From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750990AbWFELpW (ORCPT ); Mon, 5 Jun 2006 07:45:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751001AbWFELpW (ORCPT ); Mon, 5 Jun 2006 07:45:22 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:27520 "EHLO fgwmail7.fujitsu.co.jp") by vger.kernel.org with ESMTP id S1750990AbWFELpW (ORCPT ); Mon, 5 Jun 2006 07:45:22 -0400 Date: Mon, 5 Jun 2006 20:46:36 +0900 From: "Akiyama, Nobuyuki" To: ebiederm@xmission.com (Eric W. Biederman) Cc: Preben.Trarup@ericsson.com, fastboot@lists.osdl.org, linux-kernel@vger.kernel.org, vgoyal@in.ibm.com Subject: Re: [Fastboot] [RFC][PATCH] Add missing notifier before crashing Message-Id: <20060605204636.3d50fd59.akiyama.nobuyuk@jp.fujitsu.com> In-Reply-To: References: <20060530183359.a8d5d736.akiyama.nobuyuk@jp.fujitsu.com> <20060530145658.GC6536@in.ibm.com> <20060531182045.9db2fac9.akiyama.nobuyuk@jp.fujitsu.com> <20060531154322.GA8475@in.ibm.com> <20060601213730.dc9f1ec4.akiyama.nobuyuk@jp.fujitsu.com> <20060601151605.GA7380@in.ibm.com> <20060602141301.cdecf0e1.akiyama.nobuyuk@jp.fujitsu.com> <44800E1A.1080306@ericsson.com> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.6.10; i686-pc-mingw32) 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 On Fri, 02 Jun 2006 05:52:32 -0600 ebiederm@xmission.com (Eric W. Biederman) wrote: > Preben Traerup writes: > > > Since I'm one of the people who very much would like best of both worlds, > > I do belive Vivek Goyal's concern about the reliability of kdump must be > > adressed properly. > > > > I do belive the crash notifier should at least be a list of its own. > > Attaching element to the list proves your are kdump aware - in theory > > > > However: > > > > Conceptually I do not like the princip of implementing crash notifier > > as a list simply because for all (our) practical usage there will only > > be one element attached to the list anyway. > > > > And as I belive crash notifiers only will be used by a very limited > > number of users, I suggested in another mail that a simple > > > > if (function pointer) > > call functon > > > > approach to be used for this special case to keep things very simple. > > I am completely against crash notifiers. The code crash_kexec switches to > is what is notified and it can do whatever it likes. The premise is > that the kernel does not work. Therefore we cannot safely notify > kernel code. We do the very minimal to get out of the kernel, > and it is my opinion we still do to much. > > The crash_kexec entry point is not about taking crash dumps. It is > about implementing policy when the kernel panics. Generally the > policy we want is a crash dump but the mechanism is general purpose > and not limited to that. I understand it is more reliable that the notifier is executed by crash_kexec(). But I guess it take longer time than a clustering system demand and it is more complex to implement the notifier. The crash notifier I proposed is very simple and lightweight, and it is easy to use for all people. Regards, Akiyama, Nobuyuki