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From:   Thomas Gleixner <tglx@linutronix.de>
To:     =?utf-8?Q?Andr=C3=A9?= Almeida <andrealmeid@collabora.com>,
        LKML <linux-kernel@vger.kernel.org>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Adhemerval Zanella <adhemerval.zanella@linaro.org>,
        Lukasz Majewski <lukma@denx.de>,
        Florian Weimer <fweimer@redhat.com>,
        Carlos O'Donell <carlos@redhat.com>,
        "Michael Kerrisk \(man-pages\)" <mtk.manpages@gmail.com>,
        Davidlohr Bueso <dave@stgolabs.net>,
        Ingo Molnar <mingo@kernel.org>,
        Darren Hart <dvhart@infradead.org>,
        Andrei Vagin <avagin@gmail.com>,
        Kurt Kanzenbach <kurt@linutronix.de>, kernel@collabora.com
Subject: Re: [patch 3/6] futex: Get rid of the val2 conditional dance
In-Reply-To: <f8cda7fa-46e9-5add-ccb6-441323ba2042@collabora.com>
References: <20210422194417.866740847@linutronix.de> <20210422194705.125957049@linutronix.de> <f8cda7fa-46e9-5add-ccb6-441323ba2042@collabora.com>
Date:   Sat, 24 Apr 2021 00:34:00 +0200
Message-ID: <87r1j0vdev.ffs@nanos.tec.linutronix.de>
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On Fri, Apr 23 2021 at 18:40, Andr=C3=A9 Almeida wrote:
>>=20=20=20
>> -	return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);
>> +	return do_futex(uaddr, op, val, tp, uaddr2, (unsigned long)utime, val3=
);
>
> Given do_futex()'s type signature, I think it makes more sense to cast=20
> utime to u32.

It's a pointer which you better force cast to unsigned long first.

So the explicit thing would be '(u32)(unsigned long) utime' which is
what the val2 dance stupidly did with 'int'

		val2 =3D (int) (unsigned long) utime;

But with doing it at function call argument it's implicit, because the

  unsigned long  to u32 conversion is well defined

while

  (u32)ptr

is only well defined on 32bit.

Thanks,

        tglx