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From:   Namhyung Kim <namhyung@kernel.org>
Date:   Mon, 4 Dec 2023 16:06:34 -0800
Message-ID: <CAM9d7chpynqmnGpi+wpn0f3XvEtDNSisgdQcXQu_2LuHcLNuVA@mail.gmail.com>
Subject: Re: [PATCH v5 19/50] perf maps: Do simple merge if given map doesn't overlap
To:     Ian Rogers <irogers@google.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
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On Mon, Nov 27, 2023 at 2:10 PM Ian Rogers <irogers@google.com> wrote:
>
> Simplify merge in for the simple case of a non-overlapping map.
>
> Signed-off-by: Ian Rogers <irogers@google.com>

A nitpick below.

> ---
>  tools/perf/util/maps.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/tools/perf/util/maps.c b/tools/perf/util/maps.c
> index 40df08dd9bf3..14e1a169433d 100644
> --- a/tools/perf/util/maps.c
> +++ b/tools/perf/util/maps.c
> @@ -696,9 +696,20 @@ void maps__fixup_end(struct maps *maps)
>  int maps__merge_in(struct maps *kmaps, struct map *new_map)
>  {
>         struct map_rb_node *rb_node;
> +       struct rb_node *first;
> +       bool overlaps;
>         LIST_HEAD(merged);
>         int err = 0;
>
> +       down_read(maps__lock(kmaps));
> +       first = first_ending_after(kmaps, new_map);
> +       overlaps = first &&
> +               map__start(rb_entry(first, struct map_rb_node, rb_node)->map) < map__end(new_map);

Can you please break this like below?

    rb_node = first ? rb_entry(first, struct map_rb_node, rb_node) : NULL;
    overlap = rb_node && map__start(rb_node->map) < map_end(new_map);

Thanks,
Namhyung


> +       up_read(maps__lock(kmaps));
> +
> +       if (!overlaps)
> +               return maps__insert(kmaps, new_map);
> +
>         maps__for_each_entry(kmaps, rb_node) {
>                 struct map *old_map = rb_node->map;
>
> --
> 2.43.0.rc1.413.gea7ed67945-goog
>