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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A0B13C433EF for ; Sat, 19 Mar 2022 02:03:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241789AbiCSCEv (ORCPT ); Fri, 18 Mar 2022 22:04:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52700 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235982AbiCSCEq (ORCPT ); Fri, 18 Mar 2022 22:04:46 -0400 Received: from mail-pl1-x62e.google.com (mail-pl1-x62e.google.com [IPv6:2607:f8b0:4864:20::62e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 572469683F for ; Fri, 18 Mar 2022 19:03:27 -0700 (PDT) Received: by mail-pl1-x62e.google.com with SMTP id n2so8459385plf.4 for ; Fri, 18 Mar 2022 19:03:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=xoAR2yJVMUeB0bOOrib4HlR43jGO+3UNSvj/b9LiFUQ=; b=aNK7F9MGvu9GmcJTkBB1frsQTl+WFfM31pE8duZPG/4vLLu1sV8crLU1Cjqt6ZITBV j+ebcjdv7EEakCVNOmFTCad+rRqiylDyuit2aDM3kqwICNqk8IVP9Kw2C0K+0fqDTlgd HidoSZmLFdKJ62j9Tey+JqCvKeuR7G8B/D8DU169H/d4Lg4OtgYks7zl8jsBqwYgjwiP /xQBjnhKGUvX86jVpltZ9UVSzLCuKx5/mhhWxJ9TjGX0TwB6yiVjEBbbsTf740SHZbZ6 L6VhC0ALhnGwOGKScXhMnPcZq0PjKtMn30sVgzl71M6PXrqiClBe/r0qwAtnOYP+qWa9 12kg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=xoAR2yJVMUeB0bOOrib4HlR43jGO+3UNSvj/b9LiFUQ=; b=sQl/TcUscd1zlUk545ISuIYU5IP9k4Saxnt0E8r8tX9jZsCoHAbsOFSfd3Tii+9w9I 39ht1XGXra25vfZcCg0bg8GdpHzwi1sRAfahZcC7M20xE7x+dA5gI49DLzjk+HPdGcZP 5ITXjwGv/pwa8bIuHsPwZV2RYrR15mmRbWzrKIWD9m9XXT7JUtbxYfBxr8PUdOovRkSR fbZyRIUmVwpH+hrRwYUR2wzplcYSD7gv6507FhDQgYNEgmPY5JEal8zeJHgKgmWgZITA scA6GiwzBugQuHpOB2yByzdh+9qFaaFPuU8oT0FktkHs5a+JX8azzg/bMASFniwakZJh /4Ww== X-Gm-Message-State: AOAM530CFVjLTLFdf0G/OZscm0+hQD3jeVAn4Blgd5x2Kgr3AflFp6ht ooSHjQcO8AP27Cc4a5CDHsU= X-Google-Smtp-Source: ABdhPJwTP3VMs0asgQeocvUNjtfID3/u/2reGMDGPKYUq8a2WBpC0xyak0M/1dQ+o9h1SLCVcackkw== X-Received: by 2002:a17:902:e94e:b0:154:3a4:c5e8 with SMTP id b14-20020a170902e94e00b0015403a4c5e8mr2413704pll.19.1647655406845; Fri, 18 Mar 2022 19:03:26 -0700 (PDT) Received: from localhost.localdomain ([119.3.102.56]) by smtp.gmail.com with ESMTPSA id t9-20020a056a0021c900b004f7b425211bsm10225674pfj.36.2022.03.18.19.03.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Mar 2022 19:03:26 -0700 (PDT) From: Bang Li To: vgupta@kernel.org Cc: peterz@infradead.org, mingo@kernel.org, valentin.schneider@arm.com, linux-snps-arc@lists.infradead.org, linux-kernel@vger.kernel.org, Bang Li Subject: [PATCH] ARC: remove redundant READ_ONCE() in cmpxchg loop Date: Sat, 19 Mar 2022 10:03:16 +0800 Message-Id: <20220319020316.142479-1-libang.linuxer@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch reverts commit 7082a29c22ac ("ARC: use ACCESS_ONCE in cmpxchg loop"). It is not necessary to use READ_ONCE() because cmpxchg contains barrier. We can get it from commit d57f727264f1 ("ARC: add compiler barrier to LLSC based cmpxchg"). Signed-off-by: Bang Li --- arch/arc/kernel/smp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arc/kernel/smp.c b/arch/arc/kernel/smp.c index 78e6d069b1c1..56c23f3e1309 100644 --- a/arch/arc/kernel/smp.c +++ b/arch/arc/kernel/smp.c @@ -274,7 +274,7 @@ static void ipi_send_msg_one(int cpu, enum ipi_msg_type msg) * and read back old value */ do { - new = old = READ_ONCE(*ipi_data_ptr); + new = old = *ipi_data_ptr; new |= 1U << msg; } while (cmpxchg(ipi_data_ptr, old, new) != old); -- 2.25.1