linux-kernel - Re: [PATCH 2/4] perf maps: Re-use __maps__free_maps_by

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Message-ID: <CAP-5=fUqaXWm0xFCoaFYzVkWVMD3Khtxu7au5natVvDVw+fvTQ@mail.gmail.com>
Date: Wed, 8 May 2024 15:06:29 -0700
From: Ian Rogers <irogers@...gle.com>
To: James Clark <james.clark@....com>
Cc: linux-perf-users@...r.kernel.org, atrajeev@...ux.vnet.ibm.com, 
	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Adrian Hunter <adrian.hunter@...el.com>, "Liang, Kan" <kan.liang@...ux.intel.com>, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] perf maps: Re-use __maps__free_maps_by_name()

On Tue, May 7, 2024 at 7:13 AM James Clark <james.clark@....com> wrote:
>
> maps__merge_in() hard codes the steps to free the maps_by_name list. It
> seems to not map__put() each element before freeing, and it sets
> maps_by_name_sorted to true after freeing, which may be harmless but
> is inconsistent with maps__init() and other functions.
>
> maps__maps_by_name_addr() is also quite hard to read because we already
> have maps__maps_by_name() and maps__maps_by_address(), but the function
> is only used in that place so delete it.
>
> Signed-off-by: James Clark <james.clark@....com>
> ---
>  tools/perf/util/maps.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/tools/perf/util/maps.c b/tools/perf/util/maps.c
> index 61eb742d91e3..16b39db594f4 100644
> --- a/tools/perf/util/maps.c
> +++ b/tools/perf/util/maps.c
> @@ -124,11 +124,6 @@ static void maps__set_maps_by_address(struct maps *maps, struct map **new)
>
>  }
>
> -static struct map ***maps__maps_by_name_addr(struct maps *maps)
> -{
> -       return &RC_CHK_ACCESS(maps)->maps_by_name;
> -}
> -
>  static void maps__set_nr_maps_allocated(struct maps *maps, unsigned int nr_maps_allocated)
>  {
>         RC_CHK_ACCESS(maps)->nr_maps_allocated = nr_maps_allocated;
> @@ -284,6 +279,9 @@ void maps__put(struct maps *maps)
>
>  static void __maps__free_maps_by_name(struct maps *maps)
>  {
> +       if (!maps__maps_by_name(maps))
> +               return;
> +
>         /*
>          * Free everything to try to do it from the rbtree in the next search

nit: this comment is stale, it should be maps_by_address rather than the rbtree.

Reviewed-by: Ian Rogers <irogers@...gle.com>

Thanks,
Ian

>          */
> @@ -291,6 +289,9 @@ static void __maps__free_maps_by_name(struct maps *maps)
>                 map__put(maps__maps_by_name(maps)[i]);
>
>         zfree(&RC_CHK_ACCESS(maps)->maps_by_name);
> +
> +       /* Consistent with maps__init(). When maps_by_name == NULL, maps_by_name_sorted == false */
> +       maps__set_maps_by_name_sorted(maps, false);
>  }
>
>  static int map__start_cmp(const void *a, const void *b)
> @@ -1167,8 +1168,7 @@ int maps__merge_in(struct maps *kmaps, struct map *new_map)
>         }
>         maps__set_maps_by_address(kmaps, merged_maps_by_address);
>         maps__set_maps_by_address_sorted(kmaps, true);
> -       zfree(maps__maps_by_name_addr(kmaps));
> -       maps__set_maps_by_name_sorted(kmaps, true);
> +       __maps__free_maps_by_name(kmaps);
>         maps__set_nr_maps_allocated(kmaps, merged_nr_maps_allocated);
>
>         /* Copy entries before the new_map that can't overlap. */
> --
> 2.34.1
>