From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753849Ab3AGP6U (ORCPT ); Mon, 7 Jan 2013 10:58:20 -0500 Received: from relay3-d.mail.gandi.net ([217.70.183.195]:51987 "EHLO relay3-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753739Ab3AGP6T (ORCPT ); Mon, 7 Jan 2013 10:58:19 -0500 X-Originating-IP: 217.70.178.136 X-Originating-IP: 50.43.39.152 Date: Mon, 7 Jan 2013 07:58:10 -0800 From: Josh Triplett To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, edumazet@google.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu, patches@linaro.org Subject: Re: [PATCH tip/core/rcu 1/1] Tiny RCU changes for 3.9 Message-ID: <20130107155810.GC11145@leaf> References: <20130105175059.GA15961@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130105175059.GA15961@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jan 05, 2013 at 09:50:59AM -0800, Paul E. McKenney wrote: > rcu: Provide RCU CPU stall warnings for tiny RCU > > Tiny RCU has historically omitted RCU CPU stall warnings in order to > reduce memory requirements, however, lack of these warnings caused Thomas > Gleixner some debugging pain recently. Therefore, this commit adds RCU > CPU stall warnings to tiny RCU if RCU_TRACE=y. This keeps the memory > footprint small, while still enabling CPU stall warnings in kernels > built to enable them. > > This is still a bit on the high-risk side, so running this will likely > be a debugging exercise. > > Reported-by: Thomas Gleixner > Signed-off-by: Paul E. McKenney > Signed-off-by: Paul E. McKenney Did you generate this patch with something other than git? The formatting seems a bit off: it doesn't have a diffstat or the usual "---" line between the commit message and the patch. This patch seems reasonable to me, but the repeated use of #if defined(CONFIG_SMP) || defined(CONFIG_RCU_TRACE) seems somewhat annoying, and fragile if you ever decide to change the conditions. How about defining an appropriate symbol in Kconfig for stall warnings, and using that? - Josh Triplett