Re: [PATCH v2 4/5] test_printf: Append strings more efficiently

[Yafang Shao <laoar.shao@gmail.com>]

On Tue, Oct 19, 2021 at 10:33 PM Matthew Wilcox (Oracle)
<willy@infradead.org> wrote:
>
> Use scnprintf instead of snprintf + strlen.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Reviewed-by: Yafang Shao <laoar.shao@gmail.com>

> ---
>  lib/test_printf.c | 18 +++++++-----------
>  1 file changed, 7 insertions(+), 11 deletions(-)
>
> diff --git a/lib/test_printf.c b/lib/test_printf.c
> index ec584196cb99..d09993fca463 100644
> --- a/lib/test_printf.c
> +++ b/lib/test_printf.c
> @@ -614,8 +614,7 @@ page_flags_test(int section, int node, int zone, int last_cpupid,
>         int i;
>
>         if (flags & PAGEFLAGS_MASK) {
> -               snprintf(cmp_buf + size, BUF_SIZE - size, "%s", name);
> -               size = strlen(cmp_buf);
> +               size += scnprintf(cmp_buf + size, BUF_SIZE - size, "%s", name);
>                 append = true;
>         }
>
> @@ -623,17 +622,14 @@ page_flags_test(int section, int node, int zone, int last_cpupid,
>                 if (!pft[i].width)
>                         continue;
>
> -               if (append) {
> -                       snprintf(cmp_buf + size, BUF_SIZE - size, "|");
> -                       size = strlen(cmp_buf);
> -               }
> +               if (append)
> +                       size += scnprintf(cmp_buf + size, BUF_SIZE - size, "|");
>
>                 flags |= (values[i] & pft[i].mask) << pft[i].shift;
> -               snprintf(cmp_buf + size, BUF_SIZE - size, "%s=", pft[i].name);
> -               size = strlen(cmp_buf);
> -               snprintf(cmp_buf + size, BUF_SIZE - size, pft[i].fmt,
> -                        values[i] & pft[i].mask);
> -               size = strlen(cmp_buf);
> +               size += scnprintf(cmp_buf + size, BUF_SIZE - size, "%s=",
> +                               pft[i].name);
> +               size += scnprintf(cmp_buf + size, BUF_SIZE - size, pft[i].fmt,
> +                               values[i] & pft[i].mask);
>                 append = true;
>         }
>
> --
> 2.32.0
>


-- 
Thanks
Yafang