From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754667Ab1FMT4b (ORCPT ); Mon, 13 Jun 2011 15:56:31 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:40654 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753516Ab1FMT43 (ORCPT ); Mon, 13 Jun 2011 15:56:29 -0400 Date: Mon, 13 Jun 2011 21:56:13 +0200 From: Ingo Molnar To: Suresh Siddha Cc: tglx@linutronix.de, hpa@zytor.com, trenn@novell.com, prarit@redhat.com, tj@kernel.org, rusty@rustcorp.com.au, linux-kernel@vger.kernel.org, youquan.song@intel.com, stable@kernel.org Subject: Re: [patch v4 1/2] stop_machine: enable __stop_machine() to be called from the cpu online path Message-ID: <20110613195613.GA11196@elte.hu> References: <20110613175832.331826123@sbsiddha-MOBL3.sc.intel.com> <20110613175915.504721985@sbsiddha-MOBL3.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110613175915.504721985@sbsiddha-MOBL3.sc.intel.com> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.3.1 -2.0 BAYES_00 BODY: Bayes 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 * Suresh Siddha wrote: > Currently stop machine infrastructure can be called only from a cpu that is > online. But for !CONFIG_SMP, we do allow calling __stop_machine() before the > cpu is online. > > x86 for example requires stop machine infrastructure in the cpu online path > and currently implements its own stop machine (using stop_one_cpu_nowait()) > for MTRR initialization in the cpu online path. > > Enhance the __stop_machine() so that it can be called before the cpu > is onlined. This will pave the way for code consolidation and address potential > deadlocks caused by multiple mechanisms of doing system wide rendezvous. > > This will also address the behavioral differences of __stop_machine() > between SMP and UP builds. > > Signed-off-by: Suresh Siddha > Cc: stable@kernel.org # v2.6.35+ > --- > include/linux/stop_machine.h | 11 +++-- > kernel/stop_machine.c | 91 ++++++++++++++++++++++++++++++++++++++++--- > 2 files changed, 93 insertions(+), 9 deletions(-) Btw., this is *way* too risky for a -stable backport. Thanks, Ingo