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Subject: Re: [PATCH v3] LoongArch: Add support to clone a time namespace
To:     Thomas Gleixner <tglx@linutronix.de>,
        Huacai Chen <chenhuacai@kernel.org>,
        WANG Xuerui <kernel@xen0n.name>,
        Christian Brauner <brauner@kernel.org>,
        Andy Lutomirski <luto@kernel.org>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>
References: <1685519761-20425-1-git-send-email-yangtiezhu@loongson.cn>
 <87bki0hn4y.ffs@tglx>
Cc:     loongarch@lists.linux.dev, linux-kernel@vger.kernel.org,
        loongson-kernel@lists.loongnix.cn
From:   Tiezhu Yang <yangtiezhu@loongson.cn>
Message-ID: <d9684f7b-871a-e759-d6b8-4556719702a1@loongson.cn>
Date:   Wed, 31 May 2023 18:04:08 +0800
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On 05/31/2023 05:21 PM, Thomas Gleixner wrote:
> On Wed, May 31 2023 at 15:56, Tiezhu Yang wrote:
>> When execute the following command to test clone3 on LoongArch:
>>
>>   # cd tools/testing/selftests/clone3 && make && ./clone3
>>
>> we can see the following error info:
>>
>>   # [5719] Trying clone3() with flags 0x80 (size 0)
>>   # Invalid argument - Failed to create new process
>>   # [5719] clone3() with flags says: -22 expected 0
>>   not ok 18 [5719] Result (-22) is different than expected (0)
>>
>> This is because if CONFIG_TIME_NS is not set, but the flag
>> CLONE_NEWTIME (0x80) is used to clone a time namespace, it
>> will return -EINVAL in copy_time_ns().
>
> Which means that test case is broken.
>
>> With this patch, the following failed test can be fixed too:
>
> You cannot fix a broken test case by enabling functionality which
> is not guaranteed to be available on all platforms.
>
> Adding time name spaces on loongarch is a completely separate issue and
> has absolutely nothing to do with broken test cases.
>
> They are still broken when CONFIG_TIME_NS is disabled in Kconfig, no?
>
> So this wants to be two separate things:
>
>    1) Fix the broken test cases so they handle CONFIG_TIME_NS=n
>       situations correctly
>
>    2) Add support for TIME_NS to loongarch
>


Thanks for your reply and detailed suggestions,
I will do it in the next version.

Thanks,
Tiezhu