Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751452AbWKRVZv (ORCPT ); Sat, 18 Nov 2006 16:25:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752694AbWKRVZv (ORCPT ); Sat, 18 Nov 2006 16:25:51 -0500 Received: from host-233-54.several.ru ([213.234.233.54]:28371 "EHLO mail.screens.ru") by vger.kernel.org with ESMTP id S1751452AbWKRVZu (ORCPT ); Sat, 18 Nov 2006 16:25:50 -0500 Date: Sun, 19 Nov 2006 00:25:42 +0300 From: Oleg Nesterov To: Alan Stern Cc: "Paul E. McKenney" , "Paul E. McKenney" , Kernel development list Subject: Re: [patch] cpufreq: mark cpufreq_tsc() as core_initcall_sync Message-ID: <20061118212542.GA235@oleg> References: <20061118171410.GB4427@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 957 Lines: 26 On 11/18, Alan Stern wrote: > > By the way, I think the fastpath for synchronize_srcu() should be safe, > now that you have added the memory barriers into srcu_read_lock() and > srcu_read_unlock(). You might as well try putting it in. I still think the fastpath should do mb() unconditionally to be correct. > Although now that I look at it again, you have forgotten to put smp_mb() > after the atomic_inc() call and before the atomic_dec(). As I see it, currently we don't need this barrier because synchronize_srcu() does synchronize_sched() before reading ->hardluckref. But if we add the fastpath into synchronize_srcu() then yes, we need mb() after atomic_inc(). Unless I totally confused :) Oleg. - 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/