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SubjectRe: [PATCH] Fix tracing infrastructure to support multiple includes when defining CREATE_TRACE_POINTS
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On Mon, 2009-12-07 at 15:18 -0500, Neil Horman wrote:
> On Mon, Dec 07, 2009 at 03:04:42PM -0500, Steven Rostedt wrote:
> > On Thu, 2009-12-03 at 14:35 -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.
> > >
> > > Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> > >
> >
> > By itself, this patch breaks the build (for me). I take it that you
> > converted the napi.h file to use TRACE_EVENT. Currently it uses a
> > DECLARE_TRACE, which will break with this patch. We need a patch that
> > removes that DECLARE_TRACE before we can apply this patch.
> >
> Yes, I did that conversion, sorry, wasn't thinking about how that might affect
> the build. Given that converting to a TRACE_EVENT shouldn't be noticible to any
> of the users of that tracepoint (it can still be hooked in an identical
> fashion), I'd vote for just doing a monolitic patch. please find that below.
>
> Regards
> Neil
>
>
>
> 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.
>
>
> Note this patch also converts the napi_poll tracepoint to a TRACE_EVENT. This
> is done so that the TRACE_EVENT fix doesn't break the build, and because its
> rather pointless I think given the current tracing infrastructure to not have
> napi_poll be an independent event.
>
> Signed-off-by: Neil Horman <nhorman@tuxdriver.com>

Thanks, I'll give it a test. But because this now touches networking
code, I need an Acked-by from David Miller before I can pull it in.

-- Steve



>
>
> linux/tracepoint.h | 45 +++++++++++++++++++++++----------------------
> trace/define_trace.h | 1 +
> trace/events/napi.h | 25 ++++++++++++++++++++++---
> 3 files changed, 46 insertions(+), 25 deletions(-)
>
> 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
> diff --git a/include/trace/events/napi.h b/include/trace/events/napi.h
> index a8989c4..25a1709 100644
> --- a/include/trace/events/napi.h
> +++ b/include/trace/events/napi.h
> @@ -1,11 +1,30 @@
> -#ifndef _TRACE_NAPI_H_
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM napi
> +
> +#if !defined(_TRACE_NAPI_H_) || defined(TRACE_HEADER_MULTI_READ)
> #define _TRACE_NAPI_H_
>
> #include <linux/netdevice.h>
> #include <linux/tracepoint.h>
>
> -DECLARE_TRACE(napi_poll,
> +TRACE_EVENT(napi_poll,
> +
> TP_PROTO(struct napi_struct *napi),
> - TP_ARGS(napi));
> +
> + TP_ARGS(napi),
> +
> + TP_STRUCT__entry(
> + __field( struct napi_struct *, napi)
> + ),
> +
> + TP_fast_assign(
> + __entry->napi = napi;
> + ),
> +
> + TP_printk("napi poll on napi struct %p for device %s",
> + __entry->napi, __entry->napi->dev->name)
> +);
>
> #endif
> +
> +#include <trace/define_trace.h>



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