Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752844AbcDFOJE (ORCPT ); Wed, 6 Apr 2016 10:09:04 -0400 Received: from www.linutronix.de ([62.245.132.108]:43164 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750719AbcDFOJB (ORCPT ); Wed, 6 Apr 2016 10:09:01 -0400 Date: Wed, 6 Apr 2016 16:08:50 +0200 (CEST) From: Anna-Maria Gleixner To: David Vrabel cc: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, David Vrabel , rt@linutronix.de, Stefano Stabellini Subject: Re: [PREEMPT-RT] [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier transitions In-Reply-To: <57050A98.80901@cantab.net> Message-ID: References: <1459773140-43707-1-git-send-email-anna-maria@linutronix.de> <57050A98.80901@cantab.net> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001,URIBL_BLOCKED=0.001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1505 Lines: 39 On Wed, 6 Apr 2016, David Vrabel wrote: > On 04/04/16 13:32, Anna-Maria Gleixner wrote: > > Xen guests do not offline/online CPUs during suspend/resume and > > therefore FROZEN notifier transitions are not required. Add this > > explanation as a comment in the code to get not confused why > > CPU_TASKS_FROZEN masked transitions are not considered. > > > > Cc: David Vrabel > > Cc: Stefano Stabellini > > Cc: xen-devel@lists.xenproject.org > > Signed-off-by: Anna-Maria Gleixner > > --- > > arch/arm/xen/enlighten.c | 6 ++++++ > > arch/x86/xen/enlighten.c | 7 +++++++ > > drivers/xen/events/events_fifo.c | 6 ++++++ > > 3 files changed, 19 insertions(+) > > > > --- a/arch/arm/xen/enlighten.c > > +++ b/arch/arm/xen/enlighten.c > > @@ -213,6 +213,12 @@ static int xen_cpu_notification(struct n > > unsigned long action, > > void *hcpu) > > { > > + /* > > + * Xen guests do not offline/online CPUs during > > + * suspend/resume, thus CPU_TASKS_FROZEN masked transitions > > + * are not considered. > > + */ > > This may not be true for arm guests. Ok. Should the frozen transitions be handled the same way than the corresponding non frozen transitions? If yes and if it doesn't matter to mask action with ~CPU_TASKS_FROZEN in arch/x86/xen/enlighten.c and drivers/xen/events/events_fifo.c like Juergen sugessts, I could change the patch by masking action. Anna-Maria