From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754345Ab2LSKUc (ORCPT ); Wed, 19 Dec 2012 05:20:32 -0500 Received: from service87.mimecast.com ([91.220.42.44]:41319 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750779Ab2LSKUZ convert rfc822-to-8bit (ORCPT ); Wed, 19 Dec 2012 05:20:25 -0500 Date: Wed, 19 Dec 2012 10:19:34 +0000 From: Mark Rutland To: Stephen Boyd Cc: "linux-kernel@vger.kernel.org" , "linux@arm.linux.org.uk" , "nico@linaro.org" , Marc Zyngier , Will Deacon , "john.stultz@linaro.org" , "tglx@linutronix.de" , "linux-arm-kernel@lists.infradead.org" Subject: Re: [RFC PATCH 2/5] clockevents: Add generic timer broadcast receiver Message-ID: <20121219101934.GD32484@e106331-lin.cambridge.arm.com> References: <1355832418-31692-1-git-send-email-mark.rutland@arm.com> <1355832418-31692-3-git-send-email-mark.rutland@arm.com> <50D0EB67.2060802@codeaurora.org> MIME-Version: 1.0 In-Reply-To: <50D0EB67.2060802@codeaurora.org> User-Agent: Mutt/1.5.20 (2009-06-14) X-OriginalArrivalTime: 19 Dec 2012 10:19:34.0817 (UTC) FILETIME=[57B82910:01CDDDD2] X-MC-Unique: 112121910193704501 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 18, 2012 at 10:17:11PM +0000, Stephen Boyd wrote: > On 12/18/12 04:06, Mark Rutland wrote: > > diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c > > index f113755..c2dd022 100644 > > --- a/kernel/time/tick-broadcast.c > > +++ b/kernel/time/tick-broadcast.c > > @@ -125,6 +125,21 @@ int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu) > > return ret; > > } > > > > +int tick_receive_broadcast(void) > > +{ > > + struct tick_device *td = this_cpu_ptr(&tick_cpu_device); > > + struct clock_event_device *evt = td->evtdev; > > + > > + if (!evt) > > + return -ENODEV; > > + > > + if (!evt->event_handler) > > + return -EINVAL; > > + > > Does this actually happen? It's not obvious to me how it does. Taking a look at it, I don't think it does. Any tick_device's clock_event_device should have an event_handler. I'll drop this check. A tick device might not have a clock_event_device registered in some cases -- the x86 lapic timer has to deal with interrupts pending across a kexec, where interrupts are enabled before local timers are registered. I'm not sure how common this problem might be though, and whether it should be dealt with here or elsewhere. > > + evt->event_handler(evt); > > + return 0; > > +} > > + > > /* > > * Broadcast the event to the cpus, which are set in the mask (mangled). > > */ > > > -- > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, > hosted by The Linux Foundation > Thanks, Mark.