Re: [PATCH 01/22] perf thread_map: Introduce thread_map__reset function

Arnaldo Carvalho de Melo
2015-06-26T14:06:24Z

Em Fri, Jun 26, 2015 at 11:29:06AM +0200, Jiri Olsa escreveu:
> We need to reset newly allocated 'struct thread_map_data' entries,
> because we will introduce new comm memeber, which will get set
> later or not at all.

And this is an array that never shrinks, right?

At least current usage just makes it grow, ok.

- Arnaldo

> Link: http://lkml.kernel.org/n/tip-hg8xtux446qyjqkkcezwkg0v@git.kernel.org
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> tools/perf/util/thread_map.c | 17 ++++++++++++++++-
> 1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/thread_map.c b/tools/perf/util/thread_map.c
> index 368cc58c6892..562e5e2c571c 100644
> --- a/tools/perf/util/thread_map.c
> +++ b/tools/perf/util/thread_map.c
> @@ -21,11 +21,26 @@ static int filter(const struct dirent *dir)
> return 1;
> }
>
> +static void thread_map__reset(struct thread_map *map, int start, int nr)
> +{
> + size_t size = (nr - start) * sizeof(struct thread_map_data);
> +
> + memset(&map->map[start], 0, size);
> +}
> +
> static struct thread_map *thread_map__realloc(struct thread_map *map, int nr)
> {
> size_t size = sizeof(*map) + sizeof(map->map[0]) * nr;
> + int start = map ? map->nr : 0;
>
> - return realloc(map, size);
> + map = realloc(map, size);
> + /*
> + * We only realloc to add more items, let's reset new items.
> + */
> + if (map)
> + thread_map__reset(map, start, nr);
> +
> + return map;
> }
>
> #define thread_map__alloc(__nr) thread_map__realloc(NULL, __nr)
> --
> 1.9.3