perf report: Check error during report__collapse_hists()

If it returns an error, warn user and bail out instead of silently
ignoring it.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1455631723-17345-9-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-report.c

@@ -469,10 +469,11 @@ static int report__browse_hists(struct report *rep)
 	return ret;
 }
 
-static void report__collapse_hists(struct report *rep)
+static int report__collapse_hists(struct report *rep)
 {
 	struct ui_progress prog;
 	struct perf_evsel *pos;
+	int ret = 0;
 
 	ui_progress__init(&prog, rep->nr_entries, "Merging related events...");
 
@@ -484,7 +485,9 @@ static void report__collapse_hists(struct report *rep)
 
 		hists->socket_filter = rep->socket_filter;
 
-		hists__collapse_resort(hists, &prog);
+		ret = hists__collapse_resort(hists, &prog);
+		if (ret < 0)
+			break;
 
 		/* Non-group events are considered as leader */
 		if (symbol_conf.event_group &&
@@ -497,6 +500,7 @@ static void report__collapse_hists(struct report *rep)
 	}
 
 	ui_progress__finish();
+	return ret;
 }
 
 static void report__output_resort(struct report *rep)
@@ -564,7 +568,11 @@ static int __cmd_report(struct report *rep)
 		}
 	}
 
-	report__collapse_hists(rep);
+	ret = report__collapse_hists(rep);
+	if (ret) {
+		ui__error("failed to process hist entry\n");
+		return ret;
+	}
 
 	if (session_done())
 		return 0;