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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 56577C43334 for ; Wed, 5 Sep 2018 12:30:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EB38420857 for ; Wed, 5 Sep 2018 12:30:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EB38420857 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org 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 S1728126AbeIERAo (ORCPT ); Wed, 5 Sep 2018 13:00:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:47246 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727660AbeIEQ6j (ORCPT ); Wed, 5 Sep 2018 12:58:39 -0400 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 864022086C; Wed, 5 Sep 2018 12:28:36 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.91) (envelope-from ) id 1fxWvD-00029C-FT; Wed, 05 Sep 2018 08:28:35 -0400 Message-Id: <20180905122835.375399705@goodmis.org> User-Agent: quilt/0.65 Date: Wed, 05 Sep 2018 08:28:01 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-rt-users Cc: Thomas Gleixner , Carsten Emde , Sebastian Andrzej Siewior , John Kacur , Paul Gortmaker , Julia Cartwright , Daniel Wagner , tom.zanussi@linux.intel.com, stable-rt@vger.kernel.org Subject: [PATCH RT 07/22] seqlock: provide the same ordering semantics as mainline References: <20180905122754.443196118@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.14.63-rt41-rc1 stable review patch. If anyone has any objections, please let me know. ------------------ From: Julia Cartwright [ Upstream commit afa4c06b89a3c0fb7784ff900ccd707bef519cb7 ] 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 Signed-off-by: Steven Rostedt (VMware) --- include/linux/seqlock.h | 1 + 1 file changed, 1 insertion(+) diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index a59751276b94..107079a2d7ed 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -462,6 +462,7 @@ static inline unsigned read_seqbegin(seqlock_t *sl) spin_unlock_wait(&sl->lock); goto repeat; } + smp_rmb(); return ret; } #endif -- 2.18.0