Re: [PATCH] objtool/perf: Fix malloc call for new -Walloc-size

[Namhyung Kim <namhyung@kernel.org>]

Hello,

On Fri, Dec 1, 2023 at 6:33 PM Yanteng Si <siyanteng@loongson.cn> wrote:
>
> From: Sun Haiyong <sunhaiyong@loongson.cn>
>
> GCC 14 introduces a new -Walloc-size included in -Wextra which errors out
> like:
> ```
> builtin-top.c: In function ‘prompt_integer’:
> builtin-top.c:360:21: error: allocation of insufficient size ‘0’ for
> type ‘char’ with size ‘1’ [-Werror=alloc-size]
>   360 |         char *buf = malloc(0), *p;
>       |                     ^~~~~~
>
> ```
>
> So, just cast type to char, silence this error.

No, please do not.  I'm not sure if it silences the error.
The buf is to be passed to getline() so you can set it to
NULL instead.

  char *buf = NULL, *p;

Thanks,
Namhyung

>
> Signed-off-by: Sun Haiyong <sunhaiyong@loongson.cn>
> Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
> ---
>  tools/perf/builtin-top.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
> index ea8c7eca5eee..29191d966522 100644
> --- a/tools/perf/builtin-top.c
> +++ b/tools/perf/builtin-top.c
> @@ -357,7 +357,7 @@ static void perf_top__print_sym_table(struct perf_top *top)
>
>  static void prompt_integer(int *target, const char *msg)
>  {
> -       char *buf = malloc(0), *p;
> +       char *buf = (char *)malloc(0), *p;
>         size_t dummy = 0;
>         int tmp;
>
> --
> 2.42.1
>