Re: [PATCH 3/7] V2 add syscall tracepoints

[Frederic Weisbecker <fweisbec@gmail.com>]

On Thu, Jun 25, 2009 at 10:20:41AM +0800, Li Zefan wrote:
> > -#define DECLARE_TRACE(name, proto, args)				\
> > +#define DECLARE_TRACE_WITH_CALLBACK(name, proto, args, reg, unreg)	\
> >  	extern struct tracepoint __tracepoint_##name;			\
> >  	static inline void trace_##name(proto)				\
> >  	{								\
> > @@ -71,13 +73,29 @@ struct tracepoint {
> >  	}								\
> >  	static inline int register_trace_##name(void (*probe)(proto))	\
> >  	{								\
> > -		return tracepoint_probe_register(#name, (void *)probe);	\
> > +		int ret;						\
> > +		void (*func)(void) = (void (*)(void))reg;		\
> 
> The explicit cast seems unnecessary.


It seems even dangerous.
That might hide unmatching callback types passed in macro
arguments.

Frederic.


 
> > +									\
> > +		ret = tracepoint_probe_register(#name, (void *)probe);	\
> > +		if (func && !ret)					\
> > +			func();						\
> > +		return ret;						\
> >  	}								\
> >  	static inline int unregister_trace_##name(void (*probe)(proto))	\
> >  	{								\
> > -		return tracepoint_probe_unregister(#name, (void *)probe);\
> > +		int ret;						\
> > +		void (*func)(void) = (void (*)(void))unreg;		\
> > +									\
> > +		ret = tracepoint_probe_unregister(#name, (void *)probe);\
> > +		if (func && !ret)					\
> > +			func();						\
> > +		return ret;						\
> >  	}
> >  
> > +
> > +#define DECLARE_TRACE(name, proto, args)		\
> > +	DECLARE_TRACE_WITH_CALLBACK(name, TP_PROTO(proto), TP_ARGS(args), 0, 0);
> 
> I think DECLARE_TRACE_WITH_CALLBACK(..., NULL, NULL) is better.
> 
> > +
> >  #define DEFINE_TRACE(name)						\
> >  	static const char __tpstrtab_##name[]				\
> >  	__attribute__((section("__tracepoints_strings"))) = #name;	\
> > @@ -94,7 +112,7 @@ extern void tracepoint_update_probe_range(struct tracepoint *begin,
> >  	struct tracepoint *end);
> >  
> >  #else /* !CONFIG_TRACEPOINTS */
> > -#define DECLARE_TRACE(name, proto, args)				\
> > +#define DECLARE_TRACE_WITH_CALLBACK(name, proto, args, reg, unreg)	\
> >  	static inline void _do_trace_##name(struct tracepoint *tp, proto) \
> >  	{ }								\
> >  	static inline void trace_##name(proto)				\
> > @@ -108,6 +126,9 @@ extern void tracepoint_update_probe_range(struct tracepoint *begin,
> >  		return -ENOSYS;						\
> >  	}
> >  
> > +#define DECLARE_TRACE(name, proto, args)                \
> > +	DECLARE_TRACE_WITH_CALLBACK(name, TP_PROTO(proto), TP_ARGS(args), 0, 0);
> 
> ditto
> 
> > +
> >  #define DEFINE_TRACE(name)
> >  #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
> >  #define EXPORT_TRACEPOINT_SYMBOL(name)
> 
>