From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S934160AbbDVObE (ORCPT <rfc822;w@1wt.eu>);
	Wed, 22 Apr 2015 10:31:04 -0400
Received: from e34.co.us.ibm.com ([32.97.110.152]:55251 "EHLO
	e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S933456AbbDVObA (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Wed, 22 Apr 2015 10:31:00 -0400
Date: Wed, 22 Apr 2015 07:30:54 -0700
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Pranith Kumar <bobby.prani@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@kernel.org>,
        Lai Jiangshan <laijs@cn.fujitsu.com>,
        Dipankar Sarma <dipankar@in.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Josh Triplett <josh@joshtriplett.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        David Howells <dhowells@redhat.com>,
        Eric Dumazet <edumazet@google.com>,
        Darren Hart <dvhart@linux.intel.com>,
        =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>,
        Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH tip/core/rcu 11/12] rcu: Make RCU able to tolerate
 undefined CONFIG_RCU_FANOUT_LEAF
Message-ID: <20150422143054.GY5561@linux.vnet.ibm.com>
Reply-To: paulmck@linux.vnet.ibm.com
References: <20150421195529.GA17864@linux.vnet.ibm.com>
 <1429646153-20677-1-git-send-email-paulmck@linux.vnet.ibm.com>
 <1429646153-20677-11-git-send-email-paulmck@linux.vnet.ibm.com>
 <CAJhHMCC7aZ_pHhZ0g176+RpzyTw5hpwEQNbM9Fp-GHGgpBgiXQ@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAJhHMCC7aZ_pHhZ0g176+RpzyTw5hpwEQNbM9Fp-GHGgpBgiXQ@mail.gmail.com>
User-Agent: Mutt/1.5.21 (2010-09-15)
X-TM-AS-MML: disable
X-Content-Scanned: Fidelis XPS MAILER
x-cbid: 15042214-0017-0000-0000-00000A3C58E8
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, Apr 22, 2015 at 01:25:07AM -0400, Pranith Kumar wrote:
> On Tue, Apr 21, 2015 at 3:55 PM, Paul E. McKenney
> <paulmck@linux.vnet.ibm.com> wrote:
> 
> > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
> > index 2e52502bfc95..a2f64e4fdb57 100644
> > --- a/kernel/rcu/tree_plugin.h
> > +++ b/kernel/rcu/tree_plugin.h
> > @@ -86,10 +86,10 @@ static void __init rcu_bootup_announce_oddness(void)
> >                 pr_info("\tAdditional per-CPU info printed with stalls.\n");
> >         if (RCU_NUM_LVLS >= 4)
> >                 pr_info("\tFour(or more)-level hierarchy is enabled.\n");
> > -       if (CONFIG_RCU_FANOUT_LEAF != 16)
> > +       if (RCU_FANOUT_LEAF != 16)
> 
> So if CONFIG_RCU_FANOUT_LEAF is either by default 32 or 64, this check
> against 16 for build-time adjustment is a bit misleading, no?

Indeed!

However, with the fix that puts the default back to 16, this should be
once again correct.

							Thanx, Paul