Messages in this thread Patch in this message | | | From | Waiman Long <> | Subject | [PATCH v3 1/4] lib/vsprintf: Avoid redundant work with 0 size | Date | Mon, 31 Jan 2022 14:23:05 -0500 |
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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> --- 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
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