Re: [PATCH 1/4] tracing: add DEFINE_TRACE_FMT to tracepoint.h

[Mathieu Desnoyers <compudj@krystal.dyndns.org>]

* Steven Rostedt (rostedt@goodmis.org) wrote:
> 
> 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))
> 

Yes, I think this should work. Just be careful to test passing a "void"
function parameter to these when you make any changes. This is a
subtle corner-case.

Mathieu

> -- Steve
> 

-- 
Mathieu Desnoyers
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