Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751291AbbEYEoh (ORCPT ); Mon, 25 May 2015 00:44:37 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:35380 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751099AbbEYEof (ORCPT ); Mon, 25 May 2015 00:44:35 -0400 Date: Sun, 24 May 2015 21:44:32 -0700 From: Darren Hart To: Pali =?iso-8859-1?Q?Roh=E1r?= Cc: Dmitry Torokhov , Valdis Kletnieks , lkml , platform-driver-x86@vger.kernel.org, Matthew Garrett , Greg Kroah-Hartman Subject: Re: dell_rbtn - kernel panic at boot... Message-ID: <20150525044432.GA38428@fury.dvhart.com> References: <5875.1432260403@turing-police.cc.vt.edu> <201505230305.36633@pali> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <201505230305.36633@pali> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1726 Lines: 42 On Sat, May 23, 2015 at 03:05:36AM +0200, Pali Roh?r wrote: > On Saturday 23 May 2015 00:53:16 Dmitry Torokhov wrote: > > On Thu, May 21, 2015 at 7:06 PM, Valdis Kletnieks > > > > wrote: > > > So after I made both config variables =y, the resulting kernel > > > built, but died a glorious death at boot. > > > > I guess if both are built-in then, according to link order, > > dell-laptop starts first, before dell-rbtn, and dies in > > dell_rbtn_notifier_register() in call to > > driver_for_each_device(&rbtn_driver.drv, ...) because rbtn_driver has > > not been registered yet and thus half-initlalized. > > > > Thanks. > > pr_debug() messages could be useful... but no idea if we can get them. > > Is there any way to fix that dependency race condition? Could > driver_attach() function call help? I believe you can avoid this by moving dell-rbtn earlier in the Makefile than dell-laptop - but this is fragile and a hack to resolve a dependency problem. I suppose this is why thinkpad-acpi.c is huge, and why having separate drivers talk to eachother is discouraged. dell-laptop seems to be the base, while dell-rbtn is the more specific of the two - which makes dell-laptop calling a dell-rbtn function which requires dell-rbtn to have been initialized prior a poor approach. Greg, Matthew, I'm tempted to recommend this 434 line driver be rolled into dell-laptop.c. Any strong opinions? -- Darren Hart Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/