[PATCH] perf bpf filter: Add an error message for BPF filter

[Namhyung Kim]

Currently there's no error message for filter (other than the help for
the option) when it's built with NO_BPF_SKEL=1.  It should show the
BPF filter is not supported like below:

  $ sudo ./perf record -e cycles --filter ip==1 true
  BPF filter is not supported        <------------------- added

   Usage: perf record [<options>] [<command>]
      or: perf record [<options>] -- <command> [<options>]

          --filter <filter>
                            event filter

Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
 tools/perf/util/parse-events.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 6c5cf5244486..f1fa469712c4 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -2543,8 +2543,16 @@ static int set_filter(struct evsel *evsel, const void *arg)
 		perf_pmu__scan_file(pmu, "nr_addr_filters",
 				    "%d", &nr_addr_filters);
 
-	if (!nr_addr_filters)
-		return perf_bpf_filter__parse(&evsel->bpf_filters, str);
+	if (!nr_addr_filters) {
+		int ret = perf_bpf_filter__parse(&evsel->bpf_filters, str);
+
+		if (ret == -EOPNOTSUPP)
+			fprintf(stderr, "BPF filter is not supported\n");
+		else if (ret)
+			fprintf(stderr, "failed to set the BPF filter\n");
+
+		return ret;
+	}
 
 	if (evsel__append_addr_filter(evsel, str) < 0) {
 		fprintf(stderr,
-- 
2.40.0.rc1.284.g88254d51c5-goog