From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753837Ab0CBOzv (ORCPT ); Tue, 2 Mar 2010 09:55:51 -0500 Received: from e2.ny.us.ibm.com ([32.97.182.142]:37214 "EHLO e2.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753788Ab0CBOzu (ORCPT ); Tue, 2 Mar 2010 09:55:50 -0500 Date: Tue, 2 Mar 2010 06:55:45 -0800 From: "Paul E. McKenney" To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, dvhltc@us.ibm.com, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com Subject: Re: [PATCH RFC tip/core/rcu 1/2] rcu: suppress RCU lockdep warnings during early boot Message-ID: <20100302145544.GA6786@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20100301190329.GA26892@linux.vnet.ibm.com> <1267470234-27150-1-git-send-email-paulmck@linux.vnet.ibm.com> <20100302122059.GA8247@elte.hu> <20100302132718.GB6821@linux.vnet.ibm.com> <20100302141257.GA28917@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100302141257.GA28917@elte.hu> User-Agent: Mutt/1.5.15+20070412 (2007-04-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 02, 2010 at 03:12:57PM +0100, Ingo Molnar wrote: > > * Paul E. McKenney wrote: > > > On Tue, Mar 02, 2010 at 01:20:59PM +0100, Ingo Molnar wrote: > > > > > > * Paul E. McKenney wrote: > > > > > > > + if (!rcu_scheduler_active || !debug_locks) > > > > + return 1; > > > > + return lock_is_held(&rcu_lock_map); > > > > > > > + if (!rcu_scheduler_active || !debug_locks) > > > > + return 1; > > > > + return lock_is_held(&rcu_bh_lock_map); > > > > > > i guess there could be a common helper here? > > > > Will do! > > > > > Also, could we clear rcu_scheduler_active when we clear debug_locks? That way > > > only a single test is needed, a generic 'is lock debugging active'. > > > > Doing that will break synchronize_rcu(), which returns immediately if > > !rcu_scheduler_active. > > Ok - then have an debug_rcu flag which is cleared appropriately - so that the > fastpath impact is reduced? Good point, will do! Thanx, Paul