Messages in this thread Patch in this message | | | Date | Thu, 3 Dec 2009 14:35:49 -0500 | From | Neil Horman <> | Subject | Re: [PATCH] Fix tracing infrastructure to support multiple includes when defining CREATE_TRACE_POINTS |
| |
On Thu, Dec 03, 2009 at 09:15:26AM -0500, Steven Rostedt wrote: > On Wed, 2009-12-02 at 14:19 -0500, Neil Horman wrote: > > Fix tracing infrastructure to allow multiple header files with TRACE_EVENTS to > > be included with CREATE_TRACE_EVENTS defined > > > > I've been workingon adding a few tracepoints to the network stack, and in so > > doing it was convienient for me to add a second include file to > > net/core/net-traces.c with TRACE_EVENTS defined in them. net-traces.c defines > > CREATE_TRACE_EVENTS, and during the build it was failing, complaining about > > duplicate definitions of __tpstrtab_<name>. I tracked down the bug to find that > > define_trace.h redefined DECLARE_TRACE to be DEFINE_TRACE, so after the first > > run through define_trace.h (which is included from skb.h, included in > > net-trace.c first), the DECLARE_TRACE macro was left with an improper definition > > to start a new cycle with the next header. > > > > The fix I came up with was to make sure that DECLARE_TRACE was undefined at the > > end of define_trace.h, and to add a conditional re-definition in tracepoint.h. > > This places us back in the proper state to define a new set of tracepoints in a > > subsequent header file. Not sure if theres a better way to handle this, but > > this worked well for me, allowing me to include multiple headers with > > TRACE_EVENT macros in a c file with CREATE_TRACE_POINTS defined. > > > > Nice, just some comments below. ><snip> > > You duplicate the DECLARE_TRACE from above and place it into an > unprotected area. Why not move it instead of duplicating it. This is > just a bug waiting to happen if we ever need to modify DECLARE_TRACE. > > If you change it to: > > #if !defined(CONFIG_TRACEPOINTS) && !defined(DECLARE_TRACE) > > #define DECLARE_TRACE(...) .... > > #endif > > Then you can remove the first definition of it. The first time > processing the file, when it hits the #ifndef DECLARE_TRACE in the > _LINUX_TRACEPOINT_H conditional, it still does not define DECLARE_TRACE, > and then when it exits that conditional, it does.
Yeah, that makes sense to me. Although I think you mean if defined(CONFIG_TRACEPOINTS) rather than if !defined(CONFIG_TRACEPOINTS). The case I'm moving to outside the unprotected area is the one that we use if tracepoints are enabled. I just tested this new patch, and it works well for me. Thanks!
Neil
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
linux/tracepoint.h | 45 +++++++++++++++++++++++---------------------- trace/define_trace.h | 1 + 2 files changed, 24 insertions(+), 22 deletions(-)
Fix tracing infrastructure to allow multiple header files with TRACE_EVENTS to be included with CREATE_TRACE_EVENTS defined
I've been workingon adding a few tracepoints to the network stack, and in so doing it was convienient for me to add a second include file to net/core/net-traces.c with TRACE_EVENTS defined in them. net-traces.c defines CREATE_TRACE_EVENTS, and during the build it was failing, complaining about duplicate definitions of __tpstrtab_<name>. I tracked down the bug to find that define_trace.h redefined DECLARE_TRACE to be DEFINE_TRACE, so after the first run through define_trace.h (which is included from skb.h, included in net-trace.c first), the DECLARE_TRACE macro was left with an improper definition to start a new cycle with the next header.
The fix I came up with was to make sure that DECLARE_TRACE was undefined at the end of define_trace.h, and to add a conditional re-definition in tracepoint.h. This places us back in the proper state to define a new set of tracepoints in a subsequent header file.
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index 2aac8a8..311abbf 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -58,28 +58,6 @@ struct tracepoint { rcu_read_unlock_sched_notrace(); \ } while (0) -/* - * Make sure the alignment of the structure in the __tracepoints section will - * not add unwanted padding between the beginning of the section and the - * structure. Force alignment to the same alignment as the section start. - */ -#define DECLARE_TRACE(name, proto, args) \ - extern struct tracepoint __tracepoint_##name; \ - static inline void trace_##name(proto) \ - { \ - if (unlikely(__tracepoint_##name.state)) \ - __DO_TRACE(&__tracepoint_##name, \ - TP_PROTO(proto), TP_ARGS(args)); \ - } \ - static inline int register_trace_##name(void (*probe)(proto)) \ - { \ - return tracepoint_probe_register(#name, (void *)probe); \ - } \ - static inline int unregister_trace_##name(void (*probe)(proto)) \ - { \ - return tracepoint_probe_unregister(#name, (void *)probe);\ - } - #define DEFINE_TRACE_FN(name, reg, unreg) \ static const char __tpstrtab_##name[] \ @@ -173,6 +151,29 @@ static inline void tracepoint_synchronize_unregister(void) * trace event headers under one "CREATE_TRACE_POINTS" the first include * will override the TRACE_EVENT and break the second include. */ +#if defined(CONFIG_TRACEPOINTS) && !defined(DECLARE_TRACE) +/* + * Make sure the alignment of the structure in the __tracepoints section will + * not add unwanted padding between the beginning of the section and the + * structure. Force alignment to the same alignment as the section start. + */ +#define DECLARE_TRACE(name, proto, args) \ + extern struct tracepoint __tracepoint_##name; \ + static inline void trace_##name(proto) \ + { \ + if (unlikely(__tracepoint_##name.state)) \ + __DO_TRACE(&__tracepoint_##name, \ + TP_PROTO(proto), TP_ARGS(args)); \ + } \ + static inline int register_trace_##name(void (*probe)(proto)) \ + { \ + return tracepoint_probe_register(#name, (void *)probe); \ + } \ + static inline int unregister_trace_##name(void (*probe)(proto)) \ + { \ + return tracepoint_probe_unregister(#name, (void *)probe);\ + } +#endif #ifndef TRACE_EVENT /* diff --git a/include/trace/define_trace.h b/include/trace/define_trace.h index 2a4b3bf..a3e0095 100644 --- a/include/trace/define_trace.h +++ b/include/trace/define_trace.h @@ -64,6 +64,7 @@ #undef TRACE_EVENT #undef TRACE_EVENT_FN #undef TRACE_HEADER_MULTI_READ +#undef DECLARE_TRACE /* Only undef what we defined in this file */ #ifdef UNDEF_TRACE_INCLUDE_FILE
| |