----- Original Message -----
> From: "Zifei Tong" <[email protected]>
> To: "mathieu desnoyers" <[email protected]>
> Cc: [email protected], "Zifei Tong" <[email protected]>
> Sent: Wednesday, March 12, 2014 5:40:37 AM
> Subject: [PATCH] Define tracepoint callback only if TRACEPOINT_DEFINE defined
>
> Compiling tracepoint providers in clang will result in 'Wunused-function'
> warning, since tracepoint callbacks are defined but never called.
>
> lttng-gen-tp is also updated to not put TRACEPOINT_DEFINE in generated
> headers.
>
> Fixes #760
>
> Signed-off-by: Zifei Tong <[email protected]>
> ---
> doc/examples/gen-tp/sample.c | 1 +
> include/lttng/tracepoint.h | 13 ++++++++++---
> tools/lttng-gen-tp | 1 -
> 3 files changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/doc/examples/gen-tp/sample.c b/doc/examples/gen-tp/sample.c
> index dab6e7d..ae22f28 100644
> --- a/doc/examples/gen-tp/sample.c
> +++ b/doc/examples/gen-tp/sample.c
> @@ -23,6 +23,7 @@
>
> #include <unistd.h>
>
> +#define TRACEPOINT_DEFINE
Hrm, so this requires end users to change the way to use lttng-gen-tp.
I'm not sure I like that at all. This means changes in the way people do
instrumentation, and I'm trying really hard not to break that.
> #include "sample_tracepoint.h"
> int main(int argc, char **argv)
> {
> diff --git a/include/lttng/tracepoint.h b/include/lttng/tracepoint.h
> index 66e2abd..462a0fc 100644
> --- a/include/lttng/tracepoint.h
> +++ b/include/lttng/tracepoint.h
> @@ -150,8 +150,8 @@ extern "C" {
> * between caller's ip addresses within the probe using the return
> * address.
> */
> -#define _DECLARE_TRACEPOINT(_provider, _name, ...)
> \
> -extern struct tracepoint __tracepoint_##_provider##___##_name;
> \
> +#if defined(TRACEPOINT_DEFINE)
So you are adding a ifdef conditional to skip creation of a macro that defines
static inline functions. What is it achieving really other than silencing a
compiler
warning ? Anyway the compiler will optimize those static inline away if they are
not used.
I think this is a case where we might want to use __attribute__((unused)) to
just
shut up the clang warning.
Thoughts ?
Thanks,
Mathieu
> +#define _DECLARE_TRACEPOINT_CB(_provider, _name, ...)
> \
> static inline __attribute__((always_inline)) lttng_ust_notrace
> \
> void __tracepoint_cb_##_provider##___##_name(_TP_ARGS_PROTO(__VA_ARGS__));
> \
> static
> \
> @@ -174,7 +174,14 @@ void
> __tracepoint_cb_##_provider##___##_name(_TP_ARGS_PROTO(__VA_ARGS__))
> \
> } while ((++__tp_probe)->func);
> \
> end:
> \
> tp_rcu_read_unlock_bp();
> \
> -}
> \
> +}
> +#else
> +#define _DECLARE_TRACEPOINT_CB(_provider, _name, ...)
> +#endif
> +
> +#define _DECLARE_TRACEPOINT(_provider, _name, ...)
> \
> +extern struct tracepoint __tracepoint_##_provider##___##_name;
> \
> +_DECLARE_TRACEPOINT_CB(_provider, _name, __VA_ARGS__)
> \
> static inline lttng_ust_notrace
> \
> void __tracepoint_register_##_provider##___##_name(char *name,
> \
> void (*func)(void), void *data);
> \
> diff --git a/tools/lttng-gen-tp b/tools/lttng-gen-tp
> index c49e8a5..ff8c22d 100755
> --- a/tools/lttng-gen-tp
> +++ b/tools/lttng-gen-tp
> @@ -69,7 +69,6 @@ class CFile:
> /*
> * The header containing our TRACEPOINT_EVENTs.
> */
> -#define TRACEPOINT_DEFINE
> #include "{headerFilename}"
> """
> def __init__(self, filename, template):
> --
> 1.9.0
>
>
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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