From patchwork Thu Nov 19 18:52:47 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tejun Heo X-Patchwork-Id: 546617 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id B0CF61414A0 for ; Fri, 20 Nov 2015 05:55:33 +1100 (AEDT) Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b=sKbzT+eD; dkim-atps=neutral Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758723AbbKSSzG (ORCPT ); Thu, 19 Nov 2015 13:55:06 -0500 Received: from mail-yk0-f176.google.com ([209.85.160.176]:35581 "EHLO mail-yk0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933030AbbKSSxA (ORCPT ); Thu, 19 Nov 2015 13:53:00 -0500 Received: by ykba77 with SMTP id a77so120871825ykb.2; Thu, 19 Nov 2015 10:52:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=rQblOgJqhs94/smqbsU0nZRtX57zYzCwA+FTAiJfd9o=; b=sKbzT+eD84eCIRXC8ZQoqp80B+qCqLt7UqllP0FbDV4locSDQYcQ2wxXaQVwQfFCXq ZFbecRUcllS/S2u4iUuJf9QY4Vto+UUlmv/R7PS46yK/pg1jL1cQID8QZk9SnGAj9fHC u+MmE+GMHqtzFC03hiSDz0U2dVYjzvC7vRpRnPE5RhT3xKtepT0F0+0u+5j+T5/TaPXa wG12nxqlVpPZKzcX0qi4+rSUizlJKz4Sj87iQe8EJPBz+GZprqDjUfAxrKWz5ZuOjOTH JTxnfGmKZhg57ABMCbf6gpvOV9ypZFY/Ebnas67VJx2ydA09UJ2gEDZ+bR7T7bOiP/zR CMxw== X-Received: by 10.13.251.66 with SMTP id l63mr7973972ywf.279.1447959179828; Thu, 19 Nov 2015 10:52:59 -0800 (PST) Received: from mtj.duckdns.org.com ([2620:10d:c091:200::f:9c1]) by smtp.googlemail.com with ESMTPSA id v127sm8775576ywd.53.2015.11.19.10.52.58 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 19 Nov 2015 10:52:59 -0800 (PST) From: Tejun Heo To: davem@davemloft.net, pablo@netfilter.org, kaber@trash.net, kadlec@blackhole.kfki.hu, lizefan@huawei.com, hannes@cmpxchg.org Cc: netdev@vger.kernel.org, netfilter-devel@vger.kernel.org, coreteam@netfilter.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, daniel@iogearbox.net, daniel.wagner@bmw-carit.de, nhorman@tuxdriver.com, Tejun Heo Subject: [PATCH 3/7] cgroup: implement cgroup_get_from_path() and expose cgroup_put() Date: Thu, 19 Nov 2015 13:52:47 -0500 Message-Id: <1447959171-20749-4-git-send-email-tj@kernel.org> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1447959171-20749-1-git-send-email-tj@kernel.org> References: <1447959171-20749-1-git-send-email-tj@kernel.org> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Implement cgroup_get_from_path() using kernfs_walk_and_get() which obtains a default hierarchy cgroup from its path. This will be used to allow cgroup path based matching from outside cgroup proper - e.g. networking and perf. v2: Add EXPORT_SYMBOL_GPL(cgroup_get_from_path). Signed-off-by: Tejun Heo --- include/linux/cgroup.h | 7 +++++++ kernel/cgroup.c | 39 ++++++++++++++++++++++++++++++++++----- 2 files changed, 41 insertions(+), 5 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index b5ee2c4..4c3ffab 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -81,6 +81,8 @@ struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgroup, struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry, struct cgroup_subsys *ss); +struct cgroup *cgroup_get_from_path(const char *path); + int cgroup_attach_task_all(struct task_struct *from, struct task_struct *); int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from); @@ -351,6 +353,11 @@ static inline void css_put_many(struct cgroup_subsys_state *css, unsigned int n) percpu_ref_put_many(&css->refcnt, n); } +static inline void cgroup_put(struct cgroup *cgrp) +{ + css_put(&cgrp->self); +} + /** * task_css_set_check - obtain a task's css_set with extra access conditions * @task: the task to obtain css_set for diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 3190040..3db5e8f 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -434,11 +434,6 @@ static bool cgroup_tryget(struct cgroup *cgrp) return css_tryget(&cgrp->self); } -static void cgroup_put(struct cgroup *cgrp) -{ - css_put(&cgrp->self); -} - struct cgroup_subsys_state *of_css(struct kernfs_open_file *of) { struct cgroup *cgrp = of->kn->parent->priv; @@ -5753,6 +5748,40 @@ struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss) return id > 0 ? idr_find(&ss->css_idr, id) : NULL; } +/** + * cgroup_get_from_path - lookup and get a cgroup from its default hierarchy path + * @path: path on the default hierarchy + * + * Find the cgroup at @path on the default hierarchy, increment its + * reference count and return it. Returns pointer to the found cgroup on + * success, ERR_PTR(-ENOENT) if @path doens't exist and ERR_PTR(-ENOTDIR) + * if @path points to a non-directory. + */ +struct cgroup *cgroup_get_from_path(const char *path) +{ + struct kernfs_node *kn; + struct cgroup *cgrp; + + mutex_lock(&cgroup_mutex); + + kn = kernfs_walk_and_get(cgrp_dfl_root.cgrp.kn, path); + if (kn) { + if (kernfs_type(kn) == KERNFS_DIR) { + cgrp = kn->priv; + cgroup_get(cgrp); + } else { + cgrp = ERR_PTR(-ENOTDIR); + } + kernfs_put(kn); + } else { + cgrp = ERR_PTR(-ENOENT); + } + + mutex_unlock(&cgroup_mutex); + return cgrp; +} +EXPORT_SYMBOL_GPL(cgroup_get_from_path); + #ifdef CONFIG_CGROUP_DEBUG static struct cgroup_subsys_state * debug_css_alloc(struct cgroup_subsys_state *parent_css)