On Tue, Sep 04, 2012 at 11:23:06PM -0700, Josh Triplett wrote:
> Tracepoints declare a static inline trace_*_rcuidle variant of the trace
> function, to support safely generating trace events from the idle loop.
> Module code never actually uses that variant of trace functions, because
> modules don't run code that needs tracing with RCU idled. However, the
> declaration of those otherwise unused functions causes the module to
> reference rcu_idle_exit and rcu_idle_enter, which RCU does not export to
> modules.
>
> To avoid this, don't generate trace_*_rcuidle functions for tracepoints
> declared in module code.
>
> Reported-by: Steven Rostedt <rost...@goodmis.org>
> Signed-off-by: Josh Triplett <j...@joshtriplett.org>
Looks good to me, please let me know when I should remove the exports.
Sending the relevant patch is sufficient notification. ;-)
Acked-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
Thanx, Paul
> ---
> On Tue, Sep 04, 2012 at 07:46:42PM -0400, Steven Rostedt wrote:
> > 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.
>
> include/linux/tracepoint.h | 28 ++++++++++++++++++----------
> 1 file changed, 18 insertions(+), 10 deletions(-)
>
> diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
> index 802de56..2f322c3 100644
> --- a/include/linux/tracepoint.h
> +++ b/include/linux/tracepoint.h
> @@ -136,6 +136,22 @@ static inline void
> tracepoint_synchronize_unregister(void)
> postrcu; \
> } while (0)
>
> +#ifndef 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
> +
> /*
> * Make sure the alignment of the structure in the __tracepoints section will
> * not add unwanted padding between the beginning of the section and the
> @@ -151,16 +167,8 @@ static inline void
> tracepoint_synchronize_unregister(void)
> TP_ARGS(data_args), \
> TP_CONDITION(cond),,); \
> } \
> - 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()); \
> - } \
> + __DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
> + PARAMS(cond), PARAMS(data_proto), PARAMS(data_args)) \
> static inline int \
> register_trace_##name(void (*probe)(data_proto), void *data) \
> { \
> --
> 1.7.10.4
>
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