From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261960AbULKQed (ORCPT ); Sat, 11 Dec 2004 11:34:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261964AbULKQed (ORCPT ); Sat, 11 Dec 2004 11:34:33 -0500 Received: from dbl.q-ag.de ([213.172.117.3]:50369 "EHLO dbl.q-ag.de") by vger.kernel.org with ESMTP id S261960AbULKQeb (ORCPT ); Sat, 11 Dec 2004 11:34:31 -0500 Message-ID: <41BB2108.70606@colorfullife.com> Date: Sat, 11 Dec 2004 17:32:08 +0100 From: Manfred Spraul User-Agent: Mozilla/5.0 (X11; U; Linux i686; fr-FR; rv:1.7.3) Gecko/20040922 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Zwane Mwaikambo CC: George Anzinger , Lee Revell , dipankar@in.ibm.com, ganzinger@mvista.com, lkml Subject: Re: RCU question References: <41B8E6F1.4070007@mvista.com> <20041210043102.GC4161@in.ibm.com> <41B9FC3F.50601@mvista.com> <20041210204003.GC4073@in.ibm.com> <1102711532.29919.35.camel@krustophenia.net> <41BA0ECF.1060203@mvista.com> <41BA59F6.5010309@mvista.com> <41BA698E.8000603@mvista.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Zwane Mwaikambo wrote: >On Fri, 10 Dec 2004, George Anzinger wrote: > > > >>That is ok. Either we have interrupts off and no softirqs are pending and we >>proceed to the "hlt" (where the interrupt will be taken), or softirqs are >>pending, we turn interrupts on, do the softirq, turn interrupts off and try >>again. Unless some tasklet (RCU?) never "gives up" or we will exit the while >>with interrupts off and move on to the "hlt". Or did I miss something? >> >> > >But the point is that you cannot execute hlt with interrupts disabled. > > The trick is the sti instruction: It enables interrupt processing after the following instruction. Thus sti hlt cannot race - it atomically enables interrupts and waits. -- Manfred