From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Andrzej Hajda <andrzej.hajda@intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
dri-devel@lists.freedesktop.org, linux-mips@vger.kernel.org,
sparclinux@vger.kernel.org, linux-riscv@lists.infradead.org,
linux-s390@vger.kernel.org, linux-hexagon@vger.kernel.org,
linux-snps-arc@lists.infradead.org,
Boqun Feng <boqun.feng@gmail.com>,
linux-xtensa@linux-xtensa.org, Arnd Bergmann <arnd@arndb.de>,
intel-gfx@lists.freedesktop.org, linux-m68k@lists.linux-m68k.org,
openrisc@lists.librecores.org, loongarch@lists.linux.dev,
Rodrigo Vivi <rodrigo.vivi@intel.com>,
linux-arm-kernel@lists.infradead.org,
linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-alpha@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 18/19] linux/include: add non-atomic version of xchg
Date: Thu, 22 Dec 2022 14:47:42 +0200 [thread overview]
Message-ID: <Y6RR7hPZUN22ytap@smile.fi.intel.com> (raw)
In-Reply-To: <20221222114635.1251934-19-andrzej.hajda@intel.com>
On Thu, Dec 22, 2022 at 12:46:34PM +0100, Andrzej Hajda wrote:
> The pattern of setting variable with new value and returning old
> one is very common in kernel. Usually atomicity of the operation
> is not required, so xchg seems to be suboptimal and confusing in
> such cases.
FWIW,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
> ---
> include/linux/non-atomic/xchg.h | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
> create mode 100644 include/linux/non-atomic/xchg.h
>
> diff --git a/include/linux/non-atomic/xchg.h b/include/linux/non-atomic/xchg.h
> new file mode 100644
> index 00000000000000..f7fa5dd746f37d
> --- /dev/null
> +++ b/include/linux/non-atomic/xchg.h
> @@ -0,0 +1,19 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _LINUX_NON_ATOMIC_XCHG_H
> +#define _LINUX_NON_ATOMIC_XCHG_H
> +
> +/**
> + * __xchg - set variable pointed by @ptr to @val, return old value
> + * @ptr: pointer to affected variable
> + * @val: value to be written
> + *
> + * This is non-atomic variant of xchg.
> + */
> +#define __xchg(ptr, val) ({ \
> + __auto_type __ptr = ptr; \
> + __auto_type __t = *__ptr; \
> + *__ptr = (val); \
> + __t; \
> +})
> +
> +#endif
> --
> 2.34.1
>
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2022-12-22 12:47 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-22 11:46 [PATCH 00/19] Introduce __xchg, non-atomic xchg Andrzej Hajda
2022-12-22 11:46 ` [PATCH 01/19] arch/alpha: rename internal name __xchg to __arch_xchg Andrzej Hajda
2022-12-22 11:46 ` [PATCH 02/19] arch/arc: " Andrzej Hajda
2022-12-29 9:32 ` Arnd Bergmann
2022-12-29 11:33 ` [PATCH v2] arch: rename all internal names " Andrzej Hajda
2022-12-29 23:00 ` kernel test robot
2022-12-30 14:15 ` [PATCH v3] " Andrzej Hajda
2023-01-03 10:02 ` Heiko Carstens
2023-01-05 9:54 ` [PATCH v4] " Andrzej Hajda
2023-01-02 8:30 ` [PATCH v2] " Geert Uytterhoeven
2022-12-22 11:46 ` [PATCH 03/19] arch/arm: rename internal name " Andrzej Hajda
2022-12-22 11:46 ` [PATCH 04/19] arch/arm64: " Andrzej Hajda
2022-12-22 11:46 ` [PATCH 05/19] arch/hexagon: " Andrzej Hajda
2022-12-22 11:46 ` [PATCH 06/19] arch/ia64: " Andrzej Hajda
2022-12-22 11:46 ` [PATCH 07/19] arch/loongarch: " Andrzej Hajda
2022-12-22 11:46 ` [PATCH 08/19] arch/m68k: " Andrzej Hajda
2022-12-22 11:46 ` [PATCH 09/19] arch/mips: " Andrzej Hajda
2022-12-22 11:46 ` [PATCH 10/19] arch/openrisc: " Andrzej Hajda
2022-12-22 11:46 ` [PATCH 11/19] arch/parisc: " Andrzej Hajda
2022-12-22 11:46 ` [PATCH 12/19] arch/powerpc: correct logged function names in xchg helpers Andrzej Hajda
2022-12-22 11:46 ` [PATCH 13/19] arch/riscv: rename internal name __xchg to __arch_xchg Andrzej Hajda
2022-12-29 16:22 ` Palmer Dabbelt
2022-12-22 11:46 ` [PATCH 14/19] arch/s390: " Andrzej Hajda
2022-12-22 11:46 ` [PATCH 15/19] arch/sh: " Andrzej Hajda
2022-12-22 11:46 ` [PATCH 16/19] arch/sparc: " Andrzej Hajda
2022-12-22 11:46 ` [PATCH 17/19] arch/xtensa: " Andrzej Hajda
2022-12-22 11:46 ` [PATCH 18/19] linux/include: add non-atomic version of xchg Andrzej Hajda
2022-12-22 12:47 ` Andy Shevchenko [this message]
2022-12-22 11:46 ` [PATCH 19/19] drm/i915/gt: use __xchg instead of internal helper Andrzej Hajda
2022-12-22 14:12 ` [PATCH 00/19] Introduce __xchg, non-atomic xchg Geert Uytterhoeven
2022-12-22 14:17 ` Andrzej Hajda
2022-12-22 17:21 ` Andrew Morton
2022-12-29 9:54 ` Andrzej Hajda
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