From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e5.ny.us.ibm.com (e5.ny.us.ibm.com [32.97.182.145]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e5.ny.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTP id 6929667EA5 for ; Tue, 14 Nov 2006 06:39:53 +1100 (EST) Received: from d01relay02.pok.ibm.com (d01relay02.pok.ibm.com [9.56.227.234]) by e5.ny.us.ibm.com (8.13.8/8.12.11) with ESMTP id kADJdfmg027671 for ; Mon, 13 Nov 2006 14:39:41 -0500 Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay02.pok.ibm.com (8.13.6/8.13.6/NCO v8.1.1) with ESMTP id kADJdfWE135168 for ; Mon, 13 Nov 2006 14:39:41 -0500 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id kADJdfwb010646 for ; Mon, 13 Nov 2006 14:39:41 -0500 Date: Mon, 13 Nov 2006 13:39:40 -0600 To: Nathan Lynch Subject: Re: [PATCH]: PowerPC: make sure the rtas stop-self token is defined. Message-ID: <20061113193940.GA8395@austin.ibm.com> References: <20061110182253.GV30625@austin.ibm.com> <17749.4445.46239.450000@cargo.ozlabs.ibm.com> <20061111005248.GW30625@austin.ibm.com> <20061113185704.GA8253@localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20061113185704.GA8253@localdomain> From: linas@austin.ibm.com (Linas Vepstas) Cc: linuxppc-dev@ozlabs.org, Paul Mackerras List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, Nov 13, 2006 at 12:57:04PM -0600, Nathan Lynch wrote: > > I'm still not clear on what problem this patch is intended to address. There's a code path that is compiled unconditonally, that expects this token to be defined. > If the 'online' cpu attribute in sysfs can be used to attempt an > offline operation on a kernel with CONFIG_HOTPLUG_CPU=n, that's what > needs to be fixed. There are many places where cpu_die() might be called, and I am sufficiently lazy to not want to audit them to make sure that none of these code paths are taken if CONFIG_HOTPLUG_CPU=n. Besides, if I audit all of these code paths today, and find that none of them are ever called when CONFIG_HOTPLUG_CPU=n, I still have no assurance that someone might not unwittingly change one of the code paths in the future. Code that might fail because someone makes an unwitting change in the future is "brittle". The goal of my patch was to remove the brittleness. Besides, I notice that platforms/powermac/smp.c defines cpu_die() as well, which tells me that there are code paths that lead to its being called, even if CONFIG_HOTPLUG_CPU=n. That would seem to conclude the audit, right? --linas