Re: [PATCH v1 2/8] perf metric: Return early if no CPU PMU table exists

[Arnaldo Carvalho de Melo]

Em Tue, Aug 30, 2022 at 09:48:40AM -0700, Ian Rogers escreveu:
> Previous behavior is to segfault if there is no CPU PMU table and a
> metric is sought. To reproduce compile with NO_JEVENTS=1 then request
> a metric, for example, "perf stat -M IPC true".
> 
> Fixes: 00facc760903 ("perf jevents: Switch build to use jevents.py")
> Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>

Before:

  $ make -k NO_JEVENTS=1 BUILD_BPF_SKEL=1 O=/tmp/build/perf-urgent -C tools/perf install-bin
  $ perf stat -M IPC true
  Segmentation fault (core dumped)
  $

After:

  $ perf stat -M IPC true

   Usage: perf stat [<options>] [<command>]

      -M, --metrics <metric/metric group list>
                            monitor specified metrics or metric groups (separated by ,)
  $

Better, but perhaps we could provide some better message as to why the
metric provided isn't acceptable?

Anyway, applied to perf/urgent.

Thanks,

- Arnaldo

> ---
>  tools/perf/util/metricgroup.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
> index ad5cacdecd81..18aae040d61d 100644
> --- a/tools/perf/util/metricgroup.c
> +++ b/tools/perf/util/metricgroup.c
> @@ -1655,6 +1655,9 @@ int metricgroup__parse_groups(const struct option *opt,
>  	struct evlist *perf_evlist = *(struct evlist **)opt->value;
>  	const struct pmu_events_table *table = pmu_events_table__find();
>  
> +	if (!table)
> +		return -EINVAL;
> +
>  	return parse_groups(perf_evlist, str, metric_no_group,
>  			    metric_no_merge, NULL, metric_events, table);
>  }
> -- 
> 2.37.2.672.g94769d06f0-goog

-- 

- Arnaldo