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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,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 B8F53C433ED for ; Mon, 10 May 2021 18:46:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 924C861108 for ; Mon, 10 May 2021 18:46:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232445AbhEJSrg (ORCPT ); Mon, 10 May 2021 14:47:36 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:44054 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230186AbhEJSre (ORCPT ); Mon, 10 May 2021 14:47:34 -0400 Received: from pps.filterd (m0044012.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 14AIVFoC020738 for ; Mon, 10 May 2021 11:46:30 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding : content-type; s=facebook; bh=rWFLuxjlkCJpY+dUzioJAmlhNduAcTJxyvXk5dzyWIo=; b=ouzbLFe/3wo/rDw79rBNsSn8TgezE+cVrTlolHE5MX8NxiOlk7budplM3sBW5sdsFgQa xD+IQfa/4hFJd5E9Lbpyd2qKOg7QlhNFqbtDduufaw3Jae6qPK9QTp+Z/80a6NsCj2ZV PFs+OZ23qLio35ekaQxLn6bprQRS+6wOvXw= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 38eafxy2v3-9 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Mon, 10 May 2021 11:46:29 -0700 Received: from intmgw001.05.prn6.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Mon, 10 May 2021 11:46:03 -0700 Received: by devvm3388.prn0.facebook.com (Postfix, from userid 111017) id 510CA71F437F; Mon, 10 May 2021 11:46:01 -0700 (PDT) From: Roman Gushchin To: Tejun Heo , CC: Zefan Li , Johannes Weiner , , Roman Gushchin Subject: [PATCH] cgroup: inline cgroup_task_freeze() Date: Mon, 10 May 2021 11:45:56 -0700 Message-ID: <20210510184556.946798-1-guro@fb.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-GUID: 2dFkUtz5K724pHtpUMD2YGGWTVCoIxYT X-Proofpoint-ORIG-GUID: 2dFkUtz5K724pHtpUMD2YGGWTVCoIxYT X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-05-10_11:2021-05-10,2021-05-10 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 malwarescore=0 phishscore=0 mlxlogscore=399 impostorscore=0 mlxscore=0 suspectscore=0 spamscore=0 adultscore=0 priorityscore=1501 bulkscore=0 clxscore=1015 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2105100125 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org After the introduction of the cgroup.kill there is only one call site of cgroup_task_freeze() left: cgroup_exit(). cgroup_task_freeze() is currently taking rcu_read_lock() to read task's cgroup flags, but because it's always called with css_set_lock locked, the rcu protection is excessive. Simplify the code by inlining cgroup_task_freeze(). Signed-off-by: Roman Gushchin --- include/linux/cgroup.h | 18 ------------------ kernel/cgroup/cgroup.c | 3 ++- 2 files changed, 2 insertions(+), 19 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 4f2f79de083e..a72764287cb5 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -906,20 +906,6 @@ void cgroup_freeze(struct cgroup *cgrp, bool freeze)= ; void cgroup_freezer_migrate_task(struct task_struct *task, struct cgroup= *src, struct cgroup *dst); =20 -static inline bool cgroup_task_freeze(struct task_struct *task) -{ - bool ret; - - if (task->flags & PF_KTHREAD) - return false; - - rcu_read_lock(); - ret =3D test_bit(CGRP_FREEZE, &task_dfl_cgroup(task)->flags); - rcu_read_unlock(); - - return ret; -} - static inline bool cgroup_task_frozen(struct task_struct *task) { return task->frozen; @@ -929,10 +915,6 @@ static inline bool cgroup_task_frozen(struct task_st= ruct *task) =20 static inline void cgroup_enter_frozen(void) { } static inline void cgroup_leave_frozen(bool always_leave) { } -static inline bool cgroup_task_freeze(struct task_struct *task) -{ - return false; -} static inline bool cgroup_task_frozen(struct task_struct *task) { return false; diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index e640fc78d731..29be28e903ab 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -6267,7 +6267,8 @@ void cgroup_exit(struct task_struct *tsk) cset->nr_tasks--; =20 WARN_ON_ONCE(cgroup_task_frozen(tsk)); - if (unlikely(cgroup_task_freeze(tsk))) + if (unlikely(!(task->flags & PF_KTHREAD) && + test_bit(CGRP_FREEZE, &task_dfl_cgroup(task)->flags))) cgroup_update_frozen(task_dfl_cgroup(tsk)); =20 spin_unlock_irq(&css_set_lock); --=20 2.30.2