Messages in this thread | | | Date | Mon, 31 Jan 2022 22:42:43 +0200 | From | Mike Rapoport <> | Subject | Re: [PATCH v3 1/4] lib/vsprintf: Avoid redundant work with 0 size |
| |
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@redhat.com> > Acked-by: David Rientjes <rientjes@google.com> > Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org> > Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
> --- > 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.
| |