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From: Arnd Bergmann <arnd@arndb.de>
To: "André 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>
Subject: Re: [PATCH v3 2/2] perf bench: Add support for 32-bit systems with 64-bit time_t
Date: Wed, 22 Sep 2021 13:26:16 +0200	[thread overview]
Message-ID: <CAK8P3a0LsxOTYeM-o=Ee=XFD6zN7ESV_dhGmAOFSj_zJ8pBDgA@mail.gmail.com> (raw)
In-Reply-To: <9db8c79a-f704-84ce-360b-84335f926a48@collabora.com>

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

WARNING: multiple messages have this Message-ID
From: Arnd Bergmann <arnd@arndb.de>
To: "André 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>
Subject: Re: [PATCH v3 2/2] perf bench: Add support for 32-bit systems with 64-bit time_t
Date: Wed, 22 Sep 2021 13:26:16 +0200	[thread overview]
Message-ID: <CAK8P3a0LsxOTYeM-o=Ee=XFD6zN7ESV_dhGmAOFSj_zJ8pBDgA@mail.gmail.com> (raw)
In-Reply-To: <9db8c79a-f704-84ce-360b-84335f926a48@collabora.com>

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

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  reply	other threads:[~2021-09-22 11:26 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-17  6:10 [PATCH v3 1/2] perf benchmark: Call the futex syscall from a function Alistair Francis
2021-09-17  6:10 ` Alistair Francis
2021-09-17  6:10 ` [PATCH v3 2/2] perf bench: Add support for 32-bit systems with 64-bit time_t Alistair Francis
2021-09-17  6:10   ` Alistair Francis
2021-09-17  7:33   ` Arnd Bergmann
2021-09-17  7:33     ` Arnd Bergmann
2021-09-17 18:33   ` Davidlohr Bueso
2021-09-17 18:33     ` Davidlohr Bueso
2021-09-20 22:47   ` André Almeida
2021-09-20 22:47     ` André Almeida
2021-09-21  8:08     ` Arnd Bergmann
2021-09-21  8:08       ` Arnd Bergmann
2021-09-21 23:06       ` André Almeida
2021-09-21 23:06         ` André Almeida
2021-09-22 11:26         ` Arnd Bergmann [this message]
2021-09-22 11:26           ` Arnd Bergmann
2021-09-22 11:27         ` Arnd Bergmann
2021-09-22 11:27           ` Arnd Bergmann
2021-09-24  4:34       ` Alistair Francis
2021-09-24  4:34         ` Alistair Francis
2021-09-24  4:34     ` Alistair Francis
2021-09-24  4:34       ` Alistair Francis
2021-09-26 21:32       ` André Almeida
2021-09-26 21:32         ` André Almeida
2021-09-17 18:21 ` [PATCH v3 1/2] perf benchmark: Call the futex syscall from a function Davidlohr Bueso
2021-09-17 18:21   ` Davidlohr Bueso

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