Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754941AbcDDQs1 (ORCPT ); Mon, 4 Apr 2016 12:48:27 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:18960 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751495AbcDDQsZ (ORCPT ); Mon, 4 Apr 2016 12:48:25 -0400 Subject: Re: [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier transitions To: David Vrabel , Julien Grall , Anna-Maria Gleixner , linux-kernel@vger.kernel.org References: <1459773140-43707-1-git-send-email-anna-maria@linutronix.de> <57029499.7070007@arm.com> <570296C3.70805@citrix.com> Cc: xen-devel@lists.xenproject.org, sstabellini@kernel.org, rt@linutronix.de, Juergen Gross From: Boris Ostrovsky Message-ID: <57029AC7.90201@oracle.com> Date: Mon, 4 Apr 2016 12:48:07 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <570296C3.70805@citrix.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: aserv0021.oracle.com [141.146.126.233] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1247 Lines: 38 On 04/04/2016 12:30 PM, David Vrabel wrote: > On 04/04/16 17:21, Julien Grall wrote: >> (CC Stefano new e-mail address) >> >> Hello Anna-Maria, >> >> On 04/04/2016 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. > Alternatively, these could be added even if they are not encountered. > This might be more future-proof but the documentation might be clearer. > > Boris, Juergen, any opinion? Wouldn't the same comment need to be added to xen_hvm_cpu_notify()? -boris > > David>> --- a/drivers/xen/events/events_fifo.c >>> +++ b/drivers/xen/events/events_fifo.c >>> @@ -425,6 +425,12 @@ static int evtchn_fifo_cpu_notification( >>> int cpu = (long)hcpu; >>> int ret = 0; >>> >>> + /* >>> + * Xen guests do not offline/online CPUs during >>> + * suspend/resume, thus CPU_TASKS_FROZEN masked transitions >>> + * are not considered. >>> + */ >> NIT: The '*' is not aligned with the others. > If this doesn't need any other changes, I'll fix this on commit. > > David