On Mon, Jan 31, 2022 at 02:23:05PM -0500, Waiman Long wrote:
> For *scnprintf(), vsnprintf() is always called even if the input size is
> 0. That is a waste of time, so just return 0 in this case.
>
> Note that vsnprintf() will never return -1 to indicate an error. So
> skipping the call to vsnprintf() when size is 0 will have no functional
> impact at all.
>
> Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
> Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
> Reviewed-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
> Acked-by: Roman Gushchin <guro@xxxxxx>
Acked-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> ---
> lib/vsprintf.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index 3b8129dd374c..d419154b47bb 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -2895,13 +2895,15 @@ int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
> {
> int i;
>
> + if (unlikely(!size))
> + return 0;
> +
> i = vsnprintf(buf, size, fmt, args);
>
> if (likely(i < size))
> return i;
> - if (size != 0)
> - return size - 1;
> - return 0;
> +
> + return size - 1;
> }
> EXPORT_SYMBOL(vscnprintf);
>
> --
> 2.27.0
>
--
Sincerely yours,
Mike.
