From patchwork Mon Sep 17 22:41:05 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 10603555 X-Patchwork-Delegate: agross@codeaurora.org Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 674FA14DA for ; Mon, 17 Sep 2018 23:20:34 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3287C2A849 for ; Mon, 17 Sep 2018 23:20:34 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 00AB02A8FB; Mon, 17 Sep 2018 23:20:33 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BA1692A1E8 for ; Mon, 17 Sep 2018 23:20:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732249AbeIREkZ (ORCPT ); Tue, 18 Sep 2018 00:40:25 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:50410 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731666AbeIREkZ (ORCPT ); Tue, 18 Sep 2018 00:40:25 -0400 Received: from localhost (li1825-44.members.linode.com [172.104.248.44]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 67BB6707; Mon, 17 Sep 2018 23:10:53 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Neeraj Upadhyay , Thomas Gleixner , "Peter Zijlstra (Intel)" , josh@joshtriplett.org, peterz@infradead.org, jiangshanlai@gmail.com, dzickus@redhat.com, brendan.jackman@arm.com, malat@debian.org, mojha@codeaurora.org, sramana@codeaurora.org, linux-arm-msm@vger.kernel.org Subject: [PATCH 4.18 035/158] cpu/hotplug: Adjust misplaced smb() in cpuhp_thread_fun() Date: Tue, 18 Sep 2018 00:41:05 +0200 Message-Id: <20180917211712.697608630@linuxfoundation.org> X-Mailer: git-send-email 2.19.0 In-Reply-To: <20180917211710.383360696@linuxfoundation.org> References: <20180917211710.383360696@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Neeraj Upadhyay commit f8b7530aa0a1def79c93101216b5b17cf408a70a upstream. The smp_mb() in cpuhp_thread_fun() is misplaced. It needs to be after the load of st->should_run to prevent reordering of the later load/stores w.r.t. the load of st->should_run. Fixes: 4dddfb5faa61 ("smp/hotplug: Rewrite AP state machine core") Signed-off-by: Neeraj Upadhyay Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Cc: josh@joshtriplett.org Cc: peterz@infradead.org Cc: jiangshanlai@gmail.com Cc: dzickus@redhat.com Cc: brendan.jackman@arm.com Cc: malat@debian.org Cc: mojha@codeaurora.org Cc: sramana@codeaurora.org Cc: linux-arm-msm@vger.kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/1536126727-11629-1-git-send-email-neeraju@codeaurora.org Signed-off-by: Greg Kroah-Hartman --- kernel/cpu.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -608,15 +608,15 @@ static void cpuhp_thread_fun(unsigned in bool bringup = st->bringup; enum cpuhp_state state; + if (WARN_ON_ONCE(!st->should_run)) + return; + /* * ACQUIRE for the cpuhp_should_run() load of ->should_run. Ensures * that if we see ->should_run we also see the rest of the state. */ smp_mb(); - if (WARN_ON_ONCE(!st->should_run)) - return; - cpuhp_lock_acquire(bringup); if (st->single) {