From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762248AbZLPPLZ (ORCPT ); Wed, 16 Dec 2009 10:11:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762228AbZLPPLW (ORCPT ); Wed, 16 Dec 2009 10:11:22 -0500 Received: from e7.ny.us.ibm.com ([32.97.182.137]:48439 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762239AbZLPPLQ (ORCPT ); Wed, 16 Dec 2009 10:11:16 -0500 Date: Wed, 16 Dec 2009 07:11:11 -0800 From: "Paul E. McKenney" To: Peter Zijlstra 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, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com Subject: Re: [PATCH RFC tip/core/rcu 14/18] rcu: lockdep check for exiting to user space as RCU reader Message-ID: <20091216151111.GA6744@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20091215230213.GA9093@linux.vnet.ibm.com> <1260959082.17860.35.camel@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1260959082.17860.35.camel@laptop> 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, Dec 16, 2009 at 11:24:42AM +0100, Peter Zijlstra wrote: > On Tue, 2009-12-15 at 15:02 -0800, Paul E. McKenney wrote: > > From: Paul E. McKenney > > > > Proposed for 2.6.34, not for inclusion. > > > > It is illegal to return to user-space execution while running within an > > RCU read-side critical section. It turns out that CONFIG_TREE_PREEMPT_RCU > > has enough information lying around to detect this, so add the checks > > to lockdep (CONFIG_PROVE_LOCKING). > > But uhm, we already track the rcu read lock as a regular lockdep lock, > so it should already check this, no? I guess I can drop that patch, then. ;-) Thank you for looking this over! Thanx, Paul