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 90C71C38147 for ; Wed, 18 Jan 2023 15:47:07 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4NxqrV0MQsz3fD4 for ; Thu, 19 Jan 2023 02:47:06 +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=kRzthRqp; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=intel.com (client-ip=192.55.52.93; helo=mga11.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=kRzthRqp; dkim-atps=neutral Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) (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 4NxqpS5Zpcz3cfP for ; Thu, 19 Jan 2023 02:45:20 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1674056721; x=1705592721; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=Z8X5newU9XL5BwcTC700iSbaht4sEux85LO6OUO0+Oc=; b=kRzthRqpaSUCB9rLpii3U1Tz8nmImHWHhiPazVlNMZzfgFHAJ0gpx1GJ kd/vB2z4CJN4EJcVPwTfwty2eZz7T4JWUKlZa/2V3R4qnM5zXXLTR+dnF 7Sn3QZn4GdLlCqkUx4+hnF7j09F01wsPEHKaYlJqLu27FKldBSWwkEI9Q TaV4elDY8KeZs90ooUkuiAHc8Gdz6PE0aZ1TbuS2tka8Y9XSUAWS4x/B9 eFn+i39vke+FzD04LmBD6kVu1F4+Tm0HbYzZpiXlGylpAHcO0phLZwdqF L8XRg+jGXIqxIwcOYtUI/3R1VIasW56MXEc4gZHAW4GyIR9YAxLLoWvsN A==; X-IronPort-AV: E=McAfee;i="6500,9779,10594"; a="322701232" X-IronPort-AV: E=Sophos;i="5.97,226,1669104000"; d="scan'208";a="322701232" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Jan 2023 07:45:20 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10594"; a="661759280" X-IronPort-AV: E=Sophos;i="5.97,226,1669104000"; d="scan'208";a="661759280" Received: from lab-ah.igk.intel.com ([10.102.42.211]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Jan 2023 07:45:14 -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 v5 2/7] linux/include: add non-atomic version of xchg Date: Wed, 18 Jan 2023 16:44:45 +0100 Message-Id: <20230118154450.73842-2-andrzej.hajda@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230118154450.73842-1-andrzej.hajda@intel.com> References: <20230118153529.57695-1-andrzej.hajda@intel.com> <20230118154450.73842-1-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-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 Reviewed-by: Andy Shevchenko --- 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