Re: [PATCH v1 04/12] perf annotate-data: Count flexible array accesses for the whole struct

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [Low] perf annotate-data: missing member_extent() use in TUI
  get_member_overhead()
--

commit db1590c6b9cdacf042578dbb6359cc6b78b628eb
Author: Arnaldo Carvalho de Melo <acme@redhat.com>

perf annotate-data: Count flexible array accesses for the whole struct

This commit introduces member_extent() to extend a struct or union member's
sample range to the end of its last child so flexible array accesses count
toward the enclosing type in print_annotated_data_type().

> diff --git a/tools/perf/util/annotate-data.c b/tools/perf/util/annotate-data.c
> index dd9c1d7b2da8b..7fae186ffd76b 100644
> --- a/tools/perf/util/annotate-data.c
> +++ b/tools/perf/util/annotate-data.c
> @@ -2233,6 +2233,25 @@ static void print_annotated_data_value(struct type_hist *h, u64 period, int nr_s
>  		color_fprintf(stdout, color, " %7.2f", percent);
>  }
>  
> +/*
> + * A flexible array member is resolved past the end of its parent, so the
> + * parent's samples are not bounded by its size.
> + */
> +static int member_extent(struct annotated_member *member)
> +{
> +	struct annotated_member *child;
> +	int end = member->offset + member->size;
> +
> +	list_for_each_entry(child, &member->children, node) {
> +		int child_end = member_extent(child);
> +
> +		if (child_end > end)
> +			end = child_end;
> +	}
> +
> +	return end;
> +}
> +
>  static void print_annotated_data_type(struct annotated_data_type *mem_type,
>  				      struct annotated_member *member,
>  				      struct evsel *evsel, int indent)
> @@ -2240,6 +2259,7 @@ static void print_annotated_data_type(struct annotated_data_type *mem_type,
>  	struct annotated_member *child;
>  	struct type_hist *h;
>  	int i, nr_events = 0, samples = 0;
> +	int end = member_extent(member);
>  	u64 period = 0;
>  	int width = symbol_conf.show_total_period ? 11 : 7;
>  	struct evsel *pos;
> @@ -2253,10 +2273,10 @@ static void print_annotated_data_type(struct annotated_data_type *mem_type,
>  
>  		samples = 0;
>  		period = 0;
> -		for (i = 0; i < member->size; i++) {
> +		for (i = member->offset; i < end; i++) {
>  			struct type_hist_entry *entry;
>  
> -			if (!hashmap__find(&h->samples, member->offset + i, &entry))
> +			if (!hashmap__find(&h->samples, i, &entry))
>  				continue;
>  
>  			samples += entry->nr_samples;

[Severity: Low]
Should get_member_overhead() in the TUI data-type browser also use
member_extent()?

tools/perf/ui/browsers/annotate-data.c:get_member_overhead() {
	struct annotated_member *member = entry->data;
	int i, k;

	for (i = 0; i < member->size; i++) {
		struct type_hist *h;
		struct evsel *evsel;
		int offset = member->offset + i;
    ...
}

Because get_member_overhead() still iterates only up to member->size,
inspecting a struct with flexible array accesses in the TUI browser continues
to omit those samples from the enclosing struct's overhead, sample count, and
period.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261113150555.1163049-1-acme@kernel.org?part=4