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Date: Wed, 25 Feb 2009 08:01:51 -0500 (EST)
From: Steven Rostedt <rostedt@goodmis.org>
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To: Peter Zijlstra <peterz@infradead.org>
cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
       Andrew Morton <akpm@linux-foundation.org>,
       Thomas Gleixner <tglx@linutronix.de>,
       Frederic Weisbecker <fweisbec@gmail.com>, Theodore Tso <tytso@mit.edu>,
       Arjan van de Ven <arjan@infradead.org>, Pekka Paalanen <pq@iki.fi>,
       Arnaldo Carvalho de Melo <acme@redhat.com>,
       Jason Baron <jbaron@redhat.com>, Martin Bligh <mbligh@google.com>,
       Mathieu Desnoyers <compudj@krystal.dyndns.org>,
       "Frank Ch. Eigler" <fche@redhat.com>,
       KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
       Jens Axboe <jens.axboe@oracle.com>,
       Masami Hiramatsu <mhiramat@redhat.com>,
       Steven Rostedt <srostedt@redhat.com>
Subject: Re: [PATCH 1/4] tracing: add DEFINE_TRACE_FMT to tracepoint.h
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On Wed, 25 Feb 2009, Peter Zijlstra wrote:

> On Tue, 2009-02-24 at 21:56 -0500, Steven Rostedt wrote:
> 
> > +#define DEFINE_TRACE_FMT(name, proto, args, fmt)		\
> > +	DECLARE_TRACE(name, TPPROTO(proto), TPARGS(args))
> > +
> 
> If TPPROTO and TPARGS were anything but empty stubs, the above would add
> them twice, no?

I guess I can rename them too.

The problem comes from passing in more than one argument. If a proto or 
args has a comma, you get a nasty error about unmatched number of 
parameters.

I believe that they were purposely made to be empty stubs to allow for 
multiple parameters. But you are right, if that changes we need to fix it.

Since the above is only to protect against the substitution into multiple 
parameters, we could probably create a new macro name to just be

 #define PARAMS(args...) args
 #define DEFINE_TRACE_FMT(name, proto, args, fmt) \
	DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))

-- Steve