[PATCH v2 1/2] perf tools: Return first evsel for non-sample event on old kernel

[Namhyung Kim]

On old kernels that don't support sample_id_all feature,
perf_evlist__id2evsel() returns NULL for non-sampling events.
This breaks perf top when multiple events are given on command
line. Fix it by using first evsel in the evlist. This will also
prevent getting the same (potential) problem in such new tool/
old kernel combo.

Suggested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung.kim@xxxxxxx>
---
 tools/perf/util/evlist.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index a6d50e376257..3ffb3203f335 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -349,6 +349,10 @@ struct perf_evsel *perf_evlist__id2evsel(struct perf_evlist *evlist, u64 id)
 	hlist_for_each_entry(sid, pos, head, node)
 		if (sid->id == id)
 			return sid->evsel;
+
+	if (!perf_evlist__sample_id_all(evlist))
+		return list_entry(evlist->entries.next, struct perf_evsel, node);
+
 	return NULL;
 }
 
-- 
1.7.9.rc1.dirty

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