From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756297AbZLCTl6 (ORCPT ); Thu, 3 Dec 2009 14:41:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755732AbZLCTl5 (ORCPT ); Thu, 3 Dec 2009 14:41:57 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.125]:46217 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755980AbZLCTl5 (ORCPT ); Thu, 3 Dec 2009 14:41:57 -0500 Subject: Re: [PATCH] Fix tracing infrastructure to support multiple includes when defining CREATE_TRACE_POINTS From: Steven Rostedt Reply-To: rostedt@goodmis.org To: Neil Horman Cc: linux-kernel@vger.kernel.org, fweisbec@gmail.com, mingo@redhat.com, Mathieu Desnoyers In-Reply-To: <20091203193549.GA18664@hmsreliant.think-freely.org> References: <20091202191916.GA7589@hmsreliant.think-freely.org> <1259849726.12870.123.camel@gandalf.stny.rr.com> <20091203193549.GA18664@hmsreliant.think-freely.org> Content-Type: text/plain Organization: Kihon Technologies Inc. Date: Thu, 03 Dec 2009 14:42:01 -0500 Message-Id: <1259869321.12870.145.camel@gandalf.stny.rr.com> Mime-Version: 1.0 X-Mailer: Evolution 2.26.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2009-12-03 at 14:35 -0500, Neil Horman wrote: > On Thu, Dec 03, 2009 at 09:15:26AM -0500, Steven Rostedt wrote: > > On Wed, 2009-12-02 at 14:19 -0500, Neil Horman wrote: > > > Fix tracing infrastructure to allow multiple header files with TRACE_EVENTS to > > > be included with CREATE_TRACE_EVENTS defined > > > > > > I've been workingon adding a few tracepoints to the network stack, and in so > > > doing it was convienient for me to add a second include file to > > > net/core/net-traces.c with TRACE_EVENTS defined in them. net-traces.c defines > > > CREATE_TRACE_EVENTS, and during the build it was failing, complaining about > > > duplicate definitions of __tpstrtab_. I tracked down the bug to find that > > > define_trace.h redefined DECLARE_TRACE to be DEFINE_TRACE, so after the first > > > run through define_trace.h (which is included from skb.h, included in > > > net-trace.c first), the DECLARE_TRACE macro was left with an improper definition > > > to start a new cycle with the next header. > > > > > > The fix I came up with was to make sure that DECLARE_TRACE was undefined at the > > > end of define_trace.h, and to add a conditional re-definition in tracepoint.h. > > > This places us back in the proper state to define a new set of tracepoints in a > > > subsequent header file. Not sure if theres a better way to handle this, but > > > this worked well for me, allowing me to include multiple headers with > > > TRACE_EVENT macros in a c file with CREATE_TRACE_POINTS defined. > > > > > > > Nice, just some comments below. > > > > > > You duplicate the DECLARE_TRACE from above and place it into an > > unprotected area. Why not move it instead of duplicating it. This is > > just a bug waiting to happen if we ever need to modify DECLARE_TRACE. > > > > If you change it to: > > > > #if !defined(CONFIG_TRACEPOINTS) && !defined(DECLARE_TRACE) > > > > #define DECLARE_TRACE(...) .... > > > > #endif > > > > Then you can remove the first definition of it. The first time > > processing the file, when it hits the #ifndef DECLARE_TRACE in the > > _LINUX_TRACEPOINT_H conditional, it still does not define DECLARE_TRACE, > > and then when it exits that conditional, it does. > > > Yeah, that makes sense to me. Although I think you mean if > defined(CONFIG_TRACEPOINTS) rather than if !defined(CONFIG_TRACEPOINTS). The Yep, that's what I meant ;-) > case I'm moving to outside the unprotected area is the one that we use if > tracepoints are enabled. I just tested this new patch, and it works well for > me. Thanks! > > Neil > > Signed-off-by: Neil Horman OK, I'll give it some testing tonight. -- Steve