From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756885Ab3ANL35 (ORCPT ); Mon, 14 Jan 2013 06:29:57 -0500 Received: from service87.mimecast.com ([91.220.42.44]:46029 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755758Ab3ANL34 convert rfc822-to-8bit (ORCPT ); Mon, 14 Jan 2013 06:29:56 -0500 Date: Mon, 14 Jan 2013 11:29:52 +0000 From: Mark Rutland To: Thomas Gleixner Cc: "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "nico@linaro.org" , Will Deacon , Marc Zyngier , "john.stultz@linaro.org" Subject: Re: [PATCHv2 1/4] clockevents: Add generic timer broadcast receiver Message-ID: <20130114112951.GC7990@e106331-lin.cambridge.arm.com> References: <1357742770-15028-1-git-send-email-mark.rutland@arm.com> <1357742770-15028-2-git-send-email-mark.rutland@arm.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) X-OriginalArrivalTime: 14 Jan 2013 11:29:52.0545 (UTC) FILETIME=[786BE110:01CDF24A] X-MC-Unique: 113011411295503001 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 Mon, Jan 14, 2013 at 11:06:31AM +0000, Thomas Gleixner wrote: > On Wed, 9 Jan 2013, Mark Rutland wrote: > > +#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST > > +extern int tick_receive_broadcast(void); > > +#else > > +static inline int tick_receive_broadcast(void) > > +{ > > + return 0; > > +} > > What's the inline function for? If an arch does not have broadcasting > support it should not have a receive broadcast function call either. That was how this was originally structured [1], but Santosh suggested this would break the build for !GENERIC_CLOCKEVENTS_BROADCAST [1]. It means that the arch-specific receive path (i.e. IPI handler) doesn't have to be #ifdef'd, which makes it less ugly. I'm happy to have it the other way, with #ifdef'd IPI handlers. > > > +#endif > > + > > #ifdef CONFIG_GENERIC_CLOCKEVENTS > > extern void clockevents_notify(unsigned long reason, void *arg); > > #else > > diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c > > index f113755..5079bb7 100644 > > --- a/kernel/time/tick-broadcast.c > > +++ b/kernel/time/tick-broadcast.c > > @@ -125,6 +125,18 @@ 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; > > Is anything going to use the return value? I'd added this after looking at the x86 lapic timers, where interrupts might remain pending over a kexec, and lapic interrupts come up before timers are registered. The return value is useful for shutting down the timer in that case (see x86's local_apic_timer_interrupt). If you don't agree I'll remove the return value. > > Thanks, > > tglx > Thanks, Mark. [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2012-December/138486.html