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 56FEEC63793 for ; Wed, 21 Jul 2021 21:04:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 41515613D3 for ; Wed, 21 Jul 2021 21:04:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230047AbhGUUYJ (ORCPT ); Wed, 21 Jul 2021 16:24:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:34860 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229943AbhGUUYH (ORCPT ); Wed, 21 Jul 2021 16:24:07 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5C1356135A; Wed, 21 Jul 2021 21:04:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1626901483; bh=uLNy3yIK4EBO9lKuJ5GSBVXdPDG6YtLrOMDVTxwg7p8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Gu3El/Kk9uCmsl/KjH8HLKmaHv/2RDJD2+HXUoTj66/HggQXCoGI2NUC1fTUjmwqC NnS7ZhqzPq6VR7bmfHF0hsjWFvOTDTvvpaC7R9RSj70VkLHIbW0lIJ1CkSQr43WegV 1HTNB2pK5++j9NsD0khW+NWA/6+IlXHOLYv2f/4tbiwUCyUpdupS0vuNbmZPhzts16 v09UeDpUpTSC4kkzUo+LEQZuCjDYOT2MVTvYpNMu3lNKl0qgJJ3AETr0UU+wcxVZnU dLHCIFexxrkCSR7oN2urjJqxE5Vhy2iVyYB85rBpt3Wfv4g0K8MPHRSK9A0KUdTA5H jqjxHWI6i0eSw== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 251125C0A2D; Wed, 21 Jul 2021 14:04:43 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, "Paul E. McKenney" Subject: [PATCH rcu 4/7] locktorture: Mark statistics data races Date: Wed, 21 Jul 2021 14:04:38 -0700 Message-Id: <20210721210441.796995-4-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20210721210421.GA788053@paulmck-ThinkPad-P17-Gen-1> References: <20210721210421.GA788053@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 lock_stress_stats structure's ->n_lock_fail and ->n_lock_acquired fields are incremented and sampled locklessly using plain C-language statements, which KCSAN objects to. This commit therefore marks the statistics gathering with data_race() to flag the intent. While in the area, this commit also reduces the number of accesses to the ->n_lock_acquired field, thus eliminating some possible check/use confusion. Signed-off-by: Paul E. McKenney --- kernel/locking/locktorture.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c index b3adb40549bf3..313d5e613fbe6 100644 --- a/kernel/locking/locktorture.c +++ b/kernel/locking/locktorture.c @@ -738,20 +738,22 @@ static int lock_torture_reader(void *arg) static void __torture_print_stats(char *page, struct lock_stress_stats *statp, bool write) { + long cur; bool fail = false; int i, n_stress; - long max = 0, min = statp ? statp[0].n_lock_acquired : 0; + long max = 0, min = statp ? data_race(statp[0].n_lock_acquired) : 0; long long sum = 0; n_stress = write ? cxt.nrealwriters_stress : cxt.nrealreaders_stress; for (i = 0; i < n_stress; i++) { - if (statp[i].n_lock_fail) + if (data_race(statp[i].n_lock_fail)) fail = true; - sum += statp[i].n_lock_acquired; - if (max < statp[i].n_lock_acquired) - max = statp[i].n_lock_acquired; - if (min > statp[i].n_lock_acquired) - min = statp[i].n_lock_acquired; + cur = data_race(statp[i].n_lock_acquired); + sum += cur; + if (max < cur) + max = cur; + if (min > cur) + min = cur; } page += sprintf(page, "%s: Total: %lld Max/Min: %ld/%ld %s Fail: %d %s\n", -- 2.31.1.189.g2e36527f23