linux-kernel - Re: [PATCH 2/5] lib/string_kunit: add test case for strnlen

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Message-ID: <e02320c8-eff2-44af-a66c-a3c7ca9ca0ea@kylinos.cn>
Date: Thu, 8 Jan 2026 18:00:21 +0800
From: Feng Jiang <jiangfeng@...inos.cn>
To: Andy Shevchenko <andriy.shevchenko@...el.com>
Cc: Andy Shevchenko <andy.shevchenko@...il.com>, pjw@...nel.org,
 palmer@...belt.com, aou@...s.berkeley.edu, alex@...ti.fr, kees@...nel.org,
 andy@...nel.org, ebiggers@...nel.org, martin.petersen@...cle.com,
 Jason@...c4.com, conor.dooley@...rochip.com, samuel.holland@...ive.com,
 charlie@...osinc.com, ajones@...tanamicro.com, nathan@...nel.org,
 linus.walleij@...aro.org, linux-riscv@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH 2/5] lib/string_kunit: add test case for strnlen

On 2026/1/8 15:26, Andy Shevchenko wrote:
> On Thu, Jan 08, 2026 at 02:53:58PM +0800, Feng Jiang wrote:
>> On 2026/1/7 19:56, Andy Shevchenko wrote:
>>> On Wed, Jan 7, 2026 at 4:35 AM Feng Jiang <jiangfeng@...inos.cn> wrote:
> 
> ...
> 
>>>> Add a KUnit test for strnlen() to verify correctness across
>>>> different string lengths and memory alignments.
>>>
>>> Same comment as per patch 1 (it would probably require to call for
>>> arch_strnlen() or something like this).
>>
>> Thanks, makes sense.
>>
>> I'll add the performance benchmarking (random filling + timing) in V2.
>>
>> Since string functions are typically exported directly by each architecture
>> without an arch_ prefix, I'll introduce a generic_strnlen() (based on
>> lib/string.c) within the test for comparison.
> 
> Probably you want to make the existing one to have that name and use it inside
> the test and in the fallback wrapper. We don't want to have duplicate code, it
> is bad from maintenance perspective.
> 

Thanks for the suggestions!

To avoid code duplication, I'll rename the generic implementation in lib/string.c
to __generic_strnlen() and keep the original strnlen() as a wrapper. Then I'll use
the generic one in the KUnit test for comparison.

Does this approach look good to you?

-- 
With Best Regards,
Feng Jiang