From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755225Ab2GaPpH (ORCPT ); Tue, 31 Jul 2012 11:45:07 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:3717 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755054Ab2GaPpE (ORCPT ); Tue, 31 Jul 2012 11:45:04 -0400 X-Authority-Analysis: v=2.0 cv=IOWA+3TG c=1 sm=0 a=s5Htg7xnQOKvHEu9STBOug==:17 a=OpT9cpI26MMA:10 a=I5RZEMmPgckA:10 a=5SG0PmZfjMsA:10 a=Q9fys5e9bTEA:10 a=meVymXHHAAAA:8 a=ayC55rCoAAAA:8 a=y2bZKhvoUKbeMOoiDqMA:9 a=PUjeQqilurYA:10 a=s5Htg7xnQOKvHEu9STBOug==:117 X-Cloudmark-Score: 0 X-Originating-IP: 72.230.195.127 Message-ID: <1343749502.27983.57.camel@gandalf.stny.rr.com> Subject: Re: __update_max_tr: rcu_read_lock() used illegally while idle! From: Steven Rostedt To: paulmck@linux.vnet.ibm.com Cc: Fengguang Wu , Steven Rostedt , LKML , David Howells Date: Tue, 31 Jul 2012 11:45:02 -0400 In-Reply-To: <20120731151808.GF2422@linux.vnet.ibm.com> References: <20120724090330.GA9830@localhost> <1343662752.3847.2.camel@fedora> <20120731120556.GB17252@localhost> <1343741625.27983.39.camel@gandalf.stny.rr.com> <20120731144453.GB2422@linux.vnet.ibm.com> <1343746311.27983.52.camel@gandalf.stny.rr.com> <1343746583.27983.55.camel@gandalf.stny.rr.com> <20120731151808.GF2422@linux.vnet.ibm.com> Content-Type: text/plain; charset="ISO-8859-15" X-Mailer: Evolution 3.4.3-1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2012-07-31 at 08:18 -0700, Paul E. McKenney wrote: > On Tue, Jul 31, 2012 at 10:56:23AM -0400, Steven Rostedt wrote: > > On Tue, 2012-07-31 at 10:51 -0400, Steven Rostedt wrote: > > > > > > OK, I will bite. How about using something like RCU_NONIDLE(), either > > > > directly or open-coded, to make it a legal call site? > > > > > > OK, then something like: > > > > > > RCU_NONIDLE(max_data = task_uid(tsk)); > > > > > > would work when called normally or with idle? > > > > > > > The comment above RCU_NONIDLE() says: > > > > This macro may be used from process-level code only. > > > > Although I'm not sure what a 'level' is. Do you mean process-context? If > > so, then this will not work because it can be called from non process > > level code (return from interrupt), or any interrupt that enables > > interrupts. > > Yep, process context. It seems that I was naively expecting the > calls in interrupt context to be covered by rcu_irq_enter() and > rcu_irq_exit(). I take it that these calls are happening outside of > the rcu_irq_enter()-protected region? Yep, it is called by the same hooks that lockdep uses. TRACE_IRQS_ON inside the irq handler in assembly. -- Steve