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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 21638C433DF for ; Tue, 23 Jun 2020 00:52:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F18082076E for ; Tue, 23 Jun 2020 00:52:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592873566; bh=svODkwxakQ4y62OkzdQboTX2De2+sPLtPtUYQu2CPE8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ATH1WIa46c9rHIGu1O87YgLpgtNWnOAhjeScI0KZqTmYDnsTy4WyIgqc04U3nLb4h 4xRfgRhgXT8ECk7xLMGdUJXSsAWXFK8Mlq2mcOocPPRglEb6ejDsFrDFeG9e+hEbXF 7EhbdY3RXMLJIIB4ekgZA/xydUkmJj5a4vp36BW4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732417AbgFWAwn (ORCPT ); Mon, 22 Jun 2020 20:52:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:46506 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732371AbgFWAwe (ORCPT ); Mon, 22 Jun 2020 20:52:34 -0400 Received: from paulmck-ThinkPad-P72.home (50-39-105-78.bvtn.or.frontiernet.net [50.39.105.78]) (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 ACE302082F; Tue, 23 Jun 2020 00:52:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592873553; bh=svODkwxakQ4y62OkzdQboTX2De2+sPLtPtUYQu2CPE8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uLIFIiPmYRAIvgQFQvrRM2jKxv6S6VUOVkbiDzAeitui60B8MV3U+9I17PTkkbgmV RwaxmMbts/kTg7ZoecucDnrvnusVp1vkhvdAKBMv7WKvueVpMcm1Jw9v7DUaZdH+OL /1REMn3dFP8Q1Y+uehbTn8raCoFCBKr2Mjymfgy0= From: paulmck@kernel.org 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, "Joel Fernandes (Google)" , "Paul E . McKenney" Subject: [PATCH tip/core/rcu 04/14] Documentation: LKMM: Add litmus test for RCU GP guarantee where reader stores Date: Mon, 22 Jun 2020 17:52:21 -0700 Message-Id: <20200623005231.27712-4-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20200623005152.GA27459@paulmck-ThinkPad-P72> References: <20200623005152.GA27459@paulmck-ThinkPad-P72> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Joel Fernandes (Google)" This adds an example for the important RCU grace period guarantee, which shows an RCU reader can never span a grace period. Acked-by: Andrea Parri Signed-off-by: Joel Fernandes (Google) Signed-off-by: Paul E. McKenney --- Documentation/litmus-tests/README | 11 +++++++ .../litmus-tests/rcu/RCU+sync+read.litmus | 37 ++++++++++++++++++++++ 2 files changed, 48 insertions(+) create mode 100644 Documentation/litmus-tests/README create mode 100644 Documentation/litmus-tests/rcu/RCU+sync+read.litmus diff --git a/Documentation/litmus-tests/README b/Documentation/litmus-tests/README new file mode 100644 index 0000000..c4307ea --- /dev/null +++ b/Documentation/litmus-tests/README @@ -0,0 +1,11 @@ +============ +LITMUS TESTS +============ + +RCU (/rcu directory) +-------------------- + +RCU+sync+read.litmus +RCU+sync+free.litmus + Both the above litmus tests demonstrate the RCU grace period guarantee + that an RCU read-side critical section can never span a grace period. diff --git a/Documentation/litmus-tests/rcu/RCU+sync+read.litmus b/Documentation/litmus-tests/rcu/RCU+sync+read.litmus new file mode 100644 index 0000000..f341767 --- /dev/null +++ b/Documentation/litmus-tests/rcu/RCU+sync+read.litmus @@ -0,0 +1,37 @@ +C RCU+sync+read + +(* + * Result: Never + * + * This litmus test demonstrates that after a grace period, an RCU updater always + * sees all stores done in prior RCU read-side critical sections. Such + * read-side critical sections would have ended before the grace period ended. + * + * This is one implication of the RCU grace-period guarantee, which says (among + * other things) that an RCU read-side critical section cannot span a grace period. + *) + +{ +int x = 0; +int y = 0; +} + +P0(int *x, int *y) +{ + rcu_read_lock(); + WRITE_ONCE(*x, 1); + WRITE_ONCE(*y, 1); + rcu_read_unlock(); +} + +P1(int *x, int *y) +{ + int r0; + int r1; + + r0 = READ_ONCE(*x); + synchronize_rcu(); + r1 = READ_ONCE(*y); +} + +exists (1:r0=1 /\ 1:r1=0) -- 2.9.5