From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755270AbYEZKyM (ORCPT ); Mon, 26 May 2008 06:54:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753760AbYEZKx6 (ORCPT ); Mon, 26 May 2008 06:53:58 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:42185 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753463AbYEZKx5 (ORCPT ); Mon, 26 May 2008 06:53:57 -0400 Date: Mon, 26 May 2008 12:53:32 +0200 From: Ingo Molnar To: Kenji Kaneshige Cc: Andrew Morton , linux-kernel@vger.kernel.org, Jesse Barnes , Thomas Gleixner , "Rafael J. Wysocki" , drzeus-list@drzeus.cx Subject: Re: [patch, -git] pcie hotplug bootup crash fix Message-ID: <20080526105332.GA484@elte.hu> References: <20080524165828.GA29993@elte.hu> <20080524104024.a33116a3.akpm@linux-foundation.org> <483A7663.4000700@jp.fujitsu.com> <20080526084709.GA2182@elte.hu> <20080526015232.5faac5bb.akpm@linux-foundation.org> <483A9050.5000206@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <483A9050.5000206@jp.fujitsu.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Kenji Kaneshige wrote: > Although I have not considered how to implement proper fix deeply, I > don't think it's so simple. For example, current pciehp is doing like > this: > > (1) some initialization > (2) request_irq() > (3) issue command > (4) initialize slot data structure > > Maybe we want to do (2) after (4) to fix the problem. But if we simply > move (2) after (4), we cannot detect the command completion event at > (3) and it will cause command timeout. > > It's just an example, and there might be other things like this. This > example might be fixed simply, but all my worry is that fixing this > quickly might cause another regressions. This is why I think Ingo's > approach is better in a short term. > > And another reason is I'm very nervous because I already caused many > problems in pciehp since 2.6.26-rcX... :( no need to feel bad about it - i dont think what i reported is a serious problem in any fashion - it's a very narrow race as long as DEBUG_SHIRQ is off that very likely wont trigger in practice. We can do a minimal fix in v2.6.26 and something more structural in v2.6.27. Ingo