Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966665AbXEHUhW (ORCPT ); Tue, 8 May 2007 16:37:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933223AbXEHUhR (ORCPT ); Tue, 8 May 2007 16:37:17 -0400 Received: from mtagate1.uk.ibm.com ([195.212.29.134]:2532 "EHLO mtagate1.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932286AbXEHUhO (ORCPT ); Tue, 8 May 2007 16:37:14 -0400 Date: Tue, 8 May 2007 22:36:53 +0200 From: Cornelia Huck To: Linus Torvalds Cc: Adrian Bunk , Greg K-H , linux-kernel Subject: Re: Please revert 5adc55da4a7758021bcc374904b0f8b076508a11 (PCI_MULTITHREAD_PROBE) Message-ID: <20070508223653.1bb63b08@gondolin.boeblingen.de.ibm.com> In-Reply-To: References: <20070508153713.344cc881@gondolin.boeblingen.de.ibm.com> <20070508141149.GJ4226@stusta.de> <20070508183846.28a94797@gondolin.boeblingen.de.ibm.com> <20070508212117.0be9dfe5@gondolin.boeblingen.de.ibm.com> Organization: IBM Deutschland Entwicklung GmbH X-Mailer: Claws Mail 2.9.1 (GTK+ 2.10.12; i486-pc-linux-gnu) X-Legal: IBM Deutschland Entwicklung GmbH Vorsitzender des Aufsichtsrats: Johann Weihen =?ISO-8859-15?Q?Gesch=E4ftsf=FChrung:?= Herbert Kircher Sitz der Gesellschaft: =?ISO-8859-15?Q?B=F6blingen?= Registergericht: Amtsgericht Stuttgart, HRB 243294 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1260 Lines: 27 On Tue, 8 May 2007 12:31:22 -0700 (PDT), Linus Torvalds wrote: > > What if two devices become hotplugged at the same time? Does this imply > > that the bus _always_ needs to do some serializing there? > > You want to test it? Be my guest. It was more a rhetorical question. If not all drivers can handle it, serialize at the bus level. But if all drivers can, there's no reason for the bus to do it. On a bus with a small number of drivers, I prefer to have the drivers in good shape. (This kind of implies that e. g. pci needs to serialize, but css/ccw doesn't, and doesn't have to.) > But the final nail in the coffin is that doing it at the bus level is > INFERIOR. As you yourself admitted, it's better to do some things > synchronously. How so? It is possible to do some stuff synchronously. But why shouldn't other things be done asynchronously? (And there is a place both for bus-level parallelism and driver-level parallelism. Just depends on your bus/driver/device.) - 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/