From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752033AbaEBLwk (ORCPT ); Fri, 2 May 2014 07:52:40 -0400 Received: from v094114.home.net.pl ([79.96.170.134]:52246 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751733AbaEBLwi (ORCPT ); Fri, 2 May 2014 07:52:38 -0400 From: "Rafael J. Wysocki" To: Daniel Lezcano Cc: peterz@infradead.org, mingo@elte.hu, amit.kucheria@linaro.org, linaro-kernel@lists.linaro.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Nicolas Pitre Subject: Re: [PATCH V2 1/2] sched: idle: Encapsulate the code to compile it out Date: Fri, 02 May 2014 14:09:11 +0200 Message-ID: <5985714.f7hh9Ej59L@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/3.14.0-rc7+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <53635E5F.8070100@linaro.org> References: <1398859263-7632-1-git-send-email-daniel.lezcano@linaro.org> <2735426.75qSjG3M6Y@vostro.rjw.lan> <53635E5F.8070100@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Friday, May 02, 2014 10:59:11 AM Daniel Lezcano wrote: > On 05/01/2014 12:56 AM, Rafael J. Wysocki wrote: > > On Thursday, May 01, 2014 12:47:25 AM Rafael J. Wysocki wrote: > >> On Wednesday, April 30, 2014 02:01:02 PM Daniel Lezcano wrote: > >>> Encapsulate the large portion of cpuidle_idle_call inside another > >>> function so when CONFIG_CPU_IDLE=n, the code will be compiled out. > >>> Also that is benefitial for the clarity of the code as it removes > >>> a nested indentation level. > >>> > >>> Signed-off-by: Daniel Lezcano > >> > >> Well, this conflicts with > >> > >> https://patchwork.kernel.org/patch/4071541/ > >> > >> which you haven't commented on and I still want cpuidle_select() to be able to > >> return negative values because of > >> > >> https://patchwork.kernel.org/patch/4089631/ > >> > >> (and I have one more patch on top of these two that requires this). > > > > Moreover (along the lines of Nico said) after https://patchwork.kernel.org/patch/4071541/ > > we actually don't need the #ifdef CONFIG_CPU_IDLE in your patch, because cpuidle_select() > > for CONFIG_CPU_IDLE unset is a static inline returning a negative number and the compiler > > should optimize out the blocks that depend on it being non-negative. > > Thanks for the head up. > > Actually that was to solve a compilation issue with the next patch when > adding the cpuidle state in the struct rq. > > When the option CPU_IDLE is not set, the code assinging the cpu idle > state in the rq is still there while in the struct rq the field is > compiled out with the ifdef macro. If I rely on the compiler > optimization, the compilation error will happen. I see. If you don't put the new idle_state field in struct_rq under the #ifdef, you won't need to worry about the build problem. Alternatively, you can define #ifdef CONFIG_CPU_IDLE static inline void rq_set_idle_state(struct rq *rq, struct cpuidle_state *state) { rq->idle_state = state; } #else static inline void rq_set_idle_state(struct rq *rq, struct cpuidle_state *state) {} #endif and use rq_set_idle_state() to set that field. -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.