From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754384AbbERVsZ (ORCPT ); Mon, 18 May 2015 17:48:25 -0400 Received: from mail-ig0-f176.google.com ([209.85.213.176]:33771 "EHLO mail-ig0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752515AbbERVsY (ORCPT ); Mon, 18 May 2015 17:48:24 -0400 Date: Mon, 18 May 2015 14:48:19 -0700 From: Dmitry Torokhov To: Greg Kroah-Hartman Cc: Tejun Heo , "Luis R . Rodriguez" , linux-kernel@vger.kernel.org, Arjan van de Ven , Rusty Russell , Olof Johansson , Tetsuo Handa Subject: Re: [PATCH v2 0/8] Asynchronous device/driver probing support Message-ID: <20150518214819.GE19708@dtor-ws> References: <1427757610-27882-1-git-send-email-dmitry.torokhov@gmail.com> <20150331203949.GI9974@htj.duckdns.org> <20150406162251.GB36770@dtor-ws> <20150406174530.GA16070@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150406174530.GA16070@kroah.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 06, 2015 at 07:45:30PM +0200, Greg Kroah-Hartman wrote: > On Mon, Apr 06, 2015 at 09:22:51AM -0700, Dmitry Torokhov wrote: > > On Tue, Mar 31, 2015 at 04:39:49PM -0400, Tejun Heo wrote: > > > On Mon, Mar 30, 2015 at 04:20:02PM -0700, Dmitry Torokhov wrote: > > > > This series is a combination of changes proposed by Luis a couple months > > > > ago and implementation used by Chrome OS. The issue we are trying to solve > > > > here is "slow" devices and drivers spending "too much time" in their probe() > > > > methods and it affects: > > > > > > > > - overall kernel boot process when drivers are compiled into the kernel > > > > and slow devices stall entire boot progress; > > > > - systemd desire to time out module loading process. > > > > > > > > Unlike Luis' proposal we do make use of asycn_schedule() infrastructure > > > > instead of using a dedicated workqueue, so all existing synchronization > > > > points in kernel that wait for device registration still work the same. > > > > Also, the asynchronous probing is done not only during driver registration > > > > (i.e. when devices are probed asynchronously only if they are registered > > > > before the driver), but also during device registration and deferred probe > > > > handling. This way slow devices do not stall kernel boot even when drivers > > > > are compiled into the kernel. > > > > > > > > The last patch is for adventurous people to try and force > > > > fully-asynchronous boot. It works for me with limited success - I can boot > > > > Rockhip-based box to userspace as long as I force serial to be sychronously > > > > probed and ignore the fact that most devices are using "dummy" regulators > > > > as regulator subsystem really expects regulators to be registered in > > > > orderly fashion on OF-based systems. > > > > > > > > Changes from v1: > > > > > > > > - Changed verbage in change logs and code to emphasise that > > > > PROBE_PREFER_ASYNCHRONOUS is a temporary measure and the end goal is > > > > to enable asynchronous probing by default, as requested by Tejun. > > > > > > Looks good to me. Please feel free to add > > > > > > Acked-by: Tejun Heo > > > > Greg, it would be great if it could make it in 4.1. > > It's on my list of patches to review next... Greg, could we make 4.2 please? ;) Thanks. -- Dmitry