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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 0F9FEC46463 for ; Thu, 2 Aug 2018 22:26:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C1D8E215E6 for ; Thu, 2 Aug 2018 22:26:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C1D8E215E6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732332AbeHCATq (ORCPT ); Thu, 2 Aug 2018 20:19:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:35060 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732299AbeHCATq (ORCPT ); Thu, 2 Aug 2018 20:19:46 -0400 Received: from localhost.localdomain (c-98-220-238-81.hsd1.il.comcast.net [98.220.238.81]) (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 CA48D215EB; Thu, 2 Aug 2018 22:26:34 +0000 (UTC) From: Tom Zanussi To: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org Cc: rostedt@goodmis.org, tglx@linutronix.de, C.Emde@osadl.org, jkacur@redhat.com, bigeasy@linutronix.de, daniel.wagner@siemens.com, julia@ni.com, stable-rt@vger.kernel.org, Tom Zanussi Subject: [PATCH 08/15] seqlock: provide the same ordering semantics as mainline Date: Thu, 2 Aug 2018 17:25:23 -0500 Message-Id: <650bfc722354f3307e6390ddddf1e4ee4e9dced2.1533242791.git.tom.zanussi@linux.intel.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Julia Cartwright The mainline implementation of read_seqbegin() orders prior loads w.r.t. the read-side critical section. Fixup the RT writer-boosting implementation to provide the same guarantee. Also, while we're here, update the usage of ACCESS_ONCE() to use READ_ONCE(). Fixes: e69f15cf77c23 ("seqlock: Prevent rt starvation") Cc: stable-rt@vger.kernel.org Signed-off-by: Julia Cartwright Signed-off-by: Sebastian Andrzej Siewior (cherry picked from commit afa4c06b89a3c0fb7784ff900ccd707bef519cb7) Signed-off-by: Tom Zanussi --- include/linux/seqlock.h | 1 + 1 file changed, 1 insertion(+) diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index 4acd0e2fb5cb..efa234031230 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -338,6 +338,7 @@ repeat: spin_unlock_wait(&sl->lock); goto repeat; } + smp_rmb(); return ret; } #endif -- 2.14.1