From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754632AbYEZK2l (ORCPT ); Mon, 26 May 2008 06:28:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752234AbYEZK2d (ORCPT ); Mon, 26 May 2008 06:28:33 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:44892 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752184AbYEZK2c (ORCPT ); Mon, 26 May 2008 06:28:32 -0400 Message-ID: <483A9050.5000206@jp.fujitsu.com> Date: Mon, 26 May 2008 19:26:24 +0900 From: Kenji Kaneshige User-Agent: Thunderbird 2.0.0.14 (Windows/20080421) MIME-Version: 1.0 To: Andrew Morton CC: Ingo Molnar , 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 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> In-Reply-To: <20080526015232.5faac5bb.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton wrote: > On Mon, 26 May 2008 10:47:09 +0200 Ingo Molnar wrote: > >> * Kenji Kaneshige wrote: >> >>> I updated Ingo's patch. If it's ok, I'll send it to Jess Barnes with >>> some other patches for the other pciehp regression problems. >> looks good to me, thanks Kenji. >> > > It's a bit sad to add a large workaround like this. I'm surprised > that fixing it properly is considered unviable for 2.6.26. Normally > these fixes are pretty simple - just request the IRQ a bit later? > 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... :( Thanks, Kenji Kaneshige