Re: [PATCH 1/4] perf annotate-data: Convert type histogram to hashmap

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Missing index increment when hashmap lookup fails in `get_member_overhead` causes histogram columns to be scrambled across events.
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commit 4840a8fb0b1911e5130194633a0b05e4bf3e21fe
Author: Namhyung Kim <namhyung@kernel.org>

perf annotate-data: Convert type histogram to hashmap
    
This commit converts the type histogram from an array to a hashmap to
reduce memory overhead. It replaces direct array accesses with hashmap
lookups across the annotation components.

> diff --git a/tools/perf/ui/browsers/annotate-data.c b/tools/perf/ui/browsers/annotate-data.c
> index aa8c89fe2e82c..82667c6ae2e74 100644
> --- a/tools/perf/ui/browsers/annotate-data.c
> +++ b/tools/perf/ui/browsers/annotate-data.c
> @@ -62,12 +62,17 @@ static int get_member_overhead(struct annotated_data_type *adt,
>  
>  		k = 0;
>  		for_each_group_evsel(evsel, leader) {
> +			struct type_hist_entry *hist;
> +
>  			if (symbol_conf.skip_empty &&
>  			    evsel__hists(evsel)->stats.nr_samples == 0)
>  				continue;
>  
> -			h = adt->histograms[evsel->core.idx];
> -			update_hist_entry(&entry->hists[k++], &h->addr[offset]);
> +			h = &adt->histograms[evsel->core.idx];
> +			if (!hashmap__find(&h->samples, offset, &hist))
> +				continue;
> +
> +			update_hist_entry(&entry->hists[k++], hist);

[Severity: Medium]
When hashmap__find() fails (indicating an event has no samples at this byte
offset), the continue statement skips the k++ increment.

Will this cause subsequent events in the group to write their stats into the
skipped event's entry->hists[k] bucket?

If k is not advanced for the skipped event, it appears the histogram columns
for multi-event annotation data could shift and display in the wrong event
columns in the UI.

Could we ensure k is incremented even when the hashmap lookup fails to
preserve the correct column alignment?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260912054706.1475583-1-namhyung@kernel.org?part=1