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,URIBL_BLOCKED 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 3815DC433EF for ; Mon, 18 Jun 2018 08:31:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F1B2820874 for ; Mon, 18 Jun 2018 08:31:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F1B2820874 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.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 S967161AbeFRIbc (ORCPT ); Mon, 18 Jun 2018 04:31:32 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:34084 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S967124AbeFRIbX (ORCPT ); Mon, 18 Jun 2018 04:31:23 -0400 Received: from localhost (LFbn-1-12247-202.w90-92.abo.wanadoo.fr [90.92.61.202]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 0E80FC8A; Mon, 18 Jun 2018 08:31:22 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jiang Biao , Wen Yang , Tejun Heo , Jens Axboe , Sasha Levin Subject: [PATCH 4.14 028/189] blkcg: dont hold blkcg lock when deactivating policy Date: Mon, 18 Jun 2018 10:12:04 +0200 Message-Id: <20180618081210.419522594@linuxfoundation.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180618081209.254234434@linuxfoundation.org> References: <20180618081209.254234434@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jiang Biao [ Upstream commit 946b81da114b8ba5c74bb01e57c0c6eca2bdc801 ] As described in the comment of blkcg_activate_policy(), *Update of each blkg is protected by both queue and blkcg locks so that holding either lock and testing blkcg_policy_enabled() is always enough for dereferencing policy data.* with queue lock held, there is no need to hold blkcg lock in blkcg_deactivate_policy(). Similar case is in blkcg_activate_policy(), which has removed holding of blkcg lock in commit 4c55f4f9ad3001ac1fefdd8d8ca7641d18558e23. Signed-off-by: Jiang Biao Signed-off-by: Wen Yang CC: Tejun Heo Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- block/blk-cgroup.c | 5 ----- 1 file changed, 5 deletions(-) --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -1374,17 +1374,12 @@ void blkcg_deactivate_policy(struct requ __clear_bit(pol->plid, q->blkcg_pols); list_for_each_entry(blkg, &q->blkg_list, q_node) { - /* grab blkcg lock too while removing @pd from @blkg */ - spin_lock(&blkg->blkcg->lock); - if (blkg->pd[pol->plid]) { if (pol->pd_offline_fn) pol->pd_offline_fn(blkg->pd[pol->plid]); pol->pd_free_fn(blkg->pd[pol->plid]); blkg->pd[pol->plid] = NULL; } - - spin_unlock(&blkg->blkcg->lock); } spin_unlock_irq(q->queue_lock);