perf intel-bts: Fix endless record after being terminated

In __cmd_record(), when receiving SIGINT(ctrl + c), a 'done' flag will
be set and the event list will be disabled by evlist__disable() once.

While in auxtrace_record.read_finish(), the related events will be
enabled again, if they are continuous, the recording seems to be
endless.

If the intel_bts event is disabled, we don't enable it again here.

Note: This patch is NOT tested since i don't have such a machine with
intel_bts feature, but the code seems buggy same as arm-spe and
intel-pt.
Signed-off-by: Wei Li <liwei391@huawei.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Tan Xiaojun <tanxiaojun@huawei.com>
Cc: stable@vger.kernel.org # 5.4+
Link: http://lore.kernel.org/lkml/20200214132654.20395-3-adrian.hunter@intel.com
[ahunter: removed redundant 'else' after 'return']
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/arch/x86/util/intel-bts.c

@@ -420,9 +420,12 @@ static int intel_bts_read_finish(struct auxtrace_record *itr, int idx)
 	struct evsel *evsel;
 
 	evlist__for_each_entry(btsr->evlist, evsel) {
-		if (evsel->core.attr.type == btsr->intel_bts_pmu->type)
+		if (evsel->core.attr.type == btsr->intel_bts_pmu->type) {
+			if (evsel->disabled)
+				return 0;
 			return perf_evlist__enable_event_idx(btsr->evlist,
 							     evsel, idx);
+		}
 	}
 	return -EINVAL;
 }