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 9773DC6377C for ; Wed, 21 Jul 2021 20:22:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8262461241 for ; Wed, 21 Jul 2021 20:22:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240519AbhGUTlf (ORCPT ); Wed, 21 Jul 2021 15:41:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:50066 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240381AbhGUTkx (ORCPT ); Wed, 21 Jul 2021 15:40:53 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id DEF476137D; Wed, 21 Jul 2021 20:21:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1626898890; bh=wEu8mtu9foqhl4vybGYweZH7nS4hW3NBN/vzNcI3m3I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XybP3n/kcIqe8sbpm68LJpkBOtg1RehbmH5DwI2II/+DZGYFtp2oiDdIMUUygX/qH oyqIriNylwWj5XILOF29LmQEG4OSwRF41dzPwZQMQuay8MwR8MknOCO+JEnzS+/cFt HF199bgrYNTWO6hNfgu0Z4GkE/Ap1qLwigsKIRPV/ZI0GxeVzKUtyA2fRp59ixyuRn AsDIm6+jpWPdG5QHTOEQeT0iMvEV16v1F9Pulcz4yDJjbditLe7sLUAdUMbTZEnA7N d/kySepwx4db0SbuNALnTEutGYIIEN6hj7DminPbzHhqpiIo66skbhMoBicy5PnStb wH9lF/VsWR1Zw== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 4A75C5C22F7; Wed, 21 Jul 2021 13:21:29 -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 11/18] rcu: Mark lockless ->qsmask read in rcu_check_boost_fail() Date: Wed, 21 Jul 2021 13:21:19 -0700 Message-Id: <20210721202127.2129660-11-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20210721202042.GA1472052@paulmck-ThinkPad-P17-Gen-1> References: <20210721202042.GA1472052@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 Accesses to ->qsmask are normally protected by ->lock, but there is an exception in the diagnostic code in rcu_check_boost_fail(). This commit therefore applies data_race() to this access to avoid KCSAN complaining about the C-language writes protected by ->lock. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree_stall.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index 42847caa3909b..6dd6c9aa3f757 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -766,7 +766,7 @@ bool rcu_check_boost_fail(unsigned long gp_state, int *cpup) rcu_for_each_leaf_node(rnp) { if (!cpup) { - if (READ_ONCE(rnp->qsmask)) { + if (data_race(READ_ONCE(rnp->qsmask))) { return false; } else { if (READ_ONCE(rnp->gp_tasks)) -- 2.31.1.189.g2e36527f23