Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965468AbXAXAjb (ORCPT ); Tue, 23 Jan 2007 19:39:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965470AbXAXAjb (ORCPT ); Tue, 23 Jan 2007 19:39:31 -0500 Received: from smtp.osdl.org ([65.172.181.24]:44740 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965468AbXAXAja (ORCPT ); Tue, 23 Jan 2007 19:39:30 -0500 Date: Tue, 23 Jan 2007 16:38:26 -0800 From: Andrew Morton To: dipankar@in.ibm.com Cc: Ingo Molnar , Paul E McKenney , linux-kernel@vger.kernel.org Subject: Re: [mm PATCH 4/6] RCU: preemptible RCU Message-Id: <20070123163826.d4ba703a.akpm@osdl.org> In-Reply-To: <20070115192858.GE32238@in.ibm.com> References: <20070115191909.GA32238@in.ibm.com> <20070115192858.GE32238@in.ibm.com> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.6; i686-pc-linux-gnu) 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 Content-Length: 822 Lines: 29 On Tue, 16 Jan 2007 00:58:58 +0530 Dipankar Sarma wrote: > +/* > + * Wait for CPUs to acknowledge the flip. > + */ > +static int rcu_try_flip_waitack(int flipctr) > +{ > + int cpu; > + > + for_each_possible_cpu(cpu) > + if (per_cpu(rcu_flip_flag, cpu) != RCU_FLIP_SEEN) > + return 1; > + > + /* > + * Make sure our checks above don't bleed into subsequent > + * waiting for the sum of the counters to reach zero. > + */ > + smp_mb(); > + return 0; > +} Confused. If some of the possible cpus aren't online, doesn't the state machine get stuck?? - 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/