Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932339AbVISGyf (ORCPT ); Mon, 19 Sep 2005 02:54:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932338AbVISGyf (ORCPT ); Mon, 19 Sep 2005 02:54:35 -0400 Received: from b3162.static.pacific.net.au ([203.143.238.98]:19870 "EHLO cunningham.myip.net.au") by vger.kernel.org with ESMTP id S932339AbVISGye (ORCPT ); Mon, 19 Sep 2005 02:54:34 -0400 Subject: Re: PATCH: Fix race in cpu_down (hotplug cpu) From: Nigel Cunningham Reply-To: ncunningham@cyclades.com To: Nick Piggin Cc: Li Shaohua , vatsa@in.ibm.com, Andrew Morton , Linus Torvalds , Zwane Mwaikambo , lkml , Rusty Russell , Ingo Molnar In-Reply-To: <1127111784.5272.10.camel@npiggin-nld.site> References: <59D45D057E9702469E5775CBB56411F171F7E0@pdsmsx406> <20050919051024.GA8653@in.ibm.com> <1127107887.3958.9.camel@linux-hp.sh.intel.com> <20050919055715.GE8653@in.ibm.com> <1127110271.9696.97.camel@localhost> <20050919062336.GA9466@in.ibm.com> <1127111830.4087.3.camel@linux-hp.sh.intel.com> <1127111784.5272.10.camel@npiggin-nld.site> Content-Type: text/plain Organization: Cyclades Message-Id: <1127112869.9696.107.camel@localhost> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6-1mdk Date: Mon, 19 Sep 2005 16:54:29 +1000 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1053 Lines: 31 Hi. On Mon, 2005-09-19 at 16:36, Nick Piggin wrote: > On Mon, 2005-09-19 at 14:37 +0800, Shaohua Li wrote: > > On Mon, 2005-09-19 at 11:53 +0530, Srivatsa Vaddagiri wrote: > > > > default_idle should be fine as it is. IOW it should not cause __cpu_die to > > > timeout. > > Why default_idle should be fine? it can be preempted before the > > 'local_irq_disable' check. Even with Nigel's patch, there is a very > > small window at safe_halt (after 'sti' but before 'hlt'). > > > > Ah, actually I have a patch which makes all CPU idle threads > run with preempt disabled and only enable preempt when scheduling. > Would that help? Sounds to me like it should, but I'm not claiming any expertise in this area. Going off your other posts, you're thinking of this plus my original patch? Regards, Nigel - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/