs from + * underneath the device. + */ + device_lock(dev); + dev->dead = true; + device_unlock(dev); + /* Notify clients of device removal. This call must come * before dpm_sysfs_remove(). */ diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 88713f182086..74c194ac99df 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -731,15 +731,6 @@ static int __device_attach_driver(struct device_driver *drv, void *_data) bool async_allowed; int ret; - /* - * Check if device has already been claimed. This may - * happen with driver loading, device discovery/registration, - * and deferred probe processing happens all at once with - * multiple threads. - */ - if (dev->driver) - return -EBUSY; - ret = driver_match_device(drv, dev); if (ret == 0) { /* no match */ @@ -774,6 +765,15 @@ static void __device_attach_async_helper(void *_dev, async_cookie_t cookie) device_lock(dev); + /* + * Check if device has already been removed or claimed. This may + * happen with driver loading, device discovery/registration, + * and deferred probe processing happens all at once with + * multiple threads. + */ + if (dev->dead || dev->driver) + goto out_unlock; + if (dev->parent) pm_runtime_get_sync(dev->parent); @@ -784,7 +784,7 @@ static void __device_attach_async_helper(void *_dev, async_cookie_t cookie) if (dev->parent) pm_runtime_put(dev->parent); - +out_unlock: device_unlock(dev); put_device(dev); @@ -897,7 +897,7 @@ static int __driver_attach(struct device *dev, void *data) if (dev->parent && dev->bus->need_parent_lock) device_lock(dev->parent); device_lock(dev); - if (!dev->driver) + if (!dev->dead && !dev->driver) driver_probe_device(drv, dev); device_unlock(dev); if (dev->parent && dev->bus->need_parent_lock) diff --git a/include/linux/device.h b/include/linux/device.h index 1b25c7a43f4c..f73dad81e811 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -957,6 +957,10 @@ struct dev_links_info { * device. * @dma_coherent: this particular device is dma coherent, even if the * architecture supports non-coherent devices. + * @dead: This device is currently either in the process of or has + * been removed from the system. Any asynchronous events + * scheduled for this device should exit without taking any + * action. * * At the lowest level, every device in a Linux system is represented by an * instance of struct device. The device structure contains the information @@ -1051,6 +1055,7 @@ struct device { defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL) bool dma_coherent:1; #endif + bool dead:1; }; static inline struct device *kobj_to_dev(struct kobject *kobj)