From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758692AbZJGNv3 (ORCPT ); Wed, 7 Oct 2009 09:51:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753545AbZJGNv2 (ORCPT ); Wed, 7 Oct 2009 09:51:28 -0400 Received: from e2.ny.us.ibm.com ([32.97.182.142]:45213 "EHLO e2.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753440AbZJGNv2 (ORCPT ); Wed, 7 Oct 2009 09:51:28 -0400 Date: Wed, 7 Oct 2009 06:50:49 -0700 From: "Paul E. McKenney" To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, 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, Valdis.Kletnieks@vt.edu, dhowells@redhat.com Subject: Re: [PATCH tip/core/rcu 2/3] rcu: make hot-unplugged CPU relinquish its own RCU callbacks Message-ID: <20091007135049.GF6838@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20091007044748.GA12763@linux.vnet.ibm.com> <1254921372.1696.132.camel@gandalf.stny.rr.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1254921372.1696.132.camel@gandalf.stny.rr.com> 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 Wed, Oct 07, 2009 at 09:16:12AM -0400, Steven Rostedt wrote: > Paul, > > Still suffering jetlag? ;-) As a matter of fact, yes. ;-) > On Tue, 2009-10-06 at 21:48 -0700, Paul E. McKenney wrote: > > From: Paul E. McKenney > > > > The current interaction between RCU and CPU hotplug requires that > > RCU block in CPU notifiers waiting for callbacks to drain. This can > > be greatly simplified by haing each CPU relinquish its own callbacks, > having > > > and for both _rcu_barrier() and CPU_DEAD notifiers to adopt all callbacks > > that were previously relinquished. This change also eliminates the > > possibility of certain types of hangs due to the previous practice of > > waiting for callbacks to be invoked from within CPU notifiers. If you > > don't every wait, you cannot hang. > ever > > ;-) Courtesy of "git cherry-pick" and my being out of it. ;-) Thanx, Paul > > Signed-off-by: Paul E. McKenney > > -- Steve > >