[PATCH v3 06/12] perf parse-events: Always track user config changes

James Clark
2025-12-12T15:32:55Z

Requiring the 'pmu->perf_event_attr_init_default' callback to be set to
track user changes is a bit of a trap to fall in. It's hard to see that
this is required when depending on the user change tracking.

It's possible to want all 0 defaults so not set it, but at the same time
still do some programmatic setting of configs with
evsel__set_config_if_unset(). Also if a PMU reverts to 0 defaults and
deletes its existing callback, it will silently break existing uses of
evsel__set_config_if_unset().

One way to fix this would be to assert in evsel__set_config_if_unset()
if the changes weren't tracked, but that would be a possibly untested
runtime failure. Instead, always track it as it's harmless and
simplifies testing too.

Signed-off-by: James Clark <james.clark@linaro.org>
---
tools/perf/util/parse-events.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 7ef63b808d0542999fd1303b9f94cae68e38030f..bee9233437753ff706d6b149503a5e660c3972d8 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1528,12 +1528,8 @@ static int parse_events_add_pmu(struct parse_events_state *parse_state,
return -ENOMEM;
}

- /*
- * When using default config, record which bits of attr->config were
- * changed by the user.
- */
- if (pmu->perf_event_attr_init_default &&
- get_config_chgs(pmu, &parsed_terms, &config_terms)) {
+ /* Record which bits of attr->config were changed by the user. */
+ if (get_config_chgs(pmu, &parsed_terms, &config_terms)) {
parse_events_terms__exit(&parsed_terms);
return -ENOMEM;
}

--
2.34.1