From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752024Ab0DBUAz (ORCPT ); Fri, 2 Apr 2010 16:00:55 -0400 Received: from mail.windriver.com ([147.11.1.11]:36968 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750842Ab0DBUAv (ORCPT ); Fri, 2 Apr 2010 16:00:51 -0400 Message-ID: <4BB64CDA.4000405@windriver.com> Date: Fri, 02 Apr 2010 15:00:26 -0500 From: Jason Wessel User-Agent: Thunderbird 2.0.0.24 (X11/20100317) MIME-Version: 1.0 To: Linus Torvalds CC: kgdb-bugreport@lists.sourceforge.net, Will Deacon , Linux Kernel Mailing List , Russell King - ARM Linux , linux-arm@vger.kernel.org Subject: Re: [Kgdb-bugreport] [PATCH 4/5] kgdb: Use atomic operators whichuse barriers References: <1270233145-29335-1-git-send-email-jason.wessel@windriver.com><1270233145-29335-2-git-send-email-jason.wessel@windriver.com><1270233145-29335-3-git-send-email-jason.wessel@windriver.com><1270233145-29335-4-git-send-email-jason.wessel@windriver.com><1270233145-29335-5-git-send-email-jason.wessel@windriver.com> <4BB64762.6040806@windriver.com> <4BB649E3.5060606@windriver.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 02 Apr 2010 20:00:26.0641 (UTC) FILETIME=[233E7810:01CAD29F] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/02/2010 02:47 PM, Linus Torvalds wrote: > >> From: Jason Wessel >> Subject: [PATCH] kgdb: Use atomic operators which use barriers >> >> The cpu_relax() does not mandate that there is an smp memory barrier. >> As a result on the arm smp architecture the kernel debugger can hang >> on entry from time to time, as shown by the kgdb regression tests. >> > > Now your changelog makes no sense any more. > It is revised now and pushed. Regression testing on the HW I have has passed as well now. For the series the pull looks like: drivers/misc/kgdbts.c | 6 ++ kernel/kgdb.c | 205 +++++++++++++++++++++++++------------------------ 2 files changed, 109 insertions(+), 102 deletions(-) Thanks, Jason. --- From: Jason Wessel Subject: [PATCH] kgdb: use atomic_inc and atomic_dec instead of atomic_set Memory barriers should be used for the kgdb cpu synchronization. The atomic_set() does not imply a memory barrier. Reported-by: Will Deacon Signed-off-by: Jason Wessel