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 X-Spam-Level: X-Spam-Status: No, score=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 95DFEC433E3 for ; Fri, 10 Jul 2020 16:52:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4EB4E207FF for ; Fri, 10 Jul 2020 16:52:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594399948; bh=JFRVnikzffyM0kLIyVXv4/ggOBXeIFkHnh4eBvBnBLY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ZagnsujxKR50PEkom9yWDjRuAw9LqRuT99ZGOioUE+Oq6c9TbmS1GNcYzpIJJ6MFb YC1OImwZYzEiirjZ+VHV1Jr/aWhGcViHKBs4mPg8Xz+1fAKnfRZZhlhX4Qopkfe8fs lvk4zk2lqSjlNzD3yn5afVkT3s0J46EEC0bgydow= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728309AbgGJQw1 (ORCPT ); Fri, 10 Jul 2020 12:52:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:59116 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726977AbgGJQwY (ORCPT ); Fri, 10 Jul 2020 12:52:24 -0400 Received: from localhost.localdomain (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4CAB02078B; Fri, 10 Jul 2020 16:52:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594399943; bh=JFRVnikzffyM0kLIyVXv4/ggOBXeIFkHnh4eBvBnBLY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Xzei/k6DhRwA4CoPU2JfT1d96J4vveAm+XAaAkU1cr+BOf+32Tcx/dccl4I4ZPmCx sc4qnD19m1gpde2WR6qzwhjbcO9OZkyoPamVFAOYW5xvGZKM61oOqpDPK2n2MMzllD RXU/MDbaz/SgCunQxxoQ5llZ5g8r2qCnuIoyKmpk= From: Will Deacon To: linux-kernel@vger.kernel.org Cc: Will Deacon , Joel Fernandes , Sami Tolvanen , Nick Desaulniers , Kees Cook , Marco Elver , "Paul E. McKenney" , Matt Turner , Ivan Kokshaysky , Richard Henderson , Peter Zijlstra , Alan Stern , "Michael S. Tsirkin" , Jason Wang , Arnd Bergmann , Boqun Feng , Catalin Marinas , Mark Rutland , linux-arm-kernel@lists.infradead.org, linux-alpha@vger.kernel.org, virtualization@lists.linux-foundation.org, kernel-team@android.com Subject: [PATCH v3 03/19] asm/rwonce: Allow __READ_ONCE to be overridden by the architecture Date: Fri, 10 Jul 2020 17:51:47 +0100 Message-Id: <20200710165203.31284-4-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200710165203.31284-1-will@kernel.org> References: <20200710165203.31284-1-will@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The meat and potatoes of READ_ONCE() is defined by the __READ_ONCE() macro, which uses a volatile casts in an attempt to avoid tearing of byte, halfword, word and double-word accesses. Allow this to be overridden by the architecture code in the case that things like memory barriers are also required. Acked-by: Paul E. McKenney Signed-off-by: Will Deacon --- include/asm-generic/rwonce.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/include/asm-generic/rwonce.h b/include/asm-generic/rwonce.h index 92cc2f223cb3..f9dfa88fc04d 100644 --- a/include/asm-generic/rwonce.h +++ b/include/asm-generic/rwonce.h @@ -33,7 +33,9 @@ * atomicity or dependency ordering guarantees. Note that this may result * in tears! */ +#ifndef __READ_ONCE #define __READ_ONCE(x) (*(const volatile __unqual_scalar_typeof(x) *)&(x)) +#endif #define __READ_ONCE_SCALAR(x) \ ({ \ -- 2.27.0.383.g050319c2ae-goog