From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758054AbZAGOWu (ORCPT ); Wed, 7 Jan 2009 09:22:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753827AbZAGOWh (ORCPT ); Wed, 7 Jan 2009 09:22:37 -0500 Received: from mga07.intel.com ([143.182.124.22]:53016 "EHLO azsmga101.ch.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751627AbZAGOWg (ORCPT ); Wed, 7 Jan 2009 09:22:36 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.37,226,1231142400"; d="scan'208";a="97324943" Date: Wed, 7 Jan 2009 22:12:56 +0800 From: Yong Wang To: Arjan van de Ven Cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, mingo@elte.hu, akpm@linux-foundation.org, linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, linux-acpi@vger.kernel.org Subject: Re: [PATCH 4/6] fastboot: make ACPI bus drivers probe asynchronous Message-ID: <20090107141256.GA22902@ywang-moblin2.bj.intel.com> References: <20090105200959.04a626ac@infradead.org> <20090105201239.0784606e@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090105201239.0784606e@infradead.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 05, 2009 at 08:12:39PM -0800, Arjan van de Ven wrote: > > >From 34c47dd38f49e29eb7cd7fa2078efc6b8b258bb9 Mon Sep 17 00:00:00 2001 > From: Arjan van de Ven > Date: Sun, 4 Jan 2009 05:32:28 -0800 > Subject: [PATCH] fastboot: make ACPI bus drivers probe asynchronous > > the various ACPI bus drivers have non-overlapping devices and can > each be run asynchronous. Some of the ACPI drivers (especially the > battery one, but others as well) can take quite a long time to probe. > > Signed-off-by: Arjan van de Ven > --- > drivers/acpi/scan.c | 23 ++++++++++++++++------- > 1 files changed, 16 insertions(+), 7 deletions(-) > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > index 39b7233..a9e542d 100644 > --- a/drivers/acpi/scan.c > +++ b/drivers/acpi/scan.c > @@ -8,6 +8,7 @@ > #include > #include > #include > +#include > > #include > #include /* for acpi_ex_eisa_id_to_string() */ > @@ -578,6 +579,19 @@ static int acpi_start_single_object(struct acpi_device *device) > return result; > } > > +static void acpi_bus_register_async(void *data, async_cookie_t cookie) > +{ > + int ret; > + struct acpi_driver *driver = data; > + driver->drv.name = driver->name; > + driver->drv.bus = &acpi_bus_type; > + driver->drv.owner = driver->owner; > + > + async_synchronize_cookie(cookie); > + > + ret = driver_register(&driver->drv); > + WARN_ON(ret != 0); > +} > /** > * acpi_bus_register_driver - register a driver with the ACPI bus > * @driver: driver being registered > @@ -588,16 +602,11 @@ static int acpi_start_single_object(struct acpi_device *device) > */ > int acpi_bus_register_driver(struct acpi_driver *driver) > { > - int ret; > > if (acpi_disabled) > return -ENODEV; > - driver->drv.name = driver->name; > - driver->drv.bus = &acpi_bus_type; > - driver->drv.owner = driver->owner; > - > - ret = driver_register(&driver->drv); > - return ret; > + async_schedule(acpi_bus_register_async, driver); > + return 0; > } > > EXPORT_SYMBOL(acpi_bus_register_driver); For ACPI battery, button and thermal drivers whose init funtion immediately ends right after calling acpi_bus_register_driver, it might be OK. But for other drivers whose init function has more work to do and depends on acpi_bus_register_driver having *really* done its job, it is certainly not OK. In the latter case, the 'return 0' in acpi_bus_register_driver is effectively cheating those drivers that acpi_bus_register_driver has already done its job which is unfortunately not the case. Example drivers include eeepc_laptop and asus_laptop. At least I am seeing a kernel oops on eeepc because of that. -Yong