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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Wed, 22 Sep 2021 13:26:16 +0200
Message-ID: <CAK8P3a0LsxOTYeM-o=Ee=XFD6zN7ESV_dhGmAOFSj_zJ8pBDgA@mail.gmail.com>
Subject: Re: [PATCH v3 2/2] perf bench: Add support for 32-bit systems with
 64-bit time_t
To:     =?UTF-8?Q?Andr=C3=A9_Almeida?= <andrealmeid@collabora.com>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Alistair Francis <alistair.francis@opensource.wdc.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Alistair Francis <alistair23@gmail.com>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Jiri Olsa <jolsa@redhat.com>, linux-perf-users@vger.kernel.org,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Davidlohr Bueso <dave@stgolabs.net>,
        Darren Hart <dvhart@infradead.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Atish Patra <atish.patra@wdc.com>,
        Alistair Francis <alistair.francis@wdc.com>
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On Wed, Sep 22, 2021 at 1:06 AM André Almeida <andrealmeid@collabora.com> wrote:
> Às 05:08 de 21/09/21, Arnd Bergmann escreveu:
> > I would love to see the wrapper that Alistair wrote as part of some kernel
> > uapi header provided to user space. futex is used by tons of applications,
> > and we never had a library abstraction for it, so everyone has to do these
> > by hand, and they all get them slightly wrong in different ways.
>
> Why we don't have a futex() wrapper at glibc as we do have for others
> syscalls?

I think mainly because there was no agreement on what the calling
conventions should be:

The raw syscall is awkward because of the argument overloading that cannot
easily be expressed in standard C in a typesafe way. Having a per-operation
interface would avoid that problem but requires specifying what that
particular interface has to be, and there is no standard to fall back on for
this syscall.

       Arnd