From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753184AbZHBTlN (ORCPT ); Sun, 2 Aug 2009 15:41:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752982AbZHBTlN (ORCPT ); Sun, 2 Aug 2009 15:41:13 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:58946 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752810AbZHBTlM (ORCPT ); Sun, 2 Aug 2009 15:41:12 -0400 Date: Sun, 2 Aug 2009 12:39:58 -0700 From: Andrew Morton To: Ingo Molnar Cc: paulmck@linux.vnet.ibm.com, mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, torvalds@linux-foundation.org, tglx@linutronix.de, linux-tip-commits@vger.kernel.org Subject: Re: [tip:core/debug] debug lockups: Improve lockup detection Message-Id: <20090802123958.cbd497a0.akpm@linux-foundation.org> In-Reply-To: <20090802192657.GA21882@elte.hu> References: <20090802114545.f1520c81.akpm@linux-foundation.org> <20090802192657.GA21882@elte.hu> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.5; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2 Aug 2009 21:26:57 +0200 Ingo Molnar wrote: > > I think this just broke all non-x86 non-sparc SMP architectures. > > Yeah - it 'broke' them in the sense of them not having a working > trigger_all_cpu_backtrace() implementation to begin with. c'mon. It broke them in the sense that sysrq-l went from "works" to "doesn't work". It would take months for the relevant arch maintainers to even find out about this, after which they're left with dud kernels out in the field. It's better to break the build or to emit warnings than to silently and secretly break their stuff. --- a/include/linux/nmi.h~a +++ a/include/linux/nmi.h @@ -29,6 +29,9 @@ static inline void acpi_nmi_enable(void) #endif #ifndef trigger_all_cpu_backtrace +#ifdef CONFIG_SMP +#warning This architecture is missing a trigger_all_cpu_backtrace() implementation +#endif #define trigger_all_cpu_backtrace() do { } while (0) #endif _