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=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 9D5CCC3A5A1 for ; Wed, 28 Aug 2019 03:55:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 720B0217F5 for ; Wed, 28 Aug 2019 03:55:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=bytedance.com header.i=@bytedance.com header.b="F4caB0aZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726560AbfH1DzG (ORCPT ); Tue, 27 Aug 2019 23:55:06 -0400 Received: from mail-pl1-f193.google.com ([209.85.214.193]:39415 "EHLO mail-pl1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726529AbfH1DzD (ORCPT ); Tue, 27 Aug 2019 23:55:03 -0400 Received: by mail-pl1-f193.google.com with SMTP id z3so559766pln.6 for ; Tue, 27 Aug 2019 20:55:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=mxNtarX9nX57XJxkArjO2AM3QUOz0wzt/JnfD0VPOK0=; b=F4caB0aZl1+ljrrlr2ZXzSJ64Udep2IJeA7lQGcAGXBMsyDN9JCNHMO6FT0Ar5vP0v UnJCBrHKqZHlbtTQE09XNLLGK9s6lXCj0RfiEUYHCKkZZT3DyfafbE7GpO6RUlwg+E8T EDITDAEd81fTvZLyUoEhaX1ib77eZxhg/UoEi81UsG9KE3s0ZgZqgkTAa8cMari6sOBz BiasbpjnO/EnhLafHhn/4W5YObrmcFzXPTkbANjmau0q6sNwnLh/HDhWRGDe0dfDU182 lkes5Qnwe7Mcqt21kTvs3UN/UlyCzS3m/4xDlaMvoRd5eiDJFX2ROW2Xo/vuHPiT5E/i l6ZA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=mxNtarX9nX57XJxkArjO2AM3QUOz0wzt/JnfD0VPOK0=; b=AZKRM/SLiW2wSOUBDXNsNvzBGIN88sMb/S1awbMnSjOSWpsBxIQySreDrQMJIi3Tni 0OSJoOaZeQkBfNMt5B1f1xUnJAW8VCRvMyuvZG/4uoq6D9NQtKZ6MWtXnB7Uo+UCUN/Z j3WqlF+JN17ky6nxxdiPSohlJbEMdutjEn4pCC1NOgFPcjawdO9Gsz21FTHOyumwBfnR 9ozdE5tS5+YWZCL6XlzCrHhwkt7FSpYOu5BsCT0u8Gz98EMd3FnBP+eEzQJ7//f3cXkr vSsjcntAsa0dWtskwTptemJzbwUS3QDY692E/ECxGqcK9zl3MCufTRBZTcA+N9+PhT3F zxsQ== X-Gm-Message-State: APjAAAWohgbRnu5Crq9KProsHRTKOKHulyNj5skMQ8P2UM7A2pMg9CCD 5EiANzudkaC8c9Jw8OG119qfl6cRuoM6NA== X-Google-Smtp-Source: APXvYqx3e2ELfBN+TGYLKM3FzD+6OoDzIwJzZbWpZcxu0XdIQBMS++7j1DfCl/f6RY1tc9dYTvz3FQ== X-Received: by 2002:a17:902:aa43:: with SMTP id c3mr2177445plr.11.1566964502988; Tue, 27 Aug 2019 20:55:02 -0700 (PDT) Received: from localhost ([61.120.150.70]) by smtp.gmail.com with ESMTPSA id i124sm902847pfe.61.2019.08.27.20.55.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Aug 2019 20:55:02 -0700 (PDT) From: Fam Zheng To: linux-kernel@vger.kernel.org Cc: axboe@kernel.dk, paolo.valente@linaro.org, fam@euphon.net, duanxiongchun@bytedance.com, cgroups@vger.kernel.org, zhangjiachen.jc@bytedance.com, tj@kernel.org, linux-block@vger.kernel.org Subject: [PATCH v3 1/3] bfq: Fix the missing barrier in __bfq_entity_update_weight_prio Date: Wed, 28 Aug 2019 11:54:51 +0800 Message-Id: <20190828035453.18129-2-zhengfeiran@bytedance.com> X-Mailer: git-send-email 2.22.1 In-Reply-To: <20190828035453.18129-1-zhengfeiran@bytedance.com> References: <20190828035453.18129-1-zhengfeiran@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The comment of bfq_group_set_weight says the reading of prio_changed should happen before the reading of weight, but a memory barrier is missing here. Add it now, to match the smp_wmb() there. Signed-off-by: Fam Zheng Reviewed-by: Paolo Valente --- block/bfq-wf2q.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c index c9ba225081ce..05f0bf4a1144 100644 --- a/block/bfq-wf2q.c +++ b/block/bfq-wf2q.c @@ -744,6 +744,8 @@ __bfq_entity_update_weight_prio(struct bfq_service_tree *old_st, } #endif + /* Matches the smp_wmb() in bfq_group_set_weight. */ + smp_rmb(); old_st->wsum -= entity->weight; if (entity->new_weight != entity->orig_weight) { -- 2.22.1