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References: <20220312155603.1752193-1-guoren@kernel.org>
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From:   Max Filippov <jcmvbkbc@gmail.com>
Date:   Sat, 12 Mar 2022 15:50:35 -0800
Message-ID: <CAMo8Bf+p1-DqeqHV45GcZEsp+BEd+iMfeHP+i0P+KO7nv8W7Ow@mail.gmail.com>
Subject: Re: [RFC PATCH] arch: patch_text: Fixup last cpu should be master
To:     Guo Ren <guoren@kernel.org>
Cc:     linux-arm-kernel@lists.infradead.org,
        LKML <linux-kernel@vger.kernel.org>, linux-csky@vger.kernel.org,
        linux-riscv@lists.infradead.org,
        "open list:TENSILICA XTENSA PORT (xtensa)" 
        <linux-xtensa@linux-xtensa.org>,
        Guo Ren <guoren@linux.alibaba.com>,
        Will Deacon <will@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Chris Zankel <chris@zankel.net>, Arnd Bergmann <arnd@arndb.de>
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Hi Guo Ren,

On Sat, Mar 12, 2022 at 7:56 AM <guoren@kernel.org> wrote:
>
> From: Guo Ren <guoren@linux.alibaba.com>
>
> These patch_text implementations are using stop_machine_cpuslocked
> infrastructure with atomic cpu_count. The origin idea is that when

The original

> the master CPU patch_text, others should wait for it. But current
> implementation is using the first CPU as master, which couldn't
> guarantee continue CPUs are waiting. This patch changes the last

guarantee that remaining CPUs are waiting.

> CPU as the master to solve the potaintial risk.

potential

>
> Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> Signed-off-by: Guo Ren <guoren@kernel.org>
> Cc: Will Deacon <will@kernel.org>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Palmer Dabbelt <palmer@dabbelt.com>
> Cc: Peter Zijlstra <peterz@infradead.org
> Cc: Masami Hiramatsu <mhiramat@kernel.org>
> Cc: Chris Zankel <chris@zankel.net>
> Cc: Max Filippov <jcmvbkbc@gmail.com>
> Cc: Arnd Bergmann <arnd@arndb.de>
> ---
>  arch/arm64/kernel/patching.c      | 4 ++--
>  arch/csky/kernel/probes/kprobes.c | 2 +-
>  arch/riscv/kernel/patch.c         | 2 +-
>  arch/xtensa/kernel/jump_label.c   | 2 +-
>  4 files changed, 5 insertions(+), 5 deletions(-)

Reviewed-by: Max Filippov <jcmvbkbc@gmail.com>

I'm curious, is there a specific issue that prompted this patch?

-- 
Thanks.
-- Max