From: Andrzej Hajda <andrzej.hajda@intel.com>
To: linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-snps-arc@lists.infradead.org,
linux-arm-kernel@lists.infradead.org,
linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org,
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dri-devel@lists.freedesktop.org
Cc: Mark Rutland <mark.rutland@arm.com>,
Arnd Bergmann <arnd@arndb.de>,
Peter Zijlstra <peterz@infradead.org>,
Boqun Feng <boqun.feng@gmail.com>,
Andrzej Hajda <andrzej.hajda@intel.com>,
Rodrigo Vivi <rodrigo.vivi@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Subject: [PATCH 18/19] linux/include: add non-atomic version of xchg
Date: Thu, 22 Dec 2022 11:46:34 +0000 [thread overview]
Message-ID: <20221222114635.1251934-19-andrzej.hajda@intel.com> (raw)
In-Reply-To: <20221222114635.1251934-1-andrzej.hajda@intel.com>
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.
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
next prev parent reply other threads:[~2022-12-22 11:46 UTC|newest]
Thread overview: 36+ 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
2023-01-02 8:30 ` 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
2023-02-15 5:22 ` 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 ` Andrzej Hajda [this message]
2022-12-22 12:47 ` [PATCH 18/19] linux/include: add non-atomic version of xchg Andy Shevchenko
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
2022-12-23 14:23 ` Alexander Lobakin
2022-12-29 9:54 ` Andrzej Hajda
2023-01-05 16:29 ` Daniel Vetter
2023-01-10 10:53 ` [RFC DO NOT MERGE] treewide: use __xchg in most obvious places Andrzej Hajda
2023-01-10 11:07 ` Andy Shevchenko
2023-01-10 12:46 ` [Intel-gfx] " Andrzej Hajda
2023-01-10 13:52 ` Andy Shevchenko
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