On Tue, Sep 04, 2012 at 07:46:42PM -0400, Steven Rostedt wrote:
> On Tue, 2012-09-04 at 16:33 -0700, Josh Triplett wrote:
> >
> > > > +#ifdef MODULE
> > > > +#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto,
> > > > data_args) \
> > > > + static inline void trace_##name##_rcuidle(proto)
> > > > \
> > > > + {
> > > > \
> > > > + if (static_key_false(&__tracepoint_##name.key))
> > > > \
> > > > + __DO_TRACE(&__tracepoint_##name,
> > > > \
> > > > + TP_PROTO(data_proto),
> > > > \
> > > > + TP_ARGS(data_args),
> > > > \
> > > > + TP_CONDITION(cond),
> > > > \
> > > > + rcu_idle_exit(),
> > > > \
> > > > + rcu_idle_enter());
> > > > \
> > > > + }
> > > > +#else
> > > > +#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto,
> > > > data_args)
> > > > +#endif
> > > > +
> > >
> > > Egad! More macros on top of macros! Yeah I know I'm the most guilty of
> > > this, but it just seems to add one more indirection that I would like to
> > > avoid.
> >
> > This doesn't seem to add a significant amount of complexity; it forwards
> > exactly the same parameters to the helper macro, and just moves the one
> > function definition there and makes it conditional. This still seems
> > more preferable than exporting functions just so they won't get called.
>
> The change itself is not complex. But what is already there is complex
> enough. I'm talking more about adding to:
>
> $ grep '#define' include/linux/tracepoint.h
> #define _LINUX_TRACEPOINT_H
> #define PARAMS(args...) args
> #define TP_PROTO(args...) args
> #define TP_ARGS(args...) args
> #define TP_CONDITION(args...) args
> #define __DO_TRACE(tp, proto, args, cond, prercu, postrcu) \
> #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
> #define DEFINE_TRACE_FN(name, reg, unreg) \
> #define DEFINE_TRACE(name) \
> #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
> #define EXPORT_TRACEPOINT_SYMBOL(name) \
> #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
> #define DEFINE_TRACE_FN(name, reg, unreg)
> #define DEFINE_TRACE(name)
> #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
> #define EXPORT_TRACEPOINT_SYMBOL(name)
> #define DECLARE_TRACE_NOARGS(name) \
> #define DECLARE_TRACE(name, proto, args) \
> #define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
> #define TRACE_EVENT_FLAGS(event, flag)
> #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
> #define DEFINE_EVENT(template, name, proto, args) \
> #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
> #define DEFINE_EVENT_CONDITION(template, name, proto, \
> #define TRACE_EVENT(name, proto, args, struct, assign, print) \
> #define TRACE_EVENT_FN(name, proto, args, struct, \
> #define TRACE_EVENT_CONDITION(name, proto, args, cond, \
> #define TRACE_EVENT_FLAGS(event, flag)
Yeah, I've had the adventure of hand-tracing through most of those in
the past myself. :) At least they have a fairly clear hierarchy,
without particularly complex conditionals.
Ah, for a language with decent code generation facilities. :)
> > I could live with that; it seems preferable to unnecessary exports,
> > though it still seems much uglier to me than the conditional definition
> > of trace_*_rcuidle. :)
>
> We could add either. Probably keep the ugliness of tracepoints inside
> the tracepoint code than to start spreading it around to rcu. RCU has
> its own ugliness features ;-)
>
> Hence, I would be OK if you send me a patch that does what you proposed
> and removes the EXPORT from RCU.
To clarify: does what I proposed as in the macro change to avoid
defining trace_*_rcuidle in modules, or makes the change to define panicy
versions of the two functions trace_*_rcuidle needs?
- Josh Triplett
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