Fix: Use default visibility for tracepoint provider symbol

When building a probe provider `someprobe` with -fvisibility=hidden into
a shared library, the `__tracepoint_provider_someprobe` symbol is hidden,
which does not allow tracepoint instrumentation to link to it.

Fix this by using the "default" visibility attribute.

For a shared library built with -fvisibility=hidden, this changes the
output of nm for that symbol from:

000000000000417c b __tracepoint_provider_someprobe

(local BSS symbol)

to

000000000000417c B __tracepoint_provider_someprobe

(global (external) BSS symbol)

Fixes: #1296
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I308374f6cac58cca86e8eb19c872286a3da21a75

diff --git a/include/lttng/ust-tracepoint-event.h b/include/lttng/ust-tracepoint-event.h
index 63b3bd499085433552432dd9a2c396cfa6bfdf00..da52162c4a256d40278700f014949bc65f37b043 100644 (file)
--- a/include/lttng/ust-tracepoint-event.h
+++ b/include/lttng/ust-tracepoint-event.h
@@ -1056,4 +1056,5 @@ _TP_COMBINE_TOKENS(__lttng_events_exit__, TRACEPOINT_PROVIDER)(void)
        lttng_probe_unregister(&_TP_COMBINE_TOKENS(__probe_desc___, TRACEPOINT_PROVIDER));
 }
 
-int _TP_COMBINE_TOKENS(__tracepoint_provider_, TRACEPOINT_PROVIDER);
+int _TP_COMBINE_TOKENS(__tracepoint_provider_, TRACEPOINT_PROVIDER)
+__attribute__((visibility("default")));