Re: [PATCH v2 1/3] lib/vsprintf: Avoid redundant work with 0 size

[Waiman Long <longman@redhat.com>]

On 1/30/22 15:49, David Rientjes wrote:
> On Sat, 29 Jan 2022, 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.
>>
>> Signed-off-by: Waiman Long <longman@redhat.com>
>> ---
>>   lib/vsprintf.c | 8 +++++---
>>   1 file changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
>> index 3b8129dd374c..a65df546fb06 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 (!size)
>> +		return 0;
> Nit: any reason this shouldn't be unlikely()?  If the conditional for
> i < size is likely(), this seems assumed already?

Good suggestion. Will make the change in the next version.

Cheers,
Longman