From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 35A00C4332F for ; Thu, 22 Dec 2022 13:45:58 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4NdBR82BGMz3fVF for ; Fri, 23 Dec 2022 00:45:56 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=dnRQbvgK; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=intel.com (client-ip=192.55.52.120; helo=mga04.intel.com; envelope-from=andrzej.hajda@intel.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=dnRQbvgK; dkim-atps=neutral Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4Nd7rS6ZFYz3bVZ for ; Thu, 22 Dec 2022 22:49:12 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1671709753; x=1703245753; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=tIRocWwFeyLnkMyWNI6V183GDJq3vxxO+e0RyrK1iBA=; b=dnRQbvgKFGhPswUk8vFkjePyZPKIVjSmtsVioD7FCUk26tE9tj0FC2al YC28XUfKFU64LaQThPC0EoGptZwVdCbTVxTTZgoaCMHRrBVaFJq9W26kP 3xti6CpH2FSPNfSB3y/b5WMqCYCU07p7ZkqXraHIxZg7czoKodKVbFmPS zscAJVF+3fjgH51fnPwTnDgkW9J5WM7vadm+7f8x6ZuZ867zJN84jO2px +XFWiTNJowo1YqrDYfvS6A6M7zZjlOyIlKTkcvmzDCSjH6D/XqAMll3Bg jk/8p95GEznm0fyG1iy5+knk4J0rP+hFQDYc50iq24hUegZBGnsaOS7mV A==; X-IronPort-AV: E=McAfee;i="6500,9779,10568"; a="318804939" X-IronPort-AV: E=Sophos;i="5.96,265,1665471600"; d="scan'208";a="318804939" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Dec 2022 03:49:12 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10568"; a="629504949" X-IronPort-AV: E=Sophos;i="5.96,265,1665471600"; d="scan'208";a="629504949" Received: from lab-ah.igk.intel.com ([10.91.215.196]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Dec 2022 03:49:06 -0800 From: Andrzej Hajda 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, loongarch@lists.linux.dev, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Subject: [PATCH 18/19] linux/include: add non-atomic version of xchg Date: Thu, 22 Dec 2022 12:46:34 +0100 Message-Id: <20221222114635.1251934-19-andrzej.hajda@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20221222114635.1251934-1-andrzej.hajda@intel.com> References: <20221222114635.1251934-1-andrzej.hajda@intel.com> MIME-Version: 1.0 Organization: Intel Technology Poland sp. z o.o. - ul. Slowackiego 173, 80-298 Gdansk - KRS 101882 - NIP 957-07-52-316 Content-Transfer-Encoding: 8bit X-Mailman-Approved-At: Fri, 23 Dec 2022 00:29:21 +1100 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Arnd Bergmann , Peter Zijlstra , Boqun Feng , Andrzej Hajda , Rodrigo Vivi , Andrew Morton , Andy Shevchenko Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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 --- 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