perf tools: Only increase index if perf_evsel__new_idx() succeeds

Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1485952447-7013-2-git-send-email-treeze.taeung@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/parse-events.c

@@ -310,10 +310,11 @@ __add_event(struct list_head *list, int *idx,
 
 	event_attr_init(attr);
 
-	evsel = perf_evsel__new_idx(attr, (*idx)++);
+	evsel = perf_evsel__new_idx(attr, *idx);
 	if (!evsel)
 		return NULL;
 
+	(*idx)++;
 	evsel->cpus     = cpu_map__get(cpus);
 	evsel->own_cpus = cpu_map__get(cpus);