tools lib traceevent: Unregister handler when function plugin is unloaded

The function handler should be unregistered when the plugin is unloaded
otherwise it'll try to access invalid memory.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1389839478-5887-4-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/traceevent/plugin_function.c

@@ -148,6 +148,9 @@ void PEVENT_PLUGIN_UNLOADER(struct pevent *pevent)
 {
 	int i, x;
 
+	pevent_unregister_event_handler(pevent, -1, "ftrace", "function",
+					function_handler, NULL);
+
 	for (i = 0; i <= cpus; i++) {
 		for (x = 0; x < fstack[i].size && fstack[i].stack[x]; x++)
 			free(fstack[i].stack[x]);