linux-kernel - Re: [PATCH v4 1/4] lib/vsprintf: Avoid redundant work with 0 size

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Message-ID: <YgJBEgYUuu/b8ZER@alley>
Date:   Tue, 8 Feb 2022 11:08:18 +0100
From:   Petr Mladek <pmladek@...e.com>
To:     Waiman Long <longman@...hat.com>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        linux-kernel@...r.kernel.org, cgroups@...r.kernel.org,
        linux-mm@...ck.org, Ira Weiny <ira.weiny@...el.com>,
        Mike Rapoport <rppt@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Roman Gushchin <guro@...com>, Rafael Aquini <aquini@...hat.com>
Subject: Re: [PATCH v4 1/4] lib/vsprintf: Avoid redundant work with 0 size

On Wed 2022-02-02 15:30:33, 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@...hat.com>
> Acked-by: David Rientjes <rientjes@...gle.com>
> Reviewed-by: Sergey Senozhatsky <senozhatsky@...omium.org>
> Acked-by: Roman Gushchin <guro@...com>

Reviewed-by: Petr Mladek <pmladek@...e.com>

Best Regards,
Petr