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 5FC27C433E2 for ; Fri, 10 Jul 2020 16:52:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3BAB5207FF for ; Fri, 10 Jul 2020 16:52:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594399958; bh=gTXZQO1RyYx1KEQLncc7UQSL6etty75iDnDOorylNyo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=hYXaaT530h+WQNx/uswHXyLa46aLqMN7UcMCeJmXuv+SdPlnVkBmXDLj09BsF0SlG 1CE/H8CBtr63E3JhQOyfrbMYVqEVDSwEt3WBRA2sxENieZyxoqtHXSA8hC7DqZwUeo h7lFC1FRjEUNVDVQSMnG/IX236fCA9wnHfXA5JCM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728378AbgGJQwg (ORCPT ); Fri, 10 Jul 2020 12:52:36 -0400 Received: from mail.kernel.org ([198.145.29.99]:59386 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728336AbgGJQwc (ORCPT ); Fri, 10 Jul 2020 12:52:32 -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 48FF0207BB; 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=1594399952; bh=gTXZQO1RyYx1KEQLncc7UQSL6etty75iDnDOorylNyo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qPyTLF3pqs4qb8U2JHB2vHzU3ThHJ3PE1k3ZZAAEPzT80q2DNbs8iyNQFOoFd/cRV TdSU3YBe0OXAcoaCD0tdjrKCzw5McHlOyx8HVGl2NHy2tJp2UJHuW9xFuXvHeusZ4O 518hS8o32/DrYn3LkGZXqBF3E+Vl9slsioyn3KsE= 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 05/19] asm/rwonce: Remove smp_read_barrier_depends() invocation Date: Fri, 10 Jul 2020 17:51:49 +0100 Message-Id: <20200710165203.31284-6-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 Alpha overrides __READ_ONCE() directly, so there's no need to use smp_read_barrier_depends() in the core code. This also means that __READ_ONCE() can be relied upon to provide dependency ordering. Acked-by: Paul E. McKenney Signed-off-by: Will Deacon --- include/asm-generic/rwonce.h | 19 ++++--------------- 1 file changed, 4 insertions(+), 15 deletions(-) diff --git a/include/asm-generic/rwonce.h b/include/asm-generic/rwonce.h index f9dfa88fc04d..cc810f1f18ca 100644 --- a/include/asm-generic/rwonce.h +++ b/include/asm-generic/rwonce.h @@ -30,24 +30,16 @@ /* * Use __READ_ONCE() instead of READ_ONCE() if you do not require any - * atomicity or dependency ordering guarantees. Note that this may result - * in tears! + * atomicity. 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) \ -({ \ - __unqual_scalar_typeof(x) __x = __READ_ONCE(x); \ - smp_read_barrier_depends(); \ - (typeof(x))__x; \ -}) - #define READ_ONCE(x) \ ({ \ compiletime_assert_rwonce_type(x); \ - __READ_ONCE_SCALAR(x); \ + __READ_ONCE(x); \ }) #define __WRITE_ONCE(x, val) \ @@ -74,12 +66,9 @@ unsigned long __read_once_word_nocheck(const void *addr) */ #define READ_ONCE_NOCHECK(x) \ ({ \ - unsigned long __x; \ - compiletime_assert(sizeof(x) == sizeof(__x), \ + compiletime_assert(sizeof(x) == sizeof(unsigned long), \ "Unsupported access size for READ_ONCE_NOCHECK()."); \ - __x = __read_once_word_nocheck(&(x)); \ - smp_read_barrier_depends(); \ - (typeof(x))__x; \ + (typeof(x))__read_once_word_nocheck(&(x)); \ }) static __no_kasan_or_inline -- 2.27.0.383.g050319c2ae-goog