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, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 CC7E2C0650F for ; Mon, 5 Aug 2019 06:38:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A35212086D for ; Mon, 5 Aug 2019 06:38:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=bytedance-com.20150623.gappssmtp.com header.i=@bytedance-com.20150623.gappssmtp.com header.b="HkqdS5Jf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727417AbfHEGiQ (ORCPT ); Mon, 5 Aug 2019 02:38:16 -0400 Received: from mail-pg1-f194.google.com ([209.85.215.194]:32836 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726518AbfHEGiP (ORCPT ); Mon, 5 Aug 2019 02:38:15 -0400 Received: by mail-pg1-f194.google.com with SMTP id n190so4051918pgn.0 for ; Sun, 04 Aug 2019 23:38:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=H0yUp64wfUQz7/P14zeAkDAdPbazrBmBRzsKkTj102k=; b=HkqdS5JfAzU5BEi1rePzJYVVta7pmYY9kcs8THIOz9I9OoWyVYFoS8yIydBOR4khk5 NeMe6c/hV8JE8DIvkkaEz8yze8KZ1gP7tzk+8ey9ETPzgPATG5RgLbFTQ2SSaIEtF9ww 6ZFeXT8qCQpIRrKSxqf1DLd7BnjBrA5abZ3VxSqjTOBPBP18qoUm5LLlvjyrM+cfIHfV e0l9CmNfliF9bLK/71XhHxS26xy1KnswmuImQ04lHQJerW1dB/mMVqRBjda0RZ116I6g pTFy2Wo6QOPDj2YsB8/flAFkdF3Hi2A7F/xY5Wzj9oBxQdd5g1vbsMV2JkgpPKSUMnfn iV3A== 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; bh=H0yUp64wfUQz7/P14zeAkDAdPbazrBmBRzsKkTj102k=; b=eBJrt12lXQgFjdZ44XvLv2A44dcgXaE3u/j0ocosq7lQpm/vfApxvzT8uxkRg4w0l0 /S6zaftMgzTVHvCzh09inRnAHfTmCyw+j1rPnW6H2PSuNV8ERavqQCJwZkG6a/4l+RVf guzi22hJX/Ja4n6Az4CZ7bc+h+MRrosDB6bOzBKUXL9szUDUuh/ZS0CzhxZZ7ElQWuQ5 BVKK5Gy1qsm+X/medickcSnfCp2sfhxIP/YJJ9pj51qPWpPZjArOdUnSHws+ngJoHFWY TeJU03EctMigbyWr3q1J6LgcPAwqBXUoFqZKWGq1aPQNJvn/9TRb/fHLv4S/zJnCW+or Gk1A== X-Gm-Message-State: APjAAAV57L4/MIciKrhcDhjK8Vbw/dPwq1jNbXRChXHMZmSq1UMouOa8 s0QAkJWqXvxq7s/IL/fEXdzq5w== X-Google-Smtp-Source: APXvYqyWLOSI2+DYTh0Ld4S5k28wKqb34K9CG5dKxzGU+mc2z+KxEEsAAqZNhQ/hEc/DAJFUjB1lFw== X-Received: by 2002:a65:64c5:: with SMTP id t5mr62133295pgv.168.1564987094988; Sun, 04 Aug 2019 23:38:14 -0700 (PDT) Received: from localhost ([61.120.150.70]) by smtp.gmail.com with ESMTPSA id f197sm81442794pfa.161.2019.08.04.23.38.13 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sun, 04 Aug 2019 23:38:14 -0700 (PDT) From: Fam Zheng To: linux-kernel@vger.kernel.org Cc: axboe@kernel.dk, fam@euphon.net, paolo.valente@linaro.org, duanxiongchun@bytedance.com, linux-block@vger.kernel.org, tj@kernel.org, cgroups@vger.kernel.org, zhangjiachen.jc@bytedance.com Subject: [PATCH v2 1/3] bfq: Fix the missing barrier in __bfq_entity_update_weight_prio Date: Mon, 5 Aug 2019 14:38:05 +0800 Message-Id: <20190805063807.9494-2-zhengfeiran@bytedance.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190805063807.9494-1-zhengfeiran@bytedance.com> References: <20190805063807.9494-1-zhengfeiran@bytedance.com> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@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 --- 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) { -- 2.11.0