Re: [PATCH v5 1/3] perf jevents: Name the metric when a MetricExpr is missing

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [Low] perf jevents: missing file path in _read_json_events_impl()
  MetricExpr error
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commit e2d62b223b86b6803d9d5c49c56d277f5acb0d3e
Author: TAKANO Mitsuhiro <takano32@gmail.com>

perf jevents: Name the metric when a MetricExpr is missing

This commit raises a RuntimeError naming the metric when a JSON event defines
MetricName without MetricExpr, improves error reporting on parse failures, and
defers opening the output files until all tables have been parsed.

> diff --git a/tools/perf/pmu-events/jevents.py b/tools/perf/pmu-events/jevents.py
> index 080e04b51b8c5..61f778dcc1e56 100755
> --- a/tools/perf/pmu-events/jevents.py
> +++ b/tools/perf/pmu-events/jevents.py
> @@ -460,11 +460,17 @@ def _read_json_events_impl(path: str, topic: str) -> Sequence[JsonEvent]:
>      with open(path, encoding='utf-8') as f:
>        events = json.load(f, object_hook=JsonEvent)
>    except BaseException:
> -    print(f"Exception processing {path}")
> +    print(f'jevents: error: Exception processing {path}', file=sys.stderr)
>      raise
>    metrics: list[Tuple[str, str, metric.Expression]] = []
>    for event in events:
>      event.topic = topic
> +    if event.metric_name and event.metric_expr is None:
> +      # A MetricName without a MetricExpr leaves nothing to put in the
> +      # generated tables, whether or not the name has a dash, so the build
> +      # must not go on.  Name the metric instead of letting the table printer
> +      # assert on the None.
> +      raise RuntimeError(f'Metric {event.metric_name!r} has no MetricExpr')

[Severity: Low]
Does raising RuntimeError outside the try/except block without path in the
message lose the offending file name?

Model and vendor JSON tables are parsed in main() via
executor.map(_parallel_read_json_events, tasks) outside ftw(), so when a
metric is missing MetricExpr, the exception escapes the worker pool without
reporting which JSON file failed.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261111132622.2349165-1-takano32@gmail.com?part=1