From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932822Ab3DYUDp (ORCPT ); Thu, 25 Apr 2013 16:03:45 -0400 Received: from wolverine01.qualcomm.com ([199.106.114.254]:16886 "EHLO wolverine01.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757895Ab3DYUDo (ORCPT ); Thu, 25 Apr 2013 16:03:44 -0400 X-IronPort-AV: E=Sophos;i="4.87,553,1363158000"; d="scan'208";a="41454414" Message-ID: <51798C1D.9090405@codeaurora.org> Date: Thu, 25 Apr 2013 13:03:41 -0700 From: Stephen Boyd User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:17.0) Gecko/20130328 Thunderbird/17.0.5 MIME-Version: 1.0 To: Russell King - ARM Linux CC: Thomas Gleixner , Kevin Hilman , LKML , linux-arch@vger.kernel.org, Linus Torvalds , Andrew Morton , Rusty Russell , Paul McKenney , Ingo Molnar , Peter Zijlstra , "Srivatsa S. Bhat" , Magnus Damm Subject: Re: [patch 08/34] arm: Use generic idle loop References: <20130321214930.752934102@linutronix.de> <20130321215233.826238797@linutronix.de> <87zjxv9lga.fsf@linaro.org> <20130325114808.GQ4977@n2100.arm.linux.org.uk> <20130408214719.GN17995@n2100.arm.linux.org.uk> <20130409093836.GA14496@n2100.arm.linux.org.uk> In-Reply-To: <20130409093836.GA14496@n2100.arm.linux.org.uk> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/09/13 02:38, Russell King - ARM Linux wrote: > On Tue, Apr 09, 2013 at 11:20:31AM +0200, Thomas Gleixner wrote: >> On Mon, 8 Apr 2013, Russell King - ARM Linux wrote: >>> On Mon, Mar 25, 2013 at 03:02:39PM +0100, Thomas Gleixner wrote: >>> So, how can I review these changes when all there is is a git URL, and >>> I *do* not want to pull them into my tree without first looking at the >>> patches, possibly reviewing them and *replying* with the patch inline? >> the patches were CC'ed to LKML and linux-arch and I expected that you >> are at least having the latter. Find the relevant patch inlined below. > I've not been on linux-arch for a few years now, after it evolved into > yet another lkml-like list with high traffic rates, where mainly specific > x86 issues seemed to be discussed, rather than it being a way to contact > all arch maintainers. > >> It is a counter. I looked carefully at all the various slightly >> differently fcked up implementations and picked the counter based one >> as it fits all requirements. > Great, thanks. The attached patch looks fine to me. I'm pretty sure that we need to apply this patch now that rcu_idle_enter()/exit() is called lower down in the idle loop. Kevin, did you test hotplug? ----8<----- From: Stephen Boyd Subject: [PATCH] ARM: smp: Drop RCU_NONIDLE usage in cpu_die() Before f7b861b (arm: Use generic idle loop, 2013-03-21) ARM would kill the CPU within the rcu idle section. Now that the rcu_idle_enter()/exit() pair have been pushed lower down in the idle loop this is no longer true and so using RCU_NONIDLE here is no longer necessary and also harmful because RCU is not actually idle at this point. Signed-off-by: Stephen Boyd --- arch/arm/kernel/smp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 4619177..78f1eb5 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -233,7 +233,7 @@ void __ref cpu_die(void) mb(); /* Tell __cpu_die() that this CPU is now safe to dispose of */ - RCU_NONIDLE(complete(&cpu_died)); + complete(&cpu_died); /* * actual CPU shutdown procedure is at least platform (if not -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation