From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754428Ab2C0QlZ (ORCPT ); Tue, 27 Mar 2012 12:41:25 -0400 Received: from e8.ny.us.ibm.com ([32.97.182.138]:41578 "EHLO e8.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750796Ab2C0QlW (ORCPT ); Tue, 27 Mar 2012 12:41:22 -0400 Date: Tue, 27 Mar 2012 09:39:03 -0700 From: "Paul E. McKenney" To: Steven Rostedt Cc: Peter Zijlstra , linux-kernel@vger.kernel.org, mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, fweisbec@gmail.com, patches@linaro.org, torvalds@linux-foundation.org Subject: Re: [PATCH RFC] rcu: Make __rcu_read_lock() inlinable Message-ID: <20120327163902.GQ2450@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20120325205249.GA29528@linux.vnet.ibm.com> <1332748484.16159.61.camel@twins> <20120326183232.GK2450@linux.vnet.ibm.com> <1332787630.16159.182.camel@twins> <20120327051515.GO2450@linux.vnet.ibm.com> <1332851167.23924.125.camel@gandalf.stny.rr.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1332851167.23924.125.camel@gandalf.stny.rr.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12032716-9360-0000-0000-000004E6CBC7 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 27, 2012 at 08:26:07AM -0400, Steven Rostedt wrote: > On Mon, 2012-03-26 at 22:15 -0700, Paul E. McKenney wrote: > > > Hmmm... I am not yet sure whether it is easier to make RCU use legal > > in switch_to() or to detect it. I am inclined to take whatever course > > is easiest, which is likely to make it legal. :-/ > > We could just declare that we do not allow tracepoints in arch specific > "switch_to" code. Then you shouldn't need to worry about RCU in > switch_to(). Heh. I expect that to work about as well as the earlier declaration that RCU not be used in the idle loop. ;-) > sched_rcu can still work there correct? That is, a synchronize_sched() > should not be affected. As that is needed for the function tracing, and > that may be called within a switch_to. Yep, good point. Thanx, Paul