tracepoints: dont update zero-sized tracepoint sections

Zero-sized tracepoint sections can occur if tracing is enabled but
no tracepoint is defined. Do not emit a warning in that case.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
LKML-Reference: <1237394936.3132.1.camel@localhost.localdomain>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

kernel/tracepoint.c

@@ -278,10 +278,8 @@ tracepoint_update_probe_range(struct tracepoint *begin, struct tracepoint *end)
 	struct tracepoint *iter;
 	struct tracepoint_entry *mark_entry;
 
-	if (!begin) {
-		WARN_ON_ONCE(1);
+	if (!begin)
 		return;
-	}
 
 	mutex_lock(&tracepoints_mutex);
 	for (iter = begin; iter < end; iter++) {