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=-20.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 97BF3C6377B for ; Wed, 21 Jul 2021 21:10:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 82F716124B for ; Wed, 21 Jul 2021 21:10:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229885AbhGUU3c (ORCPT ); Wed, 21 Jul 2021 16:29:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:36756 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229669AbhGUU33 (ORCPT ); Wed, 21 Jul 2021 16:29:29 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 459F961208; Wed, 21 Jul 2021 21:10:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1626901805; bh=O3fYbw1yzcdhQ3YhMPLOzXAM8TD1dNNVCuBzRAISN7o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VOpHH1KEiiVBrhh8wNb4WTJ85orJQHL0HlQKqdFLJ6C7kvQBoZKx1F5xAu24y3eus m8mz/gHthJu7OFO/v7pffVyQQuhmSpp4wckMKqCGpfl7Rnpi/yZMRAQ49lEJJe6FJX 0hFRKSx+O4/DPF0ofRROs6FjFEsGG+EgVwSbqK4LUZqrkZ/CkhCTXH5i1JQWkfAKbL HzPN336ykvprBS7+CPWhqZPi2/9J0tLIT3BkKc6fA08dteScRkZjuV/o9tYh1lP8aW Kq/0JZyfRHq1tBVyIxyBXIGIm2PYo3VRMdu+ALiqjXuPj2/4q1c9G2qyMdUixPe1gx SM44XLuiNiWcQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 0D85D5C09A4; Wed, 21 Jul 2021 14:10:05 -0700 (PDT) From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org Cc: stern@rowland.harvard.edu, parri.andrea@gmail.com, will@kernel.org, peterz@infradead.org, boqun.feng@gmail.com, npiggin@gmail.com, dhowells@redhat.com, j.alglave@ucl.ac.uk, luc.maranget@inria.fr, akiyks@gmail.com, "Paul E. McKenney" , Manfred Spraul Subject: [PATCH memory-model 1/4] tools/memory-model: Make read_foo_diagnostic() more clearly diagnostic Date: Wed, 21 Jul 2021 14:10:00 -0700 Message-Id: <20210721211003.869892-1-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20210721210726.GA828672@paulmck-ThinkPad-P17-Gen-1> References: <20210721210726.GA828672@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The current definition of read_foo_diagnostic() in the "Lock Protection With Lockless Diagnostic Access" section returns a value, which could be use for any purpose. This could mislead people into incorrectly using data_race() in cases where READ_ONCE() is required. This commit therefore makes read_foo_diagnostic() simply print the value read. Reported-by: Manfred Spraul Signed-off-by: Paul E. McKenney --- tools/memory-model/Documentation/access-marking.txt | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/memory-model/Documentation/access-marking.txt b/tools/memory-model/Documentation/access-marking.txt index 1ab189f51f55d..58bff26198767 100644 --- a/tools/memory-model/Documentation/access-marking.txt +++ b/tools/memory-model/Documentation/access-marking.txt @@ -259,9 +259,9 @@ diagnostic purposes. The code might look as follows: return ret; } - int read_foo_diagnostic(void) + void read_foo_diagnostic(void) { - return data_race(foo); + pr_info("Current value of foo: %d\n", data_race(foo)); } The reader-writer lock prevents the compiler from introducing concurrency -- 2.31.1.189.g2e36527f23