linux-kernel - Re: [PATCH] generic arch_futex_atomic_op

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Message-ID: <CAK8P3a1sT6y+oWKm4ou1=Y+1n5=1_S6UhJN9kkZ6iMxw18O5yw@mail.gmail.com>
Date:   Mon, 15 Jul 2019 14:06:10 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Vasily Averin <vvs@...tuozzo.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH] generic arch_futex_atomic_op_inuser() cleanup

On Mon, Jul 15, 2019 at 12:29 PM Vasily Averin <vvs@...tuozzo.com> wrote:
>
> Looks like this code is dead and therefore looks strange.
> I've found it during manual code review and decided to send patch
> to pay your attention to this problem.
> Probably it's better to remove this code at all?
>
> On 7/15/19 1:27 PM, Vasily Averin wrote:
> > Access to 'op' variable does not require pagefault_disable(),
> > 'ret' variable should be initialized before using,
> > 'oldval' variable can be replaced by constant.
> >
> > Signed-off-by: Vasily Averin <vvs@...tuozzo.com>

I'm not following the reasoning for any of the changes here. Why do you
think we don't need the pagefault_disable() around get_user()/put_user(),
and which part of the funtion is dead code?

       Arnd