Re: [PATCH] perf metricgroup: Fix system PMU metrics

[Jiri Olsa <jolsa@redhat.com>]

On Tue, Jan 19, 2021 at 06:04:15PM +0800, John Garry wrote:
> Joakim reports that getting "perf stat" for multiple system PMU metrics
> segfaults:
> ./perf stat -a -I 1000 -M imx8mm_ddr_write.all,imx8mm_ddr_write.all
> Segmentation fault
> 
> While the same works without issue for a single metric.
> 
> The logic in metricgroup__add_metric_sys_event_iter() is broken, in that
> add_metric() @m argument should be NULL for each new metric. Fix by not
> passing a holder for that, and rather make local in
> metricgroup__add_metric_sys_event_iter().
> 
> Fixes: be335ec28efa ("perf metricgroup: Support adding metrics for system PMUs")
> Reported-by: Joakim Zhang <qiangqing.zhang@nxp.com>
> Signed-off-by: John Garry <john.garry@huawei.com>

Acked-by: Jiri Olsa <jolsa@redhat.com>

thanks,
jirka

> 
> diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
> index ee94d3e8dd65..2e60ee170abc 100644
> --- a/tools/perf/util/metricgroup.c
> +++ b/tools/perf/util/metricgroup.c
> @@ -766,7 +766,6 @@ int __weak arch_get_runtimeparam(struct pmu_event *pe __maybe_unused)
>  struct metricgroup_add_iter_data {
>  	struct list_head *metric_list;
>  	const char *metric;
> -	struct metric **m;
>  	struct expr_ids *ids;
>  	int *ret;
>  	bool *has_match;
> @@ -1058,12 +1057,13 @@ static int metricgroup__add_metric_sys_event_iter(struct pmu_event *pe,
>  						  void *data)
>  {
>  	struct metricgroup_add_iter_data *d = data;
> +	struct metric *m = NULL;
>  	int ret;
>  
>  	if (!match_pe_metric(pe, d->metric))
>  		return 0;
>  
> -	ret = add_metric(d->metric_list, pe, d->metric_no_group, d->m, NULL, d->ids);
> +	ret = add_metric(d->metric_list, pe, d->metric_no_group, &m, NULL, d->ids);
>  	if (ret)
>  		return ret;
>  
> @@ -1114,7 +1114,6 @@ static int metricgroup__add_metric(const char *metric, bool metric_no_group,
>  				.metric_list = &list,
>  				.metric = metric,
>  				.metric_no_group = metric_no_group,
> -				.m = &m,
>  				.ids = &ids,
>  				.has_match = &has_match,
>  				.ret = &ret,
> -- 
> 2.26.2
>