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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 4F800C43387 for ; Mon, 17 Dec 2018 16:31:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1F7C32133F for ; Mon, 17 Dec 2018 16:31:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388194AbeLQQbu (ORCPT ); Mon, 17 Dec 2018 11:31:50 -0500 Received: from mga18.intel.com ([134.134.136.126]:45195 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387698AbeLQQbt (ORCPT ); Mon, 17 Dec 2018 11:31:49 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 17 Dec 2018 08:31:48 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,366,1539673200"; d="scan'208";a="111088182" Received: from ahduyck-desk1.jf.intel.com ([10.7.198.76]) by orsmga003.jf.intel.com with ESMTP; 17 Dec 2018 08:31:48 -0800 Message-ID: <96fc96dc7c7856a1f415417bf287936071c32f4d.camel@linux.intel.com> Subject: Re: [driver-core PATCH v9 2/9] device core: Consolidate locking and unlocking of parent and device From: Alexander Duyck To: "Rafael J. Wysocki" , Greg Kroah-Hartman Cc: Linux Kernel Mailing List , "Luis R. Rodriguez" , "linux-nvdimm@lists.01.org" , Tejun Heo , Andrew Morton , Linux PM , Lai Jiangshan , Len Brown , Pavel Machek , zwisler@kernel.org, Dan Williams , dave.jiang@intel.com, bvanassche@acm.org Date: Mon, 17 Dec 2018 08:31:46 -0800 In-Reply-To: References: <154466182249.9126.3905559325944768059.stgit@ahduyck-desk1.jf.intel.com> <154466190393.9126.148371211828405339.stgit@ahduyck-desk1.jf.intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-2.fc28) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2018-12-14 at 11:40 +0100, Rafael J. Wysocki wrote: > somOn Thu, Dec 13, 2018 at 1:45 AM Alexander Duyck > wrote: > > > > Try to consolidate all of the locking and unlocking of both the parent and > > device when attaching or removing a driver from a given device. > > > > To do that I first consolidated the lock pattern into two functions > > __device_driver_lock and __device_driver_unlock. After doing that I then > > created functions specific to attaching and detaching the driver while > > acquiring these locks. By doing this I was able to reduce the number of > > spots where we touch need_parent_lock from 12 down to 4. > > > > This patch should produce no functional changes, it is meant to be a code > > clean-up/consolidation only. > > > > Reviewed-by: Luis Chamberlain > > Reviewed-by: Bart Van Assche > > Reviewed-by: Dan Williams > > Reviewed-by: Rafael J. Wysocki > > Signed-off-by: Alexander Duyck > > --- > > drivers/base/base.h | 2 + > > drivers/base/bus.c | 23 ++---------- > > drivers/base/dd.c | 95 ++++++++++++++++++++++++++++++++++++++++----------- > > 3 files changed, 81 insertions(+), 39 deletions(-) > > > > diff --git a/drivers/base/base.h b/drivers/base/base.h > > index 7a419a7a6235..3f22ebd6117a 100644 > > --- a/drivers/base/base.h > > +++ b/drivers/base/base.h > > @@ -124,6 +124,8 @@ extern int driver_add_groups(struct device_driver *drv, > > const struct attribute_group **groups); > > extern void driver_remove_groups(struct device_driver *drv, > > const struct attribute_group **groups); > > +int device_driver_attach(struct device_driver *drv, struct device *dev); > > +void device_driver_detach(struct device *dev); > > > > extern char *make_class_name(const char *name, struct kobject *kobj); > > > > diff --git a/drivers/base/bus.c b/drivers/base/bus.c > > index b886b15cb53b..74054481007d 100644 > > --- a/drivers/base/bus.c > > +++ b/drivers/base/bus.c > > @@ -184,11 +184,7 @@ static ssize_t unbind_store(struct device_driver *drv, const char *buf, > > > > dev = bus_find_device_by_name(bus, NULL, buf); > > if (dev && dev->driver == drv) { > > - if (dev->parent && dev->bus->need_parent_lock) > > - device_lock(dev->parent); > > - device_release_driver(dev); > > - if (dev->parent && dev->bus->need_parent_lock) > > - device_unlock(dev->parent); > > + device_driver_detach(dev); > > err = count; > > } > > put_device(dev); > > @@ -211,13 +207,7 @@ static ssize_t bind_store(struct device_driver *drv, const char *buf, > > > > dev = bus_find_device_by_name(bus, NULL, buf); > > if (dev && dev->driver == NULL && driver_match_device(drv, dev)) { > > - if (dev->parent && bus->need_parent_lock) > > - device_lock(dev->parent); > > - device_lock(dev); > > - err = driver_probe_device(drv, dev); > > - device_unlock(dev); > > - if (dev->parent && bus->need_parent_lock) > > - device_unlock(dev->parent); > > + err = device_driver_attach(drv, dev); > > > > if (err > 0) { > > /* success */ > > @@ -771,13 +761,8 @@ EXPORT_SYMBOL_GPL(bus_rescan_devices); > > */ > > int device_reprobe(struct device *dev) > > { > > - if (dev->driver) { > > - if (dev->parent && dev->bus->need_parent_lock) > > - device_lock(dev->parent); > > - device_release_driver(dev); > > - if (dev->parent && dev->bus->need_parent_lock) > > - device_unlock(dev->parent); > > - } > > + if (dev->driver) > > + device_driver_detach(dev); > > return bus_rescan_devices_helper(dev, NULL); > > } > > EXPORT_SYMBOL_GPL(device_reprobe); > > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > > index 74c194ac99df..f07c16277ed9 100644 > > --- a/drivers/base/dd.c > > +++ b/drivers/base/dd.c > > @@ -867,6 +867,64 @@ void device_initial_probe(struct device *dev) > > __device_attach(dev, true); > > } > > > > +/* > > + * __device_driver_lock - acquire locks needed to manipulate dev->drv > > + * @dev: Device we will update driver info for > > + * @parent: Parent device. Needed if the bus requires parent lock > > + * > > + * This function will take the required locks for manipulating dev->drv. > > + * Normally this will just be the @dev lock, but when called for a USB > > + * interface, @parent lock will be held as well. > > + */ > > +static void __device_driver_lock(struct device *dev, struct device *parent) > > +{ > > + if (parent && dev->bus->need_parent_lock) > > + device_lock(parent); > > + device_lock(dev); > > +} > > + > > +/* > > + * __device_driver_unlock - release locks needed to manipulate dev->drv > > + * @dev: Device we will update driver info for > > + * @parent: Parent device. Needed if the bus requires parent lock > > + * > > + * This function will release the required locks for manipulating dev->drv. > > + * Normally this will just be the the @dev lock, but when called for a > > + * USB interface, @parent lock will be released as well. > > + */ > > +static void __device_driver_unlock(struct device *dev, struct device *parent) > > +{ > > + device_unlock(dev); > > + if (parent && dev->bus->need_parent_lock) > > + device_unlock(parent); > > +} > > + > > +/** > > + * device_driver_attach - attach a specific driver to a specific device > > + * @drv: Driver to attach > > + * @dev: Device to attach it to > > + * > > + * Manually attach driver to a device. Will acquire both @dev lock and > > + * @dev->parent lock if needed. > > + */ > > +int device_driver_attach(struct device_driver *drv, struct device *dev) > > +{ > > + int ret = 0; > > + > > + __device_driver_lock(dev, dev->parent); > > + > > + /* > > + * If device has been removed or someone has already successfully > > + * bound a driver before us just skip the driver probe call. > > + */ > > + if (!dev->dead && !dev->driver) > > + ret = driver_probe_device(drv, dev); > > + > > + __device_driver_unlock(dev, dev->parent); > > + > > + return ret; > > +} > > + > > static int __driver_attach(struct device *dev, void *data) > > { > > struct device_driver *drv = data; > > @@ -894,14 +952,7 @@ static int __driver_attach(struct device *dev, void *data) > > return ret; > > } /* ret > 0 means positive match */ > > > > - if (dev->parent && dev->bus->need_parent_lock) > > - device_lock(dev->parent); > > - device_lock(dev); > > - if (!dev->dead && !dev->driver) > > - driver_probe_device(drv, dev); > > - device_unlock(dev); > > - if (dev->parent && dev->bus->need_parent_lock) > > - device_unlock(dev->parent); > > + device_driver_attach(drv, dev); > > > > return 0; > > } > > @@ -932,15 +983,11 @@ static void __device_release_driver(struct device *dev, struct device *parent) > > drv = dev->driver; > > if (drv) { > > while (device_links_busy(dev)) { > > - device_unlock(dev); > > - if (parent) > > - device_unlock(parent); > > + __device_driver_unlock(dev, parent); > > > > device_links_unbind_consumers(dev); > > - if (parent) > > - device_lock(parent); > > > > - device_lock(dev); > > + __device_driver_lock(dev, parent); > > /* > > * A concurrent invocation of the same function might > > * have released the driver successfully while this one > > This change will clash with > https://patchwork.kernel.org/patch/10729571/ somewhat which really > should go it first as a stable-candidate fix. > > I would suggest rebasing on top of that one, unless Greg has different > plans here. Greg, any opinion here? From what I can tell the patch pointed out and this one both address the same issue. The only real difference is that the patch called out would be a better stable-candidate fix. I'm just wondering if the patch set is good as is or if I need to be submitting a v10 w/ rebase on top of this patch. Thanks. - Alex