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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Tiezhu Yang <yangtiezhu@loongson.cn>,
        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>
Cc:     loongarch@lists.linux.dev, linux-kernel@vger.kernel.org,
        loongson-kernel@lists.loongnix.cn
Subject: Re: [PATCH v3] LoongArch: Add support to clone a time namespace
In-Reply-To: <1685519761-20425-1-git-send-email-yangtiezhu@loongson.cn>
References: <1685519761-20425-1-git-send-email-yangtiezhu@loongson.cn>
Date:   Wed, 31 May 2023 11:21:33 +0200
Message-ID: <87bki0hn4y.ffs@tglx>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

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,

        tglx