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Date: Mon, 11 May 2009 10:09:04 -0400 (EDT)
From: Steven Rostedt <rostedt@goodmis.org>
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To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
cc: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>,
       linux-kernel@vger.kernel.org, mingo@elte.hu, fweisbec@gmail.com,
       zhaolei@cn.fujitsu.com, laijs@cn.fujitsu.com,
       Li Zefan <lizf@cn.fujitsu.com>
Subject: Re: [PATCH v3] ftrace: add a tracepoint for
 __raise_softirq_irqoff()
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References: <49FFDF9C.7040505@cn.fujitsu.com> <20090505161604.GA15524@Krystal> <4A07D3B3.10605@cn.fujitsu.com> <20090511134019.GB10932@Krystal>
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On Mon, 11 May 2009, Mathieu Desnoyers wrote:
> 
> Yes, we should try to fix TRACE_EVENT, but we should fix it _before_ we
> start using it widely. Circular header dependencies is a real problem
> with TRACE_EVENT right now.
> 
> Until we fix this, I will be tempted to stay with a known-good solution,
> which is DECLARE/DEFINE_TRACE.

The majority of tracepoints happen is C files. Those few cases where they 
are used in headers is where the issues arise.

But...

I did not want to uglify all trace event headers with:

#ifdef CREATE_FOO_TRACE_POINTS
#undef CREATE_FOO_TRACE_POINTS
#include <trace/define_trace.h>
#endif

We would only need to do that for those trace points that need to be 
included in header files. Then the declaration C file would need to define 
both CREATE_FOO_TRACE_POINTS and CREATE_TRACE_POINTS

#define CREATE_FOO_TRACE_POINTS
#define CRATE_TRACE_POINTS
#include <trace/events/foo.h>


But this is pretty trivial to solve, and I do not consider it a show 
stopper or a major header dependency problem.

-- Steve