[lttng-dev] [RFC PATCH lttng-ust v2] Fix: allow non-LGPL modules to use tracepoints

[Sebastien Boisvert]

It links now.

Tested-by: Sebastien Boisvert <sboisvert at gydle.com>

On 06/15/2016 04:54 PM, Mathieu Desnoyers wrote:
> Non-LGPL modules that use tracepoint instrumentation, but have no
> compile unit defining either TRACEPOINT_DEFINE or
> TRACEPOINT_CREATE_PROBES fail to build due to undefined reference to
> `tracepoint_dlopen_ptr'.
> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
> ---
>  include/lttng/tracepoint.h | 23 ++++++++++++-----------
>  1 file changed, 12 insertions(+), 11 deletions(-)
> 
> diff --git a/include/lttng/tracepoint.h b/include/lttng/tracepoint.h
> index 03bc913..d469765 100644
> --- a/include/lttng/tracepoint.h
> +++ b/include/lttng/tracepoint.h
> @@ -241,17 +241,6 @@ static inline void tracepoint_disable_destructors(void)
>  	__tracepoints__disable_destructors = 1;
>  }
>  
> -#if defined(TRACEPOINT_DEFINE) || defined(TRACEPOINT_CREATE_PROBES)
> -
> -/*
> - * These weak symbols, the constructor, and destructor take care of
> - * registering only _one_ instance of the tracepoints per shared-ojbect
> - * (or for the whole main program).
> - */
> -int __tracepoint_registered
> -	__attribute__((weak, visibility("hidden")));
> -int __tracepoint_ptrs_registered
> -	__attribute__((weak, visibility("hidden")));
>  struct lttng_ust_tracepoint_dlopen tracepoint_dlopen
>  	__attribute__((weak, visibility("hidden")));
>  /*
> @@ -304,6 +293,18 @@ __tracepoint__init_urcu_sym(void)
>  }
>  #endif
>  
> +#if defined(TRACEPOINT_DEFINE) || defined(TRACEPOINT_CREATE_PROBES)
> +
> +/*
> + * These weak symbols, the constructor, and destructor take care of
> + * registering only _one_ instance of the tracepoints per shared-ojbect
> + * (or for the whole main program).
> + */
> +int __tracepoint_registered
> +	__attribute__((weak, visibility("hidden")));
> +int __tracepoint_ptrs_registered
> +	__attribute__((weak, visibility("hidden")));
> +
>  static void lttng_ust_notrace __attribute__((constructor))
>  __tracepoints__init(void);
>  static void
>