From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751195AbWFCQLp (ORCPT ); Sat, 3 Jun 2006 12:11:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751316AbWFCQLp (ORCPT ); Sat, 3 Jun 2006 12:11:45 -0400 Received: from smtp112.sbc.mail.re2.yahoo.com ([68.142.229.93]:9890 "HELO smtp112.sbc.mail.re2.yahoo.com") by vger.kernel.org with SMTP id S1751195AbWFCQLo (ORCPT ); Sat, 3 Jun 2006 12:11:44 -0400 From: Dmitry Torokhov To: Arjan van de Ven Subject: Re: [patch] Declare explicit, hardware based lock ranking in serio Date: Sat, 3 Jun 2006 12:11:42 -0400 User-Agent: KMail/1.9.1 Cc: Andrew Morton , linux-kernel@vger.kernel.org, mingo@redhat.com, Linux Portal References: <200606030756.39861.dtor_core@ameritech.net> <1149336677.3109.34.camel@laptopd505.fenrus.org> In-Reply-To: <1149336677.3109.34.camel@laptopd505.fenrus.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200606031211.42976.dtor_core@ameritech.net> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Saturday 03 June 2006 08:11, Arjan van de Ven wrote: > On Sat, 2006-06-03 at 07:56 -0400, Dmitry Torokhov wrote: > > On Saturday 03 June 2006 04:50, Arjan van de Ven wrote: > > > > Thanks. > > > > > > > > So we're taking ps2->cmd_mutex and then we're recurring back into > > > > ps2_command() and then taking ps2->serio->cmd_mutex. > > > > > > > > I suspect that's all correct/natural/expected and needs another > > > > make-lockdep-shut-up patch. > > > > > > > > > The PS/2 code has a natural device order and there is a one level > > > recursion in this device order in terms of the cmd_mutex; annotate > > > this explicit recursion as ok > > > > > > > It is not necessarily single depth - one could have 2 or more pass-through > > ports chained together, although currently in kernel we only have Synaptics > > pass-through. If we were ever to implement pass-through port for IBMs > > trackpoints then we'd have: > > > > Synaptics<->pass-through<->TP<->pass-through<->some mouse > > is there a bound to this? lockdep can deal with upto 8 or so > recursions.... > Theoretically - no, practically - 2 as shown above. At the moment the only devices that are using/may be using pass-through ports are Synaptics touchpad and IBM trackpoint. -- Dmitry