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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 441C3C433FF for ; Thu, 8 Aug 2019 19:14:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 093CE2184E for ; Thu, 8 Aug 2019 19:14:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565291660; bh=rhvPZ3zepMtbGuWGUV2mDeaLMWFgBYdBP4GuSvDUE5A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=cj2j3m3WAkPJxXK978fZByil+El8uumsD5urZIMdrTHHeVFZQIlQ9hLU3aSxegRop brx4Ss+Kq4fVyYojuMmWjodL/yHkodRKDyzEev7Dh6x3s2hctGtKEt7wHPwhlx0vHU 2Yfx06DZIdKRlm64JWdquuyMYthpG5Qjah6vcd5o= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405316AbfHHTOS (ORCPT ); Thu, 8 Aug 2019 15:14:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:42980 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404962AbfHHTIr (ORCPT ); Thu, 8 Aug 2019 15:08:47 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 96399214C6; Thu, 8 Aug 2019 19:08:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565291326; bh=rhvPZ3zepMtbGuWGUV2mDeaLMWFgBYdBP4GuSvDUE5A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CXp92f/bGjCY895J0HCCDUbuqkjnLExsFNAyLquUAQjaMz7+NhDTQKolGI/NJONhf 36W5IXxfZbmSSao/GmOqhgJ+YCv/omTLIimT83/Ygp7CnN49BSXZXYwJvVsCB1BFOT EARG12yQZENIh3pLZpb/DI6yTc0FVhg/GqyImpOE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dan Williams , "Rafael J. Wysocki" , Alexander Duyck , Sasha Levin Subject: [PATCH 4.19 03/45] driver core: Establish order of operations for device_add and device_del via bitflag Date: Thu, 8 Aug 2019 21:04:49 +0200 Message-Id: <20190808190454.008105790@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190808190453.827571908@linuxfoundation.org> References: <20190808190453.827571908@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org commit 3451a495ef244a88ed6317a035299d835554d579 upstream. Add an additional bit flag to the device_private 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 Reviewed-by: Rafael J. Wysocki Signed-off-by: Alexander Duyck Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/base/base.h | 4 ++++ drivers/base/core.c | 11 +++++++++++ drivers/base/dd.c | 22 +++++++++++----------- 3 files changed, 26 insertions(+), 11 deletions(-) diff --git a/drivers/base/base.h b/drivers/base/base.h index 7a419a7a6235b..559b047de9f75 100644 --- a/drivers/base/base.h +++ b/drivers/base/base.h @@ -66,6 +66,9 @@ struct driver_private { * probed first. * @device - pointer back to the struct device that this structure is * associated with. + * @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. * * Nothing outside of the driver core should ever touch these fields. */ @@ -76,6 +79,7 @@ struct device_private { struct klist_node knode_bus; struct list_head deferred_probe; struct device *device; + u8 dead:1; }; #define to_device_private_parent(obj) \ container_of(obj, struct device_private, knode_parent) diff --git a/drivers/base/core.c b/drivers/base/core.c index 92e2c32c22270..37a90d72f3736 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -2050,6 +2050,17 @@ 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->p->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 d48b310c47603..11d24a552ee49 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -725,15 +725,6 @@ 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 */ @@ -768,6 +759,15 @@ 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->p->dead || dev->driver) + goto out_unlock; + if (dev->parent) pm_runtime_get_sync(dev->parent); @@ -778,7 +778,7 @@ 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); @@ -891,7 +891,7 @@ 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->p->dead && !dev->driver) driver_probe_device(drv, dev); device_unlock(dev); if (dev->parent && dev->bus->need_parent_lock) -- 2.20.1