Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932266Ab1EKQQM (ORCPT ); Wed, 11 May 2011 12:16:12 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:58116 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932396Ab1EKQQF (ORCPT ); Wed, 11 May 2011 12:16:05 -0400 Subject: Re: [tip:sched/core] sched: Use bool type for rq->idle_at_tick From: Peter Zijlstra To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, rakib.mullick@gmail.com, tglx@linutronix.de, mingo@elte.hu Cc: linux-tip-commits@vger.kernel.org In-Reply-To: References: <1304100062.19359.6.camel@localhost.localdomain> Content-Type: text/plain; charset="UTF-8" Date: Wed, 11 May 2011 13:08:18 +0200 Message-ID: <1305112098.2914.211.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1867 Lines: 50 On Sat, 2011-04-30 at 07:16 +0000, tip-bot for Rakib Mullick wrote: > Commit-ID: eea502ffd4aeef233b5eadbde405a9df92d57a5e > Gitweb: http://git.kernel.org/tip/eea502ffd4aeef233b5eadbde405a9df92d57a5e > Author: Rakib Mullick > AuthorDate: Sat, 30 Apr 2011 00:01:02 +0600 > Committer: Ingo Molnar > CommitDate: Sat, 30 Apr 2011 00:17:14 +0200 > > sched: Use bool type for rq->idle_at_tick > > Searching over the scheduler code for uses of rq->idle_at_tick > shows us that it's used for making TRUE/FALSE decision. > > Still its type is 'unsigned char' so using 'bool' would be > cleaner. > > Signed-off-by: Rakib Mullick > Cc: Peter Zijlstra > Link: http://lkml.kernel.org/r/1304100062.19359.6.camel@localhost.localdomain > Signed-off-by: Ingo Molnar > --- > kernel/sched.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/kernel/sched.c b/kernel/sched.c > index f11a2a5..a492209 100644 > --- a/kernel/sched.c > +++ b/kernel/sched.c > @@ -505,7 +505,7 @@ struct rq { > > unsigned long cpu_power; > > - unsigned char idle_at_tick; > + bool idle_at_tick; > /* For active balancing */ > int post_schedule; > int active_balance; Right, so the problem I have with using bool in structures is that sizeof(_Bool) is not well defined by the C standard and is implementation dependent, meaning the struct rq layout can change between gcc versions, architectures or even between optimization levels. So for structures where the layout is relevant we must avoid bool. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/