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=-6.8 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 1FF06C43382 for ; Wed, 26 Sep 2018 21:51:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C06F021537 for ; Wed, 26 Sep 2018 21:51:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C06F021537 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727284AbeI0EGw (ORCPT ); Thu, 27 Sep 2018 00:06:52 -0400 Received: from mga09.intel.com ([134.134.136.24]:22428 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726049AbeI0EGv (ORCPT ); Thu, 27 Sep 2018 00:06:51 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 26 Sep 2018 14:51:50 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,307,1534834800"; d="scan'208";a="94009130" Received: from ahduyck-mobl.amr.corp.intel.com (HELO localhost.localdomain) ([10.7.198.154]) by orsmga001.jf.intel.com with ESMTP; 26 Sep 2018 14:51:49 -0700 Subject: [RFC workqueue/driver-core PATCH 3/5] driver core: Probe devices asynchronously instead of the driver From: Alexander Duyck To: linux-nvdimm@lists.01.org, gregkh@linuxfoundation.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, tj@kernel.org, akpm@linux-foundation.org Cc: len.brown@intel.com, dave.jiang@intel.com, rafael@kernel.org, vishal.l.verma@intel.com, jiangshanlai@gmail.com, pavel@ucw.cz, zwisler@kernel.org, dan.j.williams@intel.com Date: Wed, 26 Sep 2018 14:51:49 -0700 Message-ID: <20180926215149.13512.51991.stgit@localhost.localdomain> In-Reply-To: <20180926214433.13512.30289.stgit@localhost.localdomain> References: <20180926214433.13512.30289.stgit@localhost.localdomain> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This change makes it so that we probe devices asynchronously instead of the driver. This results in us seeing the same behavior if the device is registered before the driver or after. This way we can avoid serializing the initialization should the driver not be loaded until after the devices have already been added. The motivation behind this is that if we have a set of devices that take a significant amount of time to load we can greatly reduce the time to load by processing them in parallel instead of one at a time. In addition, each device can exist on a different node so placing a single thread on one CPU to initialize all of the devices for a given driver can result in poor performance on a system with multiple nodes. One issue I can see with this patch is that I am using the dev_set/get_drvdata functions to store the driver in the device while I am waiting on the asynchronous init to complete. For now I am protecting it by using the lack of a dev->driver and the device lock. Signed-off-by: Alexander Duyck --- drivers/base/bus.c | 23 +++-------------------- drivers/base/dd.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 45 insertions(+), 20 deletions(-) diff --git a/drivers/base/bus.c b/drivers/base/bus.c index 8bfd27ec73d6..2a17bed657ec 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -616,17 +616,6 @@ static ssize_t uevent_store(struct device_driver *drv, const char *buf, } static DRIVER_ATTR_WO(uevent); -static void driver_attach_async(void *_drv, async_cookie_t cookie) -{ - struct device_driver *drv = _drv; - int ret; - - ret = driver_attach(drv); - - pr_debug("bus: '%s': driver %s async attach completed: %d\n", - drv->bus->name, drv->name, ret); -} - /** * bus_add_driver - Add a driver to the bus. * @drv: driver. @@ -659,15 +648,9 @@ int bus_add_driver(struct device_driver *drv) klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers); if (drv->bus->p->drivers_autoprobe) { - if (driver_allows_async_probing(drv)) { - pr_debug("bus: '%s': probing driver %s asynchronously\n", - drv->bus->name, drv->name); - async_schedule(driver_attach_async, drv); - } else { - error = driver_attach(drv); - if (error) - goto out_unregister; - } + error = driver_attach(drv); + if (error) + goto out_unregister; } module_add_driver(drv->owner, drv); diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 169412ee4ae8..5ba366c1cb83 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -864,6 +864,29 @@ void device_initial_probe(struct device *dev) __device_attach(dev, true); } +static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie) +{ + struct device *dev = _dev; + + if (dev->parent && dev->bus->need_parent_lock) + device_lock(dev->parent); + device_lock(dev); + + if (!dev->driver) { + struct device_driver *drv = dev_get_drvdata(dev); + + driver_probe_device(drv, dev); + } + + dev_dbg(dev, "async probe completed\n"); + + device_unlock(dev); + if (dev->parent && dev->bus->need_parent_lock) + device_unlock(dev->parent); + + put_device(dev); +} + static int __driver_attach(struct device *dev, void *data) { struct device_driver *drv = data; @@ -891,6 +914,25 @@ static int __driver_attach(struct device *dev, void *data) return ret; } /* ret > 0 means positive match */ + if (driver_allows_async_probing(drv)) { + /* + * Instead of probing the device synchronously we will + * probe it asynchronously to allow for more parallelism. + * + * We only take the device lock here in order to guarantee + * that the dev->driver and driver_data fields are protected + */ + dev_dbg(dev, "scheduling asynchronous probe\n"); + device_lock(dev); + if (!dev->driver) { + get_device(dev); + dev_set_drvdata(dev, drv); + async_schedule(__driver_attach_async_helper, dev); + } + device_unlock(dev); + return 0; + } + if (dev->parent && dev->bus->need_parent_lock) device_lock(dev->parent); device_lock(dev);